The Study On Simulation Of Different Groundwater Exploitation Schemes In The Yaoba Oasis

The Yaobatantan is a typical desert grassland groundwater oasis,and the only water supply source comes from groundwater.With the development of oasis and the continuous growth of population,the exploitation scale of groundwater is becoming larger and larger,which has become a more serious groundwater funnel,affecting the life and production of residents,the development of local economy and the ecological security of oasis.Taking the Yaobatantan as the study area,based on the basic data of hydrogeological conditions,socio-economic and meteorological conditions in the study area,this thesis analyzes the dynamic characteristics and recharge and discharge conditions of groundwater,analyzes the development and utilization of water resources,and uses the water balance method to analyze and calculate the recharge and discharge of groundwater;Construct the hydrogeological conceptual model and mathematical model,use GMS software to construct the numerical simulation model of groundwater in the Yaobatan irrigation area based on MODFLOW,calibrate the parameters,identify and verify the model through the existing monitoring well data in the study area,and analyze the parameter sensitivity at the same time;Based on the stable operation of the model,the changes of groundwater level under different mining methods are simulated,which provides scientific basis and theoretical support for groundwater development and utilization and scientific decision-making management in Yaoba oasis,and has certain guiding significance for local water resources management.The conclusions are as follows:(1)According to the hydrogeological conditions of the study area,the water balance analysis is carried out,and it is determined that the groundwater recharge includes three parts:lateral recharge at the east boundary,flood infiltration recharge and lateral recharge at the south,North and West boundaries.The drainage mode of groundwater is manual mining,the recharge of groundwater is 37.6856 million m~3/a,the discharge of groundwater in 2020 is 21.2071 million m~3/a,the storage variable is 15.7669 million m~3/a,and the balance difference is 414800 m~3/a,The relative equilibrium difference is 1.10%,and the groundwater is in a positive equilibrium state.(2)The MODFLOW model is used to build the model of Yaobatan and simulate the groundwater level.The model identification period is from January to December 2017,the inspection period is from 2018 to 2020,and the prediction period is from 2021 to2035.In addition,the sensitivity analysis of local parameters is also carried out.The water yield,permeability coefficient and boundary flow are selected as the research objectives for sensitivity evaluation and analysis.The analysis results show that the model is the most sensitive to boundary flow.(3)Through analysis and comparison,when the mining volume is 45 million m~3/a,50 million m~3/a and 60 million m~3/a,the groundwater level will continue to decline;When the mining volume is 21 million m~3/a and 32 million m~3/a,the groundwater level begins to rise again.