Author(s): Rikushi Yasumatsu, Makoto Umeda

Linked Author(s): Makoto Umeda

Keywords: High turbidity; Suspended sediment; Climate change; Reservoir;

Abstract: High and long-term persistence of turbidity especially after a large flood event has been a burning issue in the area of river water environment. Considering the fact that reservoirs are responsible for more than half of drinking water in Japan, it is of great importance to investigate the turbidity in reservoirs to ensure water supply. Furthermore, climate change may affect the occurrence of higher turbidity in reservoirs since behavior of suspended sediment is sensitive to the condition of thermal stratification in a reservoir as well as precipitation. We applied a vertical 1-dimensional hydraulic model for future prediction of turbidity in more than 30 reservoirs in Japan. We set a reference period and a future period of the simulations as 1981-2000 and 2081-2100 respectively. Future scenario takes into account changes of temperature and solar radiation. As a result, we revealed that profiles of the water temperature and suspended sediment after a flood event might change due to climate change. Furthermore, change rates of duration of annual high turbidity outflow from reservoirs with respect to baseline scenario showed significant variability. Plus, results implied that reservoirs with smaller turn over rate were more sensitive to climatological change than other reservoirs.

DOI: https://doi.org/10.3850/38WC092019-1705

Year: 2019