Jun Magome

High‐resolution mapping of the world's reservoirs and dams for sustainable river‐flow management

Despite the recognized importance of reservoirs and dams, global datasets describing their characteristics and geographical distribution are largely incomplete. To enable advanced assessments of th ...

Groundwater use and diarrhoea in urban Nepal: novel application of a geostatistical interpolation technique linking environmental and epidemiologic survey data

Abstract 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.

FORECASTING OF THE WATER QUALITY IN A RESERVOIR USING PSEUDO GLOBAL WARMING MODEL

This research investigates the effects of climate change on the thermal structure and water quality in Urayama Reservoir. We used downscaled meteorological and hydrological data of present period (year 2000) from JRA25 and future period (2060s) by pseudo global warming models using CCCMA47 and ECHAM5. Also we applied a 3-D coupled hydrodynamic and ecological model of ELCOM-CAEDYM to the reservoir. Then we compared simulated results for present period with those for future period. The average surface water temperature in future period was predicted to increase by 1.2°C from CCCMA47 and 0.4°C from ECHAM5 compared with present period. In contrast, phytoplankton biomasses were predicted to decrease by both CCCMA47 and ECHAM5 due to water temperature increase or flood events. ECHAM5 predicted significant increase of SS concentrations because of the large amount of inflow SS by bigger floods than present period.

STUDY OF POLLUTANT TRNSPORTATION PROCESS IN THE BASIN USING GIS AND DISTRIBUTED RUNOFF MODEL

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.

ON THE CHANGE OF BASIN SCALE RIVER WATER RESIDENCE TIME BY DAM 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 1960s 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%.