Modeling the effects of the streamflow changes of Xinjiang Basin in future climate scenarios on the hydrodynamic conditions in Lake Poyang, China

Abstract

The responses of lake hydrodynamics to the hydrological processes in watersheds have been associated with the ecological evolution of and the biochemical processes in aquatic ecosystems. This paper investigates how the changes in the streamflow of Xinjiang Basin in different future climate scenarios could affect the hydrodynamic conditions in Lake Poyang. First, the hydrodynamic processes in Lake Poyang (i.e., lake level and water velocity) were simulated based on the environmental fluid dynamics code (EFDC). Error statistics indicated that the hydrodynamic model reasonably reflected the hydrodynamics in Lake Poyang. Second, the future streamflow of Xinjiang Basin from 2016 to 2050, which was projected in two future climate scenarios (Sim_RCP4.5 and Sim_RCP8.5) based on the Xin’anjiang model, was applied to hydrodynamic modeling to investigate the relationship between future discharge and hydrodynamics. Results showed that the streamflow changes of Xinjiang Basin in future climate scenarios considerably affected the seasonal distribution of the flow field in Lake Poyang. The hydrodynamic change region that exceeded the threshold values under these two climate scenarios both demonstrated a fluctuating trend and nearly covered the entire lake until April. In Sim_RCP8.5 a slightly larger area was influenced than in Sim_RCP4.5, except in January, and the eastern channel was always significantly affected by streamflow change. These analyses can enhance the present understanding of the relationships between the hydrodynamics in lakes and the hydrological processes of sub-basins.