Figure 6. Classification statistics of soil erosion area of LULC in Jiuyuangou watershed in 2010, 2015, and 2020.
We considered the conversion of cropland to other land use types in the land use space transfer as ‘gain’, and the conversion of other land use types to cropland as ‘loss’. For changes in the spatial pattern of soil erosion, we considered the increase in soil erosion grade as ‘loss’, and the decrease in soil erosion grade as ‘gain’. Therefore, we plotted a bivariate choropleth map (Figure 7) to understand spatial patterns and the association between gain, loss, and no change in soil erosion and LULCC. During the study period, some areas of the watershed were covered by ‘no change’ between LULCC and soil erosion change, mainly concentrated near roads, residential areas, cultivated land, and perennial forest land in the eastern part of the watershed. Significantly, the northeast of the watershed showed a common ‘loss’ between soil erosion change and LULCC, and cropland near residential areas in the central and southwest of the watershed showed a common ‘gain’ between soil erosion change and LULCC. At the same time, we also observed a ‘gain’ in soil erosion change with ‘no change’ in LULCC in the central and southwestern watersheds. In addition, the soil erosion level in the central and southwest part of the watershed declined, and the land use pattern followed a trend of transforming cropland into forest and grassland. Therefore, ‘gain’ was detected for both LULCC and soil erosion change in the central and southwest part of the watershed, with a high spatial correlation between LULCC and soil erosion change.