Toshio Koike
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View article: Ecohydrological Land Reanalysis: Vegetation Water Content and Soil Moisture Data by Land Data Assimilation
Ecohydrological Land Reanalysis: Vegetation Water Content and Soil Moisture Data by Land Data Assimilation Open
The accurate estimation of terrestrial water and vegetation is a grand challenge in hydrometeorology. Many previous studies developed land data assimilation systems (LDASs) and provided global‐scale land surface data sets by integrating nu…
View article: Preface: ICFM9 – River Basin Disaster Resilience and Sustainability by All
Preface: ICFM9 – River Basin Disaster Resilience and Sustainability by All Open
International audience
View article: Significance of Having Integrated Water Resource Plan in a Complex Watershed System for Better Water Management during Covid Pandemic: The Case of Mahaweli River Basin
Significance of Having Integrated Water Resource Plan in a Complex Watershed System for Better Water Management during Covid Pandemic: The Case of Mahaweli River Basin Open
Water scarcity and disasters, particularly floods and droughts, are the most devastating disasters in Sri Lanka, causing severe damage to agriculture, lives and property. This condition has been worsen further during the Covid19, due to is…
View article: Developing an Integrated Flood Management Plan under climate change for Grand River North West River basin, Mauritius
Developing an Integrated Flood Management Plan under climate change for Grand River North West River basin, Mauritius Open
In this article, the catchment of Grand River North West (GRNW) in Mauritius was selected as a case study to develop an Integrated Flood Management Plan to address the flood risks that Mauritius is and will be facing due to climate change.…
View article: Developing a flood monitoring system by utilizing real-time satellite rainfall estimates and water energy budget-based rainfall-runoff inundation model in West Africa
Developing a flood monitoring system by utilizing real-time satellite rainfall estimates and water energy budget-based rainfall-runoff inundation model in West Africa Open
The African regions have been affected by frequent flood-related disasters. To support decision-makers in flood disaster management, a real-time flood monitoring system was established in the Niger and Volta basins under the Water disaster…
View article: Attributing weather patterns to Davao River extreme rainfall from Reanalysis and GCM
Attributing weather patterns to Davao River extreme rainfall from Reanalysis and GCM Open
Extreme rainfall or heavy rainfall events (HREs) causes significant socio-economic damages annually affecting local development especially in developing countries. Thus, assessing changes in frequency and magnitude of HREs under climate ch…
View article: Evaluation of satellite precipitation products for real-time extreme river flow modeling in data scarce regions
Evaluation of satellite precipitation products for real-time extreme river flow modeling in data scarce regions Open
Inadequacy of spatio-temporal hydro-climatic data limits the efficacy of hazard monitoring and disaster risk reduction activities in disaster-prone areas. Various satellite missions are recently providing climate data, but prior evaluation…
View article: An Integrated Approach for the Climate Change Impact Assessment on the Water Resources in the Sangu River Basin, Bangladesh, under Coupled-Model Inter-Comparison Project Phase 5
An Integrated Approach for the Climate Change Impact Assessment on the Water Resources in the Sangu River Basin, Bangladesh, under Coupled-Model Inter-Comparison Project Phase 5 Open
The Sangu River basin significantly contributes to national economy significantly; however, exposures to water-related hazards are frequent. As it is expected that water-related disasters will increase manifold in the future due to global …
View article: An Integrated Approach for the Climate Change Impact Assessment on the Water Resources in the Sangu River Basin, Bangladesh
An Integrated Approach for the Climate Change Impact Assessment on the Water Resources in the Sangu River Basin, Bangladesh Open
