基于MUSLE模型的阿什河流域农业非点源污染风险评估

MUSLE-based risk evaluation of agricultural non-point source pollution in the Ash River watershed

系统评价与分析流域农业非点源污染风险,对其防控治理具有重要的指导作用。本研究以遥感影像数据、数字高程模型(DEM)、土壤图件和相关文本资料为基本信息源,基于遥感和地理信息系统技术,采用修正通用土壤流失方程(MUSLE),结合各乡镇等标污染负荷大小,对阿什河流域农业非点源污染风险进行评估分析。结果表明:1)流域地表潜在侵蚀风险存在明显的空间地域分布规律,东南部地区风险整体偏高,而西北部和中部平原地带多为中等和低侵蚀风险区;乡镇尺度上,小岭乡、玉泉镇、交界镇、红星乡和大岭乡潜在侵蚀最为严重。2)流域山地丘陵区林地面积大,侵蚀风险最高,其平均值为0.037,风险贡献率为61.88%;农业用地风险贡献率仅次于林业用地,达到20.50%;坡度上,微坡36.26%的风险贡献率在所有坡型中最高。3)乡镇侵蚀风险分布与对应非点源污染风险不能完全重叠,位于平原地带的杨树乡和双丰镇侵蚀风险良好,其单位面积污染风险值远高于乡镇平均值,应重度防控,大岭乡、小岭乡和玉泉镇侵蚀风险严重,污染防控等级为适度。

It is very important for the prevention and control management of agricultural non-point source pollution in watersheds to systematically evaluate and analyze the agricultural non-point source pollution risks. This study used the Ash River watershed as a case and applied the remote sensing image data, the digital elevation model, the soil map and related literature as basic information, the modified universal soil loss equation, the equalized-standard pollution loads of townships, and evaluated and analyzed the agricultural non-point source pollution risks in the watershed. The results showed that the potential erosion risks of most areas were in the range of low to medium conditions and also had significant spatial geographical distribution patterns. The erosion risks of mountain foothills in the southeast region had high or relatively high conditions, where the critical source areas were focused. From the township perspective, Xiaoling Village, Yuquan Town, Jiaojie Town, Hongxing Village and Daling Village were in the most serious condition of erosion risk. The potential erosion risk for the woodland, which was located in the mountainous and hilly areas, owned the highest risk rank with an average value of 0.037 and a contribution rate of 61.88%. The contribution rate of the agricultural land risks was 20.50%; In terms of the slope factor, the risk contribution rate for the slight slope was 36.26%, which was the highest in all slope types. Since the risk location of soil erosion for townships did not completely overlap with the corresponding risk location of the agricultural non-point source pollution, the prevention and control management of the agricultural non-point source pollution should be focused on Yangshu Village and Shuangfeng Town, where the pollution risks were much higher than average, even though their risks of soil erosion showed in a good condition. Dalin Village, Xiaolin Village and Yuquan Town need maintain appropriate prevention and control management as their soil erosion risks presented in a serious condition.