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This study focused on flood damage assessment for future floods under the impact of climate change. Four river basins of Southeast Asia were selected for the study. They included the Pampanga River Basin (PRB) in the Philippines, the Solo River Basin (SRB) in Indonesia, the Lower Mekong River Basin (LMRB) in Cambodia and Vietnam, and the Chao Phraya River Basin (CPRB) in Thailand. Flood damage to rice crops was assessed by flood damage functions considering flood depth and duration and the growth stage of rice plants. Flood characteristics such as flood depth, duration, and distribution were computed using the rainfall–runoff–inundation model to assess flood hazards under the present and future climatic conditions produced by MRI-AGCM3.2S. The damage assessment methodology for rice crops employed in this study was verified using data on past flood events. Then, flood damage assessment was conducted for both the present climate (1979–2003) and future climate (2075–2099) conditions, using MRI-AGCM3.2S precipitation datasets. Flood damage was assessed for worst cases chosen from each climate period and for floods of 50- and 100-year return periods with different rainfall patterns chosen from each climate scenario. The results of flood hazard and damage assessment show that the flood inundation area for a 100-year flood may increase in the future by 20% in PRB; by 66% in SRB; by 27% in LMRB; and by 27% in CPRB. The flood damage area of paddy fields for a 100-year flood may also increase in the future by 16% in PRB; by 55% in SRB; by 23% in LMRB; and by 13% in CPRB.

Background Groundwater is a common domestic water source in developing countries, but is persistently contaminated with enteropathogens. However, studies on determinants of diarrhoea have predominantly focused on piped water. This study examines the relationship between groundwater microbial quality and household diarrhoea occurrence (HDO). Methods Considering it as a proxy of enteropathogens, this study analysed Escherichia coli concentrations in groundwater wells. Ordinary kriging, a geostatistical technique in geographic information systems, was used to interpolate the E. coli concentration to survey points that had secondary survey data (n=942). The relationship between E. coli and HDO using simple and multivariate statistical analyses in SPSS was analysed. Results A total of 77% of households used groundwater. One-third of households were without piped-water access (PWA), and these households were significantly more likely to use groundwater than those with PWA. Of the 87 households that reported HDO, 77% were groundwater users. Of the groundwater users, the households with HDO consumed groundwater with significantly higher E. coli concentrations than the households without HDO. Of the households without PWA, the increase in the E. coli concentration increased the odds of HDO (adjusted odds ratio=3.15; 95% CI=1.07–9.22). Conclusion It is suggested that the groundwater microbial quality is a risk factor for HDO and illustrates this by an application of an interpolation technique relevant for developing countries.

Urban floods are a common urban disaster that threaten the economy and development of cities. Sponge cities can improve flood resistance ability and reduce floods by setting low-impact development measures (LID). Evaluating flood reduction benefits is the basic link in the construction of sponge cities. Therefore, it is of great significance to evaluate the benefits of sponge cities from the perspective of different rain patterns. In this study, we investigated the urban runoff of various rainfall patterns in Mianyang city using the Strom Water Management Model (SWMM). We employed 2–100-year return periods and three different temporal rainfall downscaling methods to evaluate rain patterns and simulate urban runoff in Mianyang, with and without the implementation of sponge city measures. After calibration, model performance was validated using multi-source data concerning flood peaks and inter-annual variations in flood magnitude. Notably, the effects of peak rainfall patterns on historical floods were generally greater than the effects of synthetic rainfalls generated by temporal downscaling. Compared to the rainfall patterns of historical flood events, the flood protection capacities of sponge cities can be easily overestimated when using the synthetic rainfall patterns generated by temporal downscaling. Overall, an earlier flood peak was associated with better flood sponge city protection capacity. In this context, the results obtained in this study provide useful reference information about the impact of rainfall pattern on urban flood control by LID, and can be used for sponge city design in other part of China.

