Spatial and temporal variation of rainfall extremes for the North Anhui Province Plain of China over 1976-2018

The North Anhui Province Plain (NAHPP), an important food production plain in China, is prone to frequent droughts and floods. To better understand the extreme events and mitigate their effects, this paper explores the spatiotemporal variation of precipitation extremes in the NAHPP during 1976 and 2018. Variation trends and spatial distributions of the annual maximum 1-day, 3-day, 7-day, and 15-day-rainfall were analyzed, and the probability distribution of rainfall extremes in the NAHPP was calculated by three distribution functions (Gumbel, P-III, and generalized extreme value). The optimal fitting function was selected based on the Kolmogorov-Smirnov test, and the rainfall in different return periods was calculated according to the optimal fitting function. The results indicate that rainfall extreme showed a 2- to 3-year periodicity on the interannual scale and 21-year periodicity on the chronological scale in the NAHPP. The rainfall extremes showed nonsignificant increase trend over the NAHPP, and some stations showed no significant decrease trend. The P-III distribution function best fit to the rainfall extremes (the maximum 1-day rainfall: 59%). The spatial distributions of rainfall extremes were similar in different return periods. As the return period increased, the estimated rainfall by the three distribution functions were slightly larger than that in the empirical return period. The findings will benefit regional water resources management and water-related risk control.