Demonstration Project Of Restoration Of Saline Groundwater And Research Of The Optimization On Restoration Schemes At The Low Reach Of Dagu River

Water is a very important natural resource for human survival and development.As a part of water resources, groundwater is also significant for us and it is the majorsource of irrigation and domestic water in many cities. Seawater intrusion occurred atthe Low Reach of Dagu River by reason of the overexploitation of groundwater. Inorder to prevent the seawater intrusion, a seepage-prevention wall was constructed inthe south of Ligezhuang and the cutoff wall worked well. Some saline water remainedin the town of Ligezhuang at the same time, but that made the removal of saline waterpossible.To determine the temporal and spatial variation of the saline water, a net ofdynamic monitoring must be set up. So we investigated the research area in detail andfinally established seventeen monitoring sites of head and groundwater quality. Thesemonitoring data can also be used in the numerical model. The monitoring resultsindicate that the western borderline of the saline water keep being in the line ofZhouchentun village—northwest of Huangjiatun village—southeast of Ligezhuangvillage—Wangjiazhuang village—Nanzhangjaizhuang village—Shilazi village—thecutoff wall. The total amount of saline water is about2.278×10~7cubic meter.The hydrogeological conditions and the materials such as the rainfall,evaporation, exploitation amount and hydrogeological parameters and so on areneeded when establishing the numerical model of the research area. The variabledensity model which couples the flow and transportation equation is established withthe SEAWAT module of the Visual MODFLOW software. We utilize the monitoringdata to identify and verify the model. The fitting result is relatively good in the entireresearch area include the demonstration area. In other words, the model can reflect thereal flow and mass transportation state of the research area, to a large extent. So the model can be used in the groundwater resource analysis and the numerical simulationof the saline groundwater restoration of the demonstration area.The restoration test of saline groundwater was carried out from September18th,2011to October11th,2011. After twenty two days, the pumping and injection hadlittle effect on the saline water, so we optimize the restoration scheme with the modeland three schemes are set down. The first scheme makes the best of the existing wells,the second and the third add two injection wells in the line of injection wells. In thethree schemes, the area of the saline water between the pumping wells and theinjection wells will reduce to a small value and large effect will be acquired afterrunning110days. Comparatively, the average rate of decrease of the saline water isthe biggest in the third scheme. The required amount of pumping and injection waterof the third scheme is the least and that of the first and the second one are similar.According to the statistics, the third scheme can save22%of the pumping amount and6%of the injection amount. In generalization, the third scheme is better than the firstand the second one. Of course, we can choose different scheme depending on the fact.