ALLOCATION AND VARIATION OF SEDIMENT FOR BRANCHING CHANNELS OF MAIN RIVER IN THE PEARL RIVER DELTA——A Case Study of the West and North River Delta

The allocation rate of sediment discharge for typical branching channels in the West and North River Delta was calculated, and the variation features of sediment was analyzed. Some conclusions were obtained: 1) With a small part being transported by tide, the sediment in the estuary of the Pearl River mainly comes from the silt carried by upstream river runoff. The river runoff and the sediment, as the dominant factors, is the basic dynamic and substance for the formation of the modern Pearl River Delta.The West River is the main sediment contributor to the Pearl estuary. 2) As compared with the data in the 1960s, the allocation rate of the sediment discharge for the branching channels of the main West River and North River keeps nearly no change. Modaomen is still the biggest sediment delivery river mouth among the 8 estuaries. 3)The sediment in the estuary of the Pearl River tends to be accumulated year by year. No evident variations have been found for the erosion and deposition in the upstream river stretch. Both erosion and deposition occur in the transitional reaches between the upstream river and the estuary, while deposition occurs all over the estuary. 4) The sea level rise and the activities of human being in the Pearl River Delta may cause unfavorable variations of the transport of sediment and runoff and should be taken seriously.