Evaluation of yield and groundwater quality for selected wells in Malaysia

In Malaysia, the use of groundwater can help to meet the increasing water demand. The utilization of the aquifers is currently contributing in water supplies, particularly for the northern states. In this study, quantitative and qualitative assessments were carried out for the groundwater exploitation in the states of Kelantan, Melaka, Terengganu and Perak. The relevant data was acquired from the Department of Mineral and Geoscience, Malaysia. The quantitative assessment mainly included the determination of the use to yield ratio (UTY). The formula was proposed to determine the UTY ratio for aquifers in Malaysia. The proposed formula was applied to determine the maximum UTY ratios for the aquifers located in the states of Kelantan, Melaka, and Terengganu, and were found to be 4.2, 5.2 and 0.6, respectively. This indicated that exploitation of groundwater was beyond the safe limit in the states of Kelantan and Melaka. The qualitative assessment showed that the groundwater is slightly acidic. In addition, the concentrations of iron and manganese were found to be higher than the allowable limits, but the chloride concentration was found within the allowable limit

Empirical model simulating rainwater harvesting system in Tropical area

Rainwater harvesting is the technique of capturing the rainfall to meet some water needs in both urban and rural areas. The volume of rainwater collected from rainwater harvesting system varies from place to place and depends mainly on the climatic condition. Typically, the rainwater harvesting system is composed of the catchment (roof), gutter, rainwater pipe, and storage tank. Reliability of a rainwater harvesting system mainly depends on the collected volume in rainwater storage tank and it is also used to check whether the collected volume of rainwater can meet a specific water demand (either for potable or non-potable uses). In the present study, a rainwater harvesting system is installed at the Faculty of Engineering, University Putra Malaysia. The system is tested using data from 24 different rain events. The collected data includes rain depth and rainwater volume. It is found that the rainwater volume ranges form 0.027 m³ to 4.03 m³. The actual data is used to produce an empirical model for predicting the collected rainwater volume. Calibration and validation processes are conducted to the proposed model and T-test shows that the model prediction is within 95% level of confidence. Also, the water consumption for toilet flushing is monitored using water meter. Reliability of the installed rainwater harvesting system for toilet flushing is computed. It is found that the system reliability ranges from 26.61 % to 100 % depending on daily water demand and recorded rainwater depth

Impact of takeoff angle of bucket type energy dissipater on scour hole

Scour holes formed downstream of bucket type energy dissipater may affect the safety and stability of the structure. In this study, a physical model is employed to study the impact of takeoff angle of bucket type energy dissipater on the scour hole. The area of longitudinal profile of the scour hole is used to evaluate the seriousness of the scour at downstream of the bucket type energy dissipater. Experimental results showed that the takeoff angle of 45° is the optimum angle which gives minimum longitudinal area of the scour hole. Also, validation of selected equations for predicting maximum scour depth at downstream of the bucket type energy dissipater showed that the equation proposed by Schoklitsch gave minimum error (33%) [1]

Regime Hydraulic Concepts and Equations: The Case of Klang River, Malaysia

Updating and testing of available river regime relationships governing the various factors involved in alluvial river design are presented. Analysis of relevant laboratory and field data, gathered from four gauging stations along the water course of Klang River in Malaysia, were undertaken in order to formulate new regime concepts and equations characterizing the river. The functional formulations, to include the slope, rating and flow equations were achieved by employing dimensional analysis techniques relating the geometry and flow parameter

Checking the adequacy of rainwater harvesting system for housing and landscaping

Rainwater harvesting has been the main source of water supply for potable and non-potable uses in the old days because the water conveyance systems were not used for water distribution and the method used for rainwater harvesting was simple and primary (rainwater was mostly collected from roofs and some was collected directly from the sky). Usage of the collected water volume from rainwater harvesting was direct and without any treatment. Presently, the water supply systems have improved but the demand is increasing due to the population growth, and development. Rainwater can be used for potable and non-potable uses. The potable uses include drinking, cooking, bathing and washing. Usually, the rainwater used for this purpose must be treated to remove the contaminants. Non-potable uses include flushing toilets, watering garden and washing floor where treatment of rainwater is not required for these purposes. The volume of rainwater collected from rainwater harvesting system varies from place to place and depends on weather. In the present study, a rainwater harvesting system was installed in the Faculty of Engineering, University Putra Malaysia, Malaysia. The system is composed of the catchment (roof), gutter, pipe, steel tank and treatment unit. From 20 different rain events, the collected volume of the rainwater from different events ranges between 0.17 m3 and 2 m3. The daily water consumption is monitored for one month and compared with the collected rainwater volume. The volume of collected rainwater is found to be adequate to meet the non-potable uses. In a tropical country like Malaysia it is easy to collect 2 m3 in a single rain while 10 m3 is collected annually in Zambia, Africa from a roof of almost of the same size. The rainwater harvesting can be used for landscaping and the computation made to determine the volumes of yield and consumption shows that rainwater is also adequate to meet the requirement for landscaping in rainy months

Validation of some bridge pier scour formulae using field and laboratory data

Estimation of maximum local scour depth at the bride pier site is necessary for the safety and economy of the designed bridge. Numerous formulae are available and almost all of these formulae were developed based on laboratory data. Validation of these formulae is necessary in order to ascertain which of the formulae will give a reasonable estimate of the local scour depth. In this study, four commonly cited formulae were selected for the validation process using both the laboratory and field data. They were the Colorado State University (CSU), Melville and Sutherland, Jain and Fisher, and Laursen and Toch formula. The experimental data was obtained from the laboratory model study done at University Putra Malaysia, whilst the field data were obtained from 14 bridges sites. Three statistical tests were carried out to determine the formula that gives minimum prediction errors. Comparison between the predicted and measured depth of scour from the experimental and field data showed that the Laursen and Toch and the CSU formulae appeared to give a reasonable estimate. Whilst the Melville and Sutherland and Jain and Fisher formulae appeared to over-predict the depth of the scour. This observation was supported by the statistical tests

Electrocatalytic oxidation of ascorbic acid mediated by ZnO microcrystalline modified glassy carbon electrode.

