Drought risk assessment in China with different spatial scales

Abstract

With the increasing impact of climate change and anthropogenic activities, drought happens in more areas with higher frequency. In this paper, we calculate the return period and the drought risk in China based on the monthly PDSI, the Palmer Drought Severity Index, data over 188 stations from 1901 to 2010. We use the theory of runs to identify the drought duration and severity. We adopt the kernel density estimation to obtain the marginal distribution function, and the Gumbel Copula function to obtain the joint distribution function. The results show that the return period of the joint distribution for the drought duration and severity can be regarded as the extreme condition of the return period of the marginal distribution for the single factor such as the drought duration or drought severity. Under the same drought severity, the return period of the joint distribution is increasing with the prolonging of the drought duration, and it approaches to the return period of the marginal distribution of the drought severity. Under the extreme drought situation, Haihe River Basin, Huaihe River Basin, Songliao River basin, and rivers in the northwest China have a higher drought risk in future 50 years. The drought risk value in China is increasing with the prolonging of predicting time.