Computational Assessment of Groundwater Potential of the Teluk Datuk – Olak Lempit Aquifer

Malaysia is endowed with abundant surface water resources. However, the distribution of the rainfall in time and space has resulted in limited availability of water of acceptable quantity and quality for domestic water use in some parts of the country. The purpose of this study was to determine areas of groundwater potential and to assess the amount of potentially available groundwater and its quality. It was envisioned that with the proposed development of the groundwater resource in the area, the available surface water and the additional groundwater would meet the domestic need of the people in the area. Several pumping tests were carried out by Geological Survey Department and Rintisan Sdn. Bhd. at Teluk Datuk - Olak Lempit aquifer. Results of the tests showed that the formation was proven to yield water of considerable quantity. THWells software was used to calculate the drawdown due to the combined effect of 2 and 4 discharge wells. The results showed that the drawdown could be as high as 18 m if pumping was carried out once a year at 5 MGD pumping rate. The drawdown would cause water from a river nearby to flow into the aquifer but would not affect the quality of well water. From the results of groundwater quality test, there were two parameters which were higher than the standards. The parameters were Ammonia Nitrogen and Chemical Oxygen Demand. The maximum length of saltwater intrusion was 1.185km when the nearest wellfield was about 14 to 15 km from the sea. This means the groundwater quality was not affected by the salt- water intrusion. A three-dimensional finite-difference groundwater flow code known as MODFLOW was used in this study. From the analysis, it could be deduced that the suitable rate of pumping for the study area was 25.5 MGD, which did not affect the surroundings including the Paya Indah wetland. If there was no recharge at all for the whole year, then the suitable rate of pumping was around 10 to 12 MGD only. With the development of this groundwater project, some of the water supply problems in the Klang Valley can be alleviated. The Teluk Datuk - Olak Lempit aquifer can be developed as a reliable alternative source of water supply

Effects of Soil Moisture Content on Groundwater Electrical Resistivity Values in Irrigation Paddy Scheme, Tanjong Karang, Malaysia

Electrical Resistivity Tomography (ERT) analyses have been conducted in Irrigation Paddy Scheme, Tanjong Karang, Malaysia as part of investigation on groundwater potential aquifer to provide an alternative water resource for paddy irrigation. Based on recent studies on groundwater resistivity in paddy field, irrigation system mentioned as soil moisture content was observed to affect the value of electrical resistivity and subsurface geological profile resulted from ERT analysis. The objective of this study was to proof any correlation between soil moisture content and electrical resistivity values and to determine at what level of soil moisture content which will be the best condition to conduct ERT survey. ERT analysis was conducted by using ABEM Terrameter SAS 4000 of Wenner-Schlumberger array with 5.0 meter and 10.0 meter for minimum and maximum electrode spacing. Visually, based on subsurface geological profile resulted from ERT analysis soil moisture content affected (changed) electrical resistivity values. With all different treatments of soil moisture ranged from 16.96% to 27.50%, electrical resistivity values decreased in certain points and in certain depth along with the increase of soil moisture content. This was proofed by ANOVA and Duncan’s multiple range tests showing that Pr > F value was less than 0.0001. Further on Chi-square test showed that at soil moisture level of 22.54%, it was the best condition which gave more correct counts of electrical resistivity values compared to well lithology. This was assumed to be the best condition to conduct ERT survey

Delineation of lithological formation in Bukit Merah, Semanggol, Perak using groundwater modelling

The knowledge of lithological formation is important to determine the potential aquifer for water resources management. This study aims to delineate the lithological formation of Bukit Merah, Semanggol using geological data. The preparation of lithological formation in the study was based on several factors such as electrical resistivity survey data, available well lithologies, geological map, and geological-related studies in the study area. The Electrical Resistivity Tomography (ERT) profile produced from the resistivity survey was interpreted based on previous studies to determine the subsurface materials on the location. The estimation of soil lithology for the remaining wells was done to generate the overall subsoil pattern in the study area. A total of 15 types of soil were classified to represent the actual lithology in the study area. The simplification of the actual lithology was carried out based on rocks and soils group. The elevation of the ground surface and each soil layer were imported into Visual MODFLOW software, then the interpolation of elevation points was done. Two interpolators; Kriging and Natural Neighbouring were used to generate ground surface and model layers similar to the topography in the study area. As a result, it has been identified that the study areas consist of 4 main layers of lithological formation which are unconsolidated deposit, sedimentary, metamorphic, and granite. The upper layer is dominated by unconsolidated with a maximum thickness of about 150 m in the coastal area. Hence, it is concluded that the unconsolidated deposit layer in Bukit Merah is highly potential with groundwater resources in the alluvium aquifer at the upper layer which has the potential to be developed for purpose of irrigation in a paddy field in the Kerian area

