Assessment Of The Drought Risk In Haihe Basin Based On3S

Drought, as one of the most serious natural disasters in Haihe Basin, presenting remarkable features as universality, season, continuity and region, has aroused widely attention of the experts in different subject disciplines. Because of the serious damage caused by drought and the significant differences in the definitions of drought, it is necessary to find out the potential law among them and a suitable way to reduce it. In view of that, some researches have been done in this paper.(1) The differences among the former definitions of drought are talked, and the concept of generalized drought is put forward, based on the water resource system theory, which describes that the drought is a common hydrological process. It means the water shortage evolution process in water system, compared with the annual average, caused by rain decrease, with the percentage of soil water content anomaly as the drought index. So the drought risk is defined as the possibility of the generalized drought occurrence, which mainly manifested as frequency and intensity.(2) By analyzing the data of the no rain days, the maximum daily precipitation, monthly precipitation and annual precipitation form each weather station in Haihe Basin, we can get a deceased trend of the precipitation in Haihe Basin since1980s. The amount of light drought, severe drought and extremely drought in the basin show a whole growth and local time downward trend, with the soil water as a drought index, which is obtained by the prototype observation, the GIS technology and the SWAT hydrological model. Especially, since1980s, the number of occurrences of drought has increased significantly.(3) The drought risk in different combination schemes of driving factors is calculated by P-Ⅲ distribution curve and mapped by using Arc GIS10, which is increased by climate change and underlying surface variation and reduced by irrigation projects. On recent conditions, Haihe Basin is facing high drought risk, which is extreme high in the south and low in the area of Diandong Plaint and Luanhe Mountain. Finally, aim to avoid drought risk and cut down the damage of drought in Haihe Basin, according to the analyze result in different driving factors, this article presents a positive and macro-control suggestion, which contains three time scale tactics, such as long time(10a～20a), middle time(5a～10a) and short time(6months～12months).