The influence of wind-induced sediment resuspension and migration on raw water turbidity in Lake Taihu, China

Lake Taihu is an important drinking water source for cities in the Yangtze River Delta region, while the dramatic fluctuation in turbidity has caused severe problems for local waterwork management. The effects of sediment resuspension and migration on turbidity of water intake in a waterworks located in the south of Lake Taihu are studied. Because the sediment behavior induced by wind disturbance was believed to be the main factor for the matter, the effect of wind field on the hydrodynamics and sediment distribution of Lake Taihu was conducted based on a wind-driven numerical model. The obtained results indicate that wind direction was more influential on the structure of flow and wave fields, while wind speed contributed more to the field intensity. The suspended sediment concentration (SSC) of water intake area was most sensitive to onshore winds, which led to significant increase in suspended sediment concentration at 3 m/s, while for alongshore winds, the incipient speed was 4 m/s, and offshore winds were less influential. In addition, the suspended sediment of the water intake area was primarily migrated from other erosion regions rather than local suspended particles. A 7-h lag was found between SSC and the measured turbidity confirmed the lag effect of wind disturbance on turbidity change. The high consistency between the 2 series demonstrated the potential of this method to turbidity prediction when combined with the weather forecast technique.