Analyses On Space-time Change Features Of Rainstorm And Risk Assessment Over Huai River Basin

By selecting the daily precipitation observed data of meteorological stations in Huaihe River Basin and using the methods of wavelet analysis and coefficient of variation and anomaly percentage, the inter-annual change and the space-time distribution features of the number of rainstorm days and precipitation in summer over Huaihe River Basin during 1958～2007 were analyzed. The results showed that: the inter-annual changes of the number of rainstorm days and precipitation from 1958 to 2007 were fierce, which positive and negative anomalies appeared alternately 1～2 years. As a result of East Asian summer monsoon inter-annual variability and East Asian circulation system, there had significantly 2-year quasi-periodic oscillations on rainstorm in summer. In the late 1990s, rainstorm days and precipitation increased obviously due to East Asian summer monsoon circulation appeared the decadal significant weakens. Because of water vapor and terrain, rainstorm mainly concentrated on the east and the southwest over the Huaihe River Basin, but less on the northwest. It was presented high in the south and low in the north by spatial distribution.Based on the hazard of the factor leading to disaster and vulnerability of the object suffered disaster, the indexes of rainfall, runoff, river density, elevation, slope, population and economic indicators were chosen. Then the index weight of each factor above is calculated by using AHP. The rainstorm disaster hazard maps, vulnerability maps and comprehensive risk maps were generated by getting weighted sum of all the factors. The rainstorm disaster risk assessment results were verified by using data of area inundated in flood. The results show that:the higher hazard areas of rainstorm in Huaihe River catchment are mainly distributed in the southern part of Henan, the northern part of Anhui and eastern part of Jiangsu province; higher vulnerability areas are mainly distributed in north-central of Henan, central of Anhui, south of Shandong and the northeast of Jiangsu province; high risk areas are mainly distributed in south of Henan, north of Anhui and east of Jiangsu province.Based on the assessment on risk of rainstorm and flood disaster in Huaihe river basin, this paper explores and discusses about measures to carry out disaster risk management from the perspective of risk management. The paper hereby puts forward the relevant measures by considering all following eight aspects together, that is deducing risk, avoiding risk, sharing risk, enhancing resistant ability toward flood disaster, improving precautionary ability, emergency reaction ability and bearing ability toward risk and averting risk of artificial aggravation.