土壤侵蚀时空分布规律及侵蚀热点分析——以陕西省王益区为例

为了评价王益区固沟保塬等水土保持措施实施后的土壤侵蚀变化状况,基于地理信息系统(GIS)技术和探索性空间数据分析(ESDA-GIS)方法,利用像元二分模型估算植被覆盖度,分析了2000年和2019年的土壤侵蚀强度分布规律,揭示了土壤侵蚀强度的空间聚集演化特征。结果表明:①王益区林草地面积大幅增加,高覆盖度(＞75%)面积增加了16.51 km²。②王益区土壤侵蚀状况明显好转。2000年和2019年土壤侵蚀面积分别高达全区面积的70.92%和55.84%;土壤侵蚀强度结构由中度侵蚀＞强烈侵蚀＞轻度侵蚀＞极强烈侵蚀转化为轻度侵蚀＞中度侵蚀＞强烈侵蚀＞极强烈侵蚀。③土壤侵蚀强度分布具有明显的空间聚集特征。全局Moran’ I指数在0.5左右,侵蚀热点区的分布由大片连续分布转化为局部集中的零散分布;侵蚀热点主要分布在(15°,25°]坡度区间,西南和东南部地区尤为明显。研究成果可为王益区水土保持规划、设计及治理提供数据支撑。

Temporal and Spatial Distribution of Soil Erosion and Erosion Hotspots Analysis:A Case Study of Wangyi District,Shaanxi Province

The aim of this study is to evaluate the soil erosion change since the implementation of ecological measures such as gully consolidation and highland protection in Wangyi District.The vegetation coverage is estimated by Dimidiate Pixel Model,the distribution of soil erosion intensity in 2000 and 2019 is analyzed and the spatial aggregation evolution characteristics of soil erosion intensity are revealed based on GIS and exploratory spatial data analysis (ESDA-GIS).The results demonstrate that:(1) The area of forest and grassland in Wangyi District has increased markedly,and the area with high coverage (>75%) grew by 16.51 km².(2) The condition of soil erosion in Wangyi district alleviated obviously.Soil erosion area in 2000 was as high as 70.92% of the whole area,and 55.84% in 2019.The structure of soil erosion intensity has also changed.In 2000,the study area was dominated by moderate erosion,followed by strong erosion,mild erosion,and extremely strong erosion in sequence,while in 2019,mild erosion dominated,followed by moderate erosion,strong erosion,and extremely strong erosion in sequence.(3) The distribution of soil erosion intensity has obvious spatial aggregation characteristics.The Global Moran’ I index is around 0.5,and the erosion hotspots transformed from large continuous distribution to locally concentrated scattered distribution.The erosion hotspots are mainly distributed in the slope range of 15°-25°,especially in the southwest and southeast regions.The research findings provide data support for water and soil conservation planning,design and treatment in Wangyi District.