基于CSLE模型的天山北坡西白杨沟流域土壤侵蚀定量评价

目的]定量评价天山北坡西白杨沟流域水土流失土壤侵蚀状况,分析其分布特征,为区域水土保持以及生态环境建设提供科学依据。方法]以新疆维吾尔自治区乌鲁木齐县西白杨沟流域为研究区,采用样地调查与地理信息系统(GIS)、遥感(RS)技术相结合方法和CSLE模型,对西白杨沟流域进行土壤水力侵蚀评价及侵蚀强度空间分布分析。结果]天山北坡西白杨沟流域平均土壤侵蚀模数748.91 t/(km~2·a)。地形对土壤侵蚀强度影响明显,在坡度20°～40°区域,土壤侵蚀模数最高,为1 127.22～1 229.62 t/(km~2·a)。缓坡(20°)区域,坡度对土壤侵蚀模数呈正效应,而在陡坡(40°～70°)区域,坡度对土壤侵蚀模数呈负效应。土壤侵蚀主要发生在南坡、东南坡和东坡;不同土地利用方式对土壤水力侵蚀程度影响不同,表现为:呈灌木林地1 709.80 t/(km~2·a)]有林地1 389.40 t/(km~2·a)]天然牧草地605.20 t/(km~2·a)]人工牧草地334.71 t/(km~2·a)]水浇地113.69 t/(km~2·a)]的趋势。结论]土壤侵蚀强度总体以微度和轻度为主,强烈侵蚀、极强烈侵蚀、剧烈侵蚀主要分布在流域的中下游和下游;天山北坡西白杨沟流域侵蚀强度的空间分布与地形、土地利用、土壤性质联系紧密。

Quantitative Assessment of Soil Erosion in West Baiyanggou Watershed on North Slopes of Tianshan Mountains Based on CSLE Model

Objective] Quantitative assessment of soil erosion in West Baiyanggou watershed on the north slopes of Tianshan Mountains and its distribution characteristics were studied in order to provide the scientific basis for ecological management and soil erosion control.Methods] Taking the West Baiyanggou watershed in Urumqi County of Xijiang Wei Autonomous Region as the research area, using the methods of sampling plot survey, geographic information system(GIS), remote sensing system(RS) and CSLE model, soil erosion was assessed and the spatial distribution of erosion intensity was analyzed.Results] The average soil erosion modulus was 748.91 t/(km²·a) in the West Baiyanggou watershed on the north slope of the Tianshan Mountains. In most areas of this watershed, the intensity of soil erosion was at weak or slight level. Strong, extreme or severe erosions were mainly distributed in the middle and lower reaches of the basin. Soil erosion was significantly impacted by the topographic factors. In the regions with slope of 20°~40°, the highest soil erosion modulus varied between 1 127.22~1 229.62 t/(km²·a). In the regions with slope < 20°, the slope factor has a positive effect on the soil erosion modulus. While in the regions with slope of 40°~70°, the slope factor has a negative effect on the soil erosion modulus. Soil erosion mainly occurred on the south slope, southeast slope and east slope, and influenced by land use types with the following rank:shrub land1 709.80 t/(km²·a)] > woodland1 389.40 t/(km²·a)] > natural grassland605.20 t/(km²·a)] > artificial pasture334.71 t/(km²·a)] > irrigated land113.69 t/(km²·a)].Conclusion] The intensity of soil erosion is generally at slightness and lightness level. Strong erosion, extremely strong erosion, and severe erosion are mainly distributed in the middle and lower reaches of the basin. Soil properties, slope and land use types were closely related to the soil erosion distribution in the study area.