Hazard assessment of drought disasters in Beijing-Tianjin-Hebei region based on Copula for recent 60 years
Received date: 2019-02-18
Revised date: 2019-06-07
Online published: 2019-11-17
Drought disaster is one of the major meteorological disasters in the Beijing-Tianjin-Hebei region, China with serious economic and food security impacts. The hazard of drought disasters is evaluated to identify the high hazard areas, and provide references for the disaster prevention and emergency control. Based on the precipitation data of 37 meteorological stations from 1958 to 2017, the standardized precipitation index at 6-month scale (SPI6) is calculated. And the drought duration and the drought severity are defined using the run theory. We use Kolmogorov-Smirnov method and AIC method to confirm the most fitted marginal distributions and the Copula function. The return periods of drought duration and drought severity are calculated under different return periods (RP 5 a, 10 a, 30 a, 50 a).The results show that the SPI6 is in a downward trend from the mid-1960s to current times. The exponential distribution and the generalized extreme value distribution are the optimal marginal distributions of drought duration and drought intensity, respectively. Frank Copula has the best fitting in the calculation of joint probability distribution. As far as the joint return periods of drought duration and drought severity show Beijing, Cangzhou, Hengshui and north Chengde of Hebei Province have a long joint return period with low hazard and the rest of the region has a short joint return period with high hazard (RP 30 a, 50 a).The theoretical joint return period of the drought disaster is close to the actual situation, which indicates that the joint return period can better reflect the situations of drought disasters.
