Response of Erosive Precipitation to Vegetation Restoration and Its Effect on Soil and Water Conservation Over China's Loess Plateau

Abstract

Large-scale vegetation restoration profoundly affects ecohydrological and hydrometeorological processes with consequent effects on soil and water conservation. However, it is still unclear how revegetation affects the joint relationship between streamflow and sediment yield from the land-atmosphere interactions perspective. In this study, we combine in situ hydro-meteorological observations, satellite observed land surface characteristics, and coupled land-atmosphere model simulations to address this knowledge gap through a case study focusing on the Loess Plateau, where a megaproject of revegetation has been implemented since 2000. We find that historical annual streamflow and sediment yield have decreased over the Loess Plateau and 12 main revegetated basins, mainly due to enhanced canopy transpiration and soil conservation functions of revegetation. However, the magnitude of sediment yield reduction is much higher than that of streamflow for both mainstream and tributaries of the Yellow River. Specifically, the mean decreasing rate of sediment yield is 2.91 times of streamflow in the mainstream Yellow River, while for tributaries, the mean decline rate of sediment yield is 1.71 times of streamflow. Despite increases in total precipitation amount, erosive precipitation exhibits a clear downward trend over the Loess Plateau after the large-scale revegetation (2000–2015). This is mainly driven by enhanced local moisture recycling caused by revegetation-induced redistribution of water and energy budgets. Decreases in erosive precipitation frequency coupled with increased precipitation amount enhance streamflow availability and simultaneously mitigate soil erosion. Our findings highlight the importance of factoring in the two-way feedbacks between revegetation and erosive precipitation when planning soil and water conservation.