Drought is a slow-developing disaster of water shortages in water cycle components adversely affecting anthropogenic water use. This study introduces a drought assessment framework of standardized indices in Pampanga (Philippines), Solo (Indonesia), and Chao Phraya (Thailand) basins. We used three existing and developed two new standardized indices to characterize meteorological, agricultural, hydrological and socio-economic droughts. We constructed a 15-arcsec (about 0.45-km) grid block-wise TOP (BTOP) model with multipurpose dam operation at individual river basin using global datasets and calibrated BTOP models with daily river discharge and dam inflow data. The simulated irrigated area is also compared with historical drought damages at each river basin. The calibrated BTOP models were run with bias-corrected MRI-AGCM3.2S precipitation to evaluate droughts under climate change. The calculated standardized indices show similar drought timing of the 1982-1983, 1987-1988, 1991-1992, 1997-1998 and 2002-2003 droughts across three river basins. In addition, the timing of these droughts coincides with historical El Niño-Southern Oscillation (ENSO) cycle events. The projected future climates demonstrate a variability of dam inflows and drought severities between four cases of the worst (RCP8.5) climate change scenario. We conclude that standardized indices are useful tools to characterize droughts at water cycle components.

Nitrogen and phosphorus concentrations in Chinese river catchments are contributed by agricultural non-point and industrial point sources causing deterioration of river water quality and degradation of ecosystem functioning for a long distance downstream. To evaluate these impacts, a distributed pollutant transport module was developed on the basis of BTOPMC (Block-Wise Use of TOPMODEL with Muskingum-Cunge Method), a grid-based distributed hydrological model, using the water flow routing process of BTOPMC as the carrier of pollutant transport due a direct runoff. The pollutant flux at each grid is simulated based on mass balance of pollutants within the grid and surface water transport of these pollutants occurs between grids in the direction of the water flow on daily time steps. The model was tested in the study area of the Lu county area situated in the Laixi River basin in the Sichuan province of southwest China. The simulated concentrations of nitrogen and phosphorus are compared with the available monthly data at several water quality stations. These results demonstrate a greater pollutant concentration in the beginning of high flow period indicating the main mechanism of pollution transport. From these preliminary results, we suggest that the distributed pollutant transport model can reflect the characteristics of the pollutant transport and reach the expected target.

This study modified the BTOPMC (Block-wise TOPMODEL with the Muskingum-Cunge routing method) distributed hydrological model to make it applicable to semi-arid regions by introducing an adjustment coefficient for infiltration capacity of the soil surface, and then applied it to two catchments above the dams in the Karun River basin, located in semi-arid mountain ranges in Iran. The application results indicated that the introduced modification improved the model performance for simulating flood peaks generated by infiltration excess overland runoff at a daily time scale. The modified BTOPMC was found to fulfil the need to reproduce important signatures of basin hydrology for water resource development, such as annual runoff, seasonal runoff, low flows and flood flows. However, it was also very clear that effective model use was significantly constrained by the scarcity of ground-gauged precipitation data. Considerable efforts to improve the precipitation data acquisition should precede water resour...

We investigate the geometry of two-dimensional polygonal cracking that forms on the air-exposed surface of dried starch slurries. Two different kinds of starches, made from potato and corn, exhibited distinguished crack evolution, and there were contrasting effects of slurry thickness on the probability distribution of the polygonal cell area. The experimental findings are believed to result from the difference in the shape and size of starch grains, which strongly influence the capillary transport of water and tensile stress field that drives the polygonal cracking., Phys. Rev. E (2017) in press; 11 pages, 11 figures

Despite the recognized importance of reservoirs and dams, global datasets describing their characteristics and geographical distribution are largely incomplete. To enable advanced assessments of the role and effects of dams within the global river network and to support strategies for mitigating ecohydrological and socioeconomic costs, we introduce here the spatially explicit and hydrologically linked Global Reservoir and Dam database (GRanD). As of early 2011, GRanD contains information regarding 6862 dams and their associated reservoirs, with a total storage capacity of 6197 km3. On the basis of these records, we estimate that about 16.7 million reservoirs larger than 0.01 ha – with a combined storage capacity of approximately 8070 km3 – may exist worldwide, increasing Earth's terrestrial surface water area by more than 305 000 km2. We find that 575 900 river kilometers, or 7.6% of the world's rivers with average flows above 1 cubic meter per second (m3 s−1), are affected by a cumulative upstream reservoir capacity that exceeds 2% of their annual flow; the impact is highest for large rivers with average flows above 1000 m3 s−1, of which 46.7% are affected. Finally, a sensitivity analysis suggests that smaller reservoirs have substantial impacts on the spatial extent of flow alterations despite their minor role in total reservoir capacity. Read More: http://www.esajournals.org/doi/abs/10.1890/100125

