Yoichi Iwami
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View article: INFLUENCE ANALYSIS OF OBSERVED RIVER CHANNEL CONDITIONS ON THE INUNDATION PROCESS IN THE LOWER MEKONG RIVER BASIN
INFLUENCE ANALYSIS OF OBSERVED RIVER CHANNEL CONDITIONS ON THE INUNDATION PROCESS IN THE LOWER MEKONG RIVER BASIN Open
This study aims to analyze the influence of observed river channel conditions on inundation simulation in terms of discharge within a river channel and inundation area and depth over a floodplain. The target area is the Lower Mekong River …
View article: DEVELOPMENT OF A FLOOD FORECASTING SYSTEM USING REGIONAL ENSEMBLE PREDICTION – APPLICATION TO THE KINUGAWA FLOOD IN 2015
DEVELOPMENT OF A FLOOD FORECASTING SYSTEM USING REGIONAL ENSEMBLE PREDICTION – APPLICATION TO THE KINUGAWA FLOOD IN 2015 Open
Recent advances in regional ensemble weather prediction systems (EPS) can considerably improve the prediction of torrential rainfall and resulting severe floods with a longer lead time. To maximize this advantage, we developed an ensemble …
View article: RCP8.5-Based Future Flood Hazard Analysis for the Lower Mekong River Basin
RCP8.5-Based Future Flood Hazard Analysis for the Lower Mekong River Basin Open
Climatic variations caused by the excessive emission of greenhouse gases are likely to change the patterns of precipitation, runoff processes, and water storage of river basins. Various studies have been conducted based on precipitation ou…
View article: A Study on Flood Forecasting in the Upper Indus Basin Considering Snow and Glacier Meltwater
A Study on Flood Forecasting in the Upper Indus Basin Considering Snow and Glacier Meltwater Open
This study considered glacier and snow meltwater by using the degree–day method with ground-based air temperature and fractional glacier/snow cover to simulate discharge at Skardu, Partab Bridge (P. Bridge), and Tarbela Dam in the Upper In…
View article: RAINFALL RUNOFF INUNDATION AND SEDIMENT TRANPORT MODEL AND ITS APPLICATION TO KAWAMATA DAM CATCHMENT
RAINFALL RUNOFF INUNDATION AND SEDIMENT TRANPORT MODEL AND ITS APPLICATION TO KAWAMATA DAM CATCHMENT Open
著者らは降雨流出氾濫モデルの一つであるRRIモデルに土砂輸送モデルを実装することで降雨・流出・氾濫・土砂輸送モデル（RRIS model）を構築した．ここでは，RRISモデルを説明すると共に，同モデルを検証するために鬼怒川上流の川俣ダムにおいて土砂流出現象を再現することを試みている．台風性降雨を経験した川俣ダム流域は土石流による大規模な土砂生産を経験し，そのときの土砂流出量は通常と比較すると同規模の降雨に対して10倍程度の土砂堆積が確認されている．これは流域内の土砂生産や貯…
View article: Comparative study on climate change impact on precipitation and floods in Asian river basins
Comparative study on climate change impact on precipitation and floods in Asian river basins Open
As many water related disasters occur frequently around the world, proper assessment of future climate change impact on floods and droughts is essential. In this study, we focused on basin-scale climate change impact assessment as necessar…
View article: The Present State of Flash Flood Forecasting Utilizing Numerical Weather Prediction in Europe
The Present State of Flash Flood Forecasting Utilizing Numerical Weather Prediction in Europe Open
近年数値天気予報の発展はめざましく,一定の条件下では予報降水量は洪水予測に役立てられている.これは,コンピュータの計算能力向上,衛星など気象観測技術の向上とデータ同化技術の発展,不確実性を考慮したアンサンブル予報の開発,によるところが大きい.欧州では,実際に5日先までの予報降水量を降雨流出モデルに導入し,ドナウ川などの国際河川の洪水予測の他,各国の洪水予測に役立てている.さらに,より小さい流域の河川についても,数値天気予報による降水量を利用したフラッシュフラッド予測の開発が…
View article: Measurement of shear velocity and bed load discharge
Measurement of shear velocity and bed load discharge Open
[2nd International Workshop on Sediment Bypass Tunnels = 第2回排砂バイパストンネルに関する国際ワークショップ] May 9-12, Kyoto-Japan, 2017.
