Effects of hydrodynamic on the mobility of phosphorous induced by sediment resuspension in a seepage affected alluvial channel
2020
Sharma, Anurag | Huang, Lei | Fang, Hongwei | Li, Xiaocui
The phosphorus (P) mobility caused by sediment resuspension was investigated in a tilting flume, considering the important effect of upward seepage. The water level and velocity were observed during the experimental run, and water samples were collected for the measurement of sediment and P concentrations. A lower value of P and sediment concentrations occurred at the upstream end of the test section, and then a stable trend was gradually observed towards the downstream end due to the sediment resuspension and deposition within the test section. A lower P release was identified for the seepage run, accompanied with a lower sediment concentration in the overlying water. These phenomena were directly linked with the turbulent flow characteristics such as time-averaged velocity, Reynolds shear stresses, and turbulence intensity. Results show that the level of turbulence decreased with the upward seepage, indicating lower P and sediment concentrations. The turbulent length scale also decreased with the upward seepage, which led to a decrease in the energy and momentum transfer induced by the larger eddy size in the near-bed region, and eventually, a lower rate of sediment resuspension and P release with upward seepage. The results of the present study are useful for civil or hydraulic engineers since the knowledge of P transport with sediment will improve the management of contaminated sediment in seepage affected alluvial channel.
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