Development of a hyper-resolution water resource model including advanced modeling of dam operations and human water usage in Japan

Climate change and increased human activities have resulted in environmental changes such as an increase in evapotranspiration and drought, and the freshwater resources we currently use may not always be available in the same locations in the future. Hence, we need to identify where water resources will be compromised by climate change.The quantification of global water stress through hyper-resolution models necessitates a comprehensive understanding of local water use patterns. The calculation of water stress requires water usage data at a grid-level resolution however, such is frequently lacking in many regions. In this study, we investigated water stress in the Japanese region using global freshwater resources model, H08, by compiling the necessary data for water stress calculations, based on the availability of detailed information on land use, topography, and water use.Water use statistics available at the prefectural and municipal level were downscaled to 1 min resolution. In addition, reservoir operations upstream of the river were incorporated into the model for each purpose. For agricultural water use, in addition to irrigation by water withdrawal from rivers near farmland, the utilization of out-of-basin water sources and conduits systems were also considered.The results reveals that potential high water stress was observed in high population density areas and industrial areas throughout the year. In areas where farmers grow crops, potential high water stress was only observed during the irrigation season. There are 9 out of 47 prefectures in Japan that have potential high water stress, and many of these areas are located in industrial areas.
The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)