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OISHI SatoruResearch Center for Urban Safety and SecurityProfessor
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■ Paper- ABSTRACT Debris‐flow affected area is typically predicted using runout simulations, often estimating the hydrograph from rainfall conditions. However, rainfall is rarely considered when predicting initiation locations, which influence the occurrence number and location. This study proposes a hybrid method combining statistical source‐location prediction based on rainfall conditions and runout simulations inputting the predicted source locations. First, logistic regression is used to predict the spatial probability of debris‐flow initiation with rainfall as an input. Next, Monte Carlo simulation based on the initiation location generated from the rainfall‐based probability yields the spatial distribution of the debris‐flow hit probability. Simulation parameters are systematically determined in advance based on topographic change obtained via aerial LiDAR observations. This method was successfully employed to estimate the spatial distribution of the debris‐flow hit probability at 1‐m resolution for a debris‐flow disaster that occurred in Hiroshima prefecture, Japan, using rainfall data obtained by radar. The simulation time indicated that hit probability can be issued prior to the event for early warning, owing to the adequate lead time of rainfall forecasts and recent developments in computational technology. The hit probability obtained in this study can be also applied to risk quantification based on rainfall conditions.Wiley, Feb. 2025, Journal of Flood Risk Management, 18(1) (1), English[Refereed]Scientific journal
- IEEE, Jul. 2023, IGARSS 2023 - 2023 IEEE International Geoscience and Remote Sensing Symposium, 1154 - 1157, English[Refereed]International conference proceedings
- University of the Aegean, Feb. 2023, Global NEST: the international Journal, 25(5) (5), 136 - 146
<p>For decades, climate models have been used to understand the present and historical climates, especially global climate models (GCMs). They are used to understand the interaction between climate system processes and forecast future climates. However, the issue of low resolution and accuracy often lead to inadequacy in capturing the variations in climate variables related to impact assessment. In order to capture the local climate changes in Hyogo Prefecture of Western Japan, a local climate modelling based on Second Generation Canadian Earth System Model (CanESM2) was applied using the statistical downscaling technique. Representative Concentration Pathway (RCP) 4.5 and 8.5 scenario were used in generating future climate models. The reliability of models was tested with Linear Regression, Pearson correlation, and Cronbach Alpha. Moderate relationship between rainfall data and both RCP scenarios was found in all chosen stations. Spatial analysis outcome showed that there is a possibility of increase in annual rainfall in Hyogo prefecture, where the increase is significant in Northern region. There is a possibility of increase in maximum and minimum temperature in four selected stations due to the increase of greenhouse gas emissions.</p>
[Refereed]Scientific journal - 2023, Atmospheric Science Letters, 24(6) (6)[Refereed]Scientific journal
- Pyroclastic density currents are one of the deadliest hazards produced by a volcano. Understanding their dynamics and generation mechanisms is critical for developing better hazard mitigation strategies. This study presents a method for retrieving velocity profiles across a natural moving PDC, applied here to a PDC generated by collapsing column during the eruption of Sinabung Volcano, Indonesia, on 19 February 2018 at the onset time of 08:53. We used an operational dual Pulse Repetition Frequency (PRF) weather radar, located ~7.8 km to the SE of the volcano, to estimate the velocity profile components of the volcanic plume: updraft, fallout, and horizontal advection. Doppler radar data was post-processed by applying two different filters: median and Laplacian, to correct errors associated with dealiased Doppler velocities. The Laplacian filter method was more effective in correcting the dealiasing errors by producing a more continuous velocity field without over smoothing its values. Following the dealiasing process, the velocity profile components were retrieved according to radar parameters such as Doppler velocities, copolar correlation, and reflectivity intensity factor. Initially, the pyroclastic clast was released at a lower exit velocity of ~120 m/s (84 s after the onset). A maximum of ~190 m/s exit velocity was then observed at 08:57:52 (292 s after onset). Lower exit velocity in the initial phase and less than 10 m/s estimated wind speed are the main factors causing the partial collapse of the plume at ~2.5 km height above the vent. The part of the collapsing column was associated with a more than 50 dBZ reflectivity intensity factor of fallout velocity exceeding −50 m/s at 126 s after the onset. Dilute PDCs were observed until 09:09:34 (994 s after onset), moving downslope at SE sector at a maximum velocity of −84 m/s (i.e., in the direction of the radar). The extracted velocity components are essential parameters in the numerical model of PDCs and tephra dispersal, enforcing the benefit of weather radar to complement the remote monitoring system of volcanic hazards.Apr. 2022, Journal of Volcanology and Geothermal Research, 424[Refereed]Scientific journal
- Predicting Flood Inundation Depth Based-on Machine Learning and Numerical SimulationRecent advances in earth observation and machine learning have enabled rapid estimation of flooded areas following catastrophic events such as torrential rains and riverbank overflows. However, estimating the actual inundation depth remains a challenge since it often requires detailed numerical simulation. This paper presents a methodology for predicting the inundation from remote sensing derived information by coupling deep learning and numerical simulation. We generate a large dataset of flood depth inundations considering several heavy rain conditions in four independent target areas. We propose a CNN-based regression framework. Our experiment demonstrates that our methodology can predict inundation depth on a separate target area not included during training, demonstrating great generalization ability.2022, CEUR Workshop Proceedings, 3207, 58 - 64International conference proceedings
- We propose a framework that estimates the inundation depth (maximum water level) and debris-flow-induced topographic deformation from remote sensing imagery by integrating deep learning and numerical simulation. A water and debris-flow simulator generates training data for various artificial disaster scenarios. We show that regression models based on Attention U-Net and LinkNet architectures trained on such synthetic data can predict the maximum water level and topographic deformation from a remote sensing-derived change detection map and a digital elevation model. The proposed framework has an inpainting capability, thus mitigating the false negatives that are inevitable in remote sensing image analysis. Our framework breaks limits of remote sensing and enables rapid estimation of inundation depth and topographic deformation, essential information for emergency response, including rescue and relief activities. We conduct experiments with both synthetic and real data for two disaster events that caused simultaneous flooding and debris flows and demonstrate the effectiveness of our approach quantitatively and qualitatively. Our code and data sets are available at https://github.com/nyokoya/dlsim.IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2022, IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, 60, English[Refereed]Scientific journal
- There have been attempts to improve the operational efficiency of construction projects and plan response countermeasures for estimated damage following disasters through the utilization of accumulated electronic data, which constructs a digital twin that can reproduce a physical space in cyberspace and feedback the cyberspace simulation results to physical space. However, the application of such simulations is limited, unless numerical models can be automatically constructed from the data. In this study, we develop a program that utilizes a data processing platform to read, transform, and integrate data to create mediated data with a common data structure. This mediated data can be used to construct analytical models for various numerical analyses. Using the program developed, a grid model of 3-D ground surface as the mediated data was constructed based on borehole data obtained through a ground survey. Each grid point has basic material parameters of soil, and these parameters are estimated from borehole data and other investigation reports. Each grid point has general geotechnical parameters and can be easily converted to a 3-D finite-element model. When the borehole data is added or changed, the analytical model can be updated with almost no cost, whereas it would be very costly to create the model manually.IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, Dec. 2021, IEEE-ASME TRANSACTIONS ON MECHATRONICS, 26(6) (6), 2881 - 2887, English[Refereed]Scientific journal
- Predictive simulation of concurrent debris flows using only pre-disaster information has been difficult, partly because of problems faced in predicting debris-flow initiation locations (i.e., slope failure). However, because catchment topography has convergent characteristics with all channels in it joining each other as they flow downstream, damage to downstream areas could be predicted using relatively inaccurate initiation points. Based on this hypothesis, this study uses debris-flow initiation points generated randomly with statistical slope failure prediction and performs a many-case simulation across numerous initiation points to quantify the effect of slope-failure locations in terms of deviations in the predicted water level and topographic change. This paper presents the results of 2D simulations based on a conventional debris-flow model that was run on a supercomputer to realise simulations of many cases. The obtained relative standard deviation was found to decrease as the debris flow and sediment-laden flood approached the downstream area, indicating that the predictability of the inundation and topographic change can be decided from the terrain characteristics.WILEY, Nov. 2021, JOURNAL OF FLOOD RISK MANAGEMENT, English[Refereed]Scientific journal
- Earthquake induced liquefaction is one of the main geo-disasters threating urban regions, which not only causes direct damages to buildings, but also delays both real-time disaster relief actions and reconstruction activities. It is thus important to assess liquefaction hazard of urban regions effectively and efficiently for disaster prevention and mitigation. Conventional assessment approaches rely on engineering indices such as the factor of safety (FS) against liquefaction, which cannot take into account directly the uncertainties of soils. In contrast, a physics simulation-based approach, by solving soil dynamics problems coupled with excess pore water pressure (EPWP) it is possible to model the uncertainties directly via Monte Carlo simulations. In this study, we demonstrate the capability of such an approach for assessing an urban region with over 10 000 sites. The permeability parameters are assumed to follow a base-10-lognormal distribution among 100 model analyses for each site. A dynamic simulation is conducted for each model analysis to obtain the EPWP results. Based on over 1 million EPWP analysis models, we obtained a probabilistic liquefaction assessment. Empowered by high performance computing, we present for the first time a probabilistic liquefaction hazard assessment for urban regions based on dynamics analysis, which consider soil uncertainties.CHINA UNIV GEOSCIENCES, WUHAN, Oct. 2021, JOURNAL OF EARTH SCIENCE, 32(5) (5), 1129 - 1138, English[Refereed]Scientific journal
- Elsevier BV, Nov. 2020, Journal of Volcanology and Geothermal Research, 405, 107040 - 107040[Refereed]Scientific journal
- © Published under licence by IOP Publishing Ltd. Since 2015, collaborative research conducted by Indonesian and Japan scientists has initiated the installation of small X-band Multi-Parameter (X-MP) radars to mitigate the occurrence of rainfall-induced lahar in three active volcanoes in Indonesia and Japan: Merapi, Sinabung, and Sakurajima. This paper discusses the technical aspects of data acquisition, processing, and performance of the X-MP radar at the Merapi and Sakurajima volcanoes by comparing the estimated rainfall intensity acquired by the radar to three empirical radar-rainfall algorithms. The algorithms are based on radar reflectivity factor (ZHH), specific differential phase shift (KDP), and differential reflectivity (ZDR). A new method of Constant Altitude Plan Position Indicator (CAPPI) interpolation by linear regression is also proposed for a more efficient computation. The first algorithm by Marshall-Palmer, which relies on ZHH, gave the lowest average and maximum rainfall values compared with the other algorithms for all rainfall event cases. On the other hand, the other two algorithms, which involve the MP of radar by Bringi and Chandrasekar and Park et al., gave closer rainfall intensity values with the estimated rainfall intensity acquired by the X-MP radar. These three rain rates give a closer temporal fluctuation when they are compared to the rain gauge-based rainfall intensity.Feb. 2020, IOP Conference Series: Earth and Environmental Science, 437(1) (1)[Refereed]International conference proceedings
- © Published under licence by IOP Publishing Ltd. The aim of this study is to develop lahar hazard vulnerability as a warning system by introducing radar-rainfall observation to data mining technique of Naïve Bayes Classifier (NBC). NBC is used to estimate lahar occurrences based on the posterior probability of rainfall, topographic factor, soil moisture, and soil type as predictors. Rainfall intensity and working rainfall were obtained from a weather radar. The soil moisture is derived from SMAP satellite imagery. A river on Mount Merapi, a very active volcano in Indonesia, was selected as the target basin. Observed rainfall and recorded lahar events in Gendol River from October 2016 to February 2018 were divided into a training dataset and a testing dataset. Qualitative evaluation through visual assessment of the hazard map product reveals that the model could estimate the occurrences of lahar. The performance of the model in terms of accuracy, Brier score, and quantitative dichotomous quality indices showed a reasonable skill. The study suggests that the NBC technique is advantageous for estimating lahar occurrences that are displayed on hazard maps. This work is expected to contribute to debris flow hazard mitigation by the data mining approach in volcanic regions.Feb. 2020, IOP Conference Series: Earth and Environmental Science, 437(1) (1)[Refereed]International conference proceedings
- Last, 2020, International Journal of Disaster Risk Science, 11(6) (6), English[Refereed]Scientific journal
- Performance of a small-compact X-MP radar to monitor extreme rainfall event on 7 July 2018Japan experienced a breaking-record rainfall event from Western Japan to the Tokai region from 28 June to 8 July 2018. This paper analyzes the peak rainfall of this event on 6-8 July 2018 in Kagoshima by a small-compact X-band Multi-Parameter (MP) radar. The aim of this paper is to know the reliability of the rain rate estimated by the radar during the extreme rainfall event. The estimated rain rate provided by the X-MP radar using an unknown algorithm (Furuno) is compared to three different radar algorithms based on radar reflectivity factor (ZH), specific differential phase shift (KDP), and differential reflectivity (ZDR). The estimated radar-based rain rate at 500m height is then compared to the ground-based rain measured by a rain gauge. The KDP-ZH -based rain algorithm gives the closest values to the unknown Furuno algorithm, which indicates the use of KDP parameter as the rain rate estimator. The spatial information of radar is able to monitor more than 250 mm rain depth, which cannot be obtained by the rain gauge. In general, the point-based comparison between hourly radar-based rain rate and ground-based rain rate shows a similar temporal fluctuation, but in general, most of the values on 7 July 2018 fall below the rain gauge measurement. The estimated Furuno rain rate and the ZHHKDP -based algorithm gives the closest values to the increase of ground-based rain depth at 1:0.94 and 1:0.89 ratios, respectively, while the ZHH-ZDR -based algorithm has the lowest ratio of 1:0.79.2020, 22nd Congress of the International Association for Hydro-Environment Engineering and Research-Asia Pacific Division, IAHR-APD 2020: "Creating Resilience to Water-Related Challenges"International conference proceedings
- © 2019 Elsevier Ltd Through quantitative measurement of the accuracy and the convergence of error, code verification can objectively assess the quality of a simulation code. A lack of analytical benchmark solution for nonlinear problems makes it difficult to verify soil dynamics simulations in geotechnical engineering. To overcome such difficulty, this study makes use of a novel code verification technique, the method of numerically manufactured solutions (MNMS). By utilizing MNMS, the accuracy of a simulation code for nonlinear soil dynamics problems was measured. The orders of the convergence rate of the errors, with respect to the spatial and to the temporal discretization, were found to be in good agreement with the theoretical orders of the numerical methods. By demonstrating the applicability of MNMS for verifying nonlinear soil dynamics simulations, it is hoped that the concept and the necessity of code verifications can be appreciated for simulations of geotechnical engineering problems.Jan. 2020, Computers and Geotechnics, 117[Refereed]Scientific journal
- Lead, Nov. 2019, 土木学会論文集, Ser. B1(水工学), Vol.75, No.2, I_1177-I_1182, 2019., 75(2) (2), I_1177 - I_1182, Japaneseビデオゾンデを用いた鉛直風速プロファイルの算出と雲物理的解析[Refereed]
- Last, Nov. 2019, Journal of Japan Society of Civil Engineers, Ser. B1(Hydraulic Engineering), Vol.75, No.2, I_1165-I_1170, 2019, 75(2) (2), I_1165 - I_1170, EnglishINVESTIGATION OF MULTIPARAMETER RADAR ERROR STRUCTURE FOR QPE BASED ON GPM DUAL-FREQUENCY PRECIPITATION RADAR[Refereed]Scientific journal
- © 2019 Elsevier B.V. Effective and efficient liquefaction hazard assessment is critical in making disaster mitigation plans for urban regions. In this paper, we present a numerical-simulation (NS)-based method for assessing urban-wide liquefaction hazard. The method includes an automatic modelling for individual sites and an application of high-performance computing (HPC) for efficient assessment. The feasibility of the method is demonstrated by conducting simulations for more than 10,000 individual sites in an urban region. The urban-wide assessment results depend on a pressure threshold of liquefaction occurrence and the dependence increases as the ground motion increases. A comparison with a conventional method using engineering indices (EI) shows a tendency of the EI-based method to predict a considerably greater number of liquefied sites than the proposed method. With the continuing improvement on numerical simulations and on computer efficiency, NS-based assessments can be regarded as promising alternatives to conventional EI-based methods for urban-wide liquefaction assessment.Aug. 2019, Engineering Geology, 258(14) (14), English[Refereed]Scientific journal
- © 2019, Fuji Technology Press. All rights reserved. Lahar flow is recognized as among the worst secondary hazards from volcanic disaster. Intense rainfall with long duration is frequently associated with lahar flow. In this study, estimation of a rainfall threshold likely to trigger lahar flow is presented in the first part. The second part discusses its implementation by assessing the growth of observed and predicted rainfall, including the uncertainties. The study area is Merapi Volcano, one of the most active volcanoes in Indonesia, including rivers on the flank of Mount Merapi that are vulnerable to debris flow. The rainfall indices needed to describe the conditions that generate lahars or not were determined empirically by evaluating the hourly and working rainfall using X-band multiparameter (X-MP) weather radar. Using past records of lahar flow, the threshold lines separating rainfall that triggers lahars or not were analyzed for the Putih, Gendol, Pabelan, and Krasak Rivers. The performance of several critical lines was evaluated using Bayesian probability based on skill rates from a contingency matrix. The study shows that the line intercept of the critical lines after a significant eruption in 2010 was higher than those lines developed before 2010, indicating that the rivers are currently at lesser risk. Good representation was shown by the thresholds verified with actual rainfall progression and lahar event information on February 17, 2016, at the Gendol and Pabelan Rivers. These rainfall critical lines were the basis for judging the debris flow occurrence by analyzing the track record of predicted rainfall progression. The uncertainty of rainfall short-term prediction from the extrapolation model was evaluated by perturbing the advection vector of rain echo motion. This ensemble forecast product could provide a plausible range of prediction possibility as assistance in gaining the confidence with which a lahar could be predicted. The scheme presented herein could serve as a useful tool for a lahar early warning system in the area of the Merapi Volcano.Aug. 2019, Journal of Disaster Research, 14(5) (5), 811 - 828[Refereed]Scientific journal
- © 2019, Fuji Technology Press. All rights reserved. This paper reports a preliminary attempt to determine volcanic ash particle size distribution using the video drop size detector (VDSD) for estimating volcanic ash amount with X-band radar. The VDSD records an image showing the size and number of particles falling into the aperture by a charge coupled device camera. Size distribution spectra of a range of particles from fine ash to small lapilli were derived in discrete form from the VDSD observation. The parameterization of the particle size distribution following Gamma function was done using volcanic ash of eruptions at the Sakurajima Volcano between December 13-21, 2014. Three Gamma distribution parameters were determined analytically. The analytical results revealed a continuous distribution of particles characterized by shape, intercept, and slope. The distribution was used to determine volcanic mass concentration, ground deposit weight, and reflectivity. Verification of these results with X-band radar observations showed that the reflectivity obtained from analytical results is similar to that fromradar observation. However, the ground deposit weight from analysis was overestimated, compared with the real weight of ash deposit on the ground. The algorithm proposed in this study is expected to provide a practical method for estimating ash distribution in the aftermath of a volcanic eruption using radar-reflectivity for cases where direct measurement at the location is not possible. An overview of the algorithm for volcanic ash retrieval from X-band radar observations is also presented.Feb. 2019, Journal of Disaster Research, 14(1) (1), 151 - 159[Refereed]Scientific journal
- National Committee for IUTAM, 2019, NCTAM papers, National Congress of Theoretical and Applied Mechanics, Japan, 65, 233 - 233, Japanese
A lack of analytical benchmark solution makes it difficult to verify soil dynamics simulations of nonlinear geotechnical problems. This study makes use of a novel code verification technique, the method of numerically manufactured solutions (MNMS), to overcome such difficulty. Using MNMS, the accuracy of a nonlinear soil dynamics simulation code based on finite element method (FEM) is verified. The orders of the convergence rate of the relative errors with respect to the discretization size are found to be in good agreement with the theoretical values prescribed by the numerical methods.
