Study on spatial and temporal variation characteristic of waterlogging in Huaihe River Basin based on SPEI

Waterlogging significantly impacts agricultural production in the Huaihe River Basin. Revealing the spatial and temporal variation characteristics of waterlogging in Huaihe River Basin is crucial for disaster prevention and mitigation, as well as ensuring the safety of agricultural production. Meteorological data, including the daily precipitation, daily temperature, sunshine hours from 30 meteorological stations were selected to calculate the standardized precipitation evapotranspiration index (SPEI) from 1965 to 2016. The SPEI was employed to identify the intensity, frequency and areas of waterlogging. Based on this, the temporal and spatial variation characteristics of waterlogging were analyzed. The results indicated that: ① During the study period, the annual SPEI in the Huaihe River Basin showed an increasing trend. Seasonally, SPEI increased in spring, summer, and autumn, but decreased in winter. ② The annual waterlogging intensity reached a maximum of 21.32, primarily consisting of mild and moderate waterlogging. The affected area for each severity level showed a nonsignificant increasing trend. ③ Seasonally, the highest waterlogging intensities were 17.64 in spring, 51.72 in summer, 24.53 in autumn and 7.14 in winter. In spring, autumn and winter, mild waterlogging events were predominant, with frequencies reaching 30.76%, 21.15% and 19.22%, respectively. The frequency of severe and above waterlogging was highest in summer, reaching 40.37%. The areas that were affected by waterlogging showed an increasing trend in all seasons except winter. These findings provide a certain scientific basis for disaster resistance and mitigation, as well as waterlogging risk prevention and control in the Huaihe River Basin.