Groundwater Numerical Simulation Of Water Supply Hydrogeological Survey Zone In Northern Santanghu Coalifeld, Xinjiang

Santanghu coalfield is a large coal base of " transports coal from west to east " planning and a key coalexploration area of the "358" Project in Xinjiang Uygur Autonomous Region. Santanghu region has an aridclimate in mid temperate zone with hot summer and cold winter. The precipitation is sparse andevaporation is strong there with nondevelopment surface water systems, meanwhile, there is no perennialriver. Currently, domestic and production water mainly comes from groundwater in Santanghu region.Water shortage becomes one of the main restriction factors of accelerating development and utilization ofcoal resources. Hydrogeological investigation of water supply should be carried out as soon as possible.Exploration results should be analysed and demonstrated in order to propose groundwater resourcesutilization plans and break bottleneck of restriction on water resources.The study summarized research status of groundwater numerical simulation home and abroad. Basedon previous exploration work, other groundwater hydrogeological data such as available research resultsmaps, borehole data, groundwater exploitation water level of observation wells, meteorology, hydrology,aquifer structure, groundwater recharge, runoff and drainage conditions and dynamic characteristics ofgroundwater were collected, then main characteristics of the aquifer and hydraulic were determined.Hydrogeological parameters and divisional parameters of study area were determined using pumping testdata. Comprehensive analysis of hydrogeological boundary conditions, stratum structure, initial conditions,source and sink terms in groundwater systems in study area and so forth was made. A three-dimensionalstructural model of hydrogeological was built using GMS software. Based on hydrogeological structuremodel, groundwater flow numerical simulation model was established using MODFLOW software and themodel parameter identification and correction is done. The fit between calculated value and measured valuefrom model identification is preferable. Parameters used in the simulation model were reasonable. Usingthe numerical simulation model was of credibility for simulation of groundwater seepage field in studyarea.Based on analysis of groundwater abundance and groundwater resources requirement, this paperproposed two kinds of groundwater exploitation schemes. One is centralized exploitation in water sourcearea while the other is scattered exploitation in detailed survey area. A20years simulation period ofgroundwater flow under different exploitation schemes was predicted by the groundwater flow simulationmodel. Main conclusions are drawn as follows：(1)Under centralized exploitation mode, scheme2and6in which groundwater table will have a largedecline after20years’ exploitation are unsustainable exploitation schemes. Scheme3and7in whichgroundwater table basically unchanged after20years’ exploitation and exploitation quantity remainsessentially constant when compared with set exploitation level are sustainable exploitation schemes.Scheme4and8in which groundwater table has been basically stable after20years’ exploitation andexploitation quantity remains essentially constant when compared with set exploitation level are sustainableexploitation schemes.(2) Considering water supply maximization, under centralized exploitation in water source area, theoptimal schemes are scheme3and7, that is we could use the three existing exploratory well (KT19, KT20and KT21) and add four wells (J1, J2, J3and J4) to mine, the total exploitation quantity is263×104m3/a and197×104m3/a, respectively, before and after water conservancy construction in southern mountain regionin detailed survey area.(3)Scattered groundwater exploitation schemes in detailed survey area are feasible with guaranteedgroundwater exploitation of431×104m3/a and256×104m3/a in detailed survey area, before and after theimplementation of water projects. Groundwater exploitation quantity consists of evaporation decrease fromphreatic water and spring discharge decrease, in scheme9and10, the water equilibrium difference after20years’exploitation are-54×104m3/a and-86×104m3/a, respectively, which is less than that in current year.(4) Subsurface flow and infiltration of the five rivers in southern mountain area are important sourceof groundwater recharge.(5)After water conservancy construction of southern mountain area in the simulation area, springdischarge in the area will decrease with time gradually, most of the springs will dry up after10years. Thesimulation area with groundwater depth less than5m will reduce which would bring certain negativeinfluence on desert vegetation.