Analysis of tubewell performance as an evaluation of the physical aquifer model being developed

Physical aquifer model is used as a tool for further understanding of groundwater concept. Demonstration and observation activities on water level drawdown in the observation well, performance of pumping well, groundwater flow and solute transport of groundwater contamination can be carried out on this aquifer model. The objective of this study is to evaluate the physical aquifer model developed in the laboratory, used as a teaching tool and research material through the analysis of well performance. Well efficiency is an indicator in determination of the performance of pumping well developed in the aquifer model. Using stepdrawdown pumping test technique, the optimum pumping discharge rate for the pumping well is determined at 0.0612m3/hr and its efficiency is calculated to be 99%. This technical evaluation helps to study further of the aquifer hydraulic properties which accomplished on this artificial aquifer model

Development of geological structure of Selangor basin using borehole lithology information

The water shortage in Selangor Northwest Project rice granary areas has been growing concern. The increase in plant capacity and the El Nino phenomenon that hit Malaysia (1998 & 2016) has cause the main source of irrigation; surface water and rainfall, could no longer meet the needs of paddy. As a consequence, paddy productivity has becoming serious concern and urge for alternative irrigation water supply. At the same time, the use of groundwater as a source of alternative supply of irrigation water has started to get attentions. However, to determine the potential groundwater aquifer, preliminary study should be made in advance. Thus, the focus of this paper is to investigate the geological structure of the Selangor Basin by means analysis of borehole information. A total of 56 tube wells data were used to obtain layers of subsurface in the study area. By using groundwater modelling software (Visual MODFLOW), a model that represents an actual geological conditions has been made. A total of 6 subsurface layers have been identified. The result of study showed that, the geological formations of the study area mainly consist of three types; alluvium, sedimentary and metamorphic rock

Effects of soil moisture content on groundwater electrical resistivity values in irrigation paddy scheme, Tanjong Karang, Malaysia

Electrical Resistivity Tomography (ERT) analyses have been conducted in Irrigation Paddy Scheme, Tanjong Karang, Malaysia as part of investigation on groundwater potential aquifer to provide an alternative water resource for paddy irrigation. Based on recent studies on groundwater resistivity in paddy field, irrigation system mentioned as soil moisture content was observed to affect the value of electrical resistivity and subsurface geological profile resulted from ERT analysis. The objective of this study was to proof any correlation between soil moisture content and electrical resistivity values and to determine at what level of soil moisture content which will be the best condition to conduct ERT survey. ERT analysis was conducted by using ABEM Terrameter SAS 4000 of Wenner-Schlumberger array with 5.0 meter and 10.0 meter for minimum and maximum electrode spacing. Visually, based on subsurface geological profile resulted from ERT analysis soil moisture content affected (changed) electrical resistivity values. With all different treatments of soil moisture ranged from 16.96% to 27.50%, electrical resistivity values decreased in certain points and in certain depth along with the increase of soil moisture content. This was proofed by ANOVA and Duncan’s multiple range tests showing that Pr > F value was less than 0.0001. Further on Chi-square test showed that at soil moisture level of 22.54%, it was the best condition which gave more correct counts of electrical resistivity values compared to well lithology. This was assumed to be the best condition to conduct ERT survey

Performance evaluation and characteristics of selected tube wells in the Coastal Alluvium Aquifer, Selangor

