Anthropogenic impacts on Holocene fluvial dynamics in the Chinese Loess Plateau, an evaluation based on landscape evolution modeling

The Yellow River catchment in central China is one of the cradles of Chinese civilization. Since the mid-Holocene, the runoff and erosion in this area, which includes the Chinese Loess Plateau, have been affected by anthropogenic land cover changes (ALCC) and Asian monsoon climatic changes. We applied the reconstructions of Holocene climate (temperature, precipitation, insolation and CO₂ concentration) and KK10 land cover change scenarios, to determine the evolution of discharge and sediment flux in the Beiluo River in the Chinese Loess Plateau using the Landlab landscape evolution model combined with a module that considers the impact of vegetation on water balance and soil erodibility. The modeling results show that climate change and ALCC resulted in large fluctuations of both discharge and sediment fluxes since the mid-Holocene. For the evolution of discharge, climate change is the dominant controlling factor, and land-use change has a secondary effect. Comparison of results of modeling scenario's with and without land-use change shows that it contributes less than 5% to changes of runoff during the time period before 1000 BCE. However, the impact of land-use change is significant for sediment load, especially since 5000 BCE. Thus, our results provide evidence for a much earlier start of the human impact on soil erosion and fluvial processes compared to earlier studies. Our modeling also shows that the incorporation of eco-hydrological processes in landscape evolution modeling is important for the accurate simulation of runoff and discharge in response to climate and land-use change, at least in a semi-arid environment.