| Since the 1980s,management aquifers research has attracted widespread attention from all over the world.Groundwater has the advantages of excellent water quality,stable and balanced water supply which is widely used in domestic,industrial,agricultural and other purposes.Groundwater resources are over-exploited,which is a universal problem in the world.For this reason,countries all over the world are exploring groundwater controlled mining technologies to achieve a balance of groundwater replenishment.Ningjin County is located in the northwestern part of Shandong Province.It is an area with relatively short water resources and the annual volume of Yellow River diversion is 52 million m~3.Ningjin County is at the end of irrigation from the Yellow River and is the most difficult area for water diversion in Dezhou City and the water supply cannot be unsatisfied.The industrial life and agricultural irrigation in Ningjin County are mainly groundwater.The problem of overexploitation of shallow and deep groundwater appears due to long-term groundwater exploitation.It is very important to reasonable development and utilization of groundwater resources and scientific management.Therefore,this thesis focuses on the groundwater overexploitation in Ningjin County.Through mathematical models,model calculations and other methods,the control red line of the overall groundwater level in Ningjin County is obtained.Therefore,we can get the maximum recoverable water volume of groundwater in Ningjin County.The main conclusions of this paper are as follows:(1)First of all,through the analysis of water supply and demand balance,we can systematically understand the relationship between water supply and use in Ningjin County.Through statistics on the overall development and utilization of various water resources in Ningjin County,we can get the current situation of water shortage and per capita water shortage in Ningjin County.(2)Secondly,we combined the actual situation of Ningjin County to establish a hydrogeological conceptual model and a mathematical model of groundwater flow,and solved it according to the definite solution conditions.We use the GMS model tosimulate and introduce in detail the selection of initial conditions,the determination of boundary conditions and the fitting of hydrogeological parameters in the solution process,so that the accuracy of the model meets the calculation requirements.This article explains the groundwater control red line theory,and brings different groundwater exploitation conditions into the model for analysis and calculation.The analysis verified that when the groundwater level was mined at2/3 of the aquifer depth,the amount of groundwater extraction reached the maximum,and the depth at this time was set as the groundwater level control red line in the freshwater area.(3)Through the balanced calculation of groundwater resources,it can be obtained that the total annual recharge of groundwater under multi-year average conditions is 4.98×10~7m~3,and the total annual discharge is 5.01×10~7m~3.Therefore,it can be concluded that the overall groundwater in Ningjin County is in a state of overexploitation.For the study of the groundwater level control red line in the saline water area,firstly,the saline water is divided into four areas in the southwest of Ningjin,the south of Ningjin,the southeast of Ningjin and the north of Ningjin.Through analysis,it is found that the mining method in the freshwater area will extract the salt water layer,so the mining method in the freshwater area is not applicable to the salt water area.Secondly,the use of solute transport and diffusion equation is an analysis of the salt-water transition zone,and the curve relationship between different concentrations and diffusion distance is calculated to obtain the thickness of the salt-water transition zone.Through the measured electrical sounding curve,the depth position of the salt water area can be obtained.Finally,through calculation,the depth of the salt water area is used to subtract the thickness of the salt water transition zone,and the reserved fresh water depth of 1 to 2 meters is subtracted to obtain the buried depth of the groundwater level control red line in the salt water area.Finally,the groundwater level control red line of the salt water area is obtained by subtracting the buried depth value from the surface elevation.(4)Finally,through the obtained groundwater level control red line of the salt water area in the freshwater area of Ningjin County,the overall groundwater level of Ningjin County is drawn.By calculating the maximum extractable amount of groundwater in Ningjin County,it provides a theoretical basis for the control and management of groundwater level in Ningjin County.The research results of this article are helpful to fully understand the determination process of groundwater control red line.It provides important guiding significance for protecting the groundwater system and realizing the sustainable development and utilization of groundwater resources. |
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