Determination of Riverbed Filtration Potential as Water Supply Source using Geoelectrical Method

Abstract

River bank filtration (RBF) is the influx of river water to the aquifer induced by a hydraulic gradient. Collector wells located on the banks in 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 where surface water from the river percolates towards the well; and groundwater of the surrounding aquifer is utilized. A study on the potential of RBF near the existing intake of Lembaga Air Perak at Sg Kampar was undertaken. Geophysical survey using resistivity traverses was made with 5 lines each on the right and left bank of the river. Three lines perpendicular and 2 lines parallel to Sg Kampar were investigated for possible water potential for RBF. The Wenner-Schlumberger configuration was chosen based on space provided in flatten areas and the depth of penetration interest in order to identify the presence of groundwater, stream-aquifer interaction and subsurface lithologies. Results from 2-dimensional profiles indicated that: (a) permeable soil saturated with water (possible groundwater and terrestrial sediments material) showed the resistivity value ranges of 0-150 ohm.m (b) semi permeable soil and weathered rock showed the resistivity value ranges of 200-1000 ohm.m and (c) impermeable soil and rock (unsaturated zone) showed the resistivity value ranges of 1000-7000 ohm.m.