鄱阳湖生态经济区小流域土壤侵蚀模拟

Soil Erosion Simulation and Its Spatiotemporal Distribution Characteristics in a Small Catchment in Poyang Lake Eco-economic Region

在Arc Gis 10.0平台下,构建了鄱阳湖生态经济区小流域土壤侵蚀SWAT模型。利用潭口和渡峰坑水文站的逐日径流、泥沙实测数据对模型进行了校准及验证,并分析了土壤侵蚀的时空分布特征。模型适用性评价结果(月径流:0.886 2≤R2≤0.967 6,0.81≤NSE≤0.87;月泥沙:0.837 4≤R2≤0.911,0.68≤NSE≤0.76)显示了良好的精度,表明建立的Arc SWAT2009模型适宜研究区的土壤侵蚀模拟。土壤侵蚀时空分布特征显示,1983-2012年汛期(4-8月)土壤侵蚀为全年的83.2%,说明强降雨是形成土壤侵蚀的主要原因;其中,87.3%的研究区面积处于微度或轻度侵蚀级别;且农业发达和城镇密集的地区土壤侵蚀强度较高,其侵蚀模数居前两位,表明人为活动可能是土壤侵蚀的重要因子之一。

Based on Arc Gis 10.0 platform, SWAT model was employed to simulate soil erosion in Poyang Lake Ecoeconomic Region. The daily runoff and sediment data observed at Tankou and Dufengkeng hydrological stations were collected for calibrating and validating this model, and thus the spatiotemporal characteristics of soil erosion were analyzed. The evaluation results with monthly streamflow 0.886 2≤R2≤0.967 6,0.81 ≤NSE≤0.87, monthly sediment 0.837 4≤ R2 ≤0.911,0.68 ≤NSE≤0.76 indicated this calibrated model could simulate the stream flow and the soil erosion accurately and reasonably in the study area. In the flood season from April to August during the period of 1982-2012, the soil erosion accounted for 83.2% of the annual total, documenting that storm rainfall was the main reason of the soil erosion. For the Region, there existed 87.3% of the area with the micro or the mild erosion. Additionally, the agriculturally advanced regions and the dense urban and town regions with the top two erosion modulus exhibited higher soil erosion levels, revealing that human activities could also result in the soil erosion besides of the storm rainfall.