Impacts Of Climate Change On Hydrology And Water Resources In The Middle Reaches Of The Yellow River Basin

Climate change is an important global environmental issue. It's significant to study impacts of climate change on hydrology and water resources in the middle reaches of the Yellow River basin, which could provide scientific supports for sustainable utilization of water resources and healthy life maintenance of the Yellow River. The mian contents include as follow:(1) Variation trend of hydro-meterological factors in the middle reaches of the Yellow River basin were tested scientifically with multi-method of moving average method, Spearman rank correlation method, Mann-Kendall rank correlation method and linear regression method.(2) The performance of six lumped conceptual hydrological models (AWBM model, SIMHYD model, TANK model, SARC model, SMAR model and YRWBM model) and two physically based distributed hydrological models (SWAT model and VIC model) in the Sanchuanhe River basin and Qingjianhe River basin were systematically compared. And YRWBM model was recommended to analyze effects of environmental change in the middle Yellow River.(3) Relationship between parameters of YRWBM model and catchment properties were developed based on the physical interpretation of the model parameters and its spatial distribution law. Regional calibration method for YRWBM model was put forward to improve accuracy and reliablity of paramerter identification. And runoff simulation for the whole middle reaches of the Yellow River basin was carried out.(4) Quantitative separation method for individual effect of climate change and human activities on runoff was put forward. And hydrological model was employed to analyze the effects of climate change and human activities on runoff in the middle reaches of the Yellow River basin. And results indicate that human activities are main reasons of runoff reduction. On average, runoff reduction induced by human activities accounts for 61.5% of total runoff decrease in the middle Yellow River basin from 1970-2000. But for different subcatchments, climate change contributes different effect.(5) Exponential relationship between air temperature and potential evaporation were established. And effect of temperature change on potential evaporation was studied. Adopting hypothetical climate scenario, sensitivity of runoff in each subregion to climate change was analyzed. Taking Sanchuanhe river basin as example, impacts of climate change on runoff components, seasonal distribution of runoff, soil moisture were studied. And results indicate that runoff in region from Longmen to Sanmenxia is most sensitive to climate change. Response of surface runoff to precipitation change is much larger than that of ground flow and snow-melt flow. Climate change could result in obvious changes in seasonal distribution of runoff and soil moisture as well.