近年，河川流量計算モデルのMuskingum-Cunge法について，通常の計算式を用いると流量が保存しないという問題点があることが指摘され，その改良法が提案された．本研究では，この改良Muskingum-Cunge法の分布型流出解析モデルへの適用について，大規模河川の黄河流域を例として詳述し，従来の方法の問題点と改良法の有効性を具体的に実証した．

Topography is a dominant factor in hillslope hydrology. TOPMODEL, which uses a topographical index derived from a simplified steady state assumption of mass balance and empirical equations of motion over a hillslope, has many advantages in this respect. Its use has been demonstrated in many small basins (catchment areas of the order of 2–500 km2) but not in large basins (catchment areas of the order of 10 000–100 000 km2). The objective of this paper is to introduce the Block-wise TOPMODEL (BTOP) as an extension of the TOPMODEL concept in a grid based framework for distributed hydrological simulation of large river basins. This extension was made by redefining the topographical index by using an effective contributing area af(a) (0⩽f(a)⩽1) per unit grid cell area instead of the upstream catchment area per unit contour length and introducing a concept of mean groundwater travel distance. Further the transmissivity parameter T0 was replaced by a groundwater dischargeability D which can provide a link between hill slope hydrology and macro hydrology. The BTOP model uses all the original TOPMODEL equations in their basic form. The BTOP model has been used as the core hydrological module of an integrated distributed hydrological model YHyM with advanced modules of precipitation, evapotranspiration, flow routing etc. Although the model has been successfully applied to many catchments around the world since 1999, there has not been a comprehensive theoretical basis presented in such applications. In this paper, an attempt is made to address this issue highlighted with an example application using the Mekong basin. Copyright © 2007 John Wiley & Sons, Ltd.

グリッド型の分布型水文モデルには，擬河道網の解像度を変えるとモデルパラメータを再調整しなければならないというグリッドサイズに起因する問題がある．近年，高解像度の擬河道網からどのような低解像度にも変換できる簡単な粗視化法（最大集水河道追跡法）が提案されたので，本論文ではこの粗視化法を用いて河川流量計算の解像度依存性を考察する．具体的には，富士川支流の早川及び中国の黄河全流域を対象として，様々な解像度の擬河道網を用いてMuskingum-Cunge法で河川流量計算を行ない，その粗視化の影響を詳細に評価した．最大集水河道追跡法は，高解像度擬河道網の河川特性量（河道長及び標高差，勾配等）を異なる解像度の擬河道網であっても精度良く保持することができるため，河川流量計算に対する擬河道網の粗視化の影響がほとんど無いことが分かった．

This study investigates the Mekong River basin hydrology for the 1980–2000 period using a grid-based distributed hydrological model called Yamanashi Hydrological Model (YHyM). The performance of the model is evaluated using data observed at different locations and the results justify the physical soundness of the model. The seasonal variations of climatic and hydrological characteristics of the basin such as soil moisture, ground water saturation deficit, runoff, precipitation, evapotranspiration, etc. are analysed. On the basis of the simulated results, it is noticeable that there is no significant trend in the precipitation, discharge, or soil moisture state of the basin during the simulated period, though there are some seasonal variations which seem to be natural. However the analysis on the precipitation elasticity (E) of the river flow shows that the E values for all sub-basins are greater than unity, which indicates that x% change in annual precipitation can cause > x% change in annual river flow. Further the basin hydrological responses are analysed for a long term synthetically-induced drought the results of which show the significance of the base flow of the Mekong River basin. Copyright © 2008 John Wiley & Sons, Ltd.

Summary The BTOPMC (Blockwise use of TOPMODEL with Muskingum–Cunge routing) model was tested for spatial and temporal transferability of the calibrated model parameters to predict various runoff components (runoff volumes, peak flows and base flows) in different physiographic regions of Nepal. To evaluate the spatial transferability, the model was calibrated and validated using available time series data in six catchments. Results show that the model performed well in simulating various runoff components and capturing the seasonal and annual variations in runoff. The model parameters of donor catchments were selected based on the similarity index and applied in other two data limited catchments using the regionalisation scheme. Results show that the model could reproduce the runoff volume, base flows, seasonal and annual variations in runoff when the model parameters were transferred spatially. To evaluate temporal transferability, two different scenarios were tested in a river catchment, Bagmati river. The first scenario used three data sets: 1994–1997 for calibration, 1998–1999 for validation, and 2000–2002 data for evaluation. The second scenario also used three data sets: 2000–2002 for calibration, 2003 for validation and 1994–1997 for evaluating transferability of model parameters. Only a marginal loss in model performance was observed when calibrated parameters were transferred from one period to another period. This study therefore suggests that the calibrated parameters of BTOPMC model can be spatially and temporally transferred within river catchments located in similar physiographic regions and especially in those catchments where data is sparse. Such regionalized models can be used for hydrological simulations to study the impacts of land use and climate changes.