View article: POINT AND NON-POINT-SOURCE NUTRIENT CIRCULATION MODELLING FOR THE TAKASAKI RIVER BASIN, CHIBA JAPAN
POINT AND NON-POINT-SOURCE NUTRIENT CIRCULATION MODELLING FOR THE TAKASAKI RIVER BASIN, CHIBA JAPAN Open
Nutrient discharge to the Takasaki River from different Point-Sources (PS) and Non-Point-Sources (NPS) are considered in this study. Land use types: agricultural areas, forests and urban areas are considered as NPS in the study. Nitrogen (…
View article: FUTURE CHANGE ON INUNDATION HAZARD CONSIDERING DURATION IN THE PAMPANGA RIVER BASIN, PHILIPPINES
FUTURE CHANGE ON INUNDATION HAZARD CONSIDERING DURATION IN THE PAMPANGA RIVER BASIN, PHILIPPINES Open
気候変動影響による洪水氾濫形態の将来変化を明らかにすることを目的としてフィリピンのパンパンガ川流域を対象に時空間的な洪水氾濫特性を分析した．氾濫解析にはRRIモデルを適用し，降雨はMRI-AGCM3.2SのRCP8.5シナリオの結果を領域気象モデルにより5kmにダウンスケーリングし地上雨量で出現頻度をバイアス補正した．その結果，将来気候では浸水面積が約1.2倍に増大するが平均浸水時間は短くなることがわかった．これは浸水面積が増大したことで湛水が早く解消するグリッドが増え，浸…
View article: EVALUATION OF BED LOAD DISCHARGE AND EFFECTIVE FRICTION ELOCITY IN RIVERS
EVALUATION OF BED LOAD DISCHARGE AND EFFECTIVE FRICTION ELOCITY IN RIVERS Open
既往の掃流砂量式の多くは有効摩擦速度を入力値としているが，有効摩擦速度の妥当性やそれを用いた流砂量に関する実河川における評価は殆ど行われていない．その理由として，これまでの観測は時空間で局所的な計測が多かったことや，有効摩擦速度を評価する手法が無かったことがあげられる．本研究では，aDcpとマルチビーム測深機を用いて準実河川スケールの実験水路にて観測を行ない，有効摩擦速度の評価方法とそれを用いて算出した掃流砂量の妥当性を評価した．その結果，aDcpが計測する河床面移動速度と…
View article: APPLICATION OF MULTIVARIATE TEMPORAL DISAGGREGATION METHOD TO ESTIMATE DAILY SECTORAL WATER CONSUMPTION
APPLICATION OF MULTIVARIATE TEMPORAL DISAGGREGATION METHOD TO ESTIMATE DAILY SECTORAL WATER CONSUMPTION Open
河川管理における渇水時の貯水池運用や，長期的な水資源計画等において，上水道の給水制限時の日使用水量を用途別に推計し，給水制限による使用水量抑制効果や，季節変動の経年変化を考慮することが重要になってきている．これまで，著者らが提案していた，月単位の用途別使用水量の時間的配分による用途別日使用水量の推計手法は，降雨の有無や曜日等の影響による日変動を考慮できなかった．本検討においては，推計のために用途別月使用水量に加えて合計日使用水量を用いることで，日変動を考慮できる多変量時系列…
View article: Ensemble Flood Forecasting of Typhoons Talas and Roke at Hiyoshi Dam Basin
Ensemble Flood Forecasting of Typhoons Talas and Roke at Hiyoshi Dam Basin Open
In order to be able to issue flood warnings not hours but days in advance, numerical weather prediction (NWP) is essential to the forecasting of flood-producing rainfall. The regional ensemble prediction system (EPS), advanced NWP on a loc…
View article: Inundation Process in the Lower Mekong River Basin
Inundation Process in the Lower Mekong River Basin Open
This study simulated the inundation process in the Lower Mekong River Basin (LMB). The LMB has suffered from severe floods, especially in 2000 and 2011. To quantify the inundation of water in a basin where large-scale inundation by river w…
View article: Rapid Global Exposure Assessment for Extreme River Flood Risk Under Climate Change
Rapid Global Exposure Assessment for Extreme River Flood Risk Under Climate Change Open
Globally, large-scale floods are one of the most serious disasters, considering increased frequency and intensity of heavy rainfall. This is not only a domestic problem but also an international water issue related to transboundary rivers …
View article: Method to Develop Critical Rainfall Conditions for Occurrences of Sediment-Induced Disasters and to Identify Areas Prone to Landslides
Method to Develop Critical Rainfall Conditions for Occurrences of Sediment-Induced Disasters and to Identify Areas Prone to Landslides Open
The present study demonstrates a method to specify critical rainfall conditions for the occurrence of a sediment disaster and identify areas prone to landslides using a simulator proposed by the current authors for sediment hazards. The si…
View article: Glacier Mass Balance and Catchment-Scale Water Balance in Bolivian Andes
Glacier Mass Balance and Catchment-Scale Water Balance in Bolivian Andes Open
In investigating glacier mass balance and water balance at Huayna Potosi West, a glacierized basin in the Bolivian Andes (Cordillera Real), we used a remote sensing method with empirical area-volume relationships, a hydrological method wit…
View article: Meteorological Drought and Flood Assessment Using the Comparative SPI Approach in Asia Under Climate Change
Meteorological Drought and Flood Assessment Using the Comparative SPI Approach in Asia Under Climate Change Open
The standardized precipitation index (SPI) has been used to monitor and analyze meteorological droughts using long-term monthly precipitation from national meteorological and hydrological services on multiple timescales. Instead of evaluat…
View article: Application of Flood Forecasting and Analysis Model (IFAS) for Wadi Flash Flood
Application of Flood Forecasting and Analysis Model (IFAS) for Wadi Flash Flood Open
The Second International Symposium on Flash Floods in Wadi Systems: 25-27 October 2016. Technische Universität Berlin, Campus El Gouna, Egypt.
