Extreme Precipitation and Hydrological Events in the Middle Reaches of Weihe Basin and Their Response to Climate

Extreme precipitation and hydrological events frequently occur in the middle reaches of the Weihe River, taking the Baoji region as an example, based on the daily precipitation data from 1960 to 2017 and the daily runoff data, six extreme precipitation indicators and two extreme flood index were selected, and the trend characteristics, recurrence period characteristics and interrelationships of extreme precipitation and hydrological events were analyzed using Gumbel probability distribution function and crossed wavelet transform and linear regression. The extreme precipitation and flood trends under the emission scenarios of RCP2.6 and RCP8.5 of the CMIP5 were predicted. The results showed that, the Gumbel distribution can fit extreme precipitation and extreme flooding, the highest annual average distribution of R×1day is Qianyang, the R90P, R95P, R99P and R×1day is Taibai, and the lowest annual average distribution of all indices is Meixian. In the nearly 45a, the extreme flood peak in Linjiacun and Qianhe both showed a significant reduction trend, while the extreme flood and flood duration also showed a significant reduction trend., and there is a critical point in the time scale of the return period, about 10–20a. The extreme precipitation and flood index under the RCP2.6 and RCP8.5 climate scenarios showed an increase trend.