Water turbidity impact on discharge decrease of groundwater recharge in recharge reservoir

The need for groundwater supply is increasing. However, with excessive exploitation, the groundwater table has drawn down, and thus resulted in land subsidence, seawater intrusion and groundwater deterioration. In order to maintain the groundwater supply, various attempts, such as the use of natural or artificial recharges, have been done. One of the artificial recharging methods which were previously studied was recharge reservoir construction in the soils with permeability less than 10-5 cm3/sec using a sand column. However, sedimentation could occur at a site where the recharge reservoir was constructed. Therefore, the levels of water turbidity, which could lead to sedimentation and blockage of groundwater flow (seepage), should be investigated. This research aimed to investigate the rate of blockage impact resulting from sedimentation in the sand column. More specifically, the aim of the research was to determine what types of sand column should be used in the field to minimize the groundwater problems. Experimental tests were carried out in the laboratory to measure the discharge of seepage through the soil layers and the sand column. The size of the physical model testing instrument was 180 cm x 115 cm x 60 cm with 12 pieces of the sand column (35 cm high), the reservoir water level of 10 cm, and three variations of water turbidity and deposition time. The research revealed that the higher the water turbidity, and the longer the period of deposition, the less the flow rate of groundwater recharge. As a result, turbid water should be prevented to infiltrate sand columns in recharge reservoirs. (C) 2015 The Authors. Published by Elsevier Ltd.