Abstract:
The study area is located in Machang, North Kelantan - Malaysia. The Machang plain is covered with Quaternary fluvial sediments overlying granite bedrock. The drainage system is dendritic with the main river flowing into the South China Sea. Eighteen of geoelectrical resistivity profiling surveys with Wenner configuration was conducted to determine the characteristics of the subsurface and the groundwater within the shallow aquifer. The groundwater sample from twenty existing shallow wells have been analysed to derive their water chemical concentration.
In the southern region, concentration of nitrate is considered to be high (more than 20 mg/l), while the nitrate concentration in the northern region is relatively zero. In the south, the soil properties are all similar. However, the Wenner inverse model shows lower resistivity values (around 10 ohm.m) at the sites with relatively high nitrate concentration in the groundwater (more than 20 mg/l). Conversely, the sites with low nitrate concentration, reveal the resistivity values of Wenner inverse models to be higher (more than 30 ohm.m).
2
The basement map of the area is generated from the interpolation of an interpreted Wenner inverse model. The areas that possibly have nitrate-contaminated groundwater have been mapped along with groundwater flow patterns. The northern part of the study area has an east to west groundwater flow pattern, making it impossible for contaminated water from the southern region to enter the northern area, despite the lower elevation of the area.
