Flood disaster and its social impacts in the upper reaches of river Hanjiang in Qing Dynasty

The frequencies of flood disasters and their impacts in Qing Dynasty in northern Shannxi were analyzed according to the statistics of local historical disaster data collection and relating information.It showed that the frequency of flood disaster was lower in 1644 ~ 1804,1 time per 3.09 year;it was higher in 1814 ~ 1854 and 1814~1853,1 time per 1.18 year and 1 time per 1.11 year.Flood disaster occured mainly in summer and autumn;Grade two and grade three disaster were relatively more.There had a significant relationship between the flood disaster occurrence and the local climate changes,topography and the reclamation activity of migration.Flood disaster had affected the economic and social development,agriculture and natural enviroment.