Numerical Simulation Of Groundwater Management Level In Cangxian Pilot Area

Over exploitation of groundwater resources had caused many environmental geological problems,such as the formation of landing funnel,ground subsidence,groundwater pollution,etc.which has seriously affected the development of social economy and the daily life of the people.Cangxian is a region with a shortage of water resources,where has formed a nationally known groundwater fall funnel due to over exploitation.The lack of groundwater resources has become the main factor restricting the economic development of Cangxian.Due to the over exploitation of groundwater,a series of environmental geological problems have been triggered in Cangzhou area,such as the formation of landing funnel,ground subsidence,groundwater pollution,etc.By the determination of the control management level of groundwater,to control the exploitation quantity of groundwater,and finally the groundwater resources in Cangxian area realized the sustainable utilization.Based on the fully understanding of hydrogeological conditions in Cangxian area,the dynamic characteristics of groundwater in Cangxian area were analyzed,The groundwater quantity model in Cangxian area is developed by the method of numerical simulation.On the basis of the existing exploiting,controlling management level of shallow groundwater in Cangxian area under 4 different actuality years were predicted,and the threshold value was confirmed.And the red,yellow,blue control line of groundwater was delimited.The results of tests show that:(1)Based on the available data,the dynamic characteristics of groundwater level in Cangxian area are analyzed,the results show that groundwater level presents a increasing trend year by year.The average of shallow groundwater level is 2.61m,the average annual rate of increase is 1.04m.The average of deep groundwater level is 8.37m,the average annual rate of increase is 3.35m.The groundwater level has a certain periodicity,which can be divided into the ascending stage and the descending stage.The minimum depth of shallow groundwater in September,whlie the minimum depth of deep groundwater in March.(2)There is no significant linear relationship between precipitation and groundwater level,but the precipitation has a hysteresis to the recharge of groundwater,the lag period is about 1 months.The precipitation has a significant linear correlation with the monthly variation of the underground water level.There is a significant correlation between groundwater level and groundwater level.(3)The conceptual model and numerical model are established respectively.After the identification and verification,the model of the groundwater flow field is obtained,then prediction of groundwater flow field in four scenarios under 2015-2030,the control level and threshold value of groundwater control are determined.The control level thresholds of shallow and deep groundwater control were determined respectively,and finally get the shallow layer and deep groundwater control water level threshold.For shallow groundwater the whole region's controlling management level is-6.4?7.3m,while it's-25.6?-107m for deep groundwater.(4)Red,yellow and blue underground warning control line.Based on the falling rate of water level,the red,yellow and blue control line of groundwater was delimited.The whole shallow regions and most of the deep regions are found to be in the general state of overdrafted,but there are serious overdraft in some areas.