Effect of sandbar in Modaomen Estuary on flood drainage of Pearl River

The Modaomen Estuary,which connect the complicated stream network of the Pearl River and the estuarine bays,is the most important water way in discharging freshwater and sediment into the estuarine bays. However,there is immense bar area evolved in the outer subaqueous delta. Consequently,the flood releasing safety is the most important issue in the regulation project of the estuary. A 2-D tidal flow numerical model is established to investigate the effects of different regulation measures on the flood release in the Modaomen Estuary,and the regulation measures include excavating a channel in the sand bar,obstructing the east channel and dredging in the east channel and the west channel. The results show that the measure of excavating a channel in the sand bar is not helpful to improving the efficiency of flood drainage. The measure of obstructing the east channel results in an increase in the water surface slope between Guadingjiao and Dajinjiao,which intensifies the water damming. The effect of channel dredging in the east channel and west channel on flood drainage is not obvious. All these results indicate that the sand bar does not have significant adverse impact on the flood drainage,which confirms the fact that the estuary sandbar system has its self-regulating effect to meet the need of flood drainage.