- © 2019, Fuji Technology Press. All rights reserved. This paper presents a theoretical method for estimating volcanic ash fall rate from the eruption of Sinabung Volcano on February 19, 2018 using an X-band multi-parameter radar (X-MP radar). The X-MP radar was run in a sectoral range height indicator (SRHI) scan mode for 6◦ angular range (azimuth of 221◦ –226◦) and at an elevation angle of 7◦ to 40◦ angular range. The distance of the radar is approximately 8 km in the Southeastern direction of the vent of Mount Sinabung. Based on a three-dimensional (3-D) image of the radar reflectivity factor, the ash column height was established to be more than 7.7 km, and in-depth information on detectable tephra could be obtained. This paper aims to present the microphysical parameters of volcanic ash measured by X-MP radar, which are the tephra concentration and the fall-out rate. These parameters were calculated in a two-step stepwise approach microphysical model using the scaled gamma distribution. The first step was ash classification based on a set of training data on synthetic ash and its estimated reflectivity factor. Using a naïve Bayesian classification, the measured reflectivity factors from the eruption were classified into the classification model. The second step was estimating the volcanic ash concentration and the fall-out rate by power-law function. The model estimated a maximum of approximately 12.9 g·m−3 of ash concentration from the coarse ash class (mean diameter Dn = 0.1 mm) and a minimum of approximately 0.8 megatons of volcanic ash mass accumulation from the eruption.2019, Journal of Disaster Research, 14(1) (1), 135 - 150[Refereed]Scientific journal
- © 2019, Fuji Technology Press. All rights reserved. Rainfall monitoring is important for providing early warning of lahar flow around Mt. Merapi. The X-band multi-parameter radar developed to support these warning systems provides rainfall information with high spatial and temporal resolution. However, this method underestimates the rainfall compared with rain gauge measurements. Herein, we performed conditional radar-rain gauge merging to obtain the optimal rainfall value distribution. By using the cokriging interpolation method, kriged gauge rainfall, and kriged radar rainfall data were obtained, which were then combined with radar rainfall data to yield the adjusted spatial rainfall. Radar-rain gauge conditional merging with cokriging interpolation provided reasonably well-adjusted spatial rainfall pattern.2019, Journal of Disaster Research, 14(1) (1), 69 - 79[Refereed]Scientific journal
- Oct. 2018, 京都大学防災研究所年報, 61(A) (A), 5 - 23, Japanese火山噴出物の放出に伴う災害の軽減に関する総合的研究[Invited]Research institution
- © The Authors, published by EDP Sciences, 2018. The integral porosity shallow water model is a type of porous shallow water model for urban flood modeling, that defines two types of porosity, namely a volumetric porosity inside the computational cell and a conveyance porosity at each edge. Porosity terms are determined directly from the underlying building geometry, hence buildings do not need to be discretized exactly. This enables simulations with significantly reduced CPU time on meshes with cell sizes larger than the building size. Here, the macroscopic model view leads to an additional source term at the unresolved building-fluid interface, yielding a building drag dissipation source term. In literature, several formulations for this term can be found. The integral porosity shallow water model is sensitive to the building drag dissipation, and using the drag parameters as a calibration parameter enhances the accuracy of model results. However, the ideal way to achieve this is still an open research question. In this contribution, we present a simple technique to estimate building drag dissipation that uses the conveyance porosity configuration to estimate the projected area inside the cell, which is then used in a drag force equation. The advantage of this approach is that it is computationally inexpensive, no additional parameters need to be stored, and only a single parameter has to be calibrated. The proposed approach is compared with drag dissipation formulations from existing literature in a laboratory experiment that features a dam-break against an isolated obstacle. The aim of the comparison is to evaluate present existing building drag dissipation models with regard to accuracy and computational cost.Sep. 2018, E3S Web of Conferences, 40[Refereed]International conference proceedings
- © The Authors, published by EDP Sciences, 2018. After three hours of intense rainfall, the city of Nice was flash flooded on October 3, 2015, resulting in casualties and severe damages in property. This study presents a porous shallow water-model based numerical simulation of the flash flood event in a district of Nice, and compares the results with a high-resolution conventional shallow water model. This contribution aims to discuss practical aspects of applying a porous shallow water model to a real world case. The porous shallow water model is an integral porosity-type shallow water model. It uses unstructured triangular meshes. The conventional shallow water model is a distributed memory parallelized high-performance computing code, that uses a uniform Cartesian grid. The study site is an approximately 5 km2 spanning district of the city of Nice, France. Topography information is available in a 1m resolution and in addition, the available digital elevation model includes inframetric structures such as walls and small bridges. In the presentation of the case study, challenges of the pre-processing step of the integral porosity shallow water model are addressed. Notably, a method to semi-automatically generate "good" triangular meshes using the open-source geoinformation system QGIS and the mesh generator Gmsh is presented. During the post-processing step, the results of the porous model are mapped back onto the high-resolution topography to make the results more meaningful. The agreement between the high-resolution reference solution and the porous model results are poor. A speed up of about 10 to 15 was observed for the present case.Sep. 2018, E3S Web of Conferences, 40[Refereed]International conference proceedings
- Effects of spatio-temporal variations of gauges and radar rainfall observations on runoff simulation© Proceeding of the 21st LAHR-APD Congress 2018. All rights reserved. X-band weather radar has considerable potential for its fine spatio-temporal resolution which is significant in the hydrological simulation. In this study, we evaluate the distribution variability of precipitation observation from X-band radar and network rain gauges in Upper Konto River Basin Indonesia which is originated from Kelud volcano. The rainfall spatial representativeness and the temporal variability of X-band radar vs. nine rain stations are compared during the observation campaign in the rainy season of February 2017. The evaluation of spatial distribution characteristic uses Kagan interpolation method in minute scale, hourly, and daily total volume of precipitation. In order to study the impact on the catchment size, the outlet of the basin in Selorejo Reservoir (235.58 km2) is used. Performance of the BTOPMC physically distributed hydrological model using 150 m resolution radar-rain was evaluated over that of using lower resolution from rain gauges. The analysis reveals that widely spread gauges give lower spatial correlation and larger error for the smaller scale of time. The advantages of X-band observation for detecting the variation of rainfall in the small area leads to better reproducibility of flood simulation, shown by RMSE of 9.85 and 7.78 m3/s for rain gauge and radar respectively. It means the radar-rainfall input could give better reproducibility of runoff simulation. It is proven that the radar provides better representativeness of rainfall spatial and temporal variation for operational runoff simulation. which is important for daily as well as seasonal reservoir operations.Sep. 2018, Proceedings - International Association for Hydro-Environment Engineering and Research (IAHR)-Asia Pacific Division (APD) Congress: Multi-Perspective Water for Sustainable Development, IAHR-APD 2018, 2, 1285 - 1293[Refereed]International conference proceedings
- Statistical properties of short-term rainfall time series as observed by XMP radar (Case of Mt. Merapi area)© Proceeding of the 21st LAHR-APD Congress 2018. All rights reserved. Flood warning systems have become increasingly necessary to reduce hazard risk, especially lahar flow disaster. An effective lahar flow early warning system should provide information timely, thus allowing sufficient waiting time to respond. As an input to the lahar flow early warning systems, short-term rainfall information derived from a rainfall nowcasting model is needed. To select an appropriate nowcasting method, determining the patterns of historical data through its statistical properties is necessary. Some analyses of historical data can be used to find the trends that are further extrapolated forward. This study aims to analyze the statistical properties of short-term rainfall time series in the area of Mt. Merapi in order to find historical data patterns. The statistical properties of short-term rainfall time series were investigated through autocorrelation and spectral analyses. Several rainfall data with 2-minutes and 10-minutes time interval obtained from XMP Radar estimation have been adopted to determine the autocorrelation coefficient and spectral density. Collerogram was used to evaluate the characteristics of autocorrelation coefficients. The results show that there is high autocorrelation coefficient variability between locations within the radar coverage area, and no time lag between XMP radar rainfall and rain gauge rainfall for 10-minutes time-scale.Sep. 2018, Proceedings - International Association for Hydro-Environment Engineering and Research (IAHR)-Asia Pacific Division (APD) Congress: Multi-Perspective Water for Sustainable Development, IAHR-APD 2018, 2, 1317 - 1324[Refereed]International conference proceedings
- 神戸大学都市安全研究センター, Mar. 2018, 神戸大学都市安全研究センター研究報告, 22, 75 - 87, Japanese
- 2018, 自然災害科学, 37(3) (3), 295 - 311, Japanese単一のXバンドMPレーダーとCバンドレーダーを活用した山地域における土砂災害危険度推定[Refereed]Scientific journal
- Japan Society of Civil Engineers, 2018, Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering), 74(5) (5), I_889 - I_894, Japanese
Estimation of a damage of sediment-related disaster accompanied with flood, inundation, and sediment supply due to landslides is important to establish a prevention plan and/or evaluate the risk of them. In this study, we have developed a 2D Distributed Rainfall and Sediment Runoff/Inundation Simulator (:DRSRIS) with coupling the 2d rainfall runoff model, inundation flow model, and sediment transport model on the staggered grid which performs on the supercomputer. The model was applied to Haki area, Fukuoka Pref., Japan, where the Kyu-shu heavy rainfall in 2017 took place based on the sediment supply distribution estimated from the actual landslide data. The calculated sediment transport volume was underestimated, however, the calculated results almost corresponded to the inundated area obtained from the survey.
[Refereed]Scientific journal - 2018, Journal of Japan Society of Civil Engineers, Ser. B1(Hydraulic Engineering), 74(4) (4), JapaneseA STUDY ON COLLECTION EFFICIENCY OF RAINDROPS CAPTURED BY VIDEOSONDES IN CLOUDS[Refereed]Scientific journal
- 2018, Journal of Japan Society of Civil Engineers, Ser. B1(Hydraulic Engineering), 74(4) (4), EnglishSPATIOTEMPORALDISTRIBUTION OF RAINFALL IN MOUNT SAKURAJIMA BASED ON WEATHER RADAR[Refereed]Scientific journal
- 2018, Journal of Japan Society of Civil Engineers, Ser. B1(Hydraulic Engineering), 74(4) (4), EnglishREAL-TIME RADAR QUANTITATIVE PRECIPITATION ESTIMATION USING MULTIVARIATE PROJECTION MODEL[Refereed]Scientific journal
- © The Author(s) 2018. To elucidate the formation of localized rainfall in a basin with heat and aridity under a weak synoptic disturbance in summer, we described the characteristics of atmospheric conditions on the Kofu Basin preceding the appearance of primary precipitating cells from 23 localized rainfall events on the Kofu Basin on days of weak synoptic disturbance at the surface from 1 June to 30 September in 2012 to 2014. Furthermore, on the basis of a case study of an event on 25 July 2014, the formation of the atmospheric conditions was described from the standpoint of moisture behavior. Owing to the thermal contrast between the Kofu Basin with heat and aridity and the outside environment, the south-component wind blowing in the valley connecting to the coastal region of Suruga Bay and the eastcomponent wind blowing in the valley connecting to the Kanto Plain entered the basin as southwesterly wind and southeasterly wind, respectively, which caused an increase in the water vapor mixing ratio and a slight decrease in temperature at the surface. Thereafter, the amount of precipitable water vapor derived from the global navigation satellite system observations (GNSS-PWV) in the central region of the Kofu Basin increased abruptly after the moderate increase in GNSS-PWV at all the observation points in the basin. Finally, a cloud appeared over the local region between the southwesterly wind and the southeasterly wind and precipitating cells appeared at that location at 3.25 to 6.25 km above sea level. We discussed the moisture transport into the Kofu Basin, the concentration of that moisture in a local region, and the appearance of precipitating cells. This is an example of the formation of atmospheric conditions leading to localized rainfall in a basin with heat and aridity.2018, Journal of the Meteorological Society of Japan, 96A(A) (A), 95 - 117, English[Refereed]Scientific journal
- 2018, Journal of Japan Society of Civil Engineers, Ser. B1(Hydraulic Engineering), 74(4) (4), I_1483 - I_1488, EnglishEMPIRICAL MODEL FOR REMOTE MONITORING OF RAIN-TRIGGERED LAHAR IN MOUNT MERAPI[Refereed]Scientific journal
- This paper presents an improvement of a mathematical interpretation of moving particle semi-implicit (MPS) method. The mathematical interpretation leads to a mathematical reformulation of MPS (MRMPS) based on Taylor expansions. The improvement of MRMPS in this paper is featured by solving a system of 9 × 9 (or 5 × 5 for two dimensional settings) equations for the gradient vector and for all the components of the Hessian matrix. Numerical experiments with various types of target functions showed that the improved MRMPS possesses a second-order convergence rate for the relative error of the gradient and a first-order convergence rate for the relative error of the Laplacian, in three-dimensional settings with randomly distributed neighboring particles. Moreover, there is no deterioration of accuracy for realistic particle configurations near free surfaces, where the neighboring particles are distributed not only randomly but also one-sided. Further, the aforementioned accuracy of the improved MRMPS can be obtained by using about 40 to 50 neighboring particles considerably less than conventional particle methods. A simplification for the improved MRMPS is also presented with less computational complexity, solving two 3 × 3 systems instead of one 9 × 9 system, at the cost of losing one order of convergence rate of error.Japan Society of Civil Engineers, 2018, Journal of Japan Society of Civil Engineers, Ser. A2 (Applied Mechanics (AM)), 74(2) (2), I_167 - I_178, Japanese[Refereed]Scientific journal
- © 2017 Elsevier Ltd After the 2010 eruption, more than 50 volcanic debris flow (lahar) events occurred during the rainy season of 2010–2011 at Mount Merapi, Indonesia. The lahars occurred following rainfall of severe intensity in the upstream area, where remaining volcanic material was deposited. Estimation of rainfall-induced lahars at Mt. Merapi is difficult and uncertain because the upstream area is dangerous and inaccessible. On 17 February 2016, a lahar occurred in the upstream region of the Gendol River on the southeastern flank of Mt. Merapi after a maximum rainfall intensity of 69 mm/h was monitored on the peak of Mt. Merapi by X-band multi-parameter (X-MP) radar. In this study, rainfall intensity estimates from X-MP radar were applied to generate boundary discharge of a numerical model of debris flow at the catchment scale. The numerical simulation was able to estimate volcanic debris flow occurrence and magnitude. The reliability of radar-rainfall data and the effects of the sabo dam on reducing the impacts of lahar disaster were also examined. The numerical lahar simulation showed relevant results that were comparable to the real condition. The closed type sabo dam caused more than 50% lahar sediment decrement and a flow delay time of 40 min. However, the sediment accumulation has caused increasing flow velocity and higher erosion rate in the 2D area. This study demonstrated the effectiveness of remote monitoring of rainfall combined with numerical debris flow modeling for applied practical use in disaster management.Dec. 2017, Advances in Water Resources, 110, 249 - 262[Refereed]Scientific journal
- Jul. 2017, Proceedings of The 3rd International Conference on Science and Technology, EnglishRain behavior at Mt. Merapi area as observed by XMPR and ARR[Refereed]International conference proceedings
- 土木学会, Mar. 2017, 土木学会論文集B1（水工学）, 73(4) (4), I_229 - I_234, Japanese[Refereed]Scientific journal
- 直接観測機器を用いた雲内部の雨滴粒径分布の把握は，雲物理と降水特性の理解や，リモートセンシングを用いた降雨量推定精度の向上として重要である．気球搭載型でありCCDカメラを備えたビデオゾンデは航空機観測よりも安全性が高いが，粒径クラスごとの観測個数が1個や2個の場合があり，ビデオゾンデで得られる粒子のサンプル数が粒径分布の推定精度に与える影響が懸念される．本研究は，ビデオゾンデ観測から得られた粒径分布とサンプル数の定量的な評価を行うことを目的とする．まず，乱数を発生させた数値実験より，ビデオゾンデのサンプル数と粒径分布パラメータの推定精度の関係を調査した．さらに，ビデオゾンデで推定された粒径分布から計算されたレーダー反射因子Zとディスドロメータから計算されたZを比較した．ビデオゾンデで4分間に70個以上の雨滴が観測された場合，300回の数値実験のうち64%以上で粒径分布の傾きパラメータを推定できていた．6事例中4事例の実際の粒径分布の推定事例において，ビデオゾンデで推定された粒径分布から計算されたZは，2.9dBZ以下の誤差の範囲内でZを推定できた．THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, 2017, Proceeding of Annual Conference, 30, 26 - 26, Japanese
- Many scientific and engineering problems, including soil dynamics problems with elasto-plasticity, are involved in solving partial differential equations numerically. The correctness and accuracy of the solutions have to be checked in a rigorous way, i.e., the code used to solve the problems has to be verified. In the field of fluid dynamics, the method of manufactured solutions (MMS) has been proposed and accepted as a de facto standard for code verification. However, we show in this paper that MMS procedures cannot be used directly for soil dynamics problems considering elasto-plasticity. The main difficulty is due to the soil elasto-plasticity which is generally formulated in a rate form coupled by an algebraic constraint (the yield surface). Instead, we propose the method of numerically manufactured solutions (MNMS) for verifying elasto-plastic problems. The concepts and the workflows of MNMS are explained in detail and two simple demonstrations are presented. Though the numerical demonstrations in the present paper are primitive, the capability of the proposed MNMS, as a general and systematic way for developers and users of numerical simulations to verify their codes being used, should not be underestimated.Japan Society of Civil Engineers, 2017, Journal of Japan Society of Civil Engineers, Ser. A2 (Applied Mechanics (AM)), 73(2) (2), I_165 - I_175, Japanese[Refereed]Scientific journal
- The present study describes estimation of charge and electric field based on the precipitation particle distribution measurement in thundercloud. An X band multi parameter (MP-X) radar and a multi LF sensor network (BOLT) as lightning detectors were used. Polarization parameters obtained from MP-X radar were used to perform the precipitation particle distinction. Distinguished particle distribution from the polarization parameters including graupel gives particle size distribution, and electric charge amount in the collision of graupel and ice crystals. By solving the Poisson equation with charge amount obtained, the electric potential and the electric field have been calculated.Japan Society of Civil Engineers, Mar. 2016, 土木学会論文集B1（水工学）, 72(4) (4), I_1247 - I_252, Japanese
In fact, the present study shows possibility to predict lightning by using MP-X radar through calculating charge and electric field in real time.[Refereed]Scientific journal - Japan Society of Civil Engineers, Mar. 2016, 土木学会論文集B1（水工学）, 72(4) (4), I_1237 - I_1242, Japanese[Refereed]Scientific journal
- 土木学会, Mar. 2016, Journal of Japan Society of Civil Engineers, Ser. B1(Hydraulic Engineering), 72(4) (4), I_865 - I_870, English[Refereed]Scientific journal
- Japan Society of Civil Engineers, Mar. 2016, Journal of Japan Society of Civil Engineers, 72(4) (4), I_865 - I_870, English[Refereed]Scientific journal
- Disaster Prevention Research Institute, Kyoto University, Feb. 2016, 京都大学防災研究所年報第58号B, (58) (58), 232 - 236, Japanese積乱雲の生成・発達を捉えるためのマルチセンサーによるRHI同期観測実験Research institution
- Disaster Prevention Research Institute, Kyoto University, Feb. 2016, 京都大学防災研究所年報第58号B, (58) (58), 294 - 304, JapaneseGNSS による湾上および山岳域における水蒸気分布と豪雨に関する研究Research institution
- This thesis describes a method to estimate particle size distribution and volume of ice particles in freezing layer using polarimetric radar. The method lead us to predict precipitation earlier than existing weather forecast. The method in this research assumes ice particles in freezing layer as ice crystals having forms of flat spheroid. Through this research, size distribution can be well estimated by using polarimetric parameter of radar. However, radar reflectivity having smaller than 20dBZ gave worse estimation of size distribution. Therefore, necessity to change the formula used in the analysis or the constants such as the dielectric constant under the condition has been proposed. In addition, it was also found that it is necessary to address the uncertainty of the videosonde for verifying the results of the radar.THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, 2016, Proceeding of Annual Conference, 29, 72 - 72, Japanese
- The Volcanological Society of Japan, 2016, PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN, 2016, 65 - 65, Japanese
- © 2017 Springer Science+Business Media Singapore. Flood control is one of the most important issues of reservoir operation. Rivers in island countries like Japan, the Philippines, and Indonesia that have smaller reservoirs than continental countries need short-term reservoir operation for flood control. In Japan, typhoons give dominant amount of water to reservoirs. Prior releasing of water that makes effective use of the capacity of a reservoir requires the forecast of rainfall amount (hyetograph). Therefore, weather forecast of typhoons is indispensable for flood control. Oishi and Masuda (Study on optimization of the integrated dam operation using ensemble prediction in the upper reaches of the Nabari River. In: Proceedings of 35th IAHR world congress (IAHR), Chengdu, 2013) developed the reservoir control operation model using stochastic dynamic programming with one-week ensemble weather forecast. One-week ensemble forecast consists of 51 members, gives many kinds of weather variables including rainfall amount, and has a lead time of one week. In fact, the frequency of updating one-week ensemble forecast is a problem for using it. Therefore, a solution for the problem is proposed. For giving highly frequent updating, we propose to use typhoon ensemble forecast which issues four times a day, but it does not include rainfall amount. By using a similarity index with observed typhoon tracks and latest ensemble forecast result, a method to give reasonable typhoon ensemble forecasted rainfall amount has been developed. Showing the techniques and theories for managing water resources using advanced weather forecasting, we discuss about the possibility of adaptive countermeasure to manage the water resources by making the most of existing structure.IAHR, Jan. 2016, Sustainable Water Resources Planning and Management Under Climate Change, 133 - 154, English[Refereed]In book
