Shaharin Ibrahim

Evaluation of Factors Influencing the Groundwater Chemistry in a Small Tropical Island of Malaysia

Groun in a very complex way. In this work, multivariate statistical analysis was used to evaluate the factors controlling the groundwater chemistry of Kapas Island (Malaysia). Principal component analysis (P dwater chemistry of small tropical islands is influenced by many factors, such as recharge, weathering and seawater intrusion, among others, which interact with each other CA) was applied to 17 hydrochemical parameters from 108 groundwater samples obtained from 18 sampling sites. PCA extracted four PCs, namely seawater intrusion, redox reaction, anthropogenic pollution and weather factors, which collectively were responsible for more than 87% of the total variance of the island’s hydrochemistry. The cluster analysis indicated that three factors (weather, redox reaction and seawater intrusion) controlled the hydrochemistry of the area, and the variables were allocated to three groups based on similarity. A Piper diagram classified the island’s water types into Ca-HCO3 water type, Na-HCO3 water type, Na-SO4-Cl water type and Na-Cl water type, indicating recharge, mixed, weathering and leached from sewage and seawater intrusion, respectively. This work will provide policy makers and land managers with knowledge of the precise water quality problems affecting the island and can also serve as a guide for hydrochemistry assessments of other islands that share similar characteristics with the island in question.

Application of Geophysical Techniques for 3D Geohazard Mapping to Delineate Cavities and Potential Sinkholes in the Northern Part of Kuala Lumpur, Malaysia

This work describes the application of the electrical resistivity (ER) method to delineating subsurface structures and cavities in Kuala Lumpur Limestone within the Batu Cave area of Selangor Darul Ehsan, Malaysia. In all, 17 ER profiles were measured by using a Wenner electrode configuration with 2 m spacing. The field survey was accompanied by laboratory work, which involves taking resistivity measurements of rock, soil, and water samples taken from the field to obtain the formation factor. The relationship between resistivity and the formation factor and porosity for all the samples was established. The porosity values were plotted and contoured. A 2-dimensional and 3-dimensional representation of the subsurface topography of the area was prepared through use of commercial computer software. The results show the presence of cavities and sinkholes in some parts of the study area. This work could help engineers and environmental managers by providing the information necessary to produce a sustainable management plan in order to prevent catastrophic collapses of structures and other related geohazard problems.

A Preliminary Appraisal of the Effect of Pumping on Seawater Intrusion and Upconing in a Small Tropical Island Using 2D Resistivity Technique

The existing knowledge regarding seawater intrusion and particularly upconing, in which both problems are linked to pumping, entirely relies on theoretical assumptions. Therefore, in this paper, an attempt is made to capture the effects of pumping on seawater intrusion and upconing using 2D resistivity measurement. For this work, two positions, one perpendicular and the other parallel to the sea, were chosen as profile line for resistivity measurement in the coastal area near the pumping wells of Kapas Island, Malaysia. Subsequently, water was pumped out of two pumping wells simultaneously for about five straight hours. Then, immediately after the pumping stopped, resistivity measurements were taken along the two stationed profile lines. This was followed by additional measurements after four and eight hours. The results showed an upconing with low resistivity of about 1–10 Ωm just beneath the pumping well along the first profile line that was taken just after the pumping stopped. The resistivity image also shows an intrusion of saline water (water enriched with diluted salt) from the sea coming towards the pumping well with resistivity values ranging between 10 and 25 Ωm. The subsequent measurements show the recovery of freshwater in the aquifer and how the saline water is gradually diluted or pushed out of the aquifer. Similarly the line parallel to the sea (L2) reveals almost the same result as the first line. However, in the second and third measurements, there were some significant variations which were contrary to the expectation that the freshwater may completely flush out the saline water from the aquifer. These two time series lines show that as the areas with the lowest resistivity (1 Ωm) shrink with time, the low resistivity (10 Ωm) tends to take over almost the entire area implying that the freshwater-saltwater equilibrium zone has already been altered. These results have clearly enhanced our current understanding and add more scientific weight to the theoretical assumptions on the effects of pumping on seawater intrusion and upconing.

Phosphorus Migration in an Unconfined Aquifer Using Modflow and Mt3dms

Abstract The rapid rate of urbanization and increasing demand for water in agriculture and industry are the reasons for considering groundwater as a main source of water. This can be a prologue to contamination of groundwater. Phosphorus as a type of nutrient that is derived from fertilizers has adverse effect on surface and subsurface water. The aim of this study was to monitor groundwater quality and the fate of contamination via three dimensional finite-different groundwater flow simulation (i.e. Visual MODFLOW version 4.2.). The study area was the campus of University Putra Malaysia. The monitoring indicated that the concentration of phosphorus is higher than those imposed by the standard of the Malaysian Department of Environment (DOE). Results of contamination transport modelling revealed the different rates of phosphorus transport in layers at the end of simulation period.

Performance of Real-Time Kinematic Global Positioning System and Automatic Level Surveying for Height Determination - A Comparison

The purpose of the research was to determinevertical accuracy of RTK-GPS in comparing with automaticlevel surveying procedure as has been applied in the vicinity of the University Putra Malaysia campus. A comparison of the differences between the two methods indicates 95% confidence accuracy. The results obtained by this experiment indicated an accuracy of 0-10 centimeters in the measurement of elevation by RTK-GPS system. The result of the present work also indicated that the RTK-GPS system might be very useful in surveying work as carried out by topographers, engineers, and surveyors etc.

Weathering Product of Granite as a Possible Source of Strategic Mineral

Several soil samples and granite bedrock samples from Cameron Highlands were analyzed for its elemental concentration using instrumental neutron activation analysis. A total of 34 elements were identified and their concentrations were determined in a single analytical session. Enrichment factor of elemental concentration in the top soil were computed. The findings indicate certain elements were enriched that may facilitates economic beneficiation.

Application of electrical resistivity imaging technique in slope stability study in Banding Island, Perak

A landslide investigation using 2D electrical resistivity imaging (ERI) has been undertaken in the Banding Island, Perak. Banding Island is underlain by Baling Formation which consist of two main facies; namely Argillaceous Facie (eastern part) and Arenaceous Facie (western part). The eastern part of the island is relatively prone to landslide and slope failure. Detailed field resistivity imaging was carried on four lines along the eastern and western parts of the Banding Island. The inferred lithological depth sections based on electrical properties clearly differentiates between the different types of rocks.