MODELING OF WATER TEMPERATURE IN THE YAMATO RIVER AND EFFECTS OF FUTURE TEMPERATURE RISE AND DEPOPULATION

Abstract

 Under the circumstance of climate change, it is essential to forecast the future temperature of rivers to protect the ecosystem and other environment. This study applied a model of river channel temperature model coupled with rainfall runoff inundation model to simulate the discharge and water temperature of the Yamato River. Despite of some weaknesses, the Nash-Sutcliffe coefficient is above 0.8 and the RMSE of river water temperature is around 1.85 °C, which means that the calculations of two models were both in good agreement with the observations. Then, we evaluated the effect of air temperature rise, as well as decrease in sewage effluent, which is one aspect of depopulation, on the river temperature of Yamato River. As a result, it is shown that the rise of air temperature poses a significant impact on river water temperature, and the effect of decrease in sewage effluent may not offset the effect of air temperature rise.