- © 2015, Fuji Technology Press. All rights reserved. The present study shows the possibility of using Xband multi-parameter radar to detect volcanic tephra for estimating the amount of volcanic tephra in the air even when the amount of volcanic tephra is very low. The model proposed in this study can detect tephra with diameters of 0.5mmto 3 mm. Through the observation experiment and the model proposal, the present study shows successful detection of volcanic tephra in the air by using X-band multi-parameter radar.Fuji Technology Press, 2016, Journal of Disaster Research, 11(1) (1), 43 - 52, English[Refereed]Scientific journal
- An analysis of lightning mechanism by calculating the time variation of the electric field and the neutralization by discharge will be conducted. X-band poralimetric Dopplar radars and the lightning detection devices are used for the present study. An analysis is based on the theory of “Riming Electrification” in which contact between graupels and ice crystals give principal electrical charge in the atmosphere. We calculate the time variation of the electric field from the MP radar. During presentation, we will explain the results estimated by calculating the amount of charge possessed by graupels.THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, 2015, Proceeding of Annual Conference, 28, 100066, Japanese
- A large quantity of volcanic ash produced by the volcanic activity leads to the urban functions failure. In the surrounding area of the volcano, it caused the landslide disaster. In order to taking quick recover action from the disaster and to predict the landslide disaster, we need to know the distribution of the real-time volcanic ash volume. Now, meteorological radar is expected. We therefore studied the volcanic ash particle size distribution in Sakurajima by videosonde which improved for volcanic ash measurement. Then amount of volcanic ash has been estimated from radar reflectivity and volcanic ash particle size distribution. From the results of this study comparing the radar reflectivity factor of X-band MP radar with the observed value on the ground, we tried to define the relationship between them. As a result, only one biggest eruption during observation campaign gave a sample having good correlation between radar and videosonde.THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, 2015, Proceeding of Annual Conference, 28, 100119, Japanese
- We evaluated a method by which to fit gamma distributions with parameters of snowflake size distributions by measuring three physical quantities using an optical sensing disdrometer. The three physical quantities are the diameters of the snowflakes that have 50 and 99 percentiles of volumes (D50 and D99, respectively) and the sum of the sixth powers of the diameters in a unit volume (Z). Snowflake size distribution was well fitted to a gamma distribution between D50 and D99, inclusive. This method prevented the snowflake volume from being considerably underestimated. Although the mean absolute error based on snowflake volume for this method was large compared with that obtained using a moment method, good estimates of snowflake volume were obtained for some samples using this method, for which the snowflake size distribution was less influenced by snowflakes 1 mm or less in diameter. The correlation coefficient was 0.989, as determined by regression analysis based on the observed and estimated snowflake volumes using this method. The estimation of the snowflake volume using this method depends on the quality control of the optimum shape parameter and requires a continuous probability distribution of snowflakes for diameters above 1 mm.The Meteorological Society of Japan, 2015, Scientific Online Letters on the Atmosphere, 11, 134 - 137, English[Refereed]Scientific journal
- STUDY ON EFFICIENCY IMPROVEMENT OF TRAIN DISPATCH UNDER SEVERE RAINFALL BY USING RADARRecently, the frequency of severe rainfall increases in Japan. The average of annual frequency of severe rainfall which is defined as rainfall having more than 50mm within one hour has become increase from 168 times per year (TPY) during the year of 1976-1986 to 226 TPY during 1999-2010 (Japan Meteorological Agency, 2012). The increasing of frequency of severe rain raise risk of sediment related disaster and inundation disaster. Trains especially local train run on reclaimed land and mountainous area have risk of such disasters when severe rain might happen. Therefore, railway companies take many kinds of countermeasures. The present study deals with the dispatching problem under severe rainfall. Each train dispatching system has defined a threshold of rainfall amount where dispatchers stop trains or they command to reduce the speed of trains. A Japanese railway company has measured the rainfall amount by their own rain gauges that locate almost every 13km and it is very difficult to change the measurement system because the company has a historical rainfall data by which the threshold of rainfall amount has been defined. On the other hand, the company has an interest for introducing radar rainfall information for dispatching trains because of increasing of severe rainfall having small spatial scale and efficiency improvement for collecting rainfall data. Many railway companies have the similar contradiction. The present study shows a statistical analysis of the uncertainty to use radar for capturing severe rainfall by using probability function of difference between rainfall amount measured by rain gauge and one by radar.IAHR-INT ASSOC HYDRO-ENVIRONMENT ENGINEERING RESEARCH, 2015, PROCEEDINGS OF THE 36TH IAHR WORLD CONGRESS, 6706 - 6710, EnglishInternational conference proceedings
- PREDICTING INDONESIAN TROPICAL MONSOONAL RAINFALL IN WEST TIMOR WITH ARTIFICIAL NEURAL NETWORKSAccurate rainfall predictions, especially for tropical monsoonal rainfall, are among the most difficult tasks in hydrology. In this article, we discuss ANN-based long-term rainfall predictions for Oekabiti, West Timor, Indonesia. Due to the remoteness of the area, the only information available is historical rainfall data. However, by basing on previous studies into the time laJapan Society of Civil Engineering, Dec. 2014, Journal of Japan Society of Civil Engineering, Ser. B1 (Hydraulic Engineering),, 70, I_91 - 96, English[Refereed]Scientific journal
- A WIRELESS MESH SENSOR NETWORK FRAMEWORK FOR RIVER FLOOD DETECTION WHICH CAN BE USED AS AN EMERGENCY COMMUNICATIONS NETWORK IN CASE OF DISASTERThis study proposes an alternative network relatively simple and inexpensive that can be used for maintaining communications capabilities during major natural disasters and other emergency situations by introducing a system that utilizes Short Message Service (SMS) over Wireless Mesh Sensor Networks (WMSNs). To create this WMSN we propose a system using the water level sensors.IAHR, Aug. 2014, 11th International Conference on Hydroinformatics HIC 2014, 104, 284 - 284, English[Refereed]International conference proceedings
- In summer, localized heavy rainfall in a short time on Kofu Basin is caused by a cumulonimbus cloud. We analyzed the characteristics of distribution and preceding surface conditions of cumulonimbus clouds appeared on Kofu Basin using X-MP radar and surface observation data from July to September in 2012. The frequency of the cumulonimbus clouds appeared on Kofu Basin was low. However, the rainfall amount brought by such a cumulonimbus cloud was large. The first appearance of cumulonimbus clouds concentrated from east side to center of Kofu Basin. Before the appearance of a cumulonimbus cloud, south-southwesterly wind with warmish and moist air from the inlet of the valley on southwest side of Kofu Basin and southeasterly wind with warmish and semimoist air crossing the mountains on east side of Kofu Basin co-existed at surface on Kofu Basin with warm and low moist air. The winds formed the convergence and the airs formed the conditional instability on Kofu basin, which formed the environment of the appearance of a cumulonimbus cloud on Kofu Basin.土木学会, Feb. 2014, 土木学会論文集B1（水工学）, 70(4) (4), 889 - 894, Japanese[Refereed]Scientific journal
- An analysis for obtaining mechanism of electrical discharge in the atmosphere has been conducted in order to mitigate the risk of lightning disaster. X-band poralimetric Dopplar radars and the lightning detection devices are used for the present study. High-resolution simultaneous data of lightning tracks and precipitation particle class has been superimposed by using three dimensional visualization software. As a result of the analysis, it is shown that the radar reflectivity factor on the lightning tracks is statistically higher than the other area. Moreover, it also shown that the volume which consists of graupels and ice crystals was dominant at the grid where lightning tracks started. The result supported the theory of “Riming Electrification” by Takahashi (1978) in which contact between graupels and ice crystals give principal electrical charge in the atmosphere.THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, 2014, Proceeding of Annual Conference, 27, 100084 - 100084, Japanese
- This study estimates amount of volcanic ash sediment by X-band radar. The volcanic ash has caused a lot of sediment disasters. The frequency of sediment disaster caused by volcanic ash is assumed to be depended on the relationship between amount of volcanic ash sediment and precipitation so that the sediment disaster may be forecasted by estimation of volcanic ash sediment. However, limited access at the area of active volcano slope prevents us from surveying the amount of sedimentation. Therefore estimation of volcanic ash by remote sensing is one of the tangible solution. However the density, shape and rotation of volcanic ash are less homogeneous than raindrop, thus estimation of volcanic ash amount is more difficult. By using numerical scattering simulation and the observation data analysis, we are developing a method for volcanic ash estimation. In the proceedings, the relationship between radar reflectivity factor and density of the volcanic ash in the air is shown as an example.THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, 2014, Proceeding of Annual Conference, 27, 100117 - 100117, Japanese
- In order to research the hydrological balance at the northern foot region of Mt. Fuji, we investigated the rainfall estimation there in last year. However, it caused impossible observation areas by a single X-MP radar. To reduce impossible observation areas, we investigated the rainfall estimation around Mt. Fuji by composition of 4 X-MP radars.THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, 2014, Proceeding of Annual Conference, 27, 100080 - 100080, Japanese
In this result, we could estimate rainfall on all over Mt. Fuji for the case of stratiform rain type by composition of 4 X-MP radars. And then we found that the estimated error of X-MP radar was smaller than that by C-band meteorological radar for the cases of stratiform and convective rain.
Therefore, we could show availability of the rainfall estimation by composition of 4 X-MP radars. - In recent years, the number of heavy rain has been increasing. Railway companies take measures against rainfall disasters. This research focuses one of the “soft” countermeasure, operation control. The decision for railway operation depends on the rainfall observed by railway rain-gauges. However, railway rain-gauges cannot observe a localized rainfall, because it is placed only every dozen kilometers.THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, 2014, Proceeding of Annual Conference, 27, 100082 - 100082, Japanese
In this research, Radar/Raingauge-Analyzed Precipitation data (analyzed precipitation) has been applied to decision making. The analyzed precipitation is almost similar to a rain-gauge data, but the analyzed precipitation has uncertainty and an error from rain-gauge data. Verification of the effect of uncertainty on operation control decision has been conducted.
According to the results, amount of analyzed precipitation can capture a localized rainfall. It was found that probabilistic decision making using the analyzed precipitation gives distinct, safe and efficient operation.
Although verification using hourly rainfall was described on the proceedings, accumulated rainfall amount will be taken into account at the presentation. - This study evaluated usefulness of using One-week Ensemble Prediction made by JMA and operation models using Dynamic Programming (DP) and Stochastic Dynamic Programming (SDP) to decide the optimized operation of discharge of the dam. To evaluate usefulness, these models were applied to operation of the Hiyoshi Dam located at the upper reaches of the Katsura River when heavy rain was brought by Typhoon 18 (MAN-YI) in 2013. From the results of the study, if One-week Ensemble Prediction is accurate to some extent, it is useful to decide the optimized operation. Moreover the proposed method which decides the amount of discharge using One-week Ensemble Prediction before it starts to rain demonstrates fully effective flood control.THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, 2014, Proceeding of Annual Conference, 27, 100098 - 100098, Japanese
- In order to improve radar observation of ice particles in terms of accuracy and physical meaning, this study investigates the relationship between actual radar reflectivity factor of ice particles and estimated hypothetical radar reflectivity factor based on diameters of measured by videosonde. Focusing the error generated by using longer axis as a representative diameter is the special characteristics of the study. Campaign observation synchronized with videosonde was conducted in BAIU season around Okinawa islands, Japan. RHI (Range Height Indicator) scan mode synchronized with videosonde that can observe precipitation particles directly. Hypothetical radar reflectivity factor was calculated from ice particles pictures taken by videosonde. The physical meaning of radar observation for ice particles is investigated in this study. Hypothetical radar reflectivity factor calculated based on diameters measured by videosonde is verified through analyzing a difference of observational characteristics between radar and videosonde for utilizing ground-based in-situ observation installing disdrometer also.THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, 2014, Proceeding of Annual Conference, 27, 100085 - 100085, Japanese
- © 2014, the Meteorological Society of Japan. A 1-month-long observation of the Ciliwung River, which flows through Jakarta in Indonesia, has revealed evidence of the persistent existence of a diurnal cycle in the water level of a tropical river. This was consistent with the diurnal cycle in rainfall observed by meteorological radar and five rain-gauge stations. The river's diurnal cycle was distinguishable from the effects of oceanic and atmospheric tides and has a locally time-locked 1-day periodicity and an amplitude of 0.05 m. The day-to-day variation in the amplitude of the river's diurnal cycle was smaller than the diurnal cycle of the rainfall.Meteorological Society of Japan, 2014, Scientific Online Letters on the Atmosphere, 10(1) (1), 141 - 144, English[Refereed]Scientific journal
- On 18 February 2013, the stratiformed precipitating system associated with an extratropical cyclone hitting the Pacific coast on Japan covered Shizuoka region and Kofu basin, which was observed by X-band multi-parameter radars. From the observation of X-band multi-parameter radars, on Kofu Basin, the brightband appeared near the surface and ascended, so that the condition of precipitation changed snowfall to rainfall. Then, the brightband height decreased gradually from Shizuoka region to Kofu Basin. Above them, it is suggested as follows; the height variation of brightband contributed to the determination of precipitating condition at surface (e.g. rainfall or snowfall), and the brightband observation by X-band multi-parameter radars installed in a low altitude site is important for the simple classification of rainfall and snowfall in the stratiformed precipitating system.THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, 2013, Proceeding of Annual Conference, 26, 120 - 120, Japanese
- As part of studies for the maintenance and utilization of water resources on the northern foot region of Mt. Fuji, we investigate the rainfall estimation there. As the preliminary study, we compared rainfall estimated by X-MP radar and C-band meteorological radar with surface rainfall on the northern foot region of Mt. Fuji. From the analyses, we found that the correlation between rainfall at surface and estimated by X-MP radar was high for the cases of stratiform and convective rain. Then, the accuracy of the rainfall estimation of X-MP radar was better than that by C-band meteorological radar.THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, 2013, Proceeding of Annual Conference, 26, 114 - 114, Japanese
- X-band Multi Parameter Radar enables to obtain detailed and various parameters to estimation of rainfall amount. It is expected to contribute to real time observation of localized heavy rainfall and disaster reduction. However, large errors in rainfall estimation have been reported over distant mountainous regions in Yamanashi because the radar beams are blocked by mountains and attenuated by strong rainfall. In this study, estimated rainfall using X-band Multi Parameter radar of University of Yamanashi was compared with rain gauge data provided by Japan Meteorological Agency and Yamanashi prefecture. Comparisons were carried out for stratiform rainfall, convective rainfall and typhoon case. As a result, the estimation accuracy was clearly different by rainfall type. And in the stratiform rainfall case, estimation accuracy was high even over the distant area from the Radar site.THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, 2013, Proceeding of Annual Conference, 26, 116 - 116, Japanese
- Assessing the Uncertainties of Radar Rainfall Prediction and Runoff Simulation Parameter: Toward an Operational Ensemble Flood Forecasting in Urban River BasinUrban river basins are vulnerable to floods due to intense rainfall, and hence posing a danger to communities. Non-structural flood measures, including forecasting and warning are indispensable to complement structural measures. Nonetheless, predictability of flash flood events is considered limited because of high spatial and temporal variability. In this research, uncertainties in the short torrential rainfall and its corresponding flood in urban river basin are explored. Uncertainty in rainfall prediction is assessed by developing ensemble prediction system. Initial condition of the translation model is perturbed based on advection vector incorrectness. An updating scheme is introduced to provide more reliable rainfall short-term prediction. Parametric uncertainty of the CDRMV3 distributed hydrological model is analyzed by perturbing the model parameters with scalar multiplier. Two sensitive parameters of the rainfall-runoff model are each perturbed five times within their physical bounds. The range of uncertainty generated by ensemble prediction and their potential for obtaining flood risk estimates is demonstrated. Understanding sources of uncertainties of complex dynamic systems and communicating the predictive uncertainties remain challenges in using ensemble operationally. Yet, the proposed system employing a fix number of members allows for a simple system, which is essential in the flash flood warning context. The approach is demonstrated through case studies in Sumiyoshi River Basin Japan, which passes through a highly urbanized area in Kobe City, Japan. Verified with observed data, the combined input-parameter ensemble could serve as a reliable and effective system for operational flood disaster prevention in urban area. The advantages of ensemble prediction over the single deterministic forecast are demonstrated. Uncertainty assessment in rainfall-runoff model parameters gives important information regarding the potential of flooding. The ensemble technique is less sophisticated and easier to be communicated to non-expert users in the operational systems. It could be a useful approach to manage the uncertainty in the flood short-term prediction in urban river basin and elevate the public security from the flash flood threat.TSINGHUA UNIV, 2013, PROCEEDINGS OF THE 35TH IAHR WORLD CONGRESS, VOLS III AND IV, English[Refereed]International conference proceedings
- Ensemble short-term rainfall-runoff prediction and its application in urban flood risk mappingThis paper describes the ensemble approach to account for the uncertainty in both rainfall and hydrological short-term prediction. The range of probabilistic products generated by ensemble prediction and their potential for obtaining flood risk estimates is demonstrated. An ensemble rainfall prediction is developed by perturbing the initial condition of the radar echo extrapolation model. The ensemble members are subsequently considered as uncertain input of the distributed hydrological model. Uncertainty in rainfall-runoff model parameters is assessed by the generalized likelihood uncertainty estimation (GLUE) method. The methodology is demonstrated through case studies in the Kofu urban river basin, Japan. The results reveal that plausible results can be achieved, thus indicating that this approach could serve as a reliable method for estimating the uncertainty range in short-term prediction of runoff dynamics. When utilized along with the flood damage model, we highlight the value of ensemble prediction for deriving flood risk information through risk mapping. © 2013 IAHS Press.IAHR, 2013, IAHS-AISH Publication, 357, 308 - 319, English[Refereed]International conference proceedings
- Effects of soil moisture on a summertime convective rainfall over a mountainous area and its contiguous plain in central JapanIn this study, two numerical experiments of convective rainfall observed on 15 August 2001, in central Japan, were conducted using a cloud-resolving, land atmosphere coupled model to investigate the effect of initial soil moisture on short-term weather phenomena. The first experiment, called WET, used the wettest soil condition observed in August 2001 as the initial soil moisture value. The other experiment, called DRY, used the driest condition in August 2001 as its initial soil moisture value. A comparison of the results for WET and DRY showed that a drier soil-moisture condition led to higher rainfall over both the mountainous region in central Japan and Nobi Plain. Greater differences in rainfall amounts were found over the plain than over the mountainous region. The difference in near-surface convergence and atmospheric stability caused by local circulation was found to play an important role in transmitting the variation in soil moisture to rainfall.INT ASSOC HYDROLOGICAL SCIENCES, 2013, CLIMATE AND LAND SURFACE CHANGES IN HYDROLOGY, 359, 246 - 252, English[Refereed]International conference proceedings
- Effects of soil moisture on a summertime convective rainfall over a mountainous area and its contiguous plain in central JapanIn this study, two numerical experiments of convective rainfall observed on 15 August 2001, in central Japan, were conducted using a cloud-resolving, land-atmosphere coupled model to investigate the effect of initial soil moisture on short-term weather phenomena. The first experiment, called WET, used the wettest soil condition observed in August 2001 as the initial soil moisture value. The other experiment, called DRY, used the driest condition in August 2001 as its initial soil moisture value. A comparison of the results for WET and DRY showed that a drier soil-moisture condition led to higher rainfall over both the mountainous region in central Japan and Nobi Plain. Greater differences in rainfall amounts were found over the plain than over the mountainous region. The difference in near-surface convergence and atmospheric stability caused by local circulation was found to play an important role in transmitting the variation in soil moisture to rainfall. Copyright © 2013 IAHS Press.IAHS, 2013, IAHS-AISH Proceedings and Reports, 359, 246 - 252, English[Refereed]International conference proceedings
