Remote sensing estimation of the soil erosion cover-management factor for China's Loess Plateau

The cover-management factor (C-factor) is used in the revised universal soil loss equation to represent the effect of vegetation cover and its management practices on hillslope erosion. Remote sensing has been widely used to estimate vegetation cover and the C-factor, but most previous studies only used the photosynthetic vegetation (PV) or green vegetation indices (VI, e.g., normalized difference VI) for estimating the C-factor and the important non-PV (NPV) component was often ignored. In this study, we developed a new technique to estimate monthly time-series C-factor using the fractional vegetation cover (FVC) including both PV and NPV, and weighted by monthly rainfall erosivity ratio. The monthly FVC was derived from the moderate resolution imaging spectroradiometer and LANDSAT data with field validation. We conducted the case-study over China's Loess Plateau and analysed the spatiotemporal variations of FVC and the C-factor and their impacts on erosion over the Plateau. Our study reveals a significant increase in total vegetation cover (TC) from 56 to 76.8%, with a mean of 71.2%, resulting in about 20% decrease in the C-factor and erosion risk during the 17-year period. Our method has an advantage in estimating the C-factor from TC at a monthly scale providing a basis for continuously and consistently monitoring of vegetation cover, erosion risk and climate impacts.