Research on the evolution trend and variation characteristics of flooding in the main stream of the Wei River

This study aims to reveal the evolution trend and variation characteristics of flooding in the main stream of the Wei River, providing references for flood control, disaster reduction, and water resources management in the basin. Considering the influence of daily runoff characteristics on flood series analysis, based on the daily flow data from six typical hydrological stations along the main stream of the Wei River from 1990 to 2020, the Block Maxima Model (BMM), the Peak Over Threshold (POT) model, Mann-Kendall test, and Pettitt test were used to analyze the evolution trend and variation characteristics of flooding. The results show that there are differences in the temporal and spatial scales of flooding occurrences in the main stream of the Wei River. In terms of temporal scale, higher flood frequencies were observed during 1990-1993, 2003-2005, 2011-2013, and 2018-2020. In terms of spatial scale, the middle and lower reaches of the Wei River are prone to frequent flooding. The annual maximum peak flow generally shows an increasing trend, while the occurrence frequency of extreme quantile floods shows a decreasing trend. The variation points of flood index sequences exhibit clustering characteristics. The findings of this study can provide a basis for flood control and water resources development, contributing to the high-quality development of the basin.