基于RUSLE模型的雅鲁藏布江流域土壤侵蚀评价

Evaluation on Soil Erosion Based on RUSLE Model in the Yarlung Zangbo River Basin

[目的]研究雅鲁藏布江流域土壤侵蚀时空变化特征,并分析气候和植被覆盖变化对土壤侵蚀的影响,以期为高寒区土壤侵蚀防治、生态系统保护和水土资源开发利用提供理论支撑。[方法]以雅鲁藏布江流域为研究区,采用RUSLE模型定量评估了1980—2017年流域土壤侵蚀的时空变化特征。[结果]1980—2017年,雅江流域土壤侵蚀强度整体呈现先减小后增加的趋势,1980—1999年年均土壤侵蚀模数波动下降,2000—2017年年均土壤侵蚀模数则呈现不显著上升趋势;流域中上游地区土壤侵蚀变化较为显著,下游地区侵蚀强度先增加后减小。年均土壤侵蚀模数与降雨侵蚀力呈显著正相关关系,Pearson相关系数为0.92,而与NDVI关系不显著。不同土地利用类型中,土壤侵蚀最强烈的是未利用地,其次是稀疏草地,由于其面积占比最高,对流域总侵蚀量的贡献比超过54%。[结论]降雨是影响雅江流域土壤侵蚀强度变化的主要因素,未来土壤侵蚀防治的重点区域应为流域东部下游降雨量较大的地区,重点防范极端降雨造成的水土流失。

[Objective]The spatial and temporal characteristics of soil erosion in the Yarlung Zangbo River basin were explored,and effects of climate and vegetation cover changes on soil erosion were analyzed,in order to provide theoretical support for soil erosion prevention,ecosystem protection,and development and utilization of water and soil resources in alpine regions.[Methods]Based on the Revised Universal Soil Loss Equation(RUSLE),the spatial and temporal change of soil erosion in the Yarlung Zangbo River basin from 1980 to 2017 was quantitatively evaluated.[Results]The soil erosion intensity in the the Yarlung Zangbo River basin showed an overall trend of first decreasing and then increasing from 1980 to 2017,the fluctuation of the multi-year average soil erosion modulus decreased from 1980 to 1999,while the annual average soil erosion modulus showed no significant increase trend from^(2)000 to 2017.The upper and middle areas of the basin had significant changes,while the erosion intensity in the lower areas increased first and then decreased.The annual average soil erosion modulus was significantly positively correlated with rainfall erosivity,with a Pearson correlation coefficient of 0.92,but not significantly correlated with NDVI.Among the different land use types,the most intense soil erosion occurred in unused land,followed by sparse grassland,which accounted for more than 54%of the total basin erosion due to its highest area ratio.[Conclusion]Rainfall is the main factor affecting the change of soil erosion intensity in the Yarlung Zangpo River basin,and the key areas for soil erosion prevention and control in the future should be the areas with relatively high rainfall in the lower reaches of eastern part of the basin,and focus on preventing soil erosion caused by extreme rainfall.