Response Of Streamflow To Climate And Land Use/Cover Change In Ebinur Basin

Located in the sensitive reaction of the global environment change and ecological fragile zone, Ebinur lake basin is a hot topic in Ecological Environment evolution in China.This thesis takes the BoErtala river and Jing He river as main object of study.Study on water cycle and effections.Application of SWAT model and the Budyko hypothesis,Research on climatic factors and land use/land cover change on runoff, respectively. we arrive at the following conclusions:Quantitative analysis of variations in the hydrological cycle components and affecting factors.The solar radiation is as important source of energy for hydrologic cycle, reduce trend in Ebinur lake area, regression rate is 31.7 MJ/m2.solar radiation mutation fell in 1985, the change of the present "to the dark".In arid zone, precipitation is as the most important influence factors in the process of the hydrologic cycle, the characteristics of the precipitation plays an irreplaceable role in the hydrological cycle. precipitation had no significant change in recent 55 years,linear trend rate is 7.95 mm / 10 a.the multiple time scales of rainfall time series exhibit considerable variation.Study on the maximum temperature, minimum temperature, average temperature, the average temperature presents the obvious growth trend in nearly 50 years, it is a rise about 1.31 ℃.the highest temperature increase of 1.097 ℃.the lowest temperature increase 2.94 ℃.We use cumulative curve’s test to detect the abrupt change points in temperature series.the results present the significant change points in 1995 for maximum temperature and in 1989 for lowest temperature and in1996 for average temperature.The average temperature race up the most significant in the autumn and winter.The highest temperature heating up the most significant in the autumn and winter.The lowest temperature of the four seasons increased significantly.Potential evaporation participated in the material migration and energyconversion of the hydrologic cycle. Quantitative analysis showed that the potential evaporation presented the tendency of increase from 1996, linear trend rate was3.43mm/10 a.the annual and seasons potential evaporation have the same trend.The result shows the abrupt change points in 1999 for spring and autumn and in 1996 for summer. Wind speed became the biggest contributor potential evaporation,Temperature diurnal range was the biggest contributor in spring potential evaporation.average temperature was the biggest contributor in autumn and summer. The study found that the actual evaporation showed a trend of increase, which had good linear relation with the precipitation;the actual evaporation controlled by precipitation.precipitation is the main cause of change in annual and spring, summer,autumn’s actual evaporation. wind is the dominant factor on the changes of actual evaporation in winter.Analysis on the hydrological data collected at three hydrological station;runoff did not vary significantly. The peak value occured in Apr. to Aug.in Jing He station and WenQuan station,Bole station monthly runoff is mainly concentrated in the winter and was steady.Based on hydrological frequency analysis of P-III Pearson curve,found that the Cv value was between 0.132 to 0.151.Constructed a distributed hydrological model SWAT, simulated the runoff in the study area on the monthly and yearly scale, and drew the conclusion that the simulation on the yearly scale was better than the simulation on the monthly scale.that the Nash-Sutcliffe model efficiency coefficient was about 0.7, and relative error was below 15%, coefficient of determination was more than 0.7 both for annual flow in calibration period, so it satisfied the simulating needs. Uncertainty analysis indicated that DEM resolutions and watershed subdivisions produced little influence on annual flow.Distinguished the effects of climate change and human activities on runoff quantitative,and the research results showed that the impact of climate change on runoff accounted for 30-40%, and the influence of human activities on runoffaccounted for 60-70%.Aiming at the effects of climate factors on runoff, using runoff sensitivity evaluation method which based on climate elasticity coefficient, the drought index and Budyko curve was evaluated for quantitative in the Ebinur lake basin. Sensitivity analysis based on the drought index showed that the drought index change 10%,namely the change rate of potential evaporation and precipitation ratio is 1%, will cause runoff change about 3.2% to 6.8%. Sensitivity analysis based on Budyko curve showed that the precipitation change about 10% will cause runoff change about5.38%, the increase 10% of potential evaporation will cause 10.54% of runoff amount.and the increase 10% of and scape parameter will cause 29.84% of runoff amount.Aiming at the effects of land use cover change on runoff, using runoff sensitivity evaluation method which based on land elasticity coefficient, was evaluated for quantitative in the Ebinur lake basin, made the consistent conclusions that the most sensitive land type was land unused and woodland.According to evaluation results of runoff response to land use, considering river system,land use cover and factors such as rainfall, based on response unit partitioned by SWAT model. Study area was divided intothree areas: highly sensitive area,moderate sensitive area and general sensitive area.