- Study on Optimization of the Integrated Dam Operation Using Ensemble Prediction in the Upper Reaches of the Nabari RiverOne week ensemble weather forecast issued by Japan Meteorological Agency has been introduced into integrated operation of multi-reservoirs system in order to develop a short term flood control model which reduces the water level of the river. Stochastic dynamic programming has been applied for decision making of releasing water from three reservoirs with the One week ensemble weather forecast. A flood happened in Nabari river basin where river authorities conducted their integrated operation of multi-reservoirs without the ensemble forecast was selected as a case study. Water level calculated by the proposed method has been compared with the result of actual decision made by authority, one calculated under ideal condition of hundred percent weather forecasting and one following a procedure of dam operation rule. Then the proposed method obtained the best optimization.TSINGHUA UNIV, 2013, PROCEEDINGS OF THE 35TH IAHR WORLD CONGRESS, VOLS III AND IV, 10438 - 10447, English[Refereed]International conference proceedings
- This study investigates an interdisciplinary scenario analysis to assess the potential impacts of climate, land use/cover and population changes on future water availability and demand in the Srepok River basin, a trans-boundary basin. Based on the output from a high-resolution Regional Climate Model (ECHAM 4, Scenarios A2 and B2) developed by the Southeast Asia-System for Analysis, Research and Training (SEA-START) Regional Center, future rainfall was downscaled to the study area and bias correction was carried out to generate the daily rainfall series. Land use/cover change was quantified using a GIS-based logistic regression approach and future population was projected from the historical data. These changes, individually or in combination, were then input into the calibrated hydrological model (HEC-HMS) to project future hydrological variables. The results reveal that surface runoff will be increased with increased future rainfall. Land use/cover change is found to have the largest impact on increased water demand, and thus reduced future water availability. The combined scenario shows an increasing level of water stress at both the basin and sub-basin levels, especially in the dry season. © 2012 Springer Science+Business Media B.V.Mar. 2012, Water Resources Management, 26(5) (5), 1387 - 1407[Refereed]Scientific journal
- Mar. 2012, Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering), Vol.68,No.4, I_355-I_360, JapaneseANALYSES OF DISTRIBUTION AND INCREASING MECHANISM OF RAIN OVER MOUNTAIN SLOPES SURROUNDING A BASIN USING X-MP RADAR[Refereed]Scientific journal
- Mar. 2012, Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering), Vol. 68, No.4, I_139-I_144ENSEMBLE FLOOD PREDICTION BY CASCADING THE UNCERTAINTY FROM RAINFALL TO RUNOFF SHORT-TERM PREDICTION[Refereed]Scientific journal
- The concept of developing a web-based platform for arranging, storing, and geospatial visualization of hydrological data with a goal of research collaboration is presented. The platform, which will help researchers arrange their own data and visualize data from observational stations in their area of interest, will be a working environment for planning and conducting research activities.THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, Mar. 2012, Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering), Vol. 68, No.4, pp.I_151-I_156, 72 - 72, Japanese[Refereed]Scientific journal
- 2012, SOLA, 8, 001-004, EnglishScientific journal
- In the present study, a stationary convective system persisting for approximately six hours over the Asagiri Highland adjoining Suruga Bay, Japan on 28 July 2010 was investigated primarily using X-band multi-parameter radar observation data. Over the Asagiri Highland with the moist southerly wind from Suruga Bay associated with thermally induced local circulations, 54 precipitating cells were generated continuously. The anvil extending southeastward from the existing precipitating cells did not prevent new precipitating cells from continuous appearance. Thus, the convective system was maintained for approximately six hours. Then, small advection of the transient cells contributed to the formation of a convective system with a horizontal scale of approximately 20 km. Among them, the precipitating cells that appeared over the gradual slope toward Mt. Kenashi, which is located in the western part of Asagiri Highland, moved toward the northwest part of Mt. Fuji. The precipitating cells were supplied with sufficient moisture because the direction was normal to that of moist southerly wind blowing from Suruga Bay. In one of those precipitating cells, two cores were identified. One was associated with a shallow convection below the melting level, and the other with a deep convection. They rained on almost the same position in the precipitating cell. The precipitating cell with such cores brought a localized heavy rainfall by efficiently converting the moisture transported from Suruga Bay into rain. © 2012, Meteorological Society of Japan.MSJ, 2012, Journal of the Meteorological Society of Japan, 90(5) (5), 807 - 831, English[Refereed]Scientific journal
- A new videosonde receiving system consisting of two receiving antennas for a set of videosonde and GPS radiosonde has been developed. The antenna for the videosondes is controlled by a GPS slave method, in which the antenna elevation and azimuth are processed every second using GPS location data obtained from a GPS radiosonde attached to the videosonde. The results of the first experimental flight conducted in Okinawa as part of a synchronized observation campaign of a C-band polarimetric radar and videosondes reveal successful reception of clear images of precipitation particles in clouds. © 2012, the Meteorological Society of Japan.2012, Scientific Online Letters on the Atmosphere, 8(1) (1), 1 - 4[Refereed]Scientific journal
- Advanced usage of GPS slant delay for detecting water vapor variation over the Osaka bayWater vapor is one of the most important meteorological variables for weather forecasting. Continuous GNSS estimation of wet tropospheric delay is one of the key techniques for detecting rapid changes of water vapor. Water vapor comes from the ocean in Japan. Therefore, observing the water vapor by GNSS on the sea, especially coastal area is required. Moreover, After Great Eastern Japan Earthquake and Tsunami (GEJET) that happened on March 11, 2011, Japanese government has a plan to deploy many GNSS wave buoys. For effective usage of them as multi-purpose monitoring system of environment of the ocean, the study for observing water vapor over the Osaka bay was conducted and it have gotten a good result by comparison with ground fixed observation. However, it is also true that GNSS observation on the ocean still cost a lot. In order to give higher spatial resolution of water vapor, an advanced method for virtually increasing the measurement point of zenith atmospheric delay is proposed by using slant delays from surrounding points that actually observe.ION-GNSS, 2012, 25th International Technical Meeting of the Satellite Division of the Institute of Navigation 2012, ION GNSS 2012, 5, 3392 - 3397, English[Refereed]International conference proceedings
- Mar. 2011, Proceedings of International Conference on Mesoscale Convective Systems and High-impact Weather (ICMCS-VIII), EnglishStructure of a Cumulonimbus Cloud Maintained for a Long Time over a Slope between Mountains in Summer SeasonScientific journal
- Mar. 2011, Annual Journal of Hydraulic Engineering, JSCE, Vol. 55, 2011, CDROM, EnglishSingular Vector Method on Short Term Rainfall Prediction Using Radar And Distributed Hydrological Model[Refereed]Scientific journal
- Mar. 2010, 水工学論文集, Vol 54, pp. 625-630, Japanese再現ビデオを用いた防災教育に対する児童の記憶の持続性と意識の把握に関する研究[Refereed]Scientific journal
- Mar. 2010, 水工学論文集, Vol 54, pp. 673-678, Japanese鉱物組成を用いた富士川流域における土砂 生産源推定に関する基礎研究[Refereed]Scientific journal
- Mar. 2010, Annual Journal of Hydraulic Engineering, JSCE, Vol 54, pp. 205-210, EnglishTHE ESTIMATION OF GROUNDWATER EXCHANGE IN AYDARKUL-ARNASAY LAKE SYSTEM BY A LAKE WATER BALANCE MODEL[Refereed]Scientific journal
- Mar. 2010, Annual Journal of Hydraulic Engineering, JSCE, Vol 54, pp. K1-K6, EnglishPROGRESSIVE WATER RESOURCES MANAGEMENT BASED ON SYSTEMATIC APPROACHES[Refereed]Scientific journal
- Mar. 2010, Annual Journal of Hydraulic Engineering, JSCE, Vol 54, pp. 121-126, EnglishIMPROVING FLOOD SIMULATION IN URBAN RIVER BASIN USING X-BAND POLARIMETRIC RADAR AND DISTRIBUTED HYDROLOGICAL MODEL[Refereed]Scientific journal
- We investigated the characteristics of distribution of specific differential phase (KDP) in the Heavy Rainfall Area (HRA) 1 observed by X-band Dual-Polarimetric Doppler Radar of University of Yamanashi on September 4, 2009. The core of KDP over 6 deg/km appeared at that of radar reflectivity (ZH) under 4 km ASL. Above 5 km ASL, KDP of 0 - 1 deg/km was distributed without the distribution of ZH. The increasing gradient of KDP from upper to lower layers appeared at 4 - 5 km ASL with the melting level. It is suggested for the distribution of KDP as follows, (1) the structure composed by rain drops (solid precipitating particles) was appeared clearly (unclearly) and (2) the increasing gradient reflected the transition of distributions from solid precipitating particles and rain drops.THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, 2010, Proceeding of Annual Conference, 23, 18 - 18, Japanese
- In this present study, rainfall data in Yamanashi was collected using X-band dual-polarimetric radar of University of Yamanshi. And the verification of accuracy concerning the rainfall amount estimation and consideration concerning the estimation difference were done by analyzing these data. As a result, the rainfall estimation by specific diffential phase KDP did not receive the rainfall attenuation easily compared with reflectivity factor ZH. In addition, from the comparison with AMeDAS, the rainfall estimation accuracy on September 4 was acceptable result. However, on October 8 was not acceptable result. For this reason, there are still problems in the rainfall estimation by KDP in Yamanashi. And it has been understood that the estimate accuracy changes by rainfall type or intensity.THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, 2010, Proceeding of Annual Conference, 23, 107 - 107, Japanese
- Difficulty on direct observation of precipitation falling processes is one of the factors that insufficient for short-time quantitative precipitation forecasting. This study discussed precipitation falling processes using by the dual polarimetric doppler radar on university of yamanashi. The elevation angle model using each altitude of the terminal fall velocity of raindrops and the doppler velocity was developed as estimating slope of strong echo region. In case of rainfall event at Aug/2/2009, model results were validated by observed echo images. This model could adequately represent time variation of elevation angle. It was indicated that slope of strong echo region was influenced by difference of between migration velocity of rain area and wind velocity on each altitude.THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, 2010, Proceeding of Annual Conference, 23, 108 - 108, Japanese
- This study calculated sediment production rate using global precipitation data by satellite observation in the Mekong River basin. Availability of using satellite observation data was discussed from comparisons of estimated sediment production rate on precipitation by ground rain gauges and observed sediment production rate. In this study, daily precipitation from the GPCP and GSMaP data set inputted to USLE as estimation of annual sediment production rate. As a result, these results were nearly value which inputted ground rain gauge data which complemented by Thiessen method. And sediment production rate by the GPCP and GSMaP were better accuracy than the observed rain gauge data. Satellite observation data is useful on using USLE method was indicated.THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, 2010, Proceeding of Annual Conference, 23, 86 - 86, Japanese
- Impact of Uncertainty of Polarimetric Radar-Rainfall Inputs on Distributed Hydrological Model in Urban River BasinIntegrating the high-resolution estimation of rainfall input from X-band polarimetric Doppler weather radar to the distributed hydrological model offers an improved storm event simulation in urban river basin. Uncertainties are inherent in radar-rainfall observation, and they may propagate into final peak flood estimates. This study investigated the influence of systematic and random error in radar-rainfall input on the performance of the distributed hydrological model. The analysis reveals that the model performance is less affected by systematic error of R(Z(KDP)) estimator. The Normalized Peak Error introduced by the feature of R(Z(H)) and R(KDP) is in the range of - 12.3% to 115.7%, and 5.8% to 66.1% respectively. Perturbed radar-rainfall data with random error intensity exceeding 0.3 is detrimental to the model performances. Analysis of sensitivity has shown that a higher sensitivity of hydrological model performance with respect to the overestimation than to the underestimation of rainfall input.WORLD ACAD UNION-WORLD ACAD PRESS, 2010, PROCEEDINGS OF 2010 INTERNATIONAL CONFERENCE ON ENVIRONMENTAL SCIENCE AND DEVELOPMENT, 491 - 495, English[Refereed]International conference proceedings
- Inundation Model Integrating with X-Band Polarimetric Radar for Flood Disaster Prevention in Urban AreaThis paper introduces a development of integrated system for flood inundation mapping in urban river basin by integrating radar observation and inundation model. An accurate high-resolution estimation of rainfall from X-band polarimetric radar was supplied to distributed hydrological model to simulate flood hydrograph due to severe rainfall. Flood stage hydrograph was obtained from 1-D flood routing model. An inundation map was produced by 2-D inundation model for highly urbanized area which considers the spatially distributed rainfall input from radar. An absorbing boundary condition is applied to the inundation model in conjunction with the explicit MacCormack and artificial viscosity scheme. The model was applied to simulate and to evaluate the past storm events in Kofu city, Japan. The validated hydrological model can reasonably simulate flood hydrograph using radar-rainfall estimates. Compared to observed inundation, the model was satisfied to provide a flood hazard map in dense urban area. The system would be useful for local government effectively plan the appropriate countermeasures.WORLD ACAD UNION-WORLD ACAD PRESS, 2010, PROCEEDINGS OF 2010 INTERNATIONAL CONFERENCE ON ENVIRONMENTAL SCIENCE AND DEVELOPMENT, 248 - 253, English[Refereed]International conference proceedings
- The impact of climate change on local discharge variability is investigated in the Kone River basin located in Central Vietnam. In this study, historical and predicted river discharge trends are discussed. The predicted discharge is simulated using the BTOPMC model based on the A1B scenario as a scientific basis for socioeconomic development and integrated water resource management in the Kone River basin, during the period 2011-2034. During the period 1979-2007, annual discharge in the Kone River basin trended upwards slightly. However, both maximum and minimum discharges declined. The results of the predicted discharge under the A1B scenario suggest that river flow will increase slightly in the Kone River basin in the future. Both annual and flood season discharges will tend to increase during the period 2011-2034. In contrast, discharge during the low flow season will tend to decrease over the same period. For the period 2011-2034, the discharge volume in the Kone River will increase by 3%, in comparison with the period 1980-1999. Water volume will decrease by about 18.6% during the flood season and increase by approximately 90.0% during the low flow season relative to the period 1980-1999. © IWA Publishing 2011.2010, Journal of Water and Climate Change, 1(4) (4), 269 - 279, English[Refereed]Scientific journal
- In order to evaluate clearly the state of water resources in the Srepok River basin - a typical rural area in South-East Asia, a Modified Water Poverty Index (MWPI) was developed. Indicators of five components of MWPI were evaluated using the benchmark approach. The cross-correlation among indicators of each component as well as among components were checked; and the high-correlated indicators were eliminated. The calculated MWPI and its components were then mapped and analysed to three different scales (basin, sub-basin and district). From the overall MWPI score, a general conclusion was drawn on the water poverty situation in the basin. The results reveal the variation of water poverty across the basin with the overall MWPI of 64.8, indicating that the basin is in a 'medium-low' water-poor situation. 'Access' and 'Capacity' components are observed to be the main causes of the water problem in the basin. There is a high disparity among the five components of MWPI when spatial and temporal variation of variables is taken into account. It is recommended that the state of water resources should be assessed based on the components rather than the composite index. The differences that scales make indicate the importance of selecting an appropriate scale for water resources assessment. By using the benchmark approach, the pertinence of MWPI results are improved and the potential for wider applicability can be extended. By examining the indicators in the five components, a policy for water development and management is proposed and specific interventions recommended. This result can provide useful information for decision-makers in prioritizing investments in the water sector. © 2010 International Association for Hydro-Environment Engineering and Research.2010, International Journal of River Basin Management, 8(3-4) (3-4), 305 - 317, English[Refereed]Scientific journal
- The objective of the study is to develop a GIS-based water infrastructure inventory (WII) for water resources assessment in the upper Srepok basin, Vietnam. The water availability and demand were estimated using common methods. Different water scarcity indicators were estimated to examine the water situation at district level under present and future conditions and future water development needs are assessed. Results reveal that the aggregated information on the basin scale misleads the issue of water situation, especially the scarcity at local level due to high spatio-temporal variations of water resources availability and demands. Most districts in the study basin will experience severe water scarcity in 2010 and 2020 in both physical and economic terms. Generated data from the WII shows very low percentage of water withdrawals in several districts with respect to available resources. Therefore, to meet future demand, significant investment in water infrastructure is needed.THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, Jul. 2009, Hydrological Research Letters, 3, 27 - 31, English[Refereed]Scientific journal
- Tonle Sap Great Lake, in the lower Mekong River basin, contributes 60% of Cambodia's inland fisheries catch. There are four types of fisheries, including the middle-scale fishery. The major species comprising the middle-scale fishery are Henicorhynchus spp. (16%), a small-bodied fish caught mainly with small-mesh nets, and Cyclocheilichthys enoplos (13%), and Channa micropeltes (7%) which are caught with a variety of gear. Here we apply the Schaefer surplus production model to the middle-scale fisheries using monitoring data collected between 1995 and 1999. Model simulations determined that the maximum sustainable yield (FMSY) for Henicorhynchus spp., was obtained with the use of 47,206 gillnets (mesh size < 50 mm) and 4269 and 1605 fishing boats for C. enoplos and C. microplestes, respectively. Over 1995-1999, there was a strong trend of increase in fishing effort and decrease of catch-per-unit-effort in the waters of Pursat, Siem Riep and Kampong Chnnang provinces. These provinces have large population centres located close to the fishing grounds; fishing in these areas should be more strictly regulated. © 2009.Jun. 2009, Journal of Great Lakes Research, 35(2) (2), 169 - 174[Refereed]Scientific journal
- May 2009, Polskie Towarzystwo Informacji Presestrzennej, Vol.35, No.5ASSESSMENT OF HALOPHYTIC VEGETATION TO IMPROVE LIVESTOCK FEEDING RESOURCES ON SALINE DESERT RANGELANDS[Refereed]Scientific journal
- Mar. 2009, 土木学会水工学論文集53, pp.31-36．, Japanese長期水文・気象データおよび衛星データを用いたアラル海流域における水循環の解析[Refereed]
- Feb. 2009, Annual Journal of Hydraulic Engineering, 53, 361 - 366, JapaneseDevelopment of hydrometeor classification system using polarimetric radar measurements synchronized with the video-sonde observation (in Japanese with English abstract)[Refereed]Scientific journal
- This study applied global warming experiment simulation result data (an A1B scenario and a present climate) by Meteorological Res. Inst. with YHyM/BTOPMC and a riverbed variation simulation model for the whole Mekong River basin. Change of sediment transportation in the Mekong River basin on the climate change was discussed. From results of the suspended sediment concentration at Chiang Saen, the value on an A1B scenario was larger than a present climate, and wash-road increase was suggested. The volume of sediment production by USLE on the A1B scenario was approximately 2 times of the present climate. The sediment production rate in upper part (a steep slope area) on the climate change will be large, and it affect to the sediment transportation in the lower part.THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, 2009, Proceeding of Annual Conference, 22, 100 - 100, Japanese
- THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, 2009, Proceeding of Annual Conference, 22, 97 - 97, Japanese
- An estimation method to calculate Probable Maximum Precipitation based on satellite based precipitation data is proposed. In the method, the cloud cluster from the global precipitation data from satellite is extracted. The region where the cloud cluster is generated easily is specified. In addition, 11 regions where the cloud cluster is generated easily were selected to compare the cloud cluster and precipitation. Two method of estimating PMP for one month was proposed by using a regression line between the monthly averaged frequency of cloud cluster and monthly averaged rainfall, most effective cloud clusters and the maximum frequency of cloud cluster. The PMP of November in Malay Peninsula was estimated as 531 mm/mon.THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, 2009, Proceeding of Annual Conference, 22, 92 - 92, Japanese
- A study having an objective to estimate the maximum snowflake diameter in high altitude of cloud through thickness of bright band observed by radar has been conducted. Data was collected during the hydro-meteorological observation project including video sonde observation. Melting layer thickness which is defined as the height between start and end of melting was estimated by using maximum snowflake diameter observed video sonde. The estimation used the snowflake melting model proposed by Matsuo and Sasyo. It was understood that the melting layer thickness estimated by the model and the observed thickness by radar bright band were relatively similar. According to the result, the maximum snowflake diameter can be estimated by using the bright band and the snowflake melting model.THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, 2009, Proceeding of Annual Conference, 22, 96 - 96, Japanese