View article: ICHARM's Initiatives for Effective Flash Flood Forecasting and Management in Arid and Semiarid Region
ICHARM's Initiatives for Effective Flash Flood Forecasting and Management in Arid and Semiarid Region Open
The Second International Symposium on Flash Floods in Wadi Systems: 25-27 October 2016. Technische Universität Berlin, Campus El Gouna, Egypt.
View article: Application of tritium in precipitation and baseflow in Japan: a case studyof groundwater transit times and storage in Hokkaido watersheds
Application of tritium in precipitation and baseflow in Japan: a case studyof groundwater transit times and storage in Hokkaido watersheds Open
In this study, we demonstrate the application of tritium in precipitation and baseflow to estimate groundwater transit times and storage volumes in Hokkaido, Japan. To establish the long-term history of tritium concentration in Japanese pr…
View article: RAPID EXPOSURE ASSESSMENT OF NATIONWIDE RIVER FLOOD FOR DISASTER RISK REDUCTION
RAPID EXPOSURE ASSESSMENT OF NATIONWIDE RIVER FLOOD FOR DISASTER RISK REDUCTION Open
considerably increased. For flood disaster risk reduction, it is important to identify and characterize flood area, locations (particularly lowland along rivers), and durations. For this purpose, flood mapping and monitoring are an imperat…
View article: Application of tritium in precipitation and river water in Japan: A case study of groundwater transit times and storage in Hokkaido watersheds
Application of tritium in precipitation and river water in Japan: A case study of groundwater transit times and storage in Hokkaido watersheds Open
In this study, we demonstrate the application of tritium in precipitation and river water to estimate groundwater transit times and storage volumes in Hokkaido, Japan. To establish the long-term history of tritium concentration in Japanese…
View article: Fluvial Fan Process due to Swing Phenomena
Fluvial Fan Process due to Swing Phenomena Open
To analyze the fan formation process due to swing phenomena of the debris flow, the authors performed a numerical simulation of debris flow by means of depth integrated two dimensional governing equations of solid-water mixture and the bed…
View article: CALIBRATION CONSIDERING FLOOD FORECASTING APTITUDES FOR HYDROLOGICAL PARAMETERS OF A DISTRIBUTED RUNOFF MODEL
CALIBRATION CONSIDERING FLOOD FORECASTING APTITUDES FOR HYDROLOGICAL PARAMETERS OF A DISTRIBUTED RUNOFF MODEL Open
The hydrological parameters of a flood forecasting model are normally calibrated based on an entire hydrograph of past flood events with an error assessment function such as mean square error and relative error. However the specific parts …
View article: ENSEMBLE FLOOD FORECASTING OF AGANO RIVER FLOOD DURING NIIGATA-FUKUSHIMA TORRENTIAL RAINFALL IN JULY 2011
ENSEMBLE FLOOD FORECASTING OF AGANO RIVER FLOOD DURING NIIGATA-FUKUSHIMA TORRENTIAL RAINFALL IN JULY 2011 Open
Recent advances of regional ensemble weather predictions have increasingly improved predictability of rainfall forecasts, which would be useful for streamflow forecasts. We have developed an ensemble flood forecasting system, composed of a…
View article: A regional process under the international initiative for IFM
A regional process under the international initiative for IFM Open
\nClimate change is likely to result in increases in the frequency or intensity of extreme weather events including floods. The International Flood Initiative (IFI), initiated in January 2005 by UNESCO and WMO and voluntary partner organiz…
View article: ESTIMATION OF DAILY HOUSEHOLD WATER CONSUMPTION USING METERED WATER CONSUMPTION DATA
ESTIMATION OF DAILY HOUSEHOLD WATER CONSUMPTION USING METERED WATER CONSUMPTION DATA Open
近年の家庭等における節水型機器の普及や，洗濯等における水の再利用など，家庭の水使用形態の変化を，長期的な水資源計画等において考慮することが重要になってきている．本論文では，上水道の給水制限時における，家庭の使用水量の変化を詳細に推計するため，複数月の使用水量の集計値である世帯別検針データから，集計値の時間的配分手法を用いて，日使用水量を推計する手法を提案した．上水道の検針データは世帯により集計期間が異なるため，給水制限時の使用水量を横並びで比較することが困難であるが，提案し…
View article: Parameter Identification to Estimate Discharges of Multiple Water Level Stations Using Colleo Optimization Software
Parameter Identification to Estimate Discharges of Multiple Water Level Stations Using Colleo Optimization Software Open
A parameter estimation is presented of a distributed hydrological model in a basin which has multiple water level stations. A problem is placed that the fittings are not always satisfactory in the cases where the discharge of one water lev…