The Sangu river basin contributes to national economy significantly; however, exposures to water-related hazards frequently. As it is expected that water-related disasters will increase manifold in the future due to global warming, the Gov…
View article: A STUDY ON VERSATILITY IMPROVEMENT OF SATELLITE SAR SOIL MOISTURE ESTIMATION ALGORITHM USING LONG-TERM SOIL MOISTURE OBSERVATION DATA IN MONGOLIA
A STUDY ON VERSATILITY IMPROVEMENT OF SATELLITE SAR SOIL MOISTURE ESTIMATION ALGORITHM USING LONG-TERM SOIL MOISTURE OBSERVATION DATA IN MONGOLIA Open
本研究は,著者らがALOS/PALSARの使用を前提に開発した既往土壌水分推定アルゴリズムの汎用性向上のための検討を実施した.まず,これまで一定であると仮定していた入射角の変化に対応させることで,ALOS2/PALSAR2データに適用した.また,既往アルゴリズムでは地表面粗度を推定するために多偏波データを用いていたが観測頻度が非常に低いことが課題であった.もしSAR観測とそれによって推定される土壌水分マップが複数あれば,マイクロ波散乱モデルを用いた逆推定により地表面粗度を推…
View article: Feasibility of Liquid Water Path Estimation of Over Land Using Satellite-Based Ka-Band Passive Microwave Data
Feasibility of Liquid Water Path Estimation of Over Land Using Satellite-Based Ka-Band Passive Microwave Data Open
We investigate the feasibility of a method of estimating liquid water path (LWP, the sum of liquid water paths of cloud and rain) over land using satellite-based Ka-band passive microwave measurements. Specifically, we utilize brightness t…
View article: Investigations of Multi-Platform Data for Developing an Integrated Flood Information System in the Kalu River Basin, Sri Lanka
Investigations of Multi-Platform Data for Developing an Integrated Flood Information System in the Kalu River Basin, Sri Lanka Open
Flood early warning systems (FEWS) are crucial for flood risk management; however, several catchments in the developing world are still far behind in all aspects of FEWS and thus, they encounter devastating damage recurrently due to limita…
View article: Assessment of Climate Change Impacts for Balancing Transboundary Water Resources Development in the Blue Nile Basin
Assessment of Climate Change Impacts for Balancing Transboundary Water Resources Development in the Blue Nile Basin Open
An assessment of climate impacts in the hydrologic system of the Blue Nile basin is useful for enhancing water management planning and basin-wide policymaking. Climate change adaptation activities predominantly require an understanding of …
View article: Improving Snow‐Process Modeling by Evaluating Reanalysis Vertical Temperature Profiles Using a Distributed Hydrological Model
Improving Snow‐Process Modeling by Evaluating Reanalysis Vertical Temperature Profiles Using a Distributed Hydrological Model Open
The use of the Japanese 55‐year Reanalysis (JRA55) vertical temperature profile (VTP) has been suggested in previous studies for estimating gridded air temperatures at high elevations in data‐scarce regions to conduct hydrological simulati…
View article: Co-Design for Enhancing Flood Resilience in Davao City, Philippines
Co-Design for Enhancing Flood Resilience in Davao City, Philippines Open
Enhancing flood resilience, including the development of social capacity and early warning systems, in addition to structural measures, is one of the key solutions to mitigating flood damage, which will be more intensified in the future du…
View article: AN OPERATION SUPPORTING SYSTEM FOR HYDROELTCTRIC DAMS: LONG AND SHORT TERM ENSEMBLE PREDICTIONS AND ITS APPLICATIONS
AN OPERATION SUPPORTING SYSTEM FOR HYDROELTCTRIC DAMS: LONG AND SHORT TERM ENSEMBLE PREDICTIONS AND ITS APPLICATIONS Open
小池ら1)は39時間の予測リードタイムを持つアンサンブル予測結果を用いて,洪水防御面と発電効率の両立を図る研究を行い,それが可能であることをシミュレーションで示した.同システムへ新たにアンサンブル3ヶ月予測を追加するため,予測情報をある一定期間の総流入量として用いることを提案し,その期間の長短が予測精度とダム操作支援へ与える影響を調べた.その結果,長すぎる期間で算出した総流入量を用いた場合は,貯水池運用を効率化できないことが分かった.暖候期と寒候期に分けて適切な期間を設定し…
View article: BASIC STUDY FOR MITIGATION MEASURES AGAINST A DRAWDOWN OF WATER LEVEL ACCOMPANYING DROUGHT IN THE PANAMA CANAL
BASIC STUDY FOR MITIGATION MEASURES AGAINST A DRAWDOWN OF WATER LEVEL ACCOMPANYING DROUGHT IN THE PANAMA CANAL Open
パナマ運河では,渇水に伴う水位低下が発生し,通航料金の増額が日本商船隊の負担増をもたらすなど,日本にとっても深刻な問題となっている.本研究では,2015年の渇水を対象に,パナマ運河に水・エネルギー収支-降雨・流出・氾濫モデルを構築して渇水緩和対策を検討したが,ダム新設を仮定した場合であっても,39cmであった渇水年の2015年と前年との水位差を30cmまでにしか緩和できず,緩和効果が小さいことが分かった.ゆえに海水の淡水化等,パナマ運河庁が既に提案する他案も考える必要がある…
View article: CONSIDERATION OF PROBLEMS THAT AROSE WHILE CONSTRUCTING A FLOOD FORECASTING SYSTEM FOR 125 RIVERS
CONSIDERATION OF PROBLEMS THAT AROSE WHILE CONSTRUCTING A FLOOD FORECASTING SYSTEM FOR 125 RIVERS Open
