Impact of Land Topography on Runoff and Soil Erosion: An Experimental Approach

Soil erosion is causing major concerns across the world, as the loss of soil jeopardises not only environmental sustainability, but also land productivity, eventually leading to reduced resources for populations that heavily rely on land.However, how runoff drives soil erosion and the impact of different land coverages on this is not yet well understood, also because of the lack of data acquired in controlled conditions.To fill this gap, experiments were performed in the Yan Gou runoff observation site (China) by controlling runoff volume, sediment transport, soil loss, and soil water content in five square plots, each with an area of 100 m 2 , covered by different vegetation and having different topography.The results presented here focus only on plots covered by citrus but have different slopes, to decouple the effects of vegetation coverage and soil topography.Assuming a constant hydrological forcing (i.e., fixed precipitation), it was observed that plots with down-slop ridge drive a larger runoff, as expected, which implies that more sediments are mobilized causing higher soil loss.At the same time, this loss of soil influences the content of water differently, which changes more significantly in the horizontal plot than in the inclined one.Comparing all plots, it was noticed that standard terraces are the most effective method to conserve soil, reducing the runoff and keeping the content of water more constant over time.