Detection Framework of Abrupt Changes and Trends in Rainfall Erosivity in Three Gorges Reservoir, China

Abstract

Rainfall erosivity is commonly used to estimate the probability of soil erosion caused by rainfall. The accurate detection of temporal changes in rainfall erosivity and the identification of abrupt changes and trends are important for understanding the physical causes of variation. In this study, a detection framework is introduced to identify temporal changes in rainfall erosivity time series as follows :(i) The significance of time series variation of rainfall erosivity is assessed based on the Hurst coefficient and divided into three levels: None, medium, and high. (ii) The detection of abrupt changes (Mann–Kendall, Moving T, and Bayesian tests) and trends (Spearman and Kendall rank correlation tests) of variate series and the correlation coefficient between the variation component and the original series is calculated. (iii) The modified series is obtained by preferentially eliminating the variation component (trend or change point) with larger correlation coefficients. (iv) We substituted the modified series into steps i to iii until the correlation coefficient was not significant. This framework is used to analyze the variation of rainfall erosivity in the Three Gorges Reservoir, China. The results showed that by using traditional methods, both an increasing trend and an upward change point were observed in Zigui station. However, after the upward change point was deducted from the annual rainfall erosivity series R(t), the resultant Rm(t) showed no statistically significant trend. Trend analysis should be performed considering the existence of an abrupt change to assess the long-term changes in rainfall erosivity series; otherwise, it would result in the wrong conclusion. In addition, the change points detected in the Rm(t) varied with the methods. Compared with the single-test method, the proposed framework can effectively reduce uncertainty.

Spatiotemporal Variability in Rainfall Erosivity and Its Teleconnection with Atmospheric Circulation Indices in China

“…This impact is particularly significant on agricultural land, slopes with insufficient vegetation cover, and exposed soil [11,12]. In the context of climate change, the increase in extreme precipitation events leads to intensified erosion, causing a multitude of disasters [4,[13][14][15][16][17][18][19][20][21]. Intense rainfall-induced erosion can penetrate the soil, leading to soil destabilization and an increased risk of landslides.…”

“…On a regional level, Feng et al developed a detection framework for RE in the Three Gorges Reservoir using various statistical methods. They noted that significant changes in land use and evaporation might be the reasons for the spatiotemporal variations in RE [20]. He et al discovered an upward trend in RE in the Luojiang River Basin from 1980 to 2019, showing a declining trend from the central part of the basin towards the periphery [12].…”