Alluvial aquifers can be found in most of the coastal areas of Peninsular Malaysia. Seven tube wells located in such aquifers in the west coast of Selangor state had their performance evaluated by carrying-out step drawdown tests. The performance of these wells was evaluated in terms of aquifer loss, well loss, specific capacity and well efficiency. The aquifer loss coefficient and well loss coefficient were found to be in the range of 0.0198 hrm-2 to 0.4014 hrm-2 and from 0.0001 hr2m-5 to 0.0410 hr2m-5, respectively. The drawdown in tube wells TW1 and TW7 is mainly influenced by well loss component as compared to the aquifer loss component, while in tube wells TW2, TW3, TW4, and TW5, the drawdown is mainly influenced by aquifer loss component. The drawdown in tube well TW6 is influenced by aquifer loss component at a low discharge rate, but at high discharge rate, it is influenced by well loss component. The specific capacity and efficiency of the tested tube wells varied from 1.329 m2hr-1 to 40.166 m2hr-1, and from 11% to 96%, respectively. Tube wells TW2 and TW4 are categorized as high productive wells, while tube wells TW1, TW3, TW5 and TW7 are categorized as moderate productive wells and tube well TW6 as low productive well

Potential Dermal Exposure Assessment of Farmers to Herbicide Imazapic in an Agriculture Area

For decades, the percentage of pesticide usage has steadily increased in order to meet the demands of food production. The aim of this study is to estimate the risk posed towards farmers through exposure to surface water containing imazapic herbicide using dermal exposure assessment (DEA). For this purpose, hazard index (HI) value was calculated to estimate the risk posed towards the farmers. Although calculated HI showed a minimum level of risk, there are concerns toward the danger of long-term exposure to the farmers of an agricultural system that could affect their quality of life.Keywords: Dermal exposure assessment; farmers; imazapic; hazard indexeISSN 2398-4279 © 2018. The Authors. Published for AMER ABRA cE-Bs by e-International Publishing House, Ltd., UK. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer–review under responsibility of AMER (Association of Malaysian Environment-Behaviour Researchers), ABRA (Association of Behavioural Researchers on Asians) and cE-Bs (Centre for Environment-Behaviour Studies), Faculty of Architecture, Planning & Surveying, Universiti Teknologi MARA, Malaysia. https://doi.org/10.21834/ajqol.v3i11.127

Prediction of groundwater contaminants from cattle farm using Visual MODFLOW

Livestock operation activities such as cleaning operation, feeding, milking and manure disposal are potential sources of contaminants into nearby surface and groundwater. In this study, the number of wastes generated from a cattle farm in Ladang 16 UPM, Serdang Selangor was estimated. Two monitoring wells were constructed at the site for groundwater quality monitoring assessment. The concentration of pollutants such as Potassium, Nitrate, and Copper was used in the simulation as an initial waste state. The simulation was conducted using Visual MODFLOW Software to predict the contaminants in groundwater. The aim was to predict the concentration of the pollutants distributed in groundwater and surface water sources in 365 days. Results of MODFLOW simulation showed that the flow of groundwater was in the direction towards the pond. The concentrations of Potassium, Nitrate, and Copper were predicted to accumulate in the groundwater to the pond within a year but the values were still below the drinking water standard. The groundwater contaminants could be due to seepage from the manure storage basin through subsoil into the shallow aquifer

Improving irrigation water delivery performance of a large-scale rice irrigation scheme

The availability of irrigation water and its equitable allocation in a large-scale rice irrigation scheme of Malaysia have been modeled. The model reliably estimates available water for irrigation at the intake of the main canal and simulates the recommended irrigation deliveries for 120 tertiary canals. Different water allocation and management scenarios were evaluated based on the sensitivity of the growth stages of rice to water, varying field-water demand, and perceived water shortages. The model provides a quantitative assessment not only of water allocation for irrigation but also of day-to-day or periodic irrigation delivery performances for a large-scale rice irrigation system. It provides 86% adequacy and 87% equity of irrigation delivery in the main season (August-December). The corresponding performance indicators provided by the model are 74 and 89% in the off-season (February-June). The dependability of water supply is higher in the off-season than in the main season, while the relative water supply (RWS) is the converse. RWS often becomes >1.0 in the main season, while such a RWS is rarely obtained in the off-season. The model augments the water delivery performance of the scheme and hence would serve as a useful tool for irrigation managers in decision making