秦岭山地丹江流域土地利用变化的土壤侵蚀效应评价

论文采用ArcGIS 10.0及InVEST土壤保持模型,分析2000—2010年秦岭山地丹江流域土地利用类型变化特征,模拟流域不同时期不同土地利用类型土壤侵蚀及土壤保持量的变化规律,并着重探讨土地利用类型方式转变对流域土壤侵蚀的影响。结果表明：1）2000—2010年间,流域裸地大比例减少90.18%（831.06 hm²）,主要转移至水域,耕地大面积减少5 197.24 hm²（4.11%）,主要流向灌丛和城镇;坡耕地还林还草初见成效,湿地的保护与恢复成效显著。2）2000—2010年间,流域土壤侵蚀状况较为严重,整体处于中度侵蚀至强度侵蚀级别,但10 a间侵蚀状况有减缓趋势;在该研究时段内,耕地大面积转为灌丛是该流域由土地利用类型变化引起的土壤侵蚀减缓的主要原因;另外,耕地转为林地以及裸地面积的减少也起到了减轻土壤侵蚀的作用;以自然生态系统为主的林地、灌丛及草地转为耕地时,土壤侵蚀强度则会明显增加。3）生态系统土壤保持功能受多方因素共同影响;2000、2010年研究区实际土壤保持量分别为5.35×10⁸、5.47×10⁸ t;占全区面积一半以上的林地和灌丛单位面积土壤保持量较为稳定,全区土壤保持功能有所提高。保证一定面积的林地、在人工干预下合理安排坡耕地还林还草区域的空间分布是秦岭山地丹江流域减少土壤侵蚀的必要措施,同时应注重对可利用耕地的保护。

Evaluation on Soil Erosion Effects Driven by Land Use Changes over Danjiang River Basin of Qinling Mountain

Using ArcGIS 10.0 and InVEST Sediment Retention Model, we analyzed the temporal and spatial characteristics of land use change from 2000 to 2010 in Danjiang River Basin, and simulated the change rules of soil erosion and soil conservation under different land use patterns in different periods in order to explore the effect of land use and land cover change on soil erosion and soil conservation. The result indicates: Bare land reduced a large percentage of 90.18 (831.06 hm²) and mainly transferred to water body. Farmland reduced a large area of 5 197.24 hm² (4.11%) mainly converted to shrubs and towns. The action of grain for green project has begun to show its effects. The reservation and recovery of wetland was particularly effective. During the last ten years, the tendency of soil erosion in this basin was slowing down, but the situation is still serious that most areas are in intensity degree or middle degree of erosion. Taking the feature of land transfer during the study period into consideration, the transition of plough to shrubs was the primary cause of alleviating soil erosion. On the contrary, the inversed transition of forest land, shrubs or grassland to plough was the mainly cause of intensification of soil erosion. The total actual soil conservation in the year of 2000 and 2010 was 5.35×10⁸ and 5.47×10⁸ t, respectively. The soil conservation of ecosystem had an improvement in the whole region because the woodland, which covered more than half of the study area, had stable quantity of soil conservation per unit area. The soil conservation function of ecosystem is a result of all factors. Ensuring a certain area of forest land, and arranging reasonable spatial distribution of grain for green project under artificial intervention are the prerequisites of preventing deterioration of large area soil erosion in Danjiang River Basin of Qinling Mountain. Meanwhile, attention should also be paid to the preservation of arable land.