Summary One of key inputs to hydrological modeling is the potential evapotranspiration, either from the interception (PET 0 ) or from the soil water of root zone (PET). The Shuttleworth–Wallace (S–W) model is developed for their estimation. In this parameterization, neither experimental measurement nor calibration is introduced. Based on IGBP land cover classification, the typical thresholds of vegetation parameters are drawn from the literature. The spatial and temporal variation of vegetation LAI is derived from the composite NOAA-AVHRR NDVI using the SiB2 method. The CRU database supplies with the required meteorological data. They are all publicly available. The developed S–W model is applicable at the global scale, particularly to the data-poor or ungauged large basins. Using the century monthly time series of CRU TS 2.0 and the monthly composite NOAA-AVHRR NDVI from 1981 to 2000, annual PET is estimated 1354 mm over the Mekong River basin, spatially distributed strikingly non-uniformly from 300 to 2040 mm, and seasonally changed significantly with LAI. By replacing the monthly with the 10-day composite NDVI and the albedo of 0.10 with 0.15 for substrate soil surface, annual PET relatively decreases less than 4% and 1.7%, respectively over the whole basin. The correlation with pan evaporation ( E pan ) is quite scattered but grouped with the vegetation types and consistent with a rough ratio as reported in the literature. In contrast, the PET and the reference evapotranspiration (RET) are vegetation-type-dependently correlated very well. The PET 0 is estimated 1.63 times of PET in average over the whole basin. The application of BTOPMC model shows that the derived LAI, PET 0 and PET behave very well in the distributed hydrological modeling.

This paper focuses on parameter regionalization for the block-wise use of the TOPMODEL with the Muskingum–Cunge routing method (BTOPMC). Pre-determined quantitative relationships with physical basin characteristics are used to reduce uncertainty in parameter estimation and enable prediction in ungauged basins. BTOPMC parameter values, which have previously resulted in efficient model performance, are applied to ten Model Parameter Estimation Experiment (MOPEX) basins without any parameter adjustment to test model performance using ‘blind’ a priori parameter estimates. It is quantitatively shown that parameters can not be satisfactorily estimated a priori without parameter adjustment, either through calibration or transfer functions linking parameters to physical basin features, referred to as ‘improved’ a priori parameter estimation. To compare model performance using different parameter estimation techniques, BTOPMC parameters are re-estimated by automatic optimization. As anticipated, model performance improves significantly when these optimized parameters are used. Good correlation of model performance is also observed between the 19-year validation and 20-year calibration results when optimized parameters are used. This indicates that BTOPMC's predictive accuracy depends strongly on calibration accuracy, implying that well-optimized parameter values can ensure the accuracy of model predictions. It appears reasonable to use optimized parameter values, selected from successful modelling applications, to make transfer functions which ‘improve’ a priori parameter estimates. The ‘improved’ a priori parameter estimation is achieved through multiple linear regression analysis relating BTOPMC parameters to soil and vegetation types within the basin being modelled. The results suggest that the preliminary parameter transfer functions are encouraging and that ‘improved’ a priori parameter estimation techniques have the potential to reduce parameter uncertainty and enable prediction in ungauged basins. To improve parameter estimation and predictive accuracy of the model, further research to determine more accurate values, and their relationship with physical basin characteristics, is needed.

Feasibility of global monitoring of water storage in large lakes and reservoirs by satellite monitoring method combined satellite images and altimeter data is analyzed. In this study, variation of water storage in 34 large lakes and reservoirs are monitored globally by using satellite images obtained from TERRA/MODIS and satellite altimetry data obtained from TOPEX/POSEIDON MGDR-B. The results show that the satellite-based monitoring method can provide information on seasonal to inter-annual variability of water storage in large lakes and reservoirs. The method used in this study utilizes only satellite data to estimate reservoir storage. This approach is capable of contributing greatly to integrated water resources management and water use quantification in large-scale regions-especially areas that have inadequate ground observations, making it very useful for determining the impact of reservoirs in the water cycle of large scale regions.

