The effect of vegetation on sediment resuspension and phosphorus release under hydrodynamic disturbance in shallow lakes

Abstract

This study was conducted to investigate the effect of vegetation on sediment resuspension and phosphorus release in response to hydrodynamic disturbances in shallow lakes using a unique instrument to simulate wind-driven current. Two common types of vegetation, Vallisneria natans and Acorus calamus of Taihu Lake (a typical shallow lake), were planted in an experiment system. The results indicated that bed shear stress in the presence of vegetation was much less than critical shear stress which led to lower resuspension. Acorus calamus led to a much greater reduction in bed shear stress and better inhibitory effects on sediment resuspension due to its robust stem and better resisting capacity. Additionally, vegetation had a significant inhibitory effect on the release of total phosphorus (TP). The effect was larger for Acorus calamus, especially under hydrodynamic disturbance induced by moderate and high wind speed. TP release by Vallisneria natans was dominated by particulate phosphorus (PP) and that of Acorus calamus was dominated by dissolved total phosphorus (DTP). PP release mechanism was same in flume SV and EV that it was mainly relevant to bed shear stress and SSC. DTP release mechanism was different between plant species.