- The coral reef indices of biological integrity was constituted based on the reef check monitoring data. Seventy six minimally disturbed sites and 72 maximallv disturbed sites in shallow water and 39 minimally disturbed sites and 37 maximally disturbed sites in deep water were classified based on the high-end and low-end percentages and ratios of hard coral, dead coral and fieshy algae. A total of 52 candidate metrics was identified and compiled, Eight and four metrics were finally selected to constitute the shallow and deep water coral reef indices respectively. The rating curve was applied for each metric to identify two lower a and upper b threshold values. A set of scores 1.3 and 5 was used to score and narrate individual metric values. Each metric value at a site presented a poor. moderated or good condition of reefs. The index was calculated by averaging all selected metric scores. The overall site classification efficiencies were of 65.97 and 66,13% for shallow and deep waters respectively. Importantly, the strong negative correlation between indices and dynamite fishing -0.286 (p<0.01) and number of yacht within 1 km -0.185 (p<0.05) in shallow water and with poison fishing -0.279(p<0.05) and coral damaged by other factors -0.283 (p<0.05) in deep water indicated that coral reef indices were sensitive responses to stressors and can be capable to use as the coral reef biological monitoring tool. © 2009 Academic Journals Inc.2009, Journal of Fisheries and Aquatic Science, 4(2) (2), 90 - 102[Refereed]Scientific journal
- By using a simple ecosystem model, the study grasps the relationship between the change in inundated areas (water level and flood extends) and the level of fish production in the Tonle Sap Basin (TSB). The model produces the fish production trends that can reflect the changes in key parameters such as flood extent and relative fish area density. The results show the continued dominance of the opportunist/white migratory species in the TSB’s fish composition. It reconfirms the hydrological and biological linkages between the TSB and the Mekong River that require a cross-sectoral and cross-boundary integrated planning and development. © 2008 Taylor and Francis Group, LLC.Sep. 2008, International Journal of River Basin Management, 6(3) (3), 277 - 282[Refereed]Scientific journal
- THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, 2008, Proceeding of Annual Conference, 21, 49 - 49, Japanese
- Mechanism of rainfall process through collecting and analyzing data from advanced radar namely COBRA is investigated in this study. The effect of COBRA for measuring rainfall process is expected in the following field; i) detailed bistatic characteristics from each type of raindrop, ii) classification of type of raindrops, iii) correction of attenuation during the severe rainfall, iv) removal of ground clatter, v) estimation of rain drop size distribution. However, classification of type of raindrops has not been done yet. Therefore, with using the Micro Rain Radar, rainfall process is investigated through estimating the rain drop size distribution.THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, 2008, Proceeding of Annual Conference, 21, 48 - 48, Japanese
- The Kyzylkum desert is a typical desert area and has unique climate condition and ecosystems. There are small oases in this area and local people use them for crop irrigation. To understand the hydrological cycle is important for local people and sustainable farming, however there are not enough data for scientific analysis. Moreover, air temperature is increasing about 0.9-1.0 degree for 100 years and 0.4-0.5 degree for 25 years in Uzbekistan which is relatively higher than global averages. The object of this study is to understand the hydrological and ecological systems in this region including climate variation and change. We started the land surface observation since November 2006 in Kyzyk ke sek.THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, 2008, Proceeding of Annual Conference, 21, 4 - 4, Japanese
- During the last decade, leaders of the Mekong Countries have found it mutually advantageous to open up the Mekong Sub-Region (MR) for development and trade, which promises some degree of political stability and regional security. Within the present political, cultural, and economic dynamics, the Mekong River Basin (MRB) - one of the major international river basins in MR - is a powerful catalyst for regional cooperation that facilitates sustainable development and regional stability; if, that is, the effective management intervention is in place to make sure that the benefits and costs of river basin development are spread equitably and peacefully. Nonetheless, there are numerous stumbling blocks in achieving integrated and balanced MRB management, such as limited success in real basin wide planning, implementation and monitoring and a poor knowledge base for supporting informed decision making and, finally, political impediments. A workable and truly regional cooperative mechanism for integrated management of the MRB is yet to be developed, regardless of the existence of numerous regional institutions and organizations. The present paper proposes new schemes with (re)designing principles and performance determinants for a regional cooperative mechanism. © 2007 International Water Resources Association.Dec. 2007, Water International, 32(4) (4), 503 - 523[Refereed]Scientific journal
- Jun. 2007, Journal of Disaster Research, 2(3) (3), 134 - 142, English[Refereed]Scientific journal
- 京都大学防災研究所, Apr. 2007, Annuals of Disaster Prevention Research Institute, Kyoto Univ., (50B) (50B), 623 - 634, JapaneseRainfall and Sediment runoff in the Lesti River Bain, Tributary of the Brantas RiverResearch institution
- X-ray powder diffraction (XRD) is widely used for geological analysis of sediment samples. In this study a method for detecting sources of sedimentation using mineral composition obtained by the qualitative phase of XRD is proposed. Possible minerals matching resulted from the Hanawalt's searchmatch method were arranged into binary matrix of mineral composition of each sampling site. Hierarchical cluster analysis was grouped samples into clusters based on mineral similarity and yielded a dendrogram. Using information of sample's environment, the meaning of dendrogram was derived for sediment fingerprinting.Japan Society of Civil Engineers, 2007, Doboku Gakkai Ronbunshuu B, 51, 121 - 126, English
The result showed that sedimentation sources in the Sengguruh reservoir mainly come from 10-30° slope of the Lesti basin and cultivated area downstream of the Brantas origin. Comparing with the field observation and satellite data, a good correlation was obtained. - Amy Darya and Syr Darya basins in the Central Asia have high sensitivity about temperature warming. In this presentation, we introduce our land surface monitoring, which is cooperated with ICBA (International Center for Biosaline Agriculture) project, and its purpose and perspective for understanding the local hydrological system.THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, 2007, Proceeding of Annual Conference, 20, 72 - 72, Japanese
- The Tonle Sap ecosystem of Cambodia is situated in the lower part of the Mekong River basin (MRB), the TS ecosystem water environment is influenced by 181,035 km(2) of its catchments and water inflow from 4000 km in length of the upper Mekong River. The water quality index (WQI) was developed based on seven environmental chemical factors of DO, NO3+NH4, TOTP, TSS, temperature, pH and conductivity at Kampong Luong monitoring station during the period 1995 - 2002. On PCA, among 15 candidate parameters, the six most variation parameters of 'concentration of TSS mg l(-1'), 'temperature C degree', 'conductivity mS m(-1)', 'ratio between N and P', 'average monthly variation of NO3+NH4N', 'average monthly variation of pH', were identified and selected to constitute the WQI. Each parameter was scored as 1, 3 and 5 and narrated, in order, as poor, fair and good conditions. The yearly WQI score was calculated from these six parameter scores in the relative year. The WQI showed that the highest score of 4.3 was in 1996, while the lowest scores were of 1.3 and 1.0 in 2002 and 1998. Importantly, the WQI was significantly (P < 0.05) correlated with the 'dai' fish catch (r(2) = 0.858) and the fish biological group 4 (r-species) (r(2) = 0.75) during the period 1995-2002 indicating that the index was sensitive to reflect the relation between water quality condition and fish production. Then the WQI should be considerably used as the biological monitoring toot for water quality - fish production assessment. The correlations (P < 0.05) between WQI and fish families of Gyrinocheilidae and Cyprinidae indicated these fish families should be considered to be used as the TS ecosystem water quality bioindicators.WIT PRESS, 2007, Sustainable Development and Planning III, Vols 1 and 2, 102, 901 - 912, English[Refereed]International conference proceedings
- The Tonle Sap ecosystem of Cambodia is situated in the lower part of the Mekong River basin (MRB), the TS ecosystem water environment is influenced by 181,035 km2 of its catchments and water inflow from 4000 km in length of the upper Mekong River. The water quality index (WQI) was developed based on seven environmental chemical factors of DO, NO3+NH4, TOTP, TSS, temperature, pH and conductivity at Kampong Luong monitoring station during the period 1995 - 2002. On PCA, among 15 candidate parameters, the six most variation parameters of 'concentration of TSS mg 1-1, 'temperature C degree', 'conductivity mS m-1, 'ratio between N and P', 'average monthly variation of NO3+NH4N', 'average monthly variation of pH', were identified and selected to constitute the WQI. Each parameter was scored as 1, 3 and 5 and narrated, in order, as poor, fair and good conditions. The yearly WQI score was calculated from these six parameter scores in the relative year. The WQI showed that the highest score of 4.3 was in 1996, while the lowest scores were of 1.3 and 1.0 in 2002 and 1998. Importantly, the WQI was significantly (P<0.05) correlated with the 'dai' fish catch (r2 = 0.858) and the fish biological group 4 (r-species) (r2 = 0.75) during the period 1995-2002 indicating that the index was sensitive to reflect the relation between water quality condition and fish production. Then the WQI should be considerably used as the biological monitoring tool for water quality - fish production assessment. The correlations (P<0.05) between WQI and fish families of Gyrinocheilidae and Cyprinidae indicated these fish families should be considered to be used as the TS ecosystem water quality bioindicators. © 2007 WIT Press.2007, WIT Transactions on Ecology and the Environment, 102, 901 - 912[Refereed]Scientific journal
- It is very important for appropriate dam operation and disaster prevention to predict severe rainfall in mountainous region. For last several years, we have developed rainfall prediction system for the Kurobe-Valley, which is consist of steep mountains and valleys. The system has been already installed and used at the dam administration offices. The system had a weak point in terms of the rainfall prediction especially at the beginning of rainfall event. In this paper, we reveal that precipitable water vapor is related with rainfall event, and propose a new index which is applicable for the signal of the beginning of rainfall event for real-time estimation.Japan Society of Civil Engineers, 2006, Doboku Gakkai Ronbunshuu B, 50, 397 - 402
- Based on hydrological and meteorological data analysis, landcover type and green-up onset and offset are estimated using time-series analysis of PAL (Pathfinder AVHRR Land) data from January 1982 to Decenber1 1998. Our results show that air temperature determines green-up time and soil moisture (which is related to precipitation, temperature, snow melting and discharge) determines the vegetation type and its response in this area. Some of detected landcover changing places during analysis period are caused by air temperature warming because it brings promoting of evapotranspiration and dry soil condition. However, most of changing places are caused by not only natural condition but human activity directly or indirectly. Water usage system in this area affects large scale hydrological cycle and vegetation types so much.THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, 2006, Proceeding of Annual Conference, 19, 23 - 23
- In order to build a connection between former study of fine sediment yield and former study of rainfall system, the observation of raindrop size distribution and sediment yield has been made in the Lesti river basin that is a tributary of the Brantas river in Indonesia.Japan Society of Civil Engineers, Feb. 2005, Doboku Gakkai Ronbunshuu B, 49(2) (2), 1087 - 1092, Japanese
The following results were obtained. Rainfall energy work which are calculated by size distribution obtained by MRR has good relationship with rainfall amount obtained by a raingage. The energy which is used for calculating sediment yield is proven to be treated as linear to rainfall amount. On the other hand, the spatially non-uniform rainfall is shown in the Lesti river basin. The methods for treating the limited rainfall data is proposed in this study. Finally, the accumulation and erosion of sediment is observed in three points in the Lesti river basin. Moreover, main items which are important to estimate the sediment yield is picked up by the observation.[Refereed] - Hydraulic and morphological characteristics of the lower Mekong RiverThe hydraulic and morphological characteristics of the lower Mekong River were investigated. A concept “segment division” was used in this study. Based on the concept, data analysis was conducted using existing data collected. The average bed elevation, average water depth, river width, representative diameter of riverbed material, friction velocity, etc at each cross section at average annual maximum discharge were obtained and their longitudinal changes in the whole lower Mekong River were shown. As the results, in segment 3 from river mouth to downstream of Tan Chau, riverbed was horizontal and average width was 1,239 m. In segment 2-2 from Tan Chau to Kratie, riverbed slope was 1/25700, representative diameter of riverbed material was 0.17 ~ 0.76 mm (fine sand ~ coarse sand), and average width was 1,645 m. The relationship between the non-dimensional tractive force and representative diameter in the lower Mekong River in case of representative diameter 0.17 ~ 0.76 mm was clarified.Korea Water Resources Association, 2005, 31st IAHR Congress 2005: Water Engineering for the Future, Choices and Challenges, 5091 - 5100, EnglishInternational conference proceedings
- Study on trends of fish resources in the Tonle Sap Basin - Their corelation with hydrological conditions of Mekong RiverThe study uses a simple ecosystem model to grasp the relationship between the change in inundated areas (water level and flood extend) and the level of fish production in the Tonle Sap Basin (TSB). The model produces the fish production trends in the TSB that can be refined to reflect the changes in key parameters such as flood extends and relative area density. It reconfirms the importance of the hydrological and biological linkages between the TSB and the Mekong River Basin, since over 60% of the fish catch in the TSB is contributed by the white fish (opportunist and non-opportunist) that migrates from the other parts of the Mekong River. It is a typical issue requiring a cross-sectoral and cross-boundary integrated planning and development.Korea Water Resources Association, 2005, 31st IAHR Congress 2005: Water Engineering for the Future, Choices and Challenges, 4453 - 4462, EnglishInternational conference proceedings
- The lifetime of Sengguruh and Sutami reservoirs have been evaluated based on erosion and sedimentation rate calculated using combination USLE (Universal Soil Loss Equation) method with distributed model in GIS. The sedimentation calculated by distributed model shows a good approximation comparing with the echo-sounding data. Results show that annual sedimentation in the Sengguruh reservoir is predicted around 2, 148, 000 ton, while Sutami reservoir is around 1, 707, 600 ton. Comparing with the echo-sounding data from those reservoirs, the error percentages in volume of sedimentation are 9.5% and 13.6% respectively. Their effective storages are predicted full of sediment in 2.78 years and 147.6 years. Finally, the verification indicated that the proposed method is well applicable to predict the erosion-sedimentation and to evaluate the reservoir lifetime in this basin.Japan Society of Civil Engineers, 2005, Doboku Gakkai Ronbunshuu B, 49, 1063 - 1068, English
- The study uses a simple ecosystem model to grasp the relationship between the change in inundated areas (water level and flood extends) and the level of fish production in the TSB. The model produces the fish production trends in the TSB that can be refined to reflect the changes in key parameters such as flood extends and relative area density. It shows the continued dominance of the opportunist species in the TSB fish composition in the years to come. It reconfirms the importance of the hydrological and biological linkages between the TSB and the Mekong River Basin, since over 60% of the fish catch in the TSB is contributed by the white fish that mitigates to and from other parts of the Mekong River. It is an issue requiring a cross-sectroral and cross-bundary integrated planning and development.THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, 2005, Proceeding of Annual Conference, 18, 5 - 5
- The paper analyses the possible cumulative impacts of the hydropower and irrigation development, and climate change (as conceptual issue) in the Mekong River Basin, and the scope for balancing water availability and demand especially in the drier years, and to assess the flood conditions. The cumulative impacts from the key development svenarios are assessed by using a simple "spreadsheet" and simulated results of the selected development scinario. The assessment of flow changes is expexted by comparing pre-difined river flow -'baseline' flow series at the selected assessment points (APs) along the Lower Mekong River starting from Chiang Saen to Kratie with the assumed changes in flow. The study results show remarkable change in flow regime of the Mekong Basin. These changes are expexted to have different implication for diffrent stretches of the river and to diffrent water use sectors and ecology. It serves as a good indicative for the furture development of the sustainable waterpolicy for the Mekong Basin.THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, 2005, Proceeding of Annual Conference, 18, 76 - 76
- The authors conducted a set of survey on suspended sediment transportation in the Kataniwa River, during the flood on September 22nd '96, and June 19th '97, and found out that the peak of wash load concentration appeared earlier than the peak of discharge, and fluctuation of wash load concentration followed the fluctuation of the rainfall intensity. To investigate these phenomena, a numerical simulation model, which describes the run-off of water and sediment transportation on the Kataniwa river basin, was developed. The model was given two processes of sediment transportation; wash load yields by the impact of raindrops and surface flow on the surface of basin, and suspended load yields in the channel. The result of simulation showed fairly good agreement with the observed data.Japan Society of Civil Engineers, Aug. 2004, Doboku Gakkai Ronbunshu, (768) (768), 33 - 43, Japanese
- 水文・水資源学会, 2004, 水文・水資源学会研究発表会要旨集, 17, 246 - 247, Japanese
- Formation of a terrace in the curved channel widened by implementation on the Hinuma riverAccretion of the point bar at a widened curve on the Hinuma River was observed from 1990 to 1997 by cross sectioning conducted after main floods. The elevation had reached to that of neighboring terrace at the end of surveying. From the investigation, the authors recognized that springing of vegetation on the point bar triggered the accretion. A numerical simulation lent credence to the hypothesis. And the simulation suggested that advection of suspended load was the most important factor for the simulation of local depositions such as the accretion of a point bar.TSINGHUA UNIVERSITY PRESS, 2004, PROCEEDINGS OF THE NINTH INTERNATIONAL SYMPOSIUM ON RIVER SEDIMENTATION, VOLS 1-4, 1802 - 1809, English[Refereed]International conference proceedings
- Bed elevation variations inside the Mega-Dike system in the Pasig-Potrero river basin using a 2D numerical model of mudflowsEquations of erosion/deposition rate of suspended sediment were used in the 2D numerical mudflow model developed by Miyazawa et al. (2002). The previous mudflow model is improved in the present study by using the equations of erosion/deposition rate applicable to mudflow, which were determined empirically by laboratory tests from Hirano et al. (1997), Egashira et al. (1993) and Winterwerp et al. (1990). The erosion/deposition rates are related with the hindered settling velocity. The revised model was applied to compute the bed elevation variations inside the Mega-Dike system in the lower Pasig-Potrero river basin. It is found that the simulated bed variation is in reasonable agreement with the measurements.MILLPRESS SCIENCE PUBLISHERS, 2003, DEBRIS-FLOW HAZARDS MITIGATION: MECHANICS, PREDICTION, AND ASSESSMENT, VOLS 1 AND 2, 659 - 670, English[Refereed]International conference proceedings
- The authors conducted a set of survey on wash load transportation at the two sites in the Hinuma River, during a fl ood on June 19th, 1997, and found out a decrease in wash load concentration between the upper site (46.0km) and the lower site (28.1km). A numerical simulation was carried out to investigate causes of the decrease. CIP scheme was introduced to solve the unsteady advection-diffusion equation in the model of wash load transportation model. Results of the simulation show that the advection dominated and the diffusion did not in the process of the wash load transportation, and lateral outflow of wash load, which was caused by the trapping of vegetation, was one of the causes of the decrease in wash load concentration.土木学会, 2003, 水工学論文集, 第47巻, pp.691 - 696, JapaneseScientific journal
- In this study, we investigate the effect of size distribution of rain drop on the wet deposition of nitrate. The numerical acid rain model which uses the bin method for calculating the cloud microphysical processes is used for the investigation. The results are as follows, i) rain which mainly consists of large size droplets makes much amount of wet deposition of nitrate, ii) accumulated rainfall amount is important to estimate the amount of wet deposition of nitrate, iii) spatial variation of wet deposition of nitrate is large, and iv) wet deposition of nitrate can be estimated by space borne radar with considering the graupel fall.土木学会, 2003, 水工学論文集, 第47巻, pp.115 - 120, JapaneseScientific journal
- 水文・水資源学会, 2003, 水文・水資源学会誌, 16(5) (5), 501 - 517, EnglishScientific journal
- 水文・水資源学会, 2002, 水文・水資源学会研究発表会要旨集, 15, 226 - 227, Japanese
- A 2D numerical modeling of mudflow and its applicability to the Mt. Pinatubo area, PhilippinesOwing to the historical eruption of Mt. Pinatubo in the Philippines on June 15, 1991, in the rainy season, the mudflow (lahar) flowed and deposited in the downstream area and brought serious damage to several villages. In order to conduct proper countermeasures against the mudflow hazard, it is necessary to estimate the deposited area of mudflow exactly. In this paper, a two-dimensional numerical model of the mudflow was developed. The resistance law of the turbulent mudflow, which has been proposed by Arai and Takahashi [1], was used in the model. The model was applied to the overland mudflow in the southeast area of Mt. Pinatubo. It was found that the proposed model is useful to be applied to the overland mudflow by giving the proper topography.WORLD SCIENTIFIC PUBL CO PTE LTD, 2002, ADVANCES IN HYDRAULICS AND WATER ENGINEERING, VOLS 1 AND 2, PROCEEDINGS, 382 - 387, English[Refereed]International conference proceedings
