Study On The Change Of Lake Water Inflow And Lake Level In Qinghai Lake Based On SWAT Model

The Qinghai Lake basin is located in the transitional zone between the arid northwestern region and the Qinghai-Tibet Plateau,and has an important location.In recent years,the level of lake water in Qinghai Lake has decreased sharply,and the lake gradually shows a shrinking state,which leads to the phenomenon of grassland desertification and the trend of expansion,which has aroused great concern.In view of the gradual decrease of water inflow,the following research is carried out in the application of SWAT model:?1?Model calibration and verification.Utilizing the seven most sensitive parameters that have been selected,the measured monthly runoff data of the Buha River is input into SWAT_CUP software.the simulation results are repeated calibration and verification for calibration of the model,and evaluate the results of calibration and determine the applicability of the SWAT model in qinghai lake basin.?2?water balance analysis and Budyko watershed characteristics analysis.According to the calibrated model output file,the water balance in the catchment was analyzed.Then the drought index calculated by the Budyko hypothesis was used to analyze the sensitive coefficient of the runoff and the characteristics of the catchment.?3?Study on the change of water level and influencing factors in Qinghai Lake.The change of water level and its influence factors of Qinghai Lake from 1961 to2013 were analyzed respectively,and a regression model was established to study the response of lake water level to impact factors.The main conclusions obtained from the above studies are as follows:?1?The correlation coefficient between simulated and measured runoff values is 0.83 and 0.80in the rate regular and verification periods,and the efficiency coefficients reach 0.74and 0.72,respectively,which satisfy the model evaluation index and proves that The model is very suitable for runoff simulation in the Qinghai Lake Basin.?2?From the results of water balance analysis of the river basin,it was found that evapotranspiration is the main cause of the drop in the water level of Qinghai Lake and the decrease of water volume,and the distribution of rainfall within the basin during the year is very uneven.?3?The relation curve of E/P^E₀/P indicates that the climate of the basin south of Qinghai lake is drier and the evapotranspiration is relatively large,and the climate in the north is humid and the evapotranspiration is relatively small.The relationship between runoff sensitivity coefficients??Q/?P??Q/?E₀ and?Q/?m?and dryness index?E₀/P?shows that,compared with arid regions,watershed humid regions responded more strongly to changes in precipitation and potential evapotranspiration;Under drought conditions,the change of precipitation is more dominant than the change of potential evapotranspiration,and the watershed characteristic parameters have significant influence on the change of precipitation and potential evapotranspiration.?4?Lake evaporation has the greatest impact on the water level of the lake,followed by precipitation on the lake and then into the lake.The runoff into the lake was divided into 4 sub-basins for analysis.The correlation between runoff from the lake and the lake water level was the largest,followed by the Shaliu River basin,then the Haergae basin,and finally the Daohe River basin.Studies above provide a reference for a better understanding of the status quo of the Qinghai Lake Basin and the causes of the changes,and also provide a reference for water resources investigation and development in the basin.