Evolution Regularity Of Shallow Groundwater In The East Plain Of Nansihu Lake In Jining

Taking east plain in Nansihu lake in Jining as a case, in this study, this paper used the existing dynamic observation data of groundwater, the 3D groundwater flow and solute transport numerical models are constructed by using nearly thirty years'survey data and the groundwater numerical simulation software FEFLOW. The model is calibrated with the levels of groundwater survey wells, the results indicated, the calibrated model has a high level of simulation precision. An analysis of evolution regularity in study area with the model calibrated is carried out.On the basis of fully collecting and analyzing relative materials such as geology, hydrogeology and environment of the east plain of Nansihu lake in Jining, the paper explaines systematically the cause, era and lithology of the main stratum in the research area, and analyzes the law of recharge, runoff, drainage and dynamic characteristics of the groundwater. After confirming the range of simulation district and object layer for calculation and generalizating hydraulic characteristics, vertical and lateral boundary, a groundwater mathematical model is set up. FEFLOW which is based on finite element method is employed to solve thenumerical equations. Before data input, overlap parameter subarea and administrative region, then divide the source sink data of each administrative region into the recharge of sub area. This simulation used the water level observed value of selecting November of 2003 to November of 2004 to identify and inspect the model, the fitting effect is all right, and it explains that the determination of aquifer structure and hydrogeological parameter, the model can be used in forecast. The analysis shows that the groundwater level fell in study area, the groundwater level has dropped 6.63m from 1976 to 2004, by an annual average of 0.24m. Based on the model, the paper predicts the groundwater flow field in 2020 year in the research area. The prediction results demonstrate that exploiting according to the predicted enlargement exploiting amount, the water levels have the tendency to decline continuously year by year, comparing to the water table of the artesian water,the water table of the phreatic water declines in evidence. The fitting model has been used to predict the flow field in 2020, the average level is 30.67m and will been droped 4.57m compared with 2004.The groundwater solute transport numerical models of the study area are constructed by using the groundwater numerical simulation software FEFLOW and taking chloridion and sulfate ion as representative contamination. This simulation used the water-chemical materials observed value of selecting January of 2002 to December of 2003 to identify and inspect the model, the fitting effect is all right, the model can be used to predict. Analyzing the chloridion concentration in study area, 15.2 percent exceeded Gradeâ…¢of the Quality standard for ground water in 1996, 38.5 percent exceeded Gradeâ…¢in 2004. Analyzing the sulfate ion concentration in study area, 18.8 percent exceeded Gradeâ…¢of the Quality standard for ground water in 1996, 27.5 percent exceeded Gradeâ…¢in 2004. Quaternary groundwater has been polluted seriously, the shallow groundwater in the city zone can not be used as drinking water. The fitting model has been used to predict the chloridion and sulfate ion concentration in 2020, the highest chloridion and sulfate ion concentration will achieved 350mg/L and 300mg/L. The most serious pollution is Jining city and urban of Zoucheng Yanzhou Wenshang have latent intimidate.The overdraft has close contact with water pollution in shallow groundwater and has potential threat to deep groundwater, area pollution resulting from excessive using of pesticides and chemical fertilizers is the major cause of pollution in the study aera. Scientific management and control sewage discharges should be strengthened in order to prevent further deterioration of the groundwater environment.