Markov chain based transition probability behaviors of drought events in the Pearl River basin, China

Abstract:

Deep understanding of transition probability behaviors of droughts is the key to real-time monitoring of droughts and also to enhancement of human mitigation to droughts. In this case, the transition probability matrix of the Markov chain is derived by the copula functions. Besides, the mean duration of a drought event with the severity not less than a certain drought category, the mean first passage time from any drought category to no drought category, and also the mean first passage time from no drought category to any drought category were analyzed in this study. The results of this study indicate that in the Pearl River basin: (1) the exceptional drought lasts about 1.5 months and the drought with the severity not less than the abnormally dry lasts about 3 months; (2) it takes about 3.5 months for the exceptional drought to be recovered to no drought while about 1.7 months for the abnormally dry to be recovered to no drought; and (3) generally, there is a moderate drought in 1 and 2 years for the severe drought, 3 years for the extreme drought, 5.5 years for the exceptional drought. Besides, the results of this study indicate higher risk of drought in the southeast part of the Pearl River basin and these regions are densely populated and economically developed, especially in the Pearl River delta. Besides, the west part of the Pearl River basin has also been identified as a region with a higher risk of drought.