黄河中游不同流域尺度土壤侵蚀评价

Evaluation of soil erosion at different watershed scales in the middle reaches of the Yellow River

黄河中游是黄河流域土壤侵蚀最严重的区段,基于GIS和RS技术,利用2000—2010年黄河中游土地覆被数据、气象数据和地形数据等,提取了该区2000—2010年植被覆盖度,应用修正的通用土壤流失方程(RUSLE)计算了逐年土壤侵蚀模数,探讨了土壤侵蚀与植被覆盖度间的相关关系,并分析了不同生态系统、不同流域尺度土壤侵蚀时空变化特征。结果表明:(1)黄河中游植被覆盖度在空间上呈西北低东南高的分布特征,在时间上呈波动上升趋势,且植被覆盖度与土壤侵蚀模数之间存在负相关关系;(2)研究区2000—2010年各生态系统的土壤侵蚀强度在减弱,侵蚀状况明显好转;(3)黄河中游二级流域的土壤侵蚀量在2000—2010年间均有不同程度的减少;(4)在整个研究时段内,三级流域中的沣河、伊河及黑河流域的土壤侵蚀量在增加,其他流域的土壤侵蚀在减少。研究结果对黄河中游地区的水土保持措施具有一定的指导意义,同时,多尺度土壤侵蚀评价方法及通过剔除降雨因素实现以植被为主导因子的土壤侵蚀评价方法也可为其他地区的土壤侵蚀评价提供借鉴。

The area of the middle reaches is the most serious soil erosion area in the Yellow River basin. Using the data of land cover, meteorological records and terrain from 2000 to 2010, we extracted the vegetation coverage based on GIS and RS, and calculated soil erosion modulus using revised universal soil loss equation （RUSLE）, and then explored the correlation between soil erosion and vegetation coverage and the temporal and spatial variation characteristics of soil erosion in different ecosystems and basin scales. Results showed that： （1） in the middle reaches of the Yellow River, the vegetation coverage was low in northwest and high in southeast and with a fluctuating upward trend over time. There was a negative correlation between the soil erosion modulus and vegetation coverage; （2） the intensity of soil erosion in different ecosystems of the study area decreased during 2000-2010 and the erosion was significantly weakening; （3） the amount of soil erosion in the Yellow River＇s secondary basin reduced to certain degrees during 2000-2010; （4） throughout the study period, the amount of soil erosion was increased in Yi River, Fenghe and Heihe watershed, and reduced in other tertiary basins. The results of this study provide some guiding significance for the soil and water conservation measures in the middle reaches of the Yellow River. The multi-scale soil erosion assessment method and the soil erosion assessment through the elimination of rain factors and recognition of the vegetation as a dominant factor of soil erosion would be a refer- ence for soil erosion assessment in other areas.