Spatiotemporal characteristics of rainfall erosivity in Yarlung Zangbo River Basin based on multiple models
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ObjectiveThe Yarlung Zangbo River Basin is a typical alpine ecologically fragile region, where complex climatic differentiation poses higher requirements for the selection of rainfall erosivity (R) models. Therefore, evaluating the applicability and differences among simplified R models is essential for accurately characterizing the spatiotemporal variation of rainfall erosivity and for supporting appropriate model selection in this region. MethodsDaily rainfall data from 25 meteorological stations across the Yarlung Zangbo River Basin from 1980 to 2020 were used as input for nine typical simplified models (A-I) to calculate R values. Model differences and their performance at stations across climatic zones were evaluated using the Mann-Kendall test, Sen's slope estimator, and hierarchical clustering analysis. Results1) The multi-year average R values estimated by the nine models varied substantially, ranging from 101 to 1 677 MJ·mm/(hm2·h). Models B, C, and E generally produced higher estimates than models D, F, and G, while model I showed no outliers at stations across all climatic zones. 2) All models exhibited consistent directions of interannual variations in R and detected highly significant abrupt change points around 2005 (P < 0.01). Most stations showed increasing trends, but the magnitudes of the estimated trends varied markedly among models. 3) The models were clustered into three groups: Group 1 (A, B, C, E, F, G), Group 2 (D), and Group 3 (H, I). The sensitivity to climate variability was ranked as Group 3 (highest) > Group 1 > Group 2 (lowest), with particularly pronounced differences in semi-arid and semi-humid zones (P < 0.01). ConclusionsThe findings demonstrate that simplified rainfall erosivity models differ significantly in estimating absolute values, variation amplitudes, and local trends of R. This study evaluates the model applicability and provides a scientific basis for selecting appropriate rainfall erosivity models for soil-erosion assessment in the cold, high-altitude and ecologically fragile areas of the Yarlung Zangbo River Basin.
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