Simulation of surface runoff and sediment yield under different land-use in a Taihang Mountains watershed, North China

• A simple distributed soil erosion model was constructed based on WetSpa extension.
• 5° and 10° are two critical slopes to affect soil erosion in the Taihang Mountains.
• Soil erosion was similar between forest, shrub and grass when slope is more then 10°.

The maintenance of water and soil resources has attracted the attention of governments and scientists world-wide. The loss of these resources is a serious problem in the Taihang Mountains, and the emerging issue with water has threatened the livelihoods of local residents and the sustainability of this region. A simple distributed soil erosion and sediment yield model (DSESYM) has been developed based on WetSpa extension. The effect of land-use change on surface runoff and sediment yield was then analyzed through applying the model in the Chongling watershed. Taking the land-use distribution of the watershed in 2000 as the baseline, fourteen scenarios were performed to characterize the effect of land-use change on surface runoff and sediment load relative to the baseline condition. These scenarios involved converting the mixed land-use to 93.89% of the area being forestland (scenario 1), shrubland (scenario 2), grassland (scenario 3), cropland (scenario 4), mixed crop/forest land (scenarios 5 and 6), mixed crop/shrub land (scenarios 7 and 8), mixed crop/grass land (scenarios 9 and 10), mixed crop/shrub/forest land (scenarios 11 and 12), and mixed crop/grass/forest land (scenarios 13 and 14). The scenario analysis revealed that when land-use was changed to 93.89% of the respective land-use in scenarios 4, 5, 7 and 9, an increase in runoff and sediment yield for single rain events compared to the baseline whereas a change to forest and shrubland caused a decrease (scenarios 1 and 2). Slope is an important factor in soil erosion, but in the study area, when the slope is more than 10°, the difference of stream flow and sediment between forest, shrub and grass was not obvious (scenarios 5, 7 and 9). The model can be used to predict surface runoff, erosion, deposition and sediment yield of each grid cell and the whole watershed in response to land-use scenarios for single rain events in the Taihang Mountains. It is easy to execute if the precipitation process data, the relationships of water and sediment for different land-use, and GIS maps of the study area are available, which makes it suitable for widespread application.