- A study of the characteristics of suspended sediment load in the Kataniwa River basinThe authors conducted a set of survey on suspended sediment load transportation in the Kataniwa River, during the flood on June 22nd-23rd'97, and analyzed the concentration of suspended sediment. The following relationships are found out through the analysis; 1) the shape of suspended load flux hydrograph is corresponding to the discharge hydrograph, 2) on the other hand, the one of wash load is not corresponding to the discharge hydrograph, but to the hyetograph. These relationships lead to the hypothesis that the suspended load yields at the riverbed and is transported with the flood flow, and that the wash load yields at the surface of the basin and pours into the channel rapidly. To investigate a mechanism of these relationships, a numerical model which evaluates concentration of suspended sediment load on a tributary basin, was newly developed. Two types of the sediment yield model were demonstrated in accordance with gain size. The larger coarser grain size was produced at the riverbed, and the smaller finer size like wash load was produced on the surface of the basin. The results of the simulation of suspended load show fairly good agreement with the observed data.WORLD SCIENTIFIC PUBL CO PTE LTD, 2002, ADVANCES IN HYDRAULICS AND WATER ENGINEERING, VOLS 1 AND 2, PROCEEDINGS, 243 - 248, English[Refereed]International conference proceedings
- 土木学会, 2002, 水工学論文集, 第46巻, pp.1 - 6, JapaneseScientific journal
- 土木学会, 2002, 水工学論文集, 第46巻, pp.941 - 946, JapaneseScientific journal
- 土木学会, 2002, 水工学論文集, 第46巻, pp.31 - 36, JapaneseScientific journal
- In flood control, the decision support information made by short-term severe rainfall prediction methods and flood control support systems are indispensable for quick and appropriate operation. On the other hand, it is difficult to forecast the weather of meso-β to γ scales numerically because of limited computational resources, stability of calculation, time and cost for computer and exactness of calculation. In this paper, based on these background, we develop the qualitative short-term severe rainfall prediction method using artificial intelligence for practical use in order to apply to river site by forecasting the time series variation of distribution of severe rainfall having a lead time of six hours, automatically.土木学会, 2001, 土木学会論文集, 2001(691) (691), 13 - 23, JapaneseScientific journal
- 電気通信学会, 2001, 電子情報通信学会, Vol.J84-B No.12, Japanese火山地域におけるGPS測位に及ぼす局地的な水蒸気変動の影響についてScientific journal
- Analysis of Temporal and Spatial Change of a Convective Thunder Storm in Tokyo Metropolitan using GPS Precipitable Water : Case Study on 23rd August in 1997.The temporal and spatial relationships between GPS precipitable water vapor (GPS-PWV) and rainfall intensity (RI) on an event of strong convective thunder storm in the Tokyo metropolitan area were investigated. RINEX, one of the standard format of GPS raw data and supplied from Geographical Survey Institute of Japan, were converted to GPS-PWV by GAMIT software on 30 min basis. The following results were obtained ; (1) A rapid increase of GPS-PWV can be observed 1 to 2 hours before a beginning of sever rainfall, (2) The hourly increment of GPS-PWV has a strong correlation with the possibility and amount of increasing of one hour later RI, and (3) GPS-PWV begins to decrease at the peak of RI. These results suggest the promising availability of GPS-PWV as one of the prior-signals of strong convective thunder storms.日本気象学会, 2000, Tenki, 47(1) (1), 7 - 15, JapaneseScientific journal
- 土木学会, 2000, Annual Journal of Hydranlic Engineering, JSCE, 第44巻, 67 - 72, JapaneseScientific journal
- 土木学会, 1999, Annual Journal of Hydranlic Engineering, JSCE, 第43巻, 251 - 256, JapaneseScientific journal
- 土木学会, 1998, 水工学論文集, 第42巻, 13 - 18, JapaneseScientific journal
- 京都大学防災研究所, 1997, Annuals of Disas. Prev. Res. , Kyoto Univ., 40(B-2) (B-2), 307 - 322, JapaneseNumerical Analysis of Effect of Topography on Severe Rainfall in Baiu Se ason using Cumulus Microphysical ModelResearch institution
- 土木学会, 1997, 水工学論文集, 第41巻(41) (41), 117 - 112, JapaneseScientific journal
- 京都大学防災研究所, 1997, Annuals of Disas. Prev. Res. Inst. , Kyoto Univ., 40(B-2) (B-2), 245 - 262, JapaneseEstimation Method of Probable Maximum Precipitation for Short Duration in Sm all Areas using a Convective Simulation ModelResearch institution
- 京都大学防災研究所, Apr. 1996, 京都大学防災研究所年報, (39) (39), 285 - 299, JapaneseSYNTHETIC OBSERVATION OF ATMOSPHERIC BOUNDARY LAYER IN THE LAKE BIWA PROJECT '95
- 京都大学防災研究所, 1996, Annuals. Disas. Prev. Res. Inst. , Kyoto Univ., 39(B-2) (B-2), 251 - 269, JapaneseNumerical Approach on the Effect of Mountainous Topography to Development of Severe RainfallResearch institution
- 2021, 砂防学会研究発表会概要集(Web), 2021土石流による地形変化と降雨流出・氾濫の予測型シミュレーション
- 2020, 土木学会関西支部年次学術講演会講演概要集(Web), 2020レーダによる大気上層の降水粒子判別と詳細な雲微物理過程モデルを用いた降雨強度推定
- 土木学会, 2020, 水工学論文集 Annual journal of Hydraulic Engineering, JSCE, 65, Ⅰ_199 - 204, JapaneseSTUDY ON DROP SIZE DISTRIBUTION MEASUREMENT IN CLOUD BY USING VIDEO SONDE AND SCALE-RM
- 土木学会, 2019, 水工学論文集 Annual journal of Hydraulic Engineering, JSCE, 64, I_1177 - 1182, JapaneseCALCULATION OF VERTICAL WIND SPEED PROFILE WITH VIDEO SONDE AND CLOUD MICROPHYSICAL ANALYSIS
- 2019, 気象研究ノート, (240) (240)降雪雲の雲物理・降雪種
- 20 Jul. 2018, 気象研究ノート, (237) (237), 84‐157, Japanese気象レーダー60年の歩みと将来展望 第3章 大学における気象レーダーの研究・利用
- Jun. 2018, AOGS, EnglishIntegrated Research on State-of-the-Art Multi-Sensors In-Situ Observation of Storm Genesis and Reduction of Serious Disaster Due to Heavy Rainfall
- 2018, 気象研究ノート, (237) (237)気象レーダー60年の歩みと将来展望 第1章 メーカーにおける気象レーダーの開発
- May 2017, 日本気象学会2017年度春期大会偏波レーダーを主としたマルチセンサーによる積乱雲の生成と発達を捉えるフィールド観測
- Springer Singapore, 01 Jan. 2016, Sustainable Water Resources Planning and Management Under Climate Change, v - vi, EnglishOthers
- This book discusses different aspects of water resources, ranging from hydrology and modeling to management and policy responses. Climate changes and the uncertainty of future hydrological regimes make sustainable water resources management a difficult task, requiring a set of approaches that address climate variability and change. The book focuses on three main themes: hydrological changes, adaptive decision-making for water resources, and institutional analysis and risk management. It discusses the applications and limitations of climate change models and scenarios related to precipitation projection, which predicts to the future availability of water. It also offers interesting examples from around the globe to describe the policy options for dealing with climate change. Addressing emerging issues that need to be resolved and techniques that can be applied for sustainable climate-change-sensitive water resources protection and management, this practical, state-of-the-art reference book is a valuable resource for researchers, students and professionals interested in sustainable water resources management in a changing climate.Springer Singapore, 01 Jan. 2016, Sustainable Water Resources Planning and Management Under Climate Change, 1 - 303, EnglishOthers
- 日本気象学会, 2015, 大会講演予講集, 108, 210 - 210, JapaneseP130 MPレーダーを用いた霰の電荷量と電場の推定(ポスター・セッション)
- 日本気象学会, 2015, 大会講演予講集, 108, 402 - 402, JapaneseP322 孤立峰の斜面上に大雨をもたらした対流性降水システムの構造(ポスター・セッション)
- 日本気象学会, 2015, 大会講演予講集, 108, 415 - 415, JapaneseP335 小型Xバンド二重偏波レーダーを用いた雹の観測(ポスター・セッション)
- 日本気象学会, 2015, 大会講演予講集, 107, 105 - 105, JapaneseP117 高分解能気象レーダーを用いた都市小河川の水位推定(ポスター・セッション)
- 日本気象学会, 2015, 大会講演予講集, 107, 106 - 106, JapaneseP118 2013年夏季における富士山周辺域での降雨分布とその要因について(ポスター・セッション)
- 日本気象学会, 2015, 大会講演予講集, 107, 90 - 90, JapaneseP102 Dual-Doppler法による風速場解析(ポスター・セッション)
- 日本気象学会, Oct. 2014, 日本気象学会2014年度秋期大会, 106, 90 - 90, Japanese沖縄集中観測キャンペーン2007-2014における成果と ビデオゾンデによる雲微物理観測の可能性
- Sep. 2014, Abstracts of Cities on Volcanoes 8, EnglishApplication of X-band polarimetric weather radar to estimate volcanic ash amount
- Water vapor that comes to flow from Osaka Bay becomes a cloud in Osaka or near Kobe , move clouds while development along the Yodogawa then , Kyoto, Kameoka heavy rain in July 2012 , and Uzi heavy rain in August 2012 is , northern Osaka I have (called Yodogawa line ) mechanism that brought heavy rain and in Kyoto . In order to capture the generation and development of cumulonimbus series of these , in addition to the polarization radar network of X-band and C-band of the Ministry of Land, Infrastructure and Transport , which are in place in the Kinki , in 2011 , the X-band polarimetric radar that was installed on its own was installed each water vapor observation , at sea coming to flow from Osaka Bay by installing a ferry or buoy RHI observation and deployment that targets the Osaka bay mouth by , cloud observations with millimeter-wave radar , a GPS receiver . I managed to video soundings in the urban areas for the first time in 2012 . In 2013 , I went experimental observation project in cooperation with separately , that RHI synchronization observe the four azimuth every 2 minutes for each Doppler lidar , millimeter wave radar , the X-band polarimetric radar . It performs a vertical cross-sectional comparison on the development of clouds and airflow change , the development of clouds and convergence of air flow corresponds well have been revealed .THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, Sep. 2014, Proceeding of Annual Conference, 27, 100037 - 100037, Japanese
- 日本気象学会, 2014, 大会講演予講集, 105, 310 - 310, JapaneseP334 ドップラーライダーにより観測された六甲おろしの構造(ポスターセッション)
- 日本気象学会, 2014, 大会講演予講集, 106, 466 - 466, JapaneseP345 複数のGPS受信機を使用した天頂大気遅延量の解析(ポスター・セッション)
- 日本気象学会, 2014, 大会講演予講集, 106, 463 - 463, JapaneseP342 偏波レーダーと雷探知装置を用いた前線通過に伴う雷と降水セルに関する研究(ポスター・セッション)
- 日本気象学会, 2014, 大会講演予講集, 106, 567 - 567, JapaneseB367 2014年2月14-15日に甲府盆地にもたらされた南岸低気圧に伴う豪雪の特徴と形成過程(南岸低気圧による大雪:その要因,実態,予測可能性,スペシャル・セッション)
- 日本気象学会, 2014, 大会講演予講集, 106, 272 - 272, JapaneseP190 超高解像レーダーと移流モデルを用いた降雨予測場に関する研究(ポスター・セッション)
- Recently, disaster due to localized heavy rainfall is noticeable under climate change and urbanization. Although prediction accuracy of heavy rainfall in large spatial scale is getting higher and higher, it is still difficult for localized heavy rainfall in smaller spatial scale to be even reproduced. Moreover, earlier detection and prediction of localized and suddenly generated heavy rainfall (so called guerrilla heavy rainfall) are very important, even if the time lag is five to ten minutes. Also, prediction and early warning of flash flood are expected. Under these circumstances, this scientific integrated research aims to execute in-situ campaign observations of precipitation using a video-sonde synchronized with the latest polarimetric Doppler radar which is expected to be effective in the rainfall estimation and prediction. Also, this research aims to develop methodologies for reducing water related disaster.THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, 25 Sep. 2013, Proceeding of Annual Conference, 26, 16 - 16, Japanese
- 日本気象学会, 2013, 大会講演予講集, 104, 279 - 279, JapaneseP195 ビデオゾンデ及びCバンド偏波レーダーを用いた氷粒子観測(ポスター・セッション)
- 日本気象学会, 2013, 大会講演予講集, 104, 198 - 198, JapaneseP114 超高解像レーダーと移流モデルを用いた降雨予測場の誤差評価に関する研究(ポスター・セッション)
- 日本気象学会, 2013, 大会講演予講集, 104, 203 - 203, JapaneseP119 ビデオゾンデと偏波レーダーCOBRAとの同期観測による雲物理情報と偏波パラメータの関係(ポスター・セッション)
- 日本気象学会, 2013, 大会講演予講集, 104, 216 - 216, JapaneseP132 冬季の南岸低気圧に伴う甲府盆地の降雷の事例解析(ポスター・セッション)
- 日本気象学会, 2012, 大会講演予講集, 101, 116 - 116, JapaneseD158 夏季に山岳域で長時間維持した積乱雲に伴う豪雨の形成(都市域における極端気象のメカニズム解明,専門分科会)
- 日本気象学会, 2012, 大会講演予講集, 101, 110 - 110, JapaneseD152 最新型偏波レーダーとビデオゾンデの同期集中観測と水災害軽減に向けた総合的基礎研究(都市域における極端気象のメカニズム解明,専門分科会)
- 日本気象学会, 2012, 大会講演予講集, 102, 205 - 205, JapaneseP121 台風1115号の通過に伴う盆地内斜面上の豪雨の形成(ポスター・セッション)
- 日本気象学会, 2012, 大会講演予講集, 102, 486 - 486, JapaneseP312 新型ビデオゾンデ受信機を用いた沖縄梅雨期のビデオゾンデ連続観測(ポスター・セッション)
- 日本気象学会, 2011, 大会講演予講集, 100, 403 - 403, JapaneseP154 夏季に山岳域で長時間停滞かつ維持した積乱雲を構成する降水セルの振る舞いと構造(ポスター・セッション)
- This paper introduces the basic theory of advanced weather radar which consists of polarimetric technique and dopplar measurement. Moreover, equations representing the cloud microphysical processes for both precipitation particls development and air mass movement are explained briefly.THE JAPANESE SOCIETY FOR MULTIPHASE FLOW, Apr. 2010, 混相流, 第24巻2号pp.154-161(2) (2), 154 - 161, JapaneseIntroduction scientific journal
- 日本気象学会, 2010, 大会講演予講集, 97, 335 - 335, JapaneseP419 X-バンド二重偏波ドップラーレーダーで観測された夏季に短時間の豪雨をもたらせた降水システムの構造(ポスターセッション)
- 日本自然災害学会, 2010, Journal of Japan Society for Natural Disaster Science, 28(4) (4), 357 - 369, JapaneseStudy on the effect of disaster prevention education to pupils with considering regionality
- Jan. 2010, 土木学会誌, Vol. 95, No. 2, pp. 30-33, Japaneseフィリピン・台風災害調査報告(速報)Others
- Jan. 2010, 平成21年度河川災害シンポジウム概要集, pp. 38-47, Japanese2009年フィリピン台風災害調査報告Others
- Study of comprehend of children's memory constitution for disaster prevention education using a video-storyThis study aims to obtain psychological aspect of children for understanding memories of disaster prevention education materials. For this purpose attitude surveys were conducted. First, a video-story was created from past landslide disaster at Mukawa of Yamanashi Prefecture in 1959. The story contains a lesson about the disaster. From the video-story, the memories of children were analyzed by dividing the video-story into illustrations and narrations. The main finding of analysis shows that a possibility that the illustrations and the narrations of the scenes chosen by children had emotional stimuli (emotional arousal) which made the children's preserve their memories.自然災害科学会, 2009, Journal of Japan Society for Natural Disaster Science, 27(4) (4), 401 - 413, Japanese
- 日本気象学会, 2009, 大会講演予講集, 96, 320 - 320, JapaneseD358 山梨大学X-バンド二重偏波ドップラーレーダーで観測された降水システムの初期観測結果(観測手法)
- 2009, 日本気象学会大会講演予稿集, (96) (96)沖縄偏波降雨レーダーCOBRAとビデオゾンデによる同期観測-2009年ビデオゾンデ観測の概要-
- Jun. 2008, 京都大学防災研究所年報(CD-ROM), (51) (51), ROMBUNNO.51B,3, Japanese中央アジア・キジルクム砂漠における地表面フラックス観測
- Study on identification of rainfall particle by using MRR based on cloud microphysical processOne of the most important problems to improve the accuracy of rainfall intensity estimation by radar is identification of type of precipitation droplets. The type of precipitation droplets are basically classified into two, ice and liquid. And then, difference of the characteristics of scattering of microwaves among the types of precipitation droplet takes effect to accuracy of rainfall intensity estimation. This study proposes a method to identify the phase of precipitation droplets by using MRR and cloud microphysical processes.日本流体力学会, 2008, 日本流体力学会年会講演論文集, 2008, 132 - 132, Japanese
- 2008, 京都大学防災研究所年報(CD-ROM), (51) (51)Classification of Hydrometeors Using a C-band Polarimetric Radar and Validation by In-Situ Campaign Observation Synchronized with Video-Sonde
- 2008, 日本農業気象学会全国大会講演要旨, 2008降水量推定・降水予測の高精度化のための偏波降雨レーダーCOBRAとビデオゾンデによる雲微物理同時観測
- 日本計算工学会, 31 Jul. 2007, Journal of the Japan Society for Computational Engineering and Science, 12(3) (3), 1623 - 1626, JapaneseZen and Art of Weather Forecasting as a Numerical Science
- 砂防学会, 15 Jan. 2007, Journal of the Japan Society of Erosion Control Engineering, 59(5) (5), 23 - 34, JapaneseDevelopment of 2D numerical model of mudflows for estimation of sediment deposition in volcanic basins
- 2006, Annual Journal of Hydraulic Engineering, JSCE, 50, 101 - 106
- 2006, 水工学論文集, 50, 881 - 886
- 日本気象学会, 2006, 大会講演予講集, 89, 191 - 191, JapaneseC308 レーダーを用いた台風内部のメソ擾乱組織の形成・破壊過程に関する研究(台風)
- 2005, 水文・水資源学会誌, 18(5) (5), 584 - 591
- 水利科学研究所, 2005, 水利科学, 48(6) (6), 64 - 80, Japanese河川・渓流の環境整備のための地域住民の参加の方法に関する研究(2)
- 日本気象学会, 2005, 大会講演予講集, 88, 388 - 388, JapaneseP191 高性能偏波レーダーを用いた台風の発生・発達メカニズムに関する研究
- 2004, 水工学論文集, 48, 283 - 288
- 水利科学研究所, 2004, 水利科学, 48(5) (5), 36 - 63, Japanese河川・渓流の環境整備のための地域住民の参加の方法に関する研究(1)
- Debris-flow capturing effect of grid type steel-made sabo dam using 3D distinct element methodIn recent years, a grid type steel-made sabo dam has become increasingly popular from the merits as the capture of debris flow, the permeability of sediment discharge in small and medium flood, and the cost performance. In order to manage the sediment in the river basin, it is necessary to estimate the debris flow capturing effect of the sabo dam quantitatively. It is considered that the three-dimensional interlocking of sediment particles near the open spaces greatly affects the blocking of the grid type sabo dam. In this paper, a numerical model of the stony debris flow is developed by considering boulders as non-continuum (31) distinct element method) and considering the others as continuum. The validity of the model is examined by a comparison with the experimental results.MILLPRESS SCIENCE PUBLISHERS, 2003, DEBRIS-FLOW HAZARDS MITIGATION: MECHANICS, PREDICTION, AND ASSESSMENT, VOLS 1 AND 2, 1, 527 - 538, English
- 日本気象学会, 2003, 大会講演予講集, 83, 338 - 338, JapaneseP238 複数の乱流計測機を用いた乱流熱輸送量空間分布観測の概要 : 琵琶湖プロジェクト2002年集中観測(CAPS)
- 京都大学防災研究所付属水資源研究センター, Apr. 2002, 水資源研究センター研究報告, (22) (22), 152 - 157, EnglishEffect of water vapor on advection of convective rainfall cells around the Lake Biwa, Japan (Copies of English Papers by the 〔Water Resources Research〕Center Staff Published in the Fiscal Year of 2000)
- 京都大学防災研究所付属水資源研究センタ-, 2000, 水資源研究センタ-研究報告, (20) (20), 19 - 27, JapaneseGPS大気遅延量を用いた水蒸気擾乱の解析に関する研究
- 京都大学防災研究所, 2000, 京都大学防災研究所年報, (44) (44), 395 - 409, JapaneseDevelopment of the prediction model for acid rain and snow considering the detailed cloud microphysical processes
- 京都大学防災研究所, 1999, Annuals of Disas. Prev. Res. Inst. Kyoto Univ., 42(B-2) (B-2), 141 - 151, JapaneseExperimental Study on the Effect of Water Vapor in Boundary Layer on the Atmospheric Delay of GPS.
- 京都大学防災研究所付属水資源研究センタ-, 1998, 水資源研究センタ-研究報告, (18) (18), 257 - 266, EnglishAnalysis and Prediction of Rainfall for Hydrological Uses
- 京都大学防災研究所付属水資源研究センタ-, 1997, 水資源研究センタ-研究報告, (17) (17), 128 - 135, EnglishStudy on Effects of Updraft on Precipitation Processes Using Two-Dimensional Cumulus Model
- 京都大学防災研究所, 1997, 京都大学防災研究所年報, (41) (41), 181 - 200, JapaneseStudy on Development of a Short Term Rainfall Forecasting Method Using Qualitative Cumulus Model
- 01 Nov. 1996, Journal of hydroscience and hydraulic engineering, 14(2) (2), 81 - 88, EnglishSTUDY ON EFFECTS OF UPDRAFT ON PRECIPITATION PROCESSES USING TWO-DIMENSIONAL CUMULUS MODEL
- 1996, 土木学会第51回年次学術講演会第II部門概要集 , pp. 806-807, Japanese琵琶湖プロジェクト'95における大気境界層の同期観測
- 京都大学防災研究所, Apr. 1994, 京都大学防災研究所年報, (37) (37), p281 - 297, JapaneseNUMERICAL APPROACH TO EFFECT OF UPDRAFT ON LOCAL RAINFALL
- Joint work, 神戸大学出版会, Mar. 2019, Japanese地域と災害, 北後明彦, 災害から一人ひとりを守る 地域づくりの基礎知識４Scholarly book
- Contributor, 気象学会, 2019気象研究ノート，第241号「南岸低気圧にともなう大雪 III:雪氷災害と予測可能性」，5.2章「2014年2月14-15に南岸低気圧によりもたらされた南岸低気圧にともなう大雪の特徴」
- 神戸大学出版会,神戸新聞総合出版センター (発売), 2019, Japanese, ISBN: 9784909364050災害から一人ひとりを守る
- Joint work, 日本気象学会, 2018, Japanese気象研究ノート 第237号「気象レーダー60年の歩みと将来展望」，3.6章「Xバンドマルチパラメータレーダーによる甲府盆地の降水に関する研究」Scholarly book
- Joint work, 日本気象学会, 2018, Japanese気象研究ノート 第237号「気象レーダー60年の歩みと将来展望」，1.4章「小型Xバンド気象レーダーによるマルチレーダーシステム」Scholarly book
- Joint work, 日本気象学会, 2018, Japanese気象研究ノート 第236号「都市における極端気象の観測・予測・情報伝達」，3.6章「都市における極端気象の観測・予測・情報伝達」Scholarly book
- Joint work, Springer, Oct. 2016, English, ISBN: 9789811020513Sustainable Water Resources Planning and Management Under Climate ChangeScholarly book
- 京都大学防災研究所, 2016, Japanese大阪湾GPSと超高解像度レーダーを用いた大阪湾域の極端気象予測精度の向上に関する研究
- Joint work, ミネルヴァ書房, Oct. 2015, Japanese震災復興学 第14章地震に伴う土砂災害と市民の減災方法Scholarly book
- Springer science+business media Singapore, English, ISBN: 9789811020490Sustainable water resources planning and management under climate change
- 日本気象学会2023年度秋季大会, Oct. 2023, JapaneseSCALEを用いた神戸市の夏季熱環境評価 − その２：神戸市沿岸域における局地循環−Oral presentation
- 日本気象学会2023年度春季大会, May 2023, JapaneseSCALEを用いた神戸市の夏季熱環境評価Poster presentation
- 第21回応用力学講演会, 2018, Japanese, Domestic conferenceFDPSを用いたSPH法による斜面崩壊シミュレーションに関する基礎研究Oral presentation
- 水文・水資源学会2015年度総会研究発表会, Sep. 2015, Japanese, Japan Society of Hydrology and Water Resarouces, Domestic conference雷探知装置とMPレーダーによる雷機構解明に向けた事例解析Oral presentation
- 水文・水資源学会2015年度総会・研究発表会, Sep. 2015, Japanese, Japan Society of Hydrology and Water Resarouces, Domestic conference複数のＸバンドＭＰレーダーを用いた富士山周辺の降雨流出過程に関する研究Oral presentation
- 水文・水資源学会2015年度総会・研究発表会, Sep. 2015, Japanese, Japan Society of Hydrology and Water Resarouces, Domestic conference桜島における火山灰粒径分布測定に基づいた気象レーダーによる火山灰堆積量推定手法の開発に関する研究Oral presentation
- 日本気象学会2015年度秋季大会, Sep. 2015, Japanese, The Meteorological Society of Japan, Domestic conferenceMPレーダーを用いた霰の電荷量と電場の推定Oral presentation
- Hyper KANAKO研究会サマーセミナー, Sep. 2015, English, Domestic conferenceHyperKANAKO Application for Lahar Simulation in Gendol River, Merapi, Yogyakarta,Oral presentation
- 水文・水資源学会2015年度総会・研究発表会, Sep. 2015, Japanese, Japan Society of Hydrology and Water Resarouces, Domestic conferenceGPSを用いた大阪湾上の水蒸気移流推定に関する研究Oral presentation
- Japan Geoscience Union Meeting, May 2015, English, Japan Geoscience Union, Domestic conferenceXMP Radar application to optimize volcanic debris flow measurement in Merapi volcanoOral presentation
- The 36th IAHR World Congress, May 2015, English, International Association for Hydro-Environment Engineering and Research, Domestic conferenceStudy on efficiency improvement of train dispatch under severe rainfall by using radarOral presentation
- Japan Geoscience Union Meeting, May 2015, English, Japan Geoscience Union, Domestic conferenceDevelopment of Pedestrian Navigation System Using Short-Term Rainfall Prediction on SmartphoneOral presentation
- 34th IAHR World Congress, Jun. 2012, English, IAHR, Brisbane, Australia, International conferenceRainwater Catchment Systems Under Climate Change: An Assessment of Brazilian and Japanese CasesOral presentation
- 5th International Conference on Flood Management, Sep. 2011, English, Public Works Research Institute, Tokyo, Japan, International conferenceENSEMBLE SHORT-TERM RAINFALL-RUNOFF PREDICTION AND ITS APPLICATION FOR URBAN FLOOD RISK MAPPINGOral presentation
- The 13th International Summer Symposium of JSCE, Aug. 2011, English, Japan Society for Civil Engineers, Tokyo, Japan, International conferenceEnsemble Rainfall Short Term Prediction for Flood Disaster Prevention in Urban River BasinOral presentation
- 34th IAHR World Congress, Jun. 2011, English, IAHR, Brisbane, Australia, International conferenceEstimation of rainfall intensity by using X-Band Polarimetric Radar with raindrop falling trajectoryOral presentation
■ Works
- 2003 - 2008人口急増地域の持続的な流域水政策シナリオ
- 2003 - 2008SUNADA CREST
- 2002 - 2007アジアモンスーン地域における人工・自然改変に伴う水資源変動予測モデルの開発
- 2002 - 2007Research Revolution 2002 (Takeuchi)
- 2001 - 2006社会変動と水循環の相互作用評価モデルの構築
- 2001 - 2006TAKARA CREST
- 1997 - 2001GPS気象学
- 1997 - 2001GPS meteorology
- 1993 - 2001琵琶湖プロジェクト
- 1993 - 2001The lake Biwa Project
- 2000河川水辺の国勢調査の活用に関する研究
- 2000Utilization of River Sensus
- 1999水・人間・地球の相互作用を考慮した持続可能な水資源環境に関する国際水文学研究(ベトナム)
- 1999Water-Man-Earth Interactions and Sustainable Water Resources-Cooperation in East Asia and Oceania(Vietnam)
- 1998東南アジア・太平洋地域の流域水利用実態およびデータ環境の国際共同調査(豪州・ニュージーランド)
- 1998International Survey on Water Resources Usage and Data Environment of the Basin around South east Asia and Pacific Area(Australia and New Zealand)
- 日本学術振興会, 科学研究費助成事業, 基盤研究(B), 神戸大学, Apr. 2021 - Mar. 2024災害脆弱性を指標にした土砂災害起源の複合災害の条件付き災害発生確率に関する研究本課題では，洪水・土砂複合災害の結果としての浸水災害を対象にして，地域のリアルタイム浸水予測可能性を論じようとしている．具体的には，詳細な降雨分布や個別の斜面崩壊場所に依存して浸水が発生する集落の浸水発生の予測可能性を主な研究対象とし，異なる研究分野で開発されたHPCシミュレーションの手法に観測情報を組み合わせて高度化を実施している．その関係を知識として蓄えることでリアルタイム浸水災害発生を予測する可能性を論じる．具体的には，以下の項目を行ってきた． 土砂洪水氾濫シミュレーションによる土砂災害起源の洪水災害の脆弱性（山野井）：土砂の輸送・堆積過程を含む洪水土砂氾濫解析プログラムを用いて多数の土砂洪水氾濫シミュレーションを実施する仕組みを実装して，スーパーコンピュータ「富岳」を用いて多数シミュレーションを異なる対象地域で実施した． 多数の斜面崩壊シミュレーションによる斜面崩壊時の不安定土砂の量と流下距離の計算（竹山・大石）：斜面崩壊シミュレーションプログラムに地形と地質データを入力して実斜面スケールでの計算を実施する仕組みを実装して，スーパーコンピュータ「富岳」およびOakforest-PACSで計算実行した．詳細な気象シミュレーション（富田・梶川）：平成30年西日本豪雨を対象に大雨発生事例をスーパーコンピュータ「富岳」で詳細に再現して降雨情報提供に目処をつけた．異なるHPCI-IDシミュレーションの連結（大谷・竹山・山野井・大石）：データ処理プラットフォームを用いて高精細気象シミュレーションと洪水土砂氾濫解析を疎結合することを試み，ライブラリの構成，スクリプトを用いてライブラリを活用する方法を取りまとめた．角田地区での斜面崩壊実験によるシミュレーション精度検証（阿波田・竹山・大石）：実施準備をして2022年度の実施計画を立てた．
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Special Purposes, Chiba University, Oct. 2019 - Mar. 2021Investigation of the effects of long-term power outage due to the 2019 typhoon FaxaiA powerful typhoon Faxai, the 15th typhoon in 2019, made landfall in Tokyo’s neighboring Chiba Prefecture around 5:00 a.m. on September 9. It caused severe structural damage especially in the southwestern part of Chiba Prefecture. It also triggered extensive and continued power outage in Chiba Prefecture. Power supply was disrupted at approximately 640 thousand houses in Chiba Prefecture as of 10:30 am on September 9. The power failure continued for about two weeks mainly in the southern part of Chiba Prefecture. In this study, various functional and structural damage caused by this typhoon was investigated. In Japan, it is anticipated that extensive power outages may occur after the Tokyo Inland and the Nankai Trough earthquakes in the near future. This study will be helpful to establish a resilient water supply system against future earthquakes.
