THREE-DIMENSIONAL NUMERICAL SIMULATION OF WIND-INDUCED CIRCULATION IN LAKE TAIHU

A three-dimensional (3-D) numerical circulation model for shallow-lake is presented and described in detail in this paper, which employs model-splitting technique in order to calculate water level, mean-depth velocities and horizontal and vertical velocities at different depth simultaneously. The results show the current circulation pattern features four eddies with two clockwise and two anticlockwise induced by prevailing wind. Opposite wind field will lead to opposite current pattern with phase shifted by 180 degrees. The surface convergence zone is located in the upwind area and the surface divergence part in the downwind region, This results in drastic vertical movement in the two zones and the return currents at the bottom with phase shifted by 180 degrees from the surface current vectors. Thus the water level decreases significantly at the leeward side and increases quickly at the windward part. Verification and calibration for the model were made based on the water-level and current data observed during the 9711 Storm in Lake Taihu. The predicted results are in satisfactory agreement with the observed data, which raises the possibility that this model can be used to decide the bottom current stress for sediment resuspension and also to simulate sediment transportation. It can provide a fundamental tool to study the nutrient release from bottom sediment in Lake Taihu.