Spatiotemporal variation characteristics of rainfall erosivity in the Yellow River Basin from 1961 to 2019

Abstract: The Yellow River Basin has been one of the most serious areas of soil erosion in China in recent years. A large area of soil erosion is distributed in the middle reaches of Loess Plateau areas. The comprehensive influence of precipitation, vegetation, soil, topography, and human activities has posed a great threat to the ecological and environmental landscapes, due mainly to a large population, and a long history of farming. Much effort has been made on the temporal and spatial variation of rainfall erosion in the whole Basin of the Yellow River. But, it is still lacking in the relationship between the rainfall erosion force and geographical factors, such as latitude, longitude, and altitude. In this study, the daily rain erosion force model was established to calculate the rainfall erosion force for each station using the daily rainfall data of 317 weather stations in the Yellow River Basin from 1961 to 2019. A systematic analysis was made to investigate the spatiotemporal distribution characteristics of rainfall erosion force in the basin. A correlation analysis was also used to determine the geographical factors, such as rainfall, longitude, latitude, and altitude. The results showed that the average rainfall erosivity was 1 223.1 MJ?mm/(hm2?h?a) in the Yellow River Basin from 1961 to 2019. The decline rate was 6.71 MJ?mm/(hm2?h?a) per 10 years. The erosion of rainfall in all four seasons showed no significant change trend, of which the erosion force of summer rainfall showed an upward trend, and the rest showed a downward trend. In terms of intra-year changes, the erosion force of rainfall reached the maximum of 317.1.4 MJ?mm/(hm2?h?a) in July, and the minimum of 0.8 MJ?mm/(hm2?h?a) in January. The rainfall erosion was high in summer and low in winter, with the summer rainfall erosion accounting for 61.3% of the year and only 0.3% in winter. The distribution range of multi-year average rainfall erosivity was 33.0-3 550.6 MJ?mm/(hm2?h?a) . The spatial distribution was basically consistent with the annual average rainfall, indicating the increasing trend from the northwest to the southeast. There was an upward trend in the annual rainfall erosion force in the upper reaches of the Yellow River Basin. The middle and lower reaches showed a downward trend. Among them, a significant increase was found at the Fangshan, Tianzhu, Guinan, and Zeku stations, as well as Jia County. The rainfall erosivity was positively correlated with the rainfall, longitude, and slope, with correlation coefficients of 0.839, 0.587, and 0.164 (P <0.01), respectively. By contrast, there was a negative correlation between latitude and altitude, with the correlation coefficients of -0.498, and -0.490 (P<0.01), respectively. Stepwise regression showed that rainfall erosion was mainly affected by the combination of rainfall, altitude, longitude, and surface slope. Among them, the contribution rate of rainfall to erosion was the largest and most positive. Latitude and altitude were the main influencing factors of the climate propensity during rainfall erosion, where the latitude also presented the largest contribution rate and a positive contribution. Consequently, a better understanding was gained of the temporal and spatial patterns of rainfall erosivity in the Yellow River Basin and the various influencing factors. The finding can provide strong support to the development of the Yellow River Basin.