Impact of sedimentation by check dam on the hydrodynamics in the channel on the Loess Plateau of China

Abstract

The sedimentation by check dam in the channel affects hydrological process. In this study, the effects of the sedimentation on the dynamic process of runoff and erosion power were investigated by dynamic coupling models (MIKE SHE model and MIKE 11 model). The study area was located in Wangmaogou watershed in the Loess Plateau of China. Four scenarios including no check dam and check dam with siltation depths of 0, 4 and 8 m were designed to study the reduction effectiveness of check dam on the hydrodynamic processes. The research showed that the silt dam not only reduced the total volume flow rate of floods but also increased the flood duration and delayed the occurrence of flood peaks. The siltation depths of the dam influenced the flow velocity and runoff shear stress. With deposition, the channel was longer in 8 m siltation compared with 0 and 4 m siltation. The shear force and unit runoff power were remarkably reduced in the scenario of 8 m siltation, followed by 4 m, and lastly by 0 m. The dam system can still vastly reduce the flow velocity along the channel in the full state and decrease the maximum flow velocity along the channel by more than 50%. The decrease in flow velocity was the main reason for the decrease in the sediment-carrying capacity of the runoff, which directly reduced the runoff erosion intensity. This study provides the scientific basis for understanding the regulation of check dam and sedimentation on hydrological process.