GIS based risk zoning and assessment of flood disaster in the middle and lower reaches of the Yangtze River Basin

Based on the digital topographical map and the data about 10 heavy floods since 1870 in the Yangtze River basin,a primary zoning and assessment of flood risk in the middle and lower reaches of the Yangtze River has been studied using Arcview GIS platform with strong function on space analysis and overlap.Firstly the flood-affected area mapping for the 10 heavy floods was conducted based on historical record data;secondly the flood risk assessment map for the Yangtze River basin is made by overlapping the 10 flood affected area distribution.The result shows that the distribution of heavy flood-inundated area has some law in the middle and lower reaches of the Yangtze River with obvious geographical characters.There are 4 extreme flood risks area,i.e.Dongting Lake basin,Poyang Lake basin and the downstream of the Gong'an county along the Yangtze River,especially in Jingjiang River and the Hanjiang Plain with low-lying land between the Yangtze River and the Hanjiang River.(Around) the extreme risks area there are high flood risk area,mainly in the lower reaches of Hanjiang River and along the Zhijiang River basin,Yuanjiang River basin,Lishui River basin,Qingjiang River basin and Taihu Lake basin.Around the extreme flood risks area and the high flood risk area along the Yangtze River is the areas with middle and lower flood risk,and the other is the safety area.The result is identical with the actual situation of the area.