Background Rainfall is one of the most significant factors leading to soil erosion, and rainfall erosivity (R) serves as a crucial indicator of the impact of rainfall on soil erosion. The southeastern Tibetan region is characterized by high mountains, steep slopes, and deeply incised valleys, with a complex underlying surface that results in severe soil erosion. To elucidate the intensity of rainfall erosivity in this area, it is essential to conduct a temporal and spatial analysis of rainfall erosivity. This study aims to provide scientific references for preventing soil and water loss and protecting the regional ecological environment.
Methods This study utilized daily rainfall data from 10 national meteorological stations in southeastern Tibet from 1961 to 2020, employing methods such as the daily rainfall erosivity model, Mann-Kendall trend test, cumulative anomaly method, wavelet analysis, and co-Kriging interpolation to explore the spatiotemporal variations in rainfall erosivity over the past 60 years.
Results 1) In the southeastern Tibetan region, the rainfall erosivity from 1961 to 2020 ranged between 1342.7 and 2979.7 MJ·mm/(hm²·h), with a multi-year average of 2161.2 MJ·mm/(hm²·h). Additionally, it has shown an increasing trend, with an annual increment of 13.76 MJ·mm/(hm²·h). 2) The rainfall erosivity in the southeastern Tibetan region showed a significant increasing trend from 1961 to 1980. After 1980, the rainfall erosivity began to exhibit fluctuations, overall displaying a downward trend. Through the M-K mutation test analysis, 1975 was identified as the year of mutation for rainfall erosivity, with the highest value reached in 1980 in the southeastern Tibetan region. 3) The seasonal rainfall erosivity in the southeastern Tibetan region is 282.55, 1625.98, 273.30, and 47.59 MJ·mm/(hm²·h) for spring, summer, autumn, and winter, respectively. All stations in the region show that summer has the highest rainfall erosivity, while winter has the lowest. The annual rainfall erosivity in the last 60 years exhibits periodic changes over 5–15 years and 20–30 years, with phases of increase, fluctuation, and decrease. 4) Spatially, the southeastern Tibetan region shows significant variability in rainfall erosivity, with the southeastern area exhibiting values >1600 MJ·mm/(hm²·h). Conversely, the western and northwestern regions have lower rainfall erosivity, while the northeastern area has the lowest values, <150 MJ·mm/(hm²·h). This clearly demonstrates the distinct differences in rainfall erosivity across various subregions of southeastern Tibet.
Conclusions The rainfall erosivity in the southeastern Tibetan region is increasing annually, primarily concentrated in the southeastern part of the area. Throughout the year, the rainfall erosivity in this region reaches its peak during the summer, making it particularly crucial for soil conservation during this period. Therefore, it is recommended to enhance soil and water conservation measures in the southeastern part of the region.
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