抄録
According to an observation record, long-term discharge at Fukakusa station in the Kamo River basin has been decreasing, which may affect water-related landscapes and the ecosystem. This study conducts a forensic analysis to investigate the dominant reasons for the streamflow reduction and attempt to quantify the contribution of each factor based on water balance analysis, trend analysis and hydrologic model simulation. The results suggest that the decreasing trend is primarily caused by the increase of drainage areas of the sewage system in Kyoto city and the reduction of intake from Lake Biwa canal to the Kamo River. These effects diminish the impact of slight increase in the annual precipitation and suppress the increase in evapotranspiration in the Kamo River basin.
