GEOGRAPHIC ENVIRONMENT CHANGE AND FLOOD CATASTROPHE IN HUAIHE RIVER BASIN DURING LAST 2000 YEARS

During the last 2000 years, flood and waterlogging catastrophes took place quite frequently in the Huaihe River Basin.In the authors'opinion, these natural calamities have a very close relation to the evolution of Hongze Lake.Formed initially within a man-made dyke that was built in the Han Dynasty about 2000 years ago, Hongze Lake brought out headward accumulation developing in the middle reaches of the Huaihe River, with its continuous aggravation on lake-bottom and consequent water-level rise.It was estimated that, on an average, there were 3400×10⁴t sediment per kilometre per year deposited on the river bed from Lutaizi to Bengbu.Therefore, the rising of water-level and the drainage difficulty in the middle reaches of the Huaihe River aggravated local flood and waterlogging catastrophe here.