Spatial-temporal Variation of Rainfall Erosivity in the Three Gorges Reservoir Area Based on Different Models

Rainfall erosivity is used as an important parameter in soil erosion forecasting models and as a key factor in estimating soil erosion.In this study,the Chongqing section of the Three Gorges Reservoir Area was used as the study area.Based on the daily rainfall data from 1972 to 2018,the Mann-Kendall test,linear correlation analysis,Morlet wavelet analysis and geoinformation technology were used to optimize a simple model suitable for the Three Gorges Reservoir Area and to study the spatial and temporal evolution characteristics and influencing factors of rainfall erosion force.Model III (the daily rainfall erosion force calculation model developed by Yun Xie et al.) has good suitability in the Three Gorges Reservoir Area,with the highest effective coefficient (over 0.76) and low relative deviation coefficient (only about 0.23).The multi-year average rainfall erosion force is 4 480.29MJ·mm/(hm²·h),and the key areas for soil and water conservation work are Kaizhou,Wanzhou and Yunyang districts and counties in that order.The main cycle of interannual variation of rainfall erosion force is 28a,and the maintenance of water and soil conservation facilities should be strengthened during the period of high rainfall erosivity.The spatial distribution of multi-year average rainfall erosion force is characterized by low in the south and high in the northeast.Rainfall erosivity is concentrated in summer,mainly affected by monsoon climate,in that season should be as little as possible to carry out large-scale foundation,slope excavation and other activities,pay attention to the arrangement and perfection of soil and water conservation measures.Rainfall and rainfall erosivity are in phase and positively correlated.Rainfall has a significant impact on the change of rainfall erosivity.