Landscape scaling of different land-use types, geomorphological styles, vegetation regionalizations, and geographical zonings differs spatial erosion patterns in a large-scale ecological restoration watershed.

Abstract

Water erosion is one of the main types of soil degradation, but few quantitative estimates have been done in the soil erosion intensity grades of different landscape scaling characteristics in a large-scale ecological restoration watershed. This study comparatively illustrates the utility of high-resolution data and geospatial technique, particularly the GIS-based RUSLE model, for an improved understanding of the spatial patterns of soil erosion under different land use types, geomorphological styles, vegetational regionalizations, and geographical zonings, aiming to promote ecological sustainable watershed management in practice. Results indicate the following:(i) The soil erosion intensity grade showed an overall decreasing trend from northwest to southeast in the Jinghe River Watershed. The percentages of intense erosion and extremely intense erosion in different land use types in 2015 were significantly lower than that in 2000 except middle- and low-coverage grasslands because of the effective implementation of "Grain for Green" project. e.g., the percentage of extremely intense erosion in dry land decreased from 41.72% in 2000 to 8.99% in 2015.(ii) The mid-elevation loessial beams and hills and mid-elevation loessial tableland were both the major sources of intense erosion and extremely intense erosion, with the contribution ratio of 41.89 and 53.94% and 35.79 and 20.83% in 2000 and 44.45 and 48.99% and 36.88 and 18.72% in 2015, respectively.(iii) The intense, extremely intense and severe erosion in the temperate typical grassland subzone accounted for 32.62, 44.47, and 9.6% in 2000 and 36.74, 40.7, and 8.1% in 2015, respectively. There were no severe and extremely intense erosion in the deciduous oak forest subzone of northern and southern warm temperate. (iv) The intense, extremely intense, and severe erosion of the loessial wide valley hills accounted for 32.19, 45.27, and 8.92% in 2000 and 36.32, 41.42, and 7.48% in 2015. The intense and extremely intense erosion of the loessial tableland accounted for 40.58 and 16.02% in 2000 and 40.57 and 14.27% in 2015. More importantly, land use types can be applied to the design and implementation of a development scheme more reliably than other landscapes because the land use system is a more scientific and fine classification based on topography, soils, and vegetation correlated with geology, geomorphology, and climate. The knowledge on the fine landscape scale will be useful for comprehensive watershed management by soil scientists, agronomists, environmental scientists, land managers, and policymakers.