Spatiotemporal dynamics of soil erosion in the ecotone between the Loess Plateau and Western Qinling Mountains based on RUSLE modeling, GIS, and remote sensing

摘要

The Maiji District of Tianshui City (Gansu Province, China) is a typical transition region in the ecotone between the Loess Plateau and the Western Qinling Mountains. Exploring the spatiotemporal dynamics of soil erosion in this ecotone is critical for the scientific and impactive mitigation of soil erosion hazards in this ecologically fragile region. With geographic information system (GIS) and remote sensing (RS), we used the revised universal soil loss equation (RUSLE) model to assess soil erosion in the Maiji District and analyzed its dynamic changes between the years 2000, 2005, 2010, and 2015. We also derived a minimum erosion cell for the study region to assess the impacts of different factors upon soil erosion. Our results showed that total soil losses in the study region changed from 2000 to 2015, being steady initially, then increasing, and finally decreasing. Among different erosion classes, slight to light erosion was the most prevalent form, while areas under moderate to higher classes of soil erosion shifted towards a lower class over time. In each year, soil loss consistently increased before it decreased with an increasing class of elevation and slope (respectively, 1500 m a.s.l. and 30 degrees as critical thresholds). However, notable differences were evident between years in soil loss trends with varying classes of vegetation coverage and rainfall erosivity; vegetation coverage could mitigate the adverse impact of rainfall erosivity and thus constrain soil erosion hazards. In conclusion, the situation of soil erosion exhibited an overall trend of improvement in the transition region of the Maiji District. While topography determines the basic pattern of soil erosion occurrence, interactions between vegetation coverage and rainfall erosivity drive the dynamic development of soil erosion in our study region. Since vegetation coverage is a manageable factor, its reasonable and responsible regulation presents an effective way to mitigate soil erosion hazards in this region of China.