Electrical resistivity tomography and induced polarization method applied for tubewell development in Alluvial deposit: A case study in MARDI Seberang Perai

Abstract

Geophysical data through electrical resistivity tomography (ERT) and induced polarization (IP) can be assisted to understanding hydrogeological characteristic of groundwater aquifer. By knowing the difference in electrical resistivity and induced polarization values in alluvium deposition will facilitate to identify any groundwater occurrence. In agriculture sector, shallow tube well will be option to farmers due to more economic. The resistivity measurements proved to be a good tool for mapping the subsurface in the Alluvium, especially when used in combination with Induced Polarization parameters. Alluvial deposits or fluvial deposits are composed of particles of gravel, sand, silt or clay size that are not bound or hardened by permeable mineral, by pressure, or thermal alteration of the grains. Consideration of gravelly deposition is the higher hydraulic conductivity. Furthermore, coarse to fine sand are the second higher followed by silt and clay are the lowest values. From the case study, the electrical resistivity tomography of these deposits ranged from 40 to 1000 Ωm, while the values of chargeability were 0 to 20 mS/m. The bottom of the aquifer consisted of a layer with gravelly sandy silt, and the resistivity was 260 Ωm, while the chargeability was 6.5 mS/m. The shallow tube well in quaternary aquifer was constructed at 51 m depth with thickness of aquifer was 24 m to 51 m depth into the ground will consider for groundwater resources. The groundwater discharge from tubewell is 6.53 m3/hr in mixed gravel, sandy and silt.