利用CSLE模型的东北漫川漫岗区土壤侵蚀评价

东北黑土区是中国重要的商品粮基地,土壤侵蚀正日益破坏着宝贵的黑土资源,严重威胁到中国粮食生产安全。土壤侵蚀评价是土壤侵蚀防治的依据和水土保持效益评估的重要途径。土壤侵蚀的多尺度特征及其影响因素的复杂性对土壤侵蚀评价提出更高的要求。为探讨土地利用和地形对土壤侵蚀的影响,以及更好地呈现土壤侵蚀评价的结果,该研究以位于东北漫川漫岗区的拜泉县为例,运用中国土壤流失方程(Chinese Soil Loss Equation,CSLE)定量评价了拜泉县的土壤侵蚀状况,分析了土地利用和地形因素对土壤侵蚀的影响,并提出了实现区域土壤侵蚀评价"落地"的方案。结果表明:拜泉县平均土壤侵蚀模数为6.77 t/(hm~2·a),土壤侵蚀面积比例为39.35%,极强烈和剧烈侵蚀的高侵蚀主要分布于拜泉县的东南部丘陵区和西北部的漫川漫岗区。坡度越大,土壤侵蚀模数越高。但随着坡长的变长,土壤侵蚀模数呈现出先增大后减小的变化趋势。对侵蚀量的贡献,来源于1～2°的坡度范围侵蚀量最大,其次为3～5°和2～3°。100～200 m的坡长对侵蚀的贡献最大,其次为200～400 m和50～100 m的坡长。坡耕地应该是土壤侵蚀防治的重点区域。在小流域的尺度上,选取土壤侵蚀面积比例进行土壤侵蚀评价,可以更好地服务于区域水土保持规划,是实现区域土壤侵蚀评价"落地"的有效途径。

Assessment of soil erosion in rolling hilly region of Northeast China using Chinese Soil Loss Equation (CSLE) model

Abstract: Black soil region in Northeast China is an important commodity grain base in China. Soil erosion can deteriorate in the valuable black soil resources; even threaten the safety of grain production. Assessment of soil erosion becomes an inevitable way to control soil erosion, and further to evaluate the benefits of soil and water conservation. However, the multi-scale complex factors can make it difficult to the accurately assess soil erosion. It is also necessary to detect the effects of land use and topography on soil erosion. Normally, the evaluation data of soil erosion include modulus, amount, and intensity of soil erosion. These indexes have different meanings and uses in regional soil erosion assessment. In order to better present the evaluation data of soil erosion, a research region was taken as Baiquan County in rolling hilly regions in Northeast China. Chinese Soil Loss Equation (CSLE) was used to quantitatively evaluate the soil erosion, and systematically analyze the influences that caused by land use and topographic factors. A "landing" scheme was proposed to achieve regional evaluation of soil erosion. The results showed that the average modulus of soil erosion in Baiquan County was 6.77 t/(hm2?a), and the area proportion of soil erosion was 39.35%, indicating a great spatial heterogeneity in soil erosion. The extremely severe erosion was mainly distributed in the hilly areas in the southeast, and the rolling hilly regions in the northwest of Baiquan. This distribution can be attributed to the slope arable land occurred in this area, together with the influence of the terrain. Specifically, the intensity of soil erosion can be high as the increase of the slope. In addition, the intensity of soil erosion showed a trend of increasing first and then decreasing, as the length of the slope becomes longer. The amount of soil erosion is also an important indicator for the evaluation of soil erosion. In the contribution to the amount of erosion, the slope from 1° to 2° showed the largest amount of erosion, followed by 3° to 5° and 2° to 3°. The slope length from 100 to 200 m can contribute the most amount of soil erosion, followed by the slope length of 200 to 400 m and 50 to 100 m. Sloping farmland was characterized by high intensity of soil erosion. Compared with the forest land, the large slope was not the main source of soil erosion amount due to high vegetation coverage and relatively low soil erosion modulus. Therefore, the sloping farmland can be the key area for soil erosion control. This infers that the selection of appropriate indicator can be significant to present the evaluation data of soil erosion. This study demonstrated that the area proportion of soil erosion can be selected for the better evaluation of regional soil erosion at the scale of small watersheds and water conservation planning. This finding can provide an effective way to achieve assessment for regional soil erosion in the "landing" scheme.