2004-2018年合肥市董铺水库水土流失风险度评价

Soil Erosion Risk Assessment in Dongpu Reservoir Areaof Hefei City During 2004-2018

本文评价了合肥市董铺水库库区水土流失风险度。基于GIS和RS技术,使用Landsat影像,运用像元二分法估算植被覆盖度;利用DEM数据计算地表坡度;使用Landsat影像解译土地利用类型。根据水利部部颁标准,对植被覆盖度、坡度和土地利用分类进行分级,应用Python语言编写三种空间要素交叉形成的水土流失风险度分类模型,对董铺水库库区的水土流失风险进行评价,运用转移矩阵和动态度定量分析了2004-2018年间董铺水库库区水土流失风险度动态变化。研究结果表明在2004年至2018年期间,水土流失风险度呈减少趋势,其中极强烈风险、强烈风险和中度风险和轻度流失土地面分别减少了2.7hm^2、79.2hm^2、43.2hm^2和721.8hm^2,微度风险土地面积增加了846.9hm^2。水土流失风险度转化主要是微度风险和其他风险度之间的转化。2004-2018年间整体水土流失风险度呈小幅减少趋势。其中,2004-2008年间水土流失风险度明显下降,水土保持措施较好,但2008-2018年间除微度和强烈风险逐期下降外,轻度和中度风险有逐期增加的趋势,水土保持措施一般。

The objective of this paper is to evaluate the soil erosion risk in Dongpu reservoir area of Hefei City. Based on the technology of Geographic Information System(GIS) and Remote Sensing(RS),using the spatial data of vegetation cover ,slope and land use,the risk of soil erosion in Dongpu reservoir area was evaluated by the classification model we proposed which was coded by Python for soil erosion risk assessment,and then dynamic changes of soil erosion risk were analyzed with the methods of transition probability matrix and dynamic index. From 2004 to 2018,the risk of soil erosion in Dongpu reservoir area was decreased,in which land area of extremely strong risk,strong risk and moderate risk decreased by 2.7 hm^2,79.2 hm^2,43.2 hm^2 and 721.8 hm^2 respectively,and slight risk increased by 846.9 hm^2. The risk transformation of soil erosion is mainly the transformation between slight risk and other risk levels. The overall risk level of soil erosion showed a slight decreasing trend from 2004 to 2018,on of which the risk of soil erosion was decreased obviously from 2004 to 2008,and the soil and water conservation measures carried out nicely. However,except for the gradual decline of micro and intensity risks,the moderate and light risk increased gradually from 2008 to 2018, and the soil and water conservation measures carried out moderately.