高解像度の擬河道網をどのような低解像度にもスケール変換できる簡単な方法を提案する．この方法で低解像度の河道を求めるには，大格子中で最大の集水面積をもつ小格子から出発し，隣接大格子の中の小格子まで河道を追跡するだけでよい．さらに大格子間に中継領域を導入すると，低解像度の擬河道網は高解像度の擬河道網の形状をより良く再現できる．提案した方法を早川流域に適用し，50m解像度の擬河道網から250m及び500m，1km解像度の粗いスケールの擬河道網を作成する．これらの擬河道網は，河道長や勾配，河道長度数分布等の地形的特性を良く再現する．黄河については，30×30小格子をまとめた大格子での擬河道網でも，元の1km解像度の擬河道網の特性を精度良く保持することがわかる．

A geo-referenced global dam reservoir database is constructed by assembling several published dam inventories and latitude/longitude coordinates that are digital obtained or decided from printed maps. This database is designed for hydrological applications on river basin scale to the global scale, and 15, 317 dams with 29 dam reservoir attributes are registered in it. A shoreline polygon data of the reservoir/lake is also provided for 4, 204 dams. The total storage capacity of the registered dams is 5, 594km3, which is equivalent to the 70% of total storage capacity of all reservoirs and lakes over the world (7, 000 km3). Since geo-referenced reservoir database which covers whole global area is rarely available, the database will greatly contribute for global scale water resources analysis and impact assessment of reservoirs on the freshwater systems.

A basin-scale pollutant load and its transportation processes are discussed in this study. The unit loading method combined with census and GIS data is used to estimate spatial distribution of pollutant load within the basin. the method allows grid-base representation of pollutant load, and makes it possible to link the pollutant production with distributed hydrological model. The spatial distribution of pollutant load and channel purification process model are then integrated into the distributed hydrological model to simulate dynamic behavior of water quality and quantity along the stream. These methods have potential to be used for understanding the water quality over the large area with less data requirement, and could be applied for integrated river basin management.

The method for monitoring the variation of reservoir storage is presented. Satellite observations are used to estimate the change of storage volume of the reservoirs, where satellite images are applied to detection of water surface and satellite altimetry is used to measure the change of water level. This method has potential to be used for monitoring reservoir storage without in-situ observations, and it could be applied to ungauged or data poor basins.The case studies are conducted in 3 large reservoirs in Africa (Akosombo, Victoria and Nasel), and the results of case studies show that the presented method can provide seasonal to inter-annual variability of reservoir storage. In addition, the relation between change of reservoir storage and precipitation is also investigated in these 3 large reservoirs.

The purpose of this study is to understand the potential impact of reservoir induced water storage on the basin scale water cycle. In this study, the increase of the basin scale residence time of river water is used as the index of the effect of reservoir on water cycle, and its spatial and temporal distribution in Japan are demonstrated. The results of analysis show that the potential increase of residence time by dam reservoirs in Japan has gradually increased from 1960's and reached to 14.5 days in 1995. The actual residence time increase is also estimated in the Tone river basin where operation and seasonal variation of river discharge are taken into account. It is shown that the estimated actual residence time is much smaller than the potential, in the case of the Tone river basin, 45%.

Climate and land use change impacts on river flow were evaluated in this study with emphasis placed on turbidity. Turbidity levels for the year 2020 were projected for Gin River, one of the prime sources of drinking water in Southern Sri Lanka. Future land use in the Gin catchment was predicted using a GIS based statistical regression approach. Regional Climate Modelling system generated the future rainfall for the SRES A2 and SRES A1B emission scenarios. Streamflow simulations were carried out using a distributed hydrologic model, and turbidity values were determined using rating curve based relationship developed between river discharge and TSS (Total Suspended Solid) concentration followed by Turbidity-TSS linear regression correlation. Increased turbidity levels are clearly evident under the SRES A2 scenario, following more pronounced increased stream flows. Projected 75th percentile monthly turbidity values in year 2020 are expected to increase during May to November compared to the baseline, and in certain months, about 100%increase is noted. 60% of the time, year 2020 turbidity levels have indicated exceedance of the water quality standards set for the potable water as well the inland waters of Sri Lanka, which would lead to exert extra challenge on future drinking water production in Southern region of Sri Lanka. ENGINEER, Vol. 48, No.01, pp. 61-70, 2015