Modification of a glassy carbon (GC) electrode surface by adhered microparticles of zinc oxide (ZnO) using electrochemical performance of microparticles of ZnO/GC electrode shows excellent electrocatalytic activity towards the oxidation of ascorbic acid in 0.1 M KH2PO4 electrolyte solution by cyclic voltammetry (CV). This paper seeks to critically examine the modification of GC electrode with Zinc oxide microparticles and the effect on oxidation of ascorbic acid using cyclic voltammetry technique. ZnO/GC electrode exhibited obvious enhancing and electrocatalyzing effect as it causes the oxidation current of ascorbic acid to increase by 1.5 times as compared to bare GC electrode. The sensitivity under conditions of cyclic voltammetry is significantly dependent on pH and ZnO dosage. The variation of scan rate study shows that the system undergoes diffusion-controlled process. Diffusion coefficient and rate constant of ascorbic acid were determined using hydrodynamic method (rotation disk electrode)with values of 5.4 x 10-6cm2s-1 and 2.5x 10-3cms-1 respectively for unmodified electrode, while the values of diffusion coefficient and rate constant of ascorbic acid using ZnO/GC electrode were 5.7 x10-6cm2s-1 and 2.1x10-3cms-1 respectively

Impacts of land use change on streamflows in the Damansara watershed, Malaysia.

Land-use change has significant impacts on hydrologic processes at the watershed level. In this study, hydrologic models and spatial data were used to assess the effects of land-use changes and predict the effects of two future land-use scenarios on the flood regime of the Damansara Watershed. Due to urban growth, the Damansara Watershed has seen increasing streamflows and experienced occasional flooding. The hydrology was modeled using the Hydrologic Engineering Center-Hydrologic Modeling System (HEC-HMS) model, and land-use changes were quantified with land-use maps. Actual storms were used to calibrate and validate HEC-HMS rainfall-runoff model. The calibrated HEC-HMS model was used to simulate future streamflows and to forecast the impact of land-use changes on downstream peak streamflow. The model also estimated the contribution of individual sub-basins to downstream peak streamflows of the entire watershed. The model predicts that changes in land-use will increase the peak streamflow, and the increase is directly proportional to the rate of urbanization. It was found that the sensitivity of the hydrologic response to land-use change increases as the recurrence interval of rainfall events decreases, and that those impacts are more pronounced in different sub-basins. The results of this study provide support for land-use planning and the management of watersheds

Evaluation of Some Proposed Methods for Protecting Bridge Substructure Using Physical Models

Bridges constructed across streams with erodable beds are normally subjected to serious scouring during the flood at piers and abutment sites. As a result, scour holes will be formed at the bridge substructure. The scour hole can be described by its maximum vertical scour depth which is called local scour depth and by the size of its projected scour area. Experience has shown that progressive depth of scour holes at the site of bridge substructures could undermine the foundation and result in bridge failure. Protection against scouring for constructed bridges is necessary to minimize the risk of failure. The formation of the scour hole at the bridge substructure is considered as very complex and this phenomenon is so involved that only very limited success has been made to predict the size of the scour hole computationally. Physical model remains the principal tool employed for estimating the size of scour hole at the site of bridge substructure. In this study, the efficiency of five different proposed methods of protecting the bridge substructure were tested using a physical model. These methods are piers with collar, pier with multiple collars, pier with slot, piles in front of piers, and using riprap. The physical model comprises a tilted flume (5 m long, 76 mm wide and 250 mm high) with sand on its bed (nominal size =0.35 mm) and a single circular cylindrical pier model which was made of hard teak wood (diameter =16 mm). A collar form steel with a diameter of 40 mm was attached to the pier model. A slot of a dimension 7 mm x 20 mm (width x depth) was opened in the upper side of the pier. Steel nails 3 mm in diameter each were used to simulate the piles. Coarse graded gravel was used as a riprap. Data collected from the physical model showed that using multiple collars around the pier can give 88% reduction in the scour area while the reduction in the maximum scour depth ranges from 73% to 64%, depending on the flow rate in the flume. It was observed that the riprap protection at the bridge substructure is also effective in reducing the maximum scour depth and reduction ranges from 100% to 68%. However, the reduction in the scour area ranges from 100% to 83%. The reduction was also dependent on the flow rate

A local scour prediction method for pile caps in complex piers

The outcomes of an experimental study on local scour at a pile cap are presented. Experiments were conducted with the approaching flow having an undisturbed flow depth and a threshold flow velocity. The main variables investigated were pile cap dimensions and location relative to the streambed. According to the rate of change in scour depth, the scour at a pile cap for different cap levels was divided into four cases. Equations for a correction factor for these four cases are derived. The correction factor Kc has the effect of reducing the scour depth from a corresponding full-depth pier of the same width as the pile cap. A new methodology is presented to estimate local scour depth at a pile cap as a component of a complex pier. The proposed method was evaluated with the results from this experimental study and historical measurements. The proposed method, which corresponds closely to the observations, can be used to predict local scour at a pile cap as a component of a complex pier in the superposition method. It is also applicable to the prediction of local scour due to a caisson being sunk onto a mobile bed in a current