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (B), Yamaguchi University, Apr. 2018 - Mar. 2021Development of a new 400MHz radiosonde sensor to measure the electric charge of precipitation particles in cloudsKnowledge of the electric charge of precipitation particles in thunderclouds is essential for understanding the mechanism of lightning generation. However, there has been no low-cost, easy-to-use meteorological observation device to measure it. Therefore, in this study, we developed a new, compact, lightweight, low-cost, and user-friendly sensor (EC sensor) equipped on the 400 MHz radiosonde. This new EC sensor can be attached to a balloon and released into a thunderstorm cloud, and the amount of positive and negative charge and the number of particles detected by the sensor every second can be monitored on the ground in real time. Although the COVID-19 epidemic prevented sufficient test flights, the new charge sonde was completed through prototype design, ground testing, and the development of data recording software.
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (S), Kyoto University, May 2015 - Mar. 2020Integrated Research on State-of-the-art Multi-sensors In-situ Observation of Storm Genesis and Reduction of Serious Disaster due to Heavy RainfallAn integrated research has been conducted to mitigate water related disasters caused by localized heavy rainfall and “guerrilla-heavy rainfall”. Multi-sensors observation toward the understanding of storm-genesis and its development was carried out at Keihanshin region and Okinawa. We have identified the structure of pairs of positive/negative vertical vortex tubes at the storm-genesis, and discovered a developing storm possesses a hierarchical structure of the vertical vortex tubes in a sense of spatial scale. Our new findings have activated a new way for the earlier risk prediction system by enhancing its practical utilization, which is one of our great contributions to the society as well as the related research area.
- 科学研究費補助金／基盤研究(B), Apr. 2016 - Mar. 2019, Principal investigatorCompetitive research funding
- 学術研究助成基金助成金／挑戦的萌芽研究, Apr. 2016 - Mar. 2019, Principal investigatorCompetitive research funding
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Challenging Exploratory Research, Kyoto University, Apr. 2016 - Mar. 2018Establishment of an immediate determination method for indicators on eruption scale and strength using data of typical volcano monitoring instruments and weather radarsWe obtained the seismic and acoustic energies and durations of 2014 and 2015 eruptions of Kuchinoerabujima. We estimated the altitude of the eruption plume by a force at the seismic source and compare with the plume altitude by visual observation for the 2015 eruption. We compared seismic waveforms and tilt changes of eruptions in Japan and clarified common features of the eruptions of Kusatsushiranesan, Ontakesan and Kuchinoerabujima. We detected the radar reflection intensity corresponding to eruption plumes of Sakurajima and Shinmoedake. We estimated the plume height of the Sakurajima eruption on November 13, 2017 as 4 km by using the radar reflection intensity, although the visual plume height was unknown due to bad weather. By comparing the radar reflection intensities of the 2017 and 2018 eruptions of Shinmoedake with the plume altitudes by visual observation, we accumulated the basic data for establishing a method for estimating altitudes of eruption plumes using weather radars.
- 日本学術振興会, 科学研究費助成事業, 基盤研究(A), 京都大学, Apr. 2015 - Mar. 2016マルチセンサー・ビデオゾンデ同期観測によるゲリラ豪雨タマゴの生起と発達過程の解明本基盤研究（A）を内包する基盤研究（S）の採択通知を5月29日に得て、5月29日からは基盤研究（S）としての研究活動に移行している。本基盤研究(A)は3年計画で「豪雨のタマゴの生成過程の研究」を重点的に実施することを目的とするのに対して、基盤研究(S)は5年計画で、本研究内容に加え、都市域で世界初観測となる境界層レーダと最先端レンジイメージングを導入して高時間・空間分解能での境界層観測を実現し、より年数をかけて豪雨のタマゴの生成過程の研究を実施するとともに水災害への応用研究も実施する。 こういった状況の中、4月にはキックオフ研究会を実施し、3年計画の場合、さらには5年計画が実現した場合のそれぞれについて、研究計画や沖縄・ならびに神戸～京都の観測計画の精緻化、共有化を行い、研究のスタートを切った。5月には、本計画で観測情報の利用を想定している別資金による小型レーダの導入に備えて、一部メンバーが新たに第2級陸上特殊無線技士養成課程講習を受講し免許の取得を行うとともに小型レーダの情報の取得体制を整えた。また、気象庁でのメソ気象研究会や日本気象学会専門セッションで本研究計画の紹介を行った。 以上のように、4月～5月にかけて、今年度スタートした基盤研究（A）ならびにそれを内包する基盤研究（S）の計画面、観測面、広報面すべてにおいて研究活動の実質的なスタートを切った。そして、本基盤研究（A）を内包する基盤研究（S）の採択通知を5月29日得て、5月28日で本基盤研究（A）としての活動を終了し、5月29日からは基盤研究（S）としての研究活動を開始した。
- 科学研究費一部基金／基盤研究(B)特設, Apr. 2013 - Mar. 2016, Principal investigatorCompetitive research funding
- 下水道革新的技術実証事業（B-DASHプロジェクト）, 2016, Principal investigator都市域における局所的集中豪雨に対する雨水管理技術実証事業Competitive research funding
- 研究成果最適展開支援プログラム（A-STEP）, 2016, Principal investigatorリアルタイム短時間降雨予測技術開発と3次元観測マルチレーダーシステムの実用性検証Competitive research funding
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (S), Kyoto University, Apr. 2010 - Mar. 2015Scientific and Integrated Research by In-situ Campaign Observations Synchronizing Video-sonde and the Latest Polarimetric Radar, Heading for Reduction of Water Related DisasterAn integrated research has been conducted to reduce water related disasters caused by localized heavy rainfall and “guerrilla-heavy rainfall”. During the in-situ observations, newly developed videosonde system was utilized to understand the life stages of convective clouds by synchronizing it with the polarimetric radar. And, another fundamental observations toward understanding storm-genesis was started over heat-island urban, by utilizing multi-sensors observations. Valuable data collected during the in-situ observations provide important information to the consequent researches, such as numerical modeling of cumulonimbus cloud, developing a method of rainfall prediction, and establishing an earlier-alert system. The earlier detection and risk prediction system for guerrilla-heavy rainfall is under test operation by the River Bureau of Japan, for its practical utilization, which is one of our great contributions to the society and the related research area as well.
- 科学技術振興機構, 研究成果最適展開支援プログラム 産学共同促進ステージ ハイリスク挑戦タイプ, 2015, Principal investigatorA-STEP「リアルタイム短時間降雨予測技術開発と3次元観測マルチレーダーシステムの実用性検証」Competitive research funding
- 研究成果最適展開支援プログラム 産学共同促進ステージ ハイリスク挑戦タイプ, 2014, Principal investigatorA-STEP「リアルタイム短時間降雨予測技術開発と3次元観測マルチレーダーシステムの実用性検証」Competitive research funding
- 研究成果最適展開支援プログラム シーズ顕在化タイプ, 2013, Principal investigatorA-STEP「超高時空間分解能を有するリアルタイム降雨予測技術の研究開発」Competitive research funding
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (C), Kobe University, 2010 - 2012, Principal investigatorIn the present study, we developed methods, algorithms and computer systems which reduce floods in urban area by optimizing the releasing discharge from smaller reservoir. Specifically, we developed hydrological simulators based on distributed hydrological model in which rainfall information from radar with some extent of error which was quantitatively utilized for giving probabilistic flood forecasting. Then, an optimized method was applied for flood control using reservoir with stochastic flood forecast. First, a probabilistic method for short term rainfall forecast was achieved by using radar echo extrapolation method with singular vector for making probabilistic ensembles. Then, a hydrological model which also deals with probabilistic spread based on generalized likelihood uncertainty estimation (GLUE). Second, an optimized control algorithm using Dynamic Programming has been applied for flood control by using reservoir. In the present study, we use Stochastic Dynamic Programming (SDP) for dealing with weekly ensemble weather forecasting issued from Japan Meteorological Agency (JMA). In the SDP, objective function was minimizing the water level at a point in lower river basin. The result of the SDP with weekly ensemble weather forecasting made water level reduced and the objectives of the present study has been achieved.Competitive research funding
- 研究成果最適展開支援プログラム シーズ顕在化タイプ, 2012, Principal investigatorA-STEP「超高時空間分解能を有するリアルタイム降雨予測技術の研究開発」Competitive research funding
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (A), Kyoto University, 2007 - 2009Improvement of Rainfall Estimation and Rainfall Prediction Using the Next Generation Polarimetric Radar and Its Impact Evaluation for Water ManagementWith a view to improve quantitative precipitation estimation and forecast for river control, the campaign observation of the next generation polarimetric radar synchronized with videosonde were carried out in Okinawa. As the result, the method of estimation of the drop size distribution and the type of precipitation particles using the polarimetric radar data was developed. Moreover, the advanced techniques of QPE and QPF were brought to realization by applying the estimation method to the numerical weather prediction, or by deeply understanding of precipitation mechanism.
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (B), University of Yamanashi, 2006 - 2008Development of Sedimentation Tracking Method based on Quantitative and Qualitative Component of River Bed本研究では,流入土砂量の他に礫種構成比,X線回折法を用いた細粒土砂の鉱物構成比,細粒土砂の粒径分布比を用いた土砂生産源の追跡方法を開発してきた. また,微地形,土地利用状況,雨滴衝撃エネルギーを考慮して新たな2 つのタイプの土砂生産モデルを開発した.
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (B), Chuo University, 2005 - 2008Formulation of precipitation、 atmospheric environment and water circulation model based on cloud physics experiment雲物理過程解明のために行った実験よりエアロゾル量の増加に伴い雲水量も増加するがエアロゾル量が閾値を超えると生成される雲水量が一定になり飽和状態になる。また上昇風速が大きくなればなるほど雲水量が増加することがわかった。ヒートアイランドを緩和させる効果のある河川周辺で行った微気象観測により河川の大きさに関わらず水面付近の気温は周囲より低く、河川上の冷気が運ばれやすい風道がある場所の気温は2~3℃周囲より低いことがわかった。
- 日本学術振興会, 科学研究費助成事業, 若手研究(B), 山梨大学, 2004 - 2006気候変動と都市化を考慮した豪雨災害リスク算定に関する研究本研究では数10分から数時間程度の可能最大降水量の算出を試み,それが気候変動や都市化に与えている影響について考察した.本研究で得られた最大の成果は,実測の雨滴粒径分布の鉛直プロファイルデータを解析することによって,降雨の時間スケール特性を規定している特徴を捉えることに成功したことである.すなわち,1時間を超える時間スケールの降雨を対象にした場合には,降雨量は上空雨水量の総量と正のよい線形相関関係を持つこと,および1時間未満の時間スケールの降雨を対象にした場合には,降雨量は落下速度の鉛直プロファイルによって規定されていることを見いだした.特に,1時間未満の時間スケールの降雨は上空1000mから400mにおける雨滴の落下速度の変化が多きときに降雨量が大きくなる関係を用いて,可能最大降水量を定量化した.一方,1時間を超える時間スケールでは上空雨水量の総量はTRMM-TMIによって算出可能であることを示して,その定量化手法を特定するところまでを検討した. 温暖化ガスの排出に伴う気候変動では,気温上昇によって空気中の水蒸気許容量を増加させたところに上空冷気塊による冷却で水滴化するために上空雨水量が増加し,1時間を超える時間スケールの可能最大降水量は増加するというシナリオが考えられるが,それはTRMM-TMIを使った検討を待たなくてはならない.また,都市化によって高層ビルが増加すると局地風系が形成されることによって,上空1000mから400mでの雨滴の落下速度の変化は大きくなることが予想されるので,1時間以内の時間スケールの可能最大降水量が増大することが考えられるが,それも詳細な数値計算の解析を待つ必要がある.
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (B), Kyoto University, 2004 - 2006Data assimilation of advanced precipitation radar to meso-scale numerical simulation and its application for rainfall and flood predictionMany kinds of precipitation processes including convective rain and stratiform rain was observed by COBRA, 400MHz WPR and ground based rainfall observation devices in 2004 (baiu season, typhoon season) and in 2006 (baiu season, typhoon season, fall and winter season). The collected data have been used for investigation and development of cloud microphysical processes including analysis of rain drops size distribution (DSD), vertical profile of DSD, evaluation of polarimetric parameter of COBRA, and development of algorithms for DSD above melting layer by 400MHz WPR. Effectiveness of polarimetric parameters of multi parameter Doppler radar “COBRA" including horizontal radar echo (ZH), vertical radar echo (ZV), differential reflectivity (ZDR) and specific differential phase shift (KDP) has been investigated. Then effectiveness of linear depolarisation ratio (LDR) was shown by comparison of observed parameters and parameters estimated parametrically non-from DSD that was obtained by disdrometer observation. Moreover, a rainfall rate estimation method has been built and evaluated by considering the polarimetric parameters. Extended Karman filter, ensemble Karman filter and four dimensional variation method have been applied to original hydrostatic numerical simulation model in order to develop assimilation methods for polarimetric parameters to cloud resolving numerical simulation. Then, it is found that ensemble Karman filter was the best way to assimilation. Meso scale processes inside typhoons were new point of view to investigate the growth and movement of typhoon. Therefore, analysis of COBRA data and numerical simulation were conducted. Then, eye wall corruption by impact of convective cell to eye wall organization was found by the analysis of COBRA data. Wind field simulated by CReSS was also analyzed for corruption of eye wall organization. Especially vorticity and divergence of horizontal wind was focused. These results were reported and will be used in the second stage that is grant-in-aid for scientific research (A) from 2007 to 2009.
