Risk Analysis of Historical Flood and Drought Disaster in Henan Province
河南省历史水旱灾害危险性分析

Flood and drought disasters are very frequent in Henan Province. Based on the frequency calculation of historical zoning flood and drought disasters from 1450 to 1979, frequency of drought year from precipitation anomaly percentage and influence degree of integrative precipitation on flood disaster risk, using GIS technique, this paper has analyzed the drought disaster risk, flood disaster risk, the integrative risk of flood and drought disaster in Henan Province from spatio-temporal scale according to the principle of the risk rises with frequency. The conclusions are as follows: 1) Extremely high risk regions of drought disaster mainly lie in Pingdingshan city, Zhengzhou city and the most of Xuchang city; high risk regions mainly lie in Xinxiang city, Jiaozuo city, Hebi city, Jiyuan city, the most of Luohe city, and the east of Luoyang city; medium risk regions mainly lie in Kaifeng city, Shangqiu city, Zhoukou city, Anyang city, Puyang city; low risk regions mainly lie in Zhumadian city, the most of Sanmenxia city, the south and west of Luoyang city; very low risk regions are mainly located in Nanyang city and Xinyang city; 2) As for flood disaster hazard, very high risk regions mainly lie in the south of Pingdingshan and Luohe city, the southwest of Zhoukou city, the southeast of Shangqiu city, and the common boundary of Kaifeng city, Zhoukou city and Shangqiu city; high risk regions mainly lie in Xuchang city, the south of Luoyang city, the most of Zhoukou city, the northwest of Shangqiu city, the south of Kaifeng city, the north of Luohe and Pingdingshan city; medium risk regions mainly lie in Sanmenxia city, Jiyuan city, Hebi city, the most of Luoyang and Zhengzhou city, etc; low risk regions mainly lie in Puyang city, the most of Xinxiang and Zhumadian city, the east of Anyang and Jiaozuo city, and the north of Xinyang city; very low risk regions are mainly located in the most of Nanyang city; 3) As to the integrative flood and drought disaster hazard, very high risk regions mainly lie in Pingdingshan city; high risk regions mainly lie in Xuchang city, Luohe city, Zhoukou city, Shangqiu city, Kaifeng city, Hebi city, Anyang city; medium risk regions mainly lie in Xinxiang city, Luoyang city, Zhengzhou city, Puyang city, Jiyuan city, Jiaozuo city, Sanmenxia city; low risk regions mainly lie in Zhumadian and Xinyang city; very low risk regions are mainly located in Nanyang city. The results can provide important basis for risk assessment and management of flood and drought disasters, disaster prevention and reduction and so on.