2024 Volume 80 Issue 16 Article ID: 23-16095
To quantitatively assess the changes in water risk due to future climate change, it is necessary to employ a water resource model that adequately incorporates the impacts of human activities on the water cycle. Specifically, for estimating water risk at a high resolution in Japan, where advanced water use practices are widespread, it is important to consider water abstraction from areas distant from rivers and from outside the basin. Therefore, in this study, we developed an irrigation network across Japan and incorporated it into the water resource model to quantitatively evaluate the effects of irrigation on water use and the mitigation of water stress. Water aqueducts for irrigation purposes existed in about 16% of the total number of Japanese land grids. In Japan, approximately 28% of the water flowing through the irrigation network was sourced from river water usage for agriculture, The modeled supply shortage also improved from 25.5 billion m3/year to 16.9 billion m3/year for the 1994 average. In regions such as the paddy fields along the coastal areas of the Japan Sea side, significant mitigation of water stress due to irrigation water from outside the river basin was observed.
