The Construction Of Management And Assessment System In Groundwater Over-exploited Regions

Groundwater is the main water supply resource in Beijing, and it takes up twothird of total supply. In the recent thirty years, the mean exploitation is25-2710~8m~3/a.After1999, the available surface water is not enough to maintain the water supply,thus the exploitation of groundwater is increasing, and this process is lowering watertable about one meter per year. Until now, the deficiency of ground water is about7010~8m~3, and it causes some problems such as land subsidence, groundwaterpollution and other ecological problems. Also the drought in Beijing makes a largedeficiency in groundwater and increases the conflict of water supply anddemand. These problems could be partly solved by artificial recharge.With the reference of research on artificial recharge by Beijing institution ofHydrology and Engineering geology, this paper collected large amount of survey dataof Beijing alluvial fan. In this thesis, Puddingstone from Xihuang Village and thesands from Yongding River bed are used to fill the sand column, and0.5g/L and1.0g/L soil solution are prepared to test the clogging process and positions. Thehydraulic conductivity increased at beginning, and the clogging appeared after40hours. In order to compare the clogging process,λwhich represents the rate ofclogging is used. The experimental result shows that the physical clogging speedλislarger, when the averaged diameter of the medium is larger, or the concentration ofsoil solution is larger. The clogging position is blow the medium surface about12cm,and the slower clogging rate causes the deeper clogging position.Based on this laboratory clogging test, the maintenance and repair rechargefacilities was tested by drying and renewing the surface layer. The result shows that,after renewed the surface layer, the initial conductivity decreased from3.6m/d to2.5m/d. And the clogging position reaches to15cm below the surface.