Publication Details

Water Security: Embarking on a River Bank Filtration Approach for Resource Abstraction

P eninsular Malaysia is drained by a dense network of rivers and streams with about 150 major river basins. Major rivers that drain into the South China Sea are the Kelantan, Terengganu, Dungun, Endau, and Sedili rivers. Major river basins in East Malaysia tend to be larger than those in Peninsular Malaysia. Out of an annual rainfall volume of 990 km3 , 360 km3 (36 per cent) are lost to evapotranspiration. The total surface runoff is 566 km3 and about 64 km3 (7 per cent of the total annual rainfall) contribute to groundwater recharge. However, about 80 per cent of the groundwater flow returns to the rivers and is therefore not considered an additional resource. The total internal water resources of Malaysia are estimated at 580 km3 /year. This shows that protection of river and groundwater are very important in order to obtain a sustainable water usage. River bank/bed filtration (RBF) offers a good practice to treat and protect the surface water as well as groundwater. It is because RBF uses the bed of a reservoir, lake or river and an adjacent sand and gravel aquifer as a natural filter. The technology can be applied directly to existing surface water reservoirs, streams, lakes and rivers, and now it is often a guiding factor in the hydrogeological investigation of new source supplies. River bank filtration is the influx of river water to the aquifer induced by a hydraulic gradient. Collector wells located on the banks at a certain distance from the river creates a pressure head difference between the river and aquifer, which induces the water from the river to flow downward through the porous media into the pumping wells. By applying this system of drinking water extraction, two different water resources are used. On the one hand, surface water from the river percolates towards the well; and groundwater of the surrounding aquifer is utilised (Michael Schön, 2006)