西汉水流域典型林草地侵蚀特征分析

    Analysis of soil erosion on typical forest and grassland in Xihanshui River Basin

    • 摘要: 为了说明西汉水流域典型林草地的侵蚀特征,为农业工程和流域治理提供依据,采用137Cs土壤侵蚀核素示踪技术,按野外采样、核素检测、模型计算三步开展研究。结果表明,6个本底区域的137Cs面积活度为1 600~2 402 Bq/m2,平均值为2 022 Bq/m2;本底区域和未扰动的林草地,剖面核素活度随深度呈指数递减分布;采样荒草地为轻度侵蚀,林地为沉积或无明显流失,退耕还林用地为中度侵蚀;侵蚀强度:林草地<荒草地<退耕还林用地;对于同坡面的不同坡位,侵蚀强度:坡面上部>中部>下部;植被发育程度影响侵蚀量的大小,对于同一土地利用类型,通常植被覆盖度越高,侵蚀速率越小,反之侵蚀速率越大。

       

      Abstract: In order to provide data for agriculture and soil & water conservation efforts, Cesium-137 technique was used to quantify soil erosion on typical forest and grassland in the Xihanshui River Basin, Cesium-137 technique was conducted by three steps: field sampling, nuclide content determination, and erosion rate calculation. The local Cesium-137 reference inventories range from 1 600 to 2 402 Bq/m2, and the average reference inventory is 2 022 Bq/m2. It shows exponential decrease of mass concentration and inventory with depth down to an undisturbed soil profile. For different land use, slight erosion occurs at grass land, deposition or no significant loss occurs at forest, and moderate erosion occurs at revegetated land. The order of soil erosion intensity is as following: forestmiddle>lower. The vegetation cover affects soil erosion and deposition rates, and in general, the rate of soil erosion is inversely proportional to the vegetation cover.

       

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