Applied the Column Experiment to study on the Physical Clogging Features of Groundwater Artificial Recharge

Abstract:

Abstract: With the completion of South-to-North Water Diversion Project in China. Except used as the industrial and domestic water, the rest of the water will be injected into the aquifers for recovering of groundwater level. Where the water can be injected and will the blockage happen during the injection time would be the key problems. Thus, a clogging test is designed for testing the reinjection property of different mediums. The clogging process of artificial recharge with sand was experimentally studied in laboratory using sand columns. The clogging degree was determined according to the changes of hydraulic conductivity and flow rate. In this experiment, two kinds of the medium are used, which are round gravel from Xihuang Village and the sands from Yongding riverbed. For simulation different injection conditions, two kinds of suspension are used as the reinjection water, which are 0.5g/l and 1g/l. The test device consists of sand column, water supply system, piezometer system and flow measuring system. By recording the piezometric head and flow in different designed time, the variation of permeability in different depth can be caculated. The permeability can be treat as an important indicator of blockage. The experimental results show that: the physical clogging speed is as twice as fast,when the medium is the sands from Yongding river and the concentration of suspended solids doubled. But there is little differences in physical clogging speed, when the medium is the round gravel from Xihuan village and the concentration of suspension doubled. Generally, the blockage would finish within 20 hours. When it finished, the permeability commonly drops 10%. And the blockage influnce range is about 10cm. Thus, water quantity, water quality and cost effectiveness should be considered to select the recharge place where the recharge speed and the clogging speed are optimized.