Potential Impacts Of Climate Change On Sediment Yield In The Xunhe River Basin

Sediment yield is an important issue in climate impact studies.Potential impact of climate change on sediment yield in the Xunhe River basin is investigated using a combination of climate,hydrological,and sediment yield models.Twenty general circulation methods under representative concentration pathways(RCPs)4.5/8.5 are downscaled using the quantile mapping method to project future climate change in the Xunhe River basin.The lumped Xin'anjiang(XAJ)hydrological model and the conceptual sediment yield model are used to simulate the runoff and sediment transport rate in the case of future climate change,and the fitting results beteewn simulated runoff/sediment yield indicate these two models suit the Xunhe River basin.According to the multi-parametric sensitivity analysis method,the evaporation coefficient CKE,parameter N_w and K_w are sensitive parameter in the XAJ hydrological model as CKE influence the water balance,and N_w and K_w affect the value and time of peak discharge.In the conceptual sediment yield model,the probable max erosion protection resistance R_cm,the mean gully sediment concentration C_gm and parameter B_v in gully erosion velocity factor,are relatively sensitive parameters as these parameters influence the sediment yield balance,while parameters N_s and K_s are both sensitive in the sediment concentration process as N_sand K_s influence the value and time of peak sediment transport rate.Furthermore,the input data,model structure,and parameters should all be considered sensibly,accoding to generalized likelihood uncertainty estimation method.The parameter uncertainty adds model uncertainty since the value of model parameter is not unique when the model performance is best.The uncertainty is propagated from precipitation to runoff and from runoff to sediment yield.Under RCP4.5/8.5 scenarios,the average annual precipitation,runoff,and sediment yield might tend to increase in the future with a larger increase under RCP8.5.Future precipitation,runoff,and sediment yield display varying tendencies in different months owing to seasonal variation characteristics.These results suggest that future sediment yield might increase under the influences of climate and runoff change,which will serve as a guideline for sediment resource management.