The Study On Groundwater Reducing Mining Scheme And Optimization Of Monitoring Well Network In The Minqin Basin

Minqin Basin is on the lower reaches of the Shiyang River Basin.It is one of the typical desert oasis in China,surrounded by Badain Jaran desert and Tengger Desert in the east,west and north.With the increase of population and development of social economy of Shiyang River Basin,the utilization of water resources is more and more increased up the stream,the remaining water resources is on the decrease that get into Minqin Basin.Minqin Basin had to increase the exploitation of groundwater resources,leading to the groundwater level decreasing,and then ecological degradation and desertification.The problem of groundwater overexploitation in the Minqin Basin can't wait to be solved,This is related to the ecological security of the whole Hexi Corridor.Based on the study of the hydrogeological conditions in Minqin Basin,this paper establishes a numerical model of groundwater in Minqin Basin.Evaluating groundwater resources in Minqin Basin,the average supply during 2001-2010 is20556.24×104m3/a,the average evacuation is 31290.38×104m3/a,and the annual average is 10734.14×104m3/a.the mining situation of Minqin is evaluated by the qualitative and quantitative method.it set up different groundwater reducing mining schemes.The prediction model is used to calculate the groundwater resources balance,the fluctuation of the monitoring wells and the area of the groundwater level less than5 m.Based on the constraints requirement of groundwater reducing mining,the final groundwater reducing mining is 10000×104m3/a.According to the national economic planning and the key management plan of the Shiyang River Basin,this scheme is feasible.In this case,the amount of groundwater storage resources was recovered,the groundwater level was stable and uplifted,and the ecological environment of the basin was gradually restored.In order to provide good data to support for the implementation and supervision of the groundwater reducing mining project,the existing groundwater monitoring well network in Minqin Basin is researched and analyzed by ordinary Kriging method.The variation function is calculated as?(h)=0.575h1.6187.In the study area,28 monitoring wells were added and other 2 monitoring wells were reduced to optimize the density of the existing groundwater monitoring network.Most of the theoretical variance of monitoring wells is near 0.5-0.6,which meets the needs of groundwater monitoring in Minqin Basin.Based on the optimized monitoring well pattern and the groundwater reducing mining scheme,the depth of water level in September is as the red line of groundwater table management in that year by the prediction model,which provides technical support for the implementation of groundwater dual control management—the total quantity control of groundwater withdrawal and the groundwater table control in the study area.