Flood disasters in the middle reaches of river Fenhe during Ming and Qing periods

Through collecting,sorting and analyzing historical documents,a study on the temporal and spatial characteristics and the cause of the flood disasters in the middle reaches of river Fenhe during Ming and Qing periods was conducted.The results showed that there were 218 of flood disasters occurred in the middle reaches of river Fenhe and approximately happened once per 2.5 years in this periods.In the later stage of Ming dynasty and the earlier and later stage of Qing dynasty,the occurrence of flood disasters were higher,but in the earlier and middle stage of Ming dynasty and the middle stage of Qing dynasty,the disasters decreased obviously.The occurring frequency of flood disasters increased obviously in the tributaries of upper reaches in the middle of the river Fenhe,especially in Taiyuan,Jiexiu,Pingyao,Fenyang,Xiaoyi,Wenshui counties.According to the grade series of flood disasters,the occurring frequency of flood disasters at grade second was the highest,and then the first grade and third grade.The occurring frequency of flood disasters at fourth grade was the lowest.Finally,reasons for the high occurring frequency of flood disasters was analyzed,climate,topography and water type distribution was the important reason to cause flood disasters,and the human factors such as the large scale of land reclamation and vegetation destruction also played the important roles to accelerate the flood disasters.