Changes in rainfall erosivity from combined effects of multiple factors in China’s Loess Plateau

Abstract

Rainfall erosivity is a key factor leading to soil erosion, and it is thus critical to investigate its spatiotemporal variability and controlling factors. Despite that the effects of a single factor have been largely investigated, the combined effects of multiple factors have rarely been considered. This study first investigated the spatiotemporal variability of rainfall erosivity in the Loess Plateau for 1961–2020, and then examined its relations to rainfall amount, temperature, and large-scale atmospheric circulation patterns by the bivariate and multiple wavelet coherence analysis. Averaged over the Loess Plateau, the annual rainfall erosivity had an insignificant increase at the rate of 1.74 MJ mm·ha−1·h−1·a−1. However, the changes exhibited spatial variability with a downward trend in the southeast and southwest, while an upward trend in the west, northeast and central regions. The regional-scale controlling factor was found to be rainfall amount, rather than temperature. For global atmospheric circulation, ENSO (El Niño-Southern Oscillation) and ENSO–AO (Arctic Oscillation) control rainfall erosivity individually or simultaneously at different timescales. This study provides technical support on how to identify the combined effects of multiple factors, and the results are helpful to project rainfall erosivity and control soil erosion.