Numerical Analysis Of The Saline Groundwater Restoration Scheme In Ligezhuang Region

Ligezhuang saline groundwater region is located in the south east of Ligezhuang Twon, Qingdao City, and it is range of about 15.2 km2. Because of its high concentration of chloride in groundwater, its groundwater can not satisfy the requirements of industry, agriculture, and living, that seriously affects the local production and living of residents, and restricts the local economic development. Therefore, it urgently needs the study about restoration of saline ground water in Ligezhuang Region, which can provide a scientific basis for repairing the saline groundwater in this region.According to the existing information of rainfall, evaporation, groundwater mining and hydro-geological in Ligezhuang region, combining the situation of site investigation and monitoring, the article analysed the changes of saline groundwater distribution and its impact factors. And on the basis of identifing the type of pumping wells, radius of influence, specific well discharge, the layout of wells and interference coefficient, three saline groundwater restoration schemes were designed including wells continuous pumping without interference scheme, wells continuous pumping with interference scheme and wells intermittent pumping with interference scheme. The variable density groundwater simulation software Visual-MODFLOW software SEAWAT modules was used to simulate and analyse the three schemes to select the most optimized saline groundwater restoration scheme.Through the study something was found that in the current condition of Ligezhuang Region, the scope of saline groundwater would be gradually reduced, but the rate of decrease was very slow and the reduce region was focus on the west side of salt groundwater; at the same time there was a slow rising trend on chloride concentration in the central area of saline groundwater. Therefore, in the maintenance of the existing conditions, the saline groundwater in Ligezhuang Region will not automatically be restored. Rainfall and evaporation didn't affect the changes in the distribution of salinewater very significantly, but the extraction of saline groundwater did. Under the present circumstances little salt groundwater extraction would not impact on the distribution of saline groundwater, but the artificial extraction will accelerate to reduce the scope of saline groundwater distribution and decrease the concentration of saline groundwater. The extraction of saline ground and the rate of saline groundwater decreasing were positively correlated. Extraction of saline water is one factor of the saline groundwater restoration and the surrounding freshwater displacement is another one. Wells intermittent pumping scheme takes full advantage of these two factors (reducing the space between wells would increase the total number of wells in the study region and improve the rate of extracting groundwater; intermittent pumping would enhance the role of surrounding freshwater displacement) to be the most optimized in three saline groundwater scheme. There are a total of 45 pumping wells with the space of 350 mile in the wells intermittent pumping with interference scheme and the interference factor of wells is 0.18 ~ 0.21 and two pumping phases (the first phase with 9 months pumping, the second phase with 3 months pumping, stopping to pump for 6 months in the middle of two phases) with a total pumping capacity of 1369.06×104m3. After pumping beginning for 36 months, the area of saline water reduced from 15.2 km2 to 1.53 km2, and the concentration line of 450mg/L completely disappeared.