Spatio-temporal evolution of rainfall erosivity and its response to ENSO in Henan Province

Introduction Severe soil erosion in agricultural regions poses a threat to land degradation and endangers food security. Rainfall erosivity is the potential ability of rainfall to cause soil erosion, and is a key factor in soil erosion prediction models. The research on the spatio-temporal evolution of rainfall erosivity provides support for soil and water conservation and food security. Methods The daily rainfall data from 90 meteorological stations in Henan Province from 1981 to 2020 were collected and rainfall erosivity was calculated using the Xie model in current study. The spatio-temporal evolution of rainfall erosivity was analyzed from 1981 to 2020. Factors characterizing El Niño Southern Oscillation (ENSO), including Niño3.4 sea surface temperatures anomalies (SST), Western Hemisphere Warm Pool (WHWP) and Trans-Niño Index (TNI), were selected to investigate the response of rainfall erosivity to ENSO in Henan Province. Results The results showed that the annual average rainfall erosivity in Henan Province ranged from 1696 to 6106 MJ mm hm -2 h -1 , with a decreasing trend from the southeast to the northwest. Rainfall erosivity was uneven throughout the year in Henan Province, with the highest proportion occurring in summer (70.62%). Among the 90 stations, 67.78% of them exhibited a decline in rainfall erosivity from 1981 to 2020. The Mann-Kendall statistical test indicated that the annual rainfall erosivity exhibited a decreasing trend from 1985 to 1995 and from 2012 to 2020, and an increasing trend from 1981 to 1985 and from 2003 to 2011.The correlation analysis indicated significant correlation between ENSO and rainfall erosivity. The rainfall erosivity without ENSO events exhibited a higher magnitude than that with ENSO events. During ENSO warm events, the rainfall erosivity was 64.24% of that without ENSO events. Conclusion The results revealed the spatio-temporal evolution of rainfall erosivity in Henan Province from 1981 to 2020 and its response to ENSO and provided a scientific reference for soil erosion prediction and soil and water conservation measures formulation.