- 日本学術振興会, 科学研究費助成事業, 基盤研究(C), 中央大学, 2005 - 2005「アジアにおける水物質循環モデル・ソフトウェアに関する国際フォーラム」の企画調査1.WORKSHOP [Recent Development of Water Resources and Hydrology](ベトナム) 上記博覧会の趣意と成果を広く国内外に発信するために、2005年5月には日本学術会議内に設置されたアジア学術会議主催の「The 5^
Science Council of Asia(SCA) Conference」において、アジア学術会議委員である本研究代表者が同ワークショップを開催した。同ワークショップでは、我国の水物質循環モデル開発の経緯、現状の取り組みを述べ、アジア諸国の大学・研究機関、財団、民間企業へ我国の水物質循環モデル・ソフトウェアに対する将来構想を示した。さらにアジア諸国が抱える水資源問題について意見を交換し、水物質循環モデル・ソフトウェアの開発を各国協力して進めることにより国際的な水資源問題の解決の原動力となす意思を確認した。同ワークショップの報告を受けアジア学術会議は、アジア地域における水資源問題の国際的・将来的重要性を認識し、アジア学術会議における水文セッションの常設を決定した。 2.水物質循環モデル・ソフトウェア博覧会2005 本研究代表者らは、国内外の水物質循環に関連するモデル・ソフトウェアの開発と精度の向上を図るとともに、これらの成果を国内外に発信することで、わが国の国際貢献の一助となることを目的として同博覧会を2005年12月に企画した。国内外の大学・研究機関、財団、民間企業から30ブースの出展と500名を超える来場者があり、水物質循環モデル・ソフトウェアの現状の問題点及び今後の方向性についての議論が盛況に行われた。 この博覧会に出展されたモデル・ソフトウェアについて、モデル・ソフトウェアカタログとして日本語・英語版の冊子となってまとめられている. Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (A), KYOTO UNIVERSITY, 2001 - 2003Comprehensive research on water, energy, and material cycle by synchronizing satellite, intensified, and continuous observations -The Lake Biwa Project 3rd stageThe intensive field campaign of the areal distribution of turbulent fluxes (CAPS2003) was implemented on the harvested paddy field by the members of the Lake Biwa Project and other young scientists from the flux research group. The 30 participants came from 11 universities and institute. The observation was organized by permanent energy balance measurement station, one Doppler lidar (3-dimensional distribution of wind and aerozol), two Doppler sodars (vertical profile of wind), one scintillation meter (path average sensible heat flux), GPS sonde (vertical profile of temperature, humidity, and wind), 4 super flux sites (sensible and latent heat fluxes, radiation budget), 4 sat sites (sensible heat flux), 3 flux profile sites (vertical profile of sensible heat flux), 24 thermocouples (fluctuation of air temperature). Furthermore, to estimate the distribution of energy balance components, radiometer and thermometers were installed at the same place for calibration. The main characteristics of this CAPS2003 is that the target area (200m x 100m) is much smaller than that of CAPS2002 (1200m x 500m). The arrangement of the sensors was "cross-shape", and all data from sensors in the central zone were recorded by one 64ch logger. This perfect synchronizing aims to the tracking of the detailed structure of the turbulent flow. All the processed (quality checked) data from CAPS2002 and CAPS2003 were included in the database and opened on the Web site. As for the numerical modeling, the non-hydrostatic meteorological model ARPS and the advanced land surface scheme SiBUC were coupled. By the grid-nesting system from the synoptic scale to the local scale, the detailed local wind field was simulated and the effects of the land surface processes on the local circulation were analyzed in detail. Also, the dataset of the distribution of the energy and water budget components in the Lake Biwa Basin was re-constructed by the off-line simulation of the improved land surface model SiBUC.Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (B), Tokyo Institute of Technology, 2001 - 2002Joint Field Survey for Promoting the Integrated Manila Bay-Laguna Lake and Surrounding Watersheds Environmental Study Project1) Field survey on hydraulic and water quality environments in Manila Bay-Laguna Lake coupling system and development of numerical simulation models Intensive field surveys were performed at Manila Bay, Laguna Lake and Pasig River in 2001 October (wet season), at Laguna Lake in 2002 February (dry season) and at Manila Bay 2003 February (dry season). With these surveys, the characteristic features of the hydraulic and water quality environments in these periods were clarified. Especially, the importance has been revealed for the effects of the spatial non-uniformity of the wind field on Laguna Lake, the environmental loads from the tributaries of the Pasig River through the Metro Manila area, the 3-D structure of the currents in Manila Bay and others. Further, by conducting a long-term continuous field measurement at Laguna Lake and Pasig River for the period from March to June, 2002, it was succeeded in observing the phenomenon that the brackish water from Manila Bay intrudes into the Laguna Lake in the end of the dry season. In addition to these field surveys, it was also attempted to develop numerical simulation models for currents in Manila Bay and Laguna Lake, respectively. For the former, with the basis of dual-sigma POM, a 3-D current model by Nadaoka & Nihei, nesting techniques and the effect of non-hydrostatic pressure distribution were examined. For the latter, on the other hand, a field survey to examine the hydrodynamic effects of the fishpen was conducted in Laguna Lake in 2003 March. 2) Field survey on distributions and sources of heavy metals in relation to surrounding watersheds Analyses have been made for the existing samples of bottom mud taken in Manila Bay and newly obtained bottom mud samples taken in Pasig River and Laguna Lake, revealing the characteristic distributions of various heavy metal components and their possible source areas. Special attention has been paid on the lead, as its distribution may show appreciable human effects. As one of the possible sources of the lead, roadside dust was sampled and analyzed. 3) Numerical simulation of mudflow in Mt. Pinatubo watershed area A two-dimensional numerical model of mudflow was developed and applied to the watershed area of Mt. Pinatubo, giving reasonable results.日本学術振興会, 科学研究費助成事業, 奨励研究(A), 山梨大学, 2000 - 2001GPSとマルチパラメータレーダーを用いた豪雨の詳細な構造解析降雨時の水蒸気動態を主としてGPS,マルチパラメータレーダー,メソ気象モデル,雲解像数値モデルによって解析した. ・X-BAIU98, 99の解析 1998年梅雨期に長崎県橘湾周辺,1999年梅雨期に鹿児島県甑島列島で行われた降雨観測実験データのうち,GPS, 2重偏波レーダー,雲解像モデルを用いて主として小規模水蒸気擾乱について考察した.その結果,小さなスケールの線状エコーのような水蒸気のコントラストが比較的明確な対流性降雨の場合には,雲解像モデルの出力結果とGPS位相残差データはよい対応関係を示し,その変動量は大気遅延量で10〜20mm/10分程度であることが示された. ・琵琶湖における解析 1998, 1999年に琵琶湖周辺で生起した局地豪雨現象をGPS, 3次元レーダー,メソ気象モデル,雲解像モデルを用いて,主として降雨生起後の移流方向について考察した.そこでは,GPS可降水量の絶対値が少ないときでは,雨域の移動は下層の可降水量収束方向に進むこと,可降水量の絶対値が大きいときでは,雨域の移動方向は可降水量の収束方向に依存しないこと,メソγスケールの水蒸気変動をシミュレーションによって捉えるためには,モデルの水平スケールを1km以下にしなくてはならないことが示された. ・GPSつくば稠密観測の解析 2000年につくば市周辺で行われた稠密観測結果を気象庁気象研究所/数値予報課非静力学モデル(MRI/NPD NHM),雲解像モデルを用いて,主として雲中の雨滴粒径分布と小規模水蒸気変動について考察した.その結果,雲内の水蒸気変動は雨滴粒径分布の増大に伴う下降風の発生によって減少するが,雲の発達に伴って生じる潜熱放出による鉛直上昇風の発生によって増大することが示された.すなわち,雨滴粒径分布および潜熱放出量を適切に推定する必要がある.Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (B), KYOTO UNIVERSITY, 1999 - 2001Development of flood control supporting system based on Severe Rainfall prediction system using Artificial Intelligence (SRAI)The purpose of this research is in making the flood control support system, and the application of this to an actual flood. The accuracy improvement of Severe Rainfall prediction system using Artificial Intellige nee (SRAI) which is the kernel of the system was done became indispensable for that. SRAI is the method to qual itatively forecast the breaking out and development of the rainy cloud of small area and short term, by using the radar, the GMS image, and the numerical prediction data as an initial value. It was difficult for GPV to achieve the forecast accuracy improvement time because it used the data from RSM (Regional Spectral Model) as an initial value. Then, the forecast value of the NHM (Meteorological Research Institute/ Numerical Prediction Division Non Hydrostatic Model), which was the next generation numeric meteorological model (5km space resolution every hour) was introduced, and the improvement of the forecast accuracy was aimed at. The accuracy of rainfall forecast of two-three hours has been improved. In addition, because the improvement of the rainfall forecast accuracy was able to be expected, the mixing ratio of "cloud water" and "rain water" which NHM forecast was made to be used as an initial value of SRAI in the process of the research on the accuracy improvement, has been used. Therefore, SRAI in the present stage is a system which can forecast the rainfall for a short time by taking, and processing all information on NHM. However, because a lot of time had been spared to development, the application case was not able to be increased. It will be assumed to be a problem to improve reliability to the user by increasing the application case in the future. It has pride that making an application for the forecast by a numeric meteorological model to the management site in the river and the reservoir by overcoming the problem of NHM (The rainfall of 100 % cannot be forecasted, necessary of highly meteorological knowledge is necessary for the interpretation, and a large amount of data) by using NHM at the end is a big result in this research.Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (B)., KYOTO UNIVERSITY, 1998 - 2000Continuous Operation of Storage Reservoir using Virtual Reality Technology1) According to the knowledge level for reservoir operation, we proposed the knowledge acquisition process to find abnormality of weather situation and acquire the new information or countermeasure. The data of typhoon path, rainfall, and runoff characteristics are classified and added into knowledge base after integration with fuzzy set concept. 2) Hyetograph and hydrograph are predicted through fuzzy-neuro prediction combined with fuzzy inference theory and neural network. Hydrograph was predicted with two approaches ; one was application of predicted hyetograph and the other was direct application of only observed inflow. Moreover, the acquired knowledge level was represented through the information theory. 3) The virtual reality concept was introduced into the operation instructions where the panel operation, gate control and controlled results at upper or downstream points were reproduced with three-dimensional graphical system. The trainee can understand the real operation results of storage reservoir in control office. 4) All of programming was applied to be structured with Visual C++ on personal computer. This software will support to make the proposed program compact and effective. As we obtained the monitored data different from the real-time data, the real application was not taken in this research.Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (A)., KYOTO UNIVERSITY, 1998 - 2000Water-Man-Earth Interactions and Sustainable Water Resources-Cooperation in East Asia and OceaniaProblem regarding water, which is associated with population increasing, environmental change, development ofindustry and climate change, is very important for sustainable development of human being. We strongly and systematically promote an international cooperative research for solving the water problem of the target area by gatherins a lot of hydrological researchersunder name of AP-FRIEND. 1. We held three meetings at which many Japanese and non-Japanese researchers gathered. The meeting was held at Teague in Korea (November 7- 17, 1998), Nangjing in China (October 18-21, 1999) and Christchurch in New Zealand (November 18-27, 2000). At these meetings, discussions regarding database of hydrological observation data at eastern Asia and Oceania as well as total river basin management including flood and drought. 2. We support the Japan-Vietnam cooperative research by sending Japanese hydrological researchers to Mekong delta from March 5-12, 1999. The researchers surveyed river hydrological database at Vietnam. At the same time, they investigate the effect of human activity on the sedimentation and environment of the Mekong River. 3. We invited a Korean researcherto Japan and we dispatch Japanese researchersto Vietnam, Thailand, Australia and New Zealand to discuss the comparative hydrology and cooperative research. The subjects are as follows, cooperative research far scaling up problem off flood model, cooperative research for effect of vegetation change on flood volume, vegetation activity survey and cooperative research for effect of human activity and change of environment and climate on water resources.日本学術振興会, 科学研究費助成事業, 奨励研究(A), 京都大学, 1998 - 1999地表面過程が局地豪雨に与える影響に関する観測及び数値実験的研究主として山岳地で生起する局地的集中豪雨についてその地形条件が豪雨生起後の降雨の時・空間分布に与える影響を導くことによって,実時間での降雨予測のための知見を提供することを目的に以下の観測および数値実験を行った.これにより,本研究で計画していた観測データの収集,数値モデルの開発とそれを用いたシミュレーション,および解析が達成された. 観測 6月22日〜7月3日にかけて九州南西部にて行われたX-BAIU99およびGPS気象学の合同観測に参加し,地形の影響を受けていない鹿児島県甑島列島にてGPS,地上気象測器,ラジオゾンデ,レーダーによる測地・気象観測を行った.それによって,豪雨時の海洋上における水蒸気の移流や相変化量を考察する基礎資料を収集した. 計算1 小規模水蒸気擾乱の変動特性をGPS視線方向大気遅延量から算出するためフーリエスペクトルを用いた方法を考案し,それを1998年の琵琶湖プロジェクトにおけるGPS,1次元風速分布観測データに適用し,方法の妥当性を検証した. 計算2 1998年梅雨期に長崎橘湾周辺で観測されたラジオゾンデ,レーダーデータと3次元雲解像モデルを利用して,豪雨時の水蒸気変動状況を再現した. 解析 上記の観測および計算方法と計算結果を利用して,豪雨時の水蒸気変動を考察し,豪雨をもたらす対流性降雨およびその周辺の層上性降雨が水蒸気変動に与える影響は異なっていることが,数値計算によって示された.観測データを詳細データに検討することによって,豪雨が水蒸気擾乱に与える影響はGPS可降水量や,視線方向大気遅延量を用いることによって,観測可能であることが示された.Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (B), KYOTO UNIVERSITY, 1998 - 1999Study on the long distance transportation of acid snow and its effect on runoff processesIn the project, study on the acid snow in the northern part of the Lake BIWA has been done. In the study, transportation, reaction and deposition processes are modeled both physically and chemically. Then the cloud microphysics model that considers the chemical processes of acid snow has been developed. We verify the models by comparison with water quality observation. We also developed the model of runoff process which consists of snow fall, snow storage, snow melt, penetration processes. Finally we also verify the model by comparison with observed data. Development of the numerical model of acid snow : Cloud numerical model that includes the explicit type cloud microphysical processes has been developed based on cloud model made by Oishi. Then we consider the generation and deposition processes of SOx and NOx diagnostically. We obtained the result that the mixing ratio of SOx and NOx is quite bigger than observed data. Therefore, we are now in process of development of the model which prognosticate the chemical transportation processes. This model is one of the best models in the world since it can calculate the distribution of cloud droplet diameter that is very important factor for chemical processes. Modeling of Acid snow runoff process and its application to basin scale : We had the important observation period and routine measuring system in very small basin (5.4 Km^2) for making the model of acid snow runoff process. Then we made the application of the models for considering a basin scale by using a water quantity model, a water quality model, a hybrid model and a multi layer model. We obtained the result that the daily variation of snow melting, decreasing of pH by acid shock, daily variation of pH in the river is well explained.Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for International Scientific Research., KYOTO UNIVERSITY, 1997 - 1997Water Use and Date Environment in Southeast Asia and the PacificStudies have been carried out for the sustainable and sound water resources environment in Southeast Asia and Pacific region. The studies are as follows : (1) Many researchers gathered from Southeast and the pacific region surveyed the representative basins to investigate natural and social conditions and water use in the countries. Also investigated are : the exsistence of hydro-meteorological, water demand/use and socio-economical data, their format, quality and accessibility and as well as preparedness for establishment of database management systems in each country. The similarity and difference of the important water issues are clarified through meetings and site visitings in : Thailand and Lao (December 1997), Australia and New Zealand (March 1998) and Malaysia and Indonesia (March 1998). (2) The data regarding hydrology and water resources in the above mentioned countries has been collected. The researchers held technical discussion on how to collect the data regarding hydrology and water resuources in the countries and proposed the design of database management system, data format for common use. (3) In addition, based on the results of surveys, information exchange, collected data and discussions, a workshop regarding establishment of water archive and comparative studies on hydrology and water resources has been held in order to obtain the clear vision for future research.Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (A), KYOTO UNIVERSITY, 1995 - 1997Analysis and Prediction of Local Heavy Rainfall in Mountainous and Urban AreaIn this project, investigators have proposed the severe rainfall prediction system as well as they have analyzed the local heavy rainfall. The analysis of local heavy rainfall has been done by twoapproaches. First, investigators observed several severe reinfall events mainly with radio sonde and rain gage under condition of severe rainfall in Baiu. Second, investigators developed a cumulus cloud model which has terrain following coordinate and detailed microphysics model. Using the model, investigators simulate severe rainfall events. The processes and result of the analysis is as follows ; 1) Hydrological and meteorological observations have been done under condition of severe rainfall which came mainly from Baiu fronts at the Kuzuryu river basin in Fukui Prefecture. Observation period is June 20-30,1996 and July 2-10,1997. Observations have been done with radio sonds (two to three hourly), optical and normal rain gage (once par one to ten minutes), car bone X band radar (continuous). 2) Numerical cumulus model which has detailed cloud microphysics have been computed with observation data as initial and verification data. Investigators analyze the effect of topography, wind field, atmospheric and thermodynamic stability and water vapor on cloud microphysical processes which control the cumulus generation and dissipation. As results of the analysis, investigators obtained results that the amount of hail generation is important factor for rainfall amount from cumulus. Moreover, they found that water vapor and vertical wind are important factor for hail generation. 3) Investigators proposed that GPS is suitable observation system for water vapor observation. Moreover, they developed a new equation system in order to obtain the water vapor disturbance of cumulus scale using GPS.Investigators found that the equation system made good results using numerical simulation data. They also investigated efficiency of the equation system using observed GPS data. Investigation found that the equation system is effective under good observation condition. They also found that the observation data are affected by many kind of error sources. Finally, the vertical wind field observation by Doppler radar and water vapor observation by GPS are proposed as a effective observation system for severe rainfall prediction.日本学術振興会, 科学研究費助成事業, 基盤研究(C), 京都大学, 1996 - 1996降雨の3次元構造を考慮したレーダーを用いた地上雨量の推定レーダー雨量計の有効性については様々なところで議論されている.しかし,レーダー雨量計を用いて地上における降雨強度や総降雨量の推定を行う際の様々な問題があり,十分な精度が得られていないのが現状である.その原因の一つとして,雨滴粒径分布が降雨の種類によって変化し,その鉛直分布も変化することがあげられる.落下する雨滴粒径分布の変化を雨滴の分裂・併合・蒸発などの微物理過程を考慮したモデルで表現したり,指数分布で雨滴粒径分布を表現し,その分布の傾きを降雨強度によって分類するなどの試みは行われている.しかし,それらの結果とレーダー雨量推定精度向上とは必ずしも結びついていない.申請者らはこれらの問題を根本的に解決するために降雨タイプに依存した形で雨滴粒径分布の鉛直構造を考慮したレーダー雨量推定手法の構築を目指し,実際に地上と鉛直方向の雨滴粒径分布を観測・解析することにより降雨タイプに依存した雨滴粒径分布パラメータとその鉛直分布を明らかにすることを試みた.鉛直方向の雨滴粒径分布の観測は,雨滴の落下速度のドップラースペクトルから雨滴粒径分布を推定することが可能な京都大学超高層電波研究センターのMUレーダー(Middle and Upper Radar)を用いて行った. 地上における雨滴粒径分布については,降雨タイプ別の定式化を行った.降雨期間中に降雨タイプがあまり変化しない梅雨前線に伴う降雨に関しては定式化を行うことができたが,台風性,秋雨前線などの降雨タイプでは降雨期間中に,より小さい時・空間スケールの降雨タイプが変化するために今回用いた降雨タイプによる定式化では十分に雨滴粒径分布を表現することができないことが明らかになった.対流性,層状性などのより小さな時・空間スケールでの降雨タイプによる定式化を行う必要である. 鉛直方向の雨滴粒径分布については,指数分布で推定されるパラメータの鉛直分布を時系列で追跡することによって,時々刻々変化する降雨タイプの雨滴粒径分布の鉛直分布をとらえることができ,その降雨タイプは10分程度で変化しており,定式化には10分間の平均値で行うことができることを示した.Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (B), KYOTO UNIVERSITY, 1995 - 1996Applications of Geographic Information Systems and Remote Sensing to Analysis and Prevention of Water-Related Disasters in Urban Areasl)Using simulation images degraded from remote sensing images acquired in the Shonai River basin, Takara and Oka have quantitatively investigated the effects of spatial resolution on land cover classification accuracy, a vegetation index NDVI and evapotranspiration estimates based on NDVI.Takara also has constructed a distributed flood runoff model for the Yada River basin and investigated the performance of the model with regard to spatial resolutions of 50m and 250m based on a 50-m digital elevation model as well as parameter values, which were obtained on the basis of a l0-m land use map and remote sensing images. 2)Oka, Takara and Chikamori have made datasets of river stage and precipitation in the Ogura experimental basin. Conducting detailed surveying through topographical maps, aerial photographs and site visiting, they also have made datasets for geographic information such as rivers, artificial drainage channels, pipe lines for water supply and sewage, roads, delineation of land use and contour lines, with GIS. 3)Nakakita has made datasets for precipitations in Kinki and Kyushu acquired radar raingage systems. Investigating a one-year sequence of spatial rainfall distribution acquired at five-minute intervals by the Kunimisan Radar Raingage System in Kyushu, he has found out a strong linear relationship between rainfall and topography (elevation) and proposed a stochastic model of rainfall distribution. 4)Hori has integrated a GIS with a computer model, which can simulate the changing process of inhabitants' attitude on flood disaster due to their experience and time passage. The model is applied to a historical flood event in Nagasaki. 5)For urban storm drainage, Chikamori has proposed a method of optimal operation of pumping systems based on the predicted water stage at pumping stations. 6)Introducing the GPV (Grid Point Value), which is numerically forecasted by the Japanese Meteorological Agency, and the AMeDAS information into GIS,Oishi has developed the qualitative cumulus model using a qualitative reasoning technique to simulate or forecast severe rainfall at local scale.日本学術振興会, 科学研究費助成事業, 奨励研究(A), 京都大学, 1995 - 1995情報工学的推論手法を用いた局地豪雨予測手法の開発に関する研究気象情報から気象現況を定性的に推論するアルゴリズムとルールを作成し、それを計算機中で表現し,実際の豪雨現象に適用してケーススタディを行うことでアルゴリズムの検証を行うことを目標に以下の研究を行った. 1.気象庁・数値予報出力値であるGPV(Grid Point Value)を用いて前線の位置を判断するアルゴリズムを開発した.このアルゴリズムは気象現象に詳しい人間が前線の位置を判断する手法を模して,事例毎に変化するGPVの値を相対的に判断して事例毎に適当なしきい値を判断して2値化を行うことにより前線を抽出する機能を備えている.さらに,アルゴリズムの検証段階において人間が空間的に分布している数値を判断する際には全領域の値の分布具合を判断して空間をいくつかに分解し,その中で前線を抽出して最後にそれぞれで求められた前線を結合していることが判明した. 2.偏微分方程式により表現されている大気の連続式を通して,GPVで得られるメソαスケールの風の情報から地形の影響を受けて生起するメソγスケールの鉛直風分布を求める定性モデルを開発し,その実現を行った.ここで得られた鉛直風分布と大気の安定度,および水蒸気の供給状況が局地豪雨をもたらすような積雲の生起を予測する推論材料である.また,この定性モデルの開発は,診断的解法ではあるが,今まで常微分方程式系だけが定性推論モデルとなることが可能であったという壁を乗り越えて偏微分方程式系も定性モデル化する手法を提案するものである. 3.積雲の数値シミュレーションを通して局地豪雨をもたらすような積雲の生起・発達に影響を与える種々の定量・定性的要因を獲得し,それらを実際の局地豪雨予測に活用するために1次元定性積雲モデル,それを2次元に拡張した2次元定性積雲モデルの基礎的フレームを考案した. これらの研究を行う上で,特に大量のデータを必要とするGPVの解析に際して,計算機の主記憶装置,外部記憶装置を拡張したことが研究の進捗に非常に効果的に機能した.日本学術振興会, 科学研究費助成事業, 一般研究(B), 京都大学, 1994 - 1995水文循環モデルのスケールアップ・ダウンと水資源システムへの応用水文循環のスケールアップおよびスケールダウンを考えるに当たって鍵となるのは,地形,蒸発散量および降水量分布のそれである。一方ではstbchasticな議論も非常に重要である。すなわち,平均的な物理量が互いにどういう関係にあるかを様々なスケール毎に個別に議論するだけでは現象を理解したことにはならず,スケール間の関連および相違が説明づけられなければならない。さらには,洪水防御計画や水質源計画に対する降水量分布や水位,流量のstochasticな構造の情報は,今や実用上欠くことのできないものとなっている。以上が,大気との相互作用という視点以外に,水文プロパ-の水循環のモデル化において考慮されなければならない点である。 本研究は以上の視点をベースに,水文循環モデルのスケールアップ・ダウンと水資源システムへの応用を一貫した課題として取り組むための突破口となるべく,イ)流域特性のメッシュ集中化によるマクロ水文モデルの開発,2)降雨分布の時空間分布特性の物理-確率過程モデルの開発,3)大気-降水-土壌・湖面-地表・地中・地下水流出-蒸発散の相互作用の観測,モデリグ,4)雲の存在を重視した降水過程のモデル化と観測,5)地形情報のスケールアップ・ダウンと流出モデルのそれに蒸発散および降水分布特性が及ぼす影響の明確化,6)種々の時間,空間スケールで得られる水文情報の洪水防御計画,水資源計画への活用手法の開発,7)地上および衛星リモートセンシング情報の有効利用手法の開発,を各研究者が連携しながら進めたものである。本研究は,「水文循環モデルのスケールアップ・ダウンと水資源システムへの応用」を完全に確立する事を目指したのではなく,その展望や突破口を具体的に形で示すことにあった。各課題一貫してこれから進むべき方向を研究成果として具体的に示せたことにより,突破口としての役割を果せたと言える。日本学術振興会, 科学研究費助成事業, 一般研究(C), 京都大学, 1994 - 1994陸域の影響を詳細に考慮した局地的豪雨分布特性の解析本研究で行ったことは,相互に関連しながらも以下の5つに分類される. 1.土地利用スケールが地上からの熱・水フラックスに及ぼす影響:都市,植生を取り込んだ詳細な熱収支モデルを開発し,それを用いた数値実験によって,土地利用スケールと平均顕熱・潜熱フラックスとの関係を明らかにした. 2.地上からの熱・水フラックスが降雨分布に及ぼす影響:陸面過程,降雨モデルを含んだ数値モデルを用いて,都市化に伴う地上からの顕熱フラックスの局所化,土壌水分量の局所化が降雨を発生させるかどうかの解析を行い,豪雨発生の可能性を見いだした. 3.上昇気流が積雲の発達に及ぼす影響:山岳斜面による強制上昇流を想定し,微物理過程を含んだ積雲数値モデルを用いて,初期鉛直上昇流と積雲の発達度合い,もたらされる降水量との関係を明らかにした. 4.地形分布が降雨分布に及ぼす影響:鹿児島豪雨のレーダー観測情報を用いて,どの程度大きなスケールになると降雨分布特性と地形分布特性が大きく関連してくるかを,雨域の発達・衰弱量の時間的・空間的持続性を指標に調査し,1日程度の時間スケールで見た場合は,20km程度の平均スケールになると関係が顕著に現れることを見いだした. 5.降雨予測:レーダー情報と数値予報結果を結合させた短時間降雨予測手法を開発するとともに,情報工学的手法を用いた局地降雨予測手法の開発を行った. 6.降雨が流出系の及ぼす影響のモデル化:任意の流域でこの影響を評価することを容易にするために,流出系の構造的モデル化を図った.災害時の水資源問題Competitive research funding降雨観測と降雨予測を基礎にした洪水土砂災害予測警報システムの開発Competitive research funding効果的な防災教育に関する研究Competitive research funding雲物理過程を考慮した豪雨の発生・発達予測Competitive research funding