中小河川の水位予測システム構築時において,生じる問題の解決策を類型化するため,全国125河川の水位予測システムを構築した.構築する中で,(1)解析雨量の仕様の影響により小流域の水位波形の再現性が低い,(2)降雨プロダクトの精度が原因となり水収支が一致しない,(3)HQ式の精度低下により低水の再現性が低い,といった問題が生じていた.これらの問題の解決策として,(1)時間解像度のより細かい降雨プロダクトの使用,(2)他の降雨プロダクトの使用,(3)横断図修正によるHQ式の再作成…
View article: STUDY ON A PARTICLE-FILTER APPLICATION METHOD FOR FLOOD FORECASTING CONSIDERING RAINFALL-RUNOFF CHARACTERISTICS
STUDY ON A PARTICLE-FILTER APPLICATION METHOD FOR FLOOD FORECASTING CONSIDERING RAINFALL-RUNOFF CHARACTERISTICS Open
流域の特性上,急激な水位上昇が起こりやすい中小河川におけるリアルタイム水位予測システムの構築に向け,表面流・中間流・河道流のような時定数が異なる流出過程を表現する降雨流出モデルに粒子フィルタを適用した際の応答特性について検討した.その結果,水位上昇時において粒子フィルタによる斜面水深に対する負の補正が働いた場合,流出の時間遅れによって予測水位が低下することが分かった.また,粒子フィルタの補正係数を逐次修正するアルゴリズムを加え,初期分布の与え方を変えることで予測水位の精度低…
View article: Evolution of Japan's flood control planning and policy in response to climate change risks and social changes
Evolution of Japan's flood control planning and policy in response to climate change risks and social changes Open
Building a sustainable society by strengthening disaster resilience is a common goal in the world. It is crucial to promote cooperation between the general public and the science community by sharing data, information, knowledge, experienc…
View article: Drought Monitoring over West Africa Based on an Ecohydrological Simulation (2003–2018)
Drought Monitoring over West Africa Based on an Ecohydrological Simulation (2003–2018) Open
In Africa, droughts are causing significant damage to human health and the economy. In West Africa, a severe decline in food production due to agricultural droughts has been reported in recent years. In this study, we simulated ecohydrolog…
View article: Ecohydrological land reanalysis
Ecohydrological land reanalysis Open
The accurate estimation of terrestrial water and vegetation is a grand challenge in hydrometeorology. Many previous studies developed land data assimilation systems (LDASs) and provided global-scale land surface datasets by integrating num…
View article: Development of an Integrated Approach for the Assessment of Climate Change Impacts on the Hydro-Meteorological Characteristics of the Mahaweli River Basin, Sri Lanka
Development of an Integrated Approach for the Assessment of Climate Change Impacts on the Hydro-Meteorological Characteristics of the Mahaweli River Basin, Sri Lanka Open
Climate change is increasingly sensed by nations vulnerable to water-related disasters, and governments are acting to mitigate disasters and achieve sustainable development. Uncertainties in General Circulation Models’ (GCM) rainfall proje…
View article: Adequacy of Near Real-Time Satellite Precipitation Products in Driving Flood Discharge Simulation in the Fuji River Basin, Japan
Adequacy of Near Real-Time Satellite Precipitation Products in Driving Flood Discharge Simulation in the Fuji River Basin, Japan Open
Flood management is an important topic worldwide. Precipitation is the most crucial factor in reducing flood-related risks and damages. However, its adequate quality and sufficient quantity are not met in many parts of the world. Currently…
View article: INVESTIGATION OF ENSEMBLE DAM INFLOW SIMULATION IN SAI RIVER BASIN
INVESTIGATION OF ENSEMBLE DAM INFLOW SIMULATION IN SAI RIVER BASIN Open
本研究は犀川流域における発電ダムを対象に効率的なダム操作のために重要となるダム流入量予測について検討した.まず,暖候期から寒候期まで水循環過程を高い精度で表現できる流出モデル(WEB-DHM-4cS)を構築した.2015年8月~2018年7月の3年間を通して検証し,上流部の高瀬ダム,下流の生坂ダム地点において各年とも低水から洪水,融雪出水まで観測と良く一致していることを示した.次に,生坂ダム(第三類),高瀬ダム(第一類)地点における2018年7~9月の出水イベントを対象に流…
View article: Radiative Characteristics at 89 and 36 GHz for Satellite-Based Cloud Water Estimation Over Land
Radiative Characteristics at 89 and 36 GHz for Satellite-Based Cloud Water Estimation Over Land Open
Satellite-based passive microwave (PMW) remote sensing is an essential technique to clarify long-term and large-scale distribution patterns of cloud water content (CWC). However, most CWC estimation methods are not implemented over land be…
View article: A multi-sector multi-region economic growth model of drought and the value of water: A case study in Pakistan
A multi-sector multi-region economic growth model of drought and the value of water: A case study in Pakistan Open
This study integrates ecohydrological vegetation and multi-sector multi-region economic growth models to evaluate the impacts of drought on markets and value the economic value of water. The values of several parameters of the agricultural…