Groundwater exploitation in Southern Johor Bahru, Malaysia: prospects and challenges while drilling and its mitigation measures

Abstract

Exploration of groundwater sources are increasing worldwide due to the water scarcity. In this study, groundwater exploitation was carried out around Southern Johor Bahru in Malaysia, to understand the subsurface geology, identify potential high yielding aquifers, assess the drilling challenges and determine required mitigation to deal with these challenges. Three exploratory wells were developed for this purpose; 2 wells located in volcanic-sedimentary rock and 1 in Older alluvium. It was found that the volcanic-sedimentary rocks have higher potential for groundwater extraction compared to Older alluvium in Southern Johor Bahru. The fracture with major opening (>4 cm) and litho-contact dominantly control the groundwater occurrence and productivity of volcanic-sedimentary rocks. In addition, the nature of fissures or fractures such as density and aperture influence the groundwater productivity. Whereas the primary porosity of rocks (<5%) is found not to control groundwater productivity except at completely weathered to residual soil zones (up to 47%). Also, the thickness of weathered layer does not substantially contribute to the groundwater productivity at the study area. The optimum depth for well development is more than 150 m for an approximate yield of 37–60 m3/hr at the study area. The length of casing is approximately 30 m depending on the thickness of weathered zone. Finally, the drilling issues such as air loss and mud loss were encountered in volcanic-sedimentary rock and Older Alluvium respectively.