Emergent stationarity in Yellow River sediment transport and the underlying shift of dominance: from streamflow to vegetation

摘要

Soil erosion and sediment transport play important roles in terrestriallandscape evolution and biogeochemical cycles of nutrients and contaminants.Although discharge is considered to be a controlling factor in sedimenttransport, its correlation with sediment concentration varies across theYellow River basin (YRB) and is not fully understood. This paper providesanalysis from gauges across the YRB covering a range of climates, topographiccharacteristics, and degrees of human intervention. Our results show thatdischarge control on sediment transport is dampened at gauges with large meanannual discharge, where sediment concentration becomes more and more stable.This emergent stationarity can be attributed to vegetation resistance. Ouranalysis shows that sediment concentration follows a bell shape withvegetation index (normalized difference vegetation index, NDVI) at an annualscale despite heterogeneity in climate and landscape. We obtain thecounterintuitive result that, as mean annual discharge increases, the dominantcontrol on sediment transport shifts from streamflow erosion to vegetationretardation in the YRB.