基于GIS和RUSLE的三峡库区小流域土壤侵蚀量估算研究

本研究以三峡库区菱角塘小流域为研究对象,在GIS技术的支持下,通过遥感技术和野外调查进行信息采集,对修正的通用土壤流失方程(RUSLE)各因子进行量化分析,从而对三峡库区菱角塘小流域土壤侵蚀量进行定量评价,并对土壤侵蚀强度进行分级;在此基础上分析不同坡度和土地利用类型的土壤侵蚀空间分布特征。结果表明,菱角塘小流域年土壤侵蚀量为208.32t/a,土壤侵蚀模数为1 987.75t/(km2·a),属于轻度侵蚀。28.62%的区域为中度、强度或极强度侵蚀,但是其侵蚀量却占总侵蚀量的82.36%,是预防和加强水土流失治理的重点区域。土壤侵蚀主要发生在坡度为15°~35°的区域,其中15°~25°的坡度土壤侵蚀属于中度侵蚀;坡耕地侵蚀最为严重,15°~25°的坡耕地侵蚀量占总侵蚀量的57.15%,表明坡耕地是该小流域水土流失的主要策源地。同时用137 Cs核素示踪技术测定的坡耕地和林地土壤侵蚀模数证实了RUSLE模型具有较高的准确性和可靠性,该模型在库区地块尺度具有一定的推广价值。

Estimation of Soil Erosion in Small Watershed of the Three Gorges Reservoir Region Based on GIS and RUSLE

Lingjiao pond small watershed in the Three Gorges Reservoir Region (TGRR) was chosen as the study area, quantification and analysis for each factor in the Revised Universal Soil Loss Equation (RUSLE) were carried out through Geographic Information System (GIS), Remote Sensing (RS) as well as field investigation. Soil erosion amount for Lingjiao pond small watershed in the TGRR was evaluated by RUSLE. Meanwhile, soil erosion intensity was classified according to criterion. Then the spatial distribution characteristics of soil erosion for different slope grades and different land use types were analyzed. Results indicate that the annual soil erosion amount is 208.32 t/a, and the soil erosion modulus is 1987.75 t/(km²·a) and the erosion intensity is classified as slight degree erosion. The moderate erosion, strong erosion and extremely strong erosion area account for 28.62% of the small watershed area, thus its soil erosion amount was account for 82.36% for the total soil erosion amount. Soil erosion is mainly occurred on slope degree between 15° and 35°. The soil erosion for 15°-25° slope grades belongs to moderate degree erosion. Soil erosion for sloping cultivated land is the most serious among different land use types. The soil erosion amount for 15°-25° sloping cultivated land accounts for 57.15% of the total soil erosion amount, indicating that sloping cultivated land is the critical area for soil and water loss in the small watershed. Compared with soil erosion modulus estimated by ¹³⁷Cs technique for sloping cultivated land as well as forestland, our results agree with the ¹³⁷Cs-estimated soil erosion modulus. Therefore, RUSLE has high accuracy and is reliable for the study area and it has good popularization value under block scale in the TGRR.