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.
The use of an artificial neural network (ANN) is becoming common due to its ability to analyse complex
nonlinear events. An ANN has a flexible, convenient and easy mathematical structure to identify the
nonlinear relationships between input and output data sets. This capability could efficiently be employed
for the different hydrological models such as rainfall-runoff models, which are inherently nonlinear in
nature and therefore, representing their physical characteristics is challenging. In this research, ANN
modelling is developed with the use of the MATLAB toolbox for predicting river stream flow coming
into the Ringlet reservoir in Cameron Highland, Malaysia. A back propagation algorithm is used to train
the ANN. The results indicate that the artificial neural network is a powerful tool in modelling rainfallrunoff.
The obtained results could help the water resource managers to operate the reservoir properly in
the case of extreme events such as flooding and drought.
Malaysia is a tropical country and it is subjected to flooding in both the urban and rural areas. Flood
modelling can help to reduce the impacts of flood hazard by taking extra precautions. HEC-RAS model was used to predict the flood levels at selected reach of the Langat River with a total length of 34.4 km. The Langat River is located in the state of Selangor, Malaysia and it is subjected to regular flooding. The selected reach of the Langat River has insufficient data and a methodology was proposed to overcome this particular problem. Since complete floodplain data for the area are not available, the modelling therefore assumed vertical walls at the left and right banks of the Langat River and all the predicted flood levels above the banks were based on this assumption. The HECRAS model was calibrated and the values of Manning’s coefficients of roughness for the Langat River were found to range from 0.04 to 0.10. The discharge values were calculated for 5, 10, 25, 50, and 100 year return periods and the maximum predicted flood depth ranged from 2.1m to 7.8m. Meanwhile, the model output was verified using the historical record and the error between the recorded and predicted water levels was found to range from 3% to 15%.
Branching channel flow refers to any side water withdrawals from rivers or main channels.
Branching channels have wide application in many practical projects, such as irrigation and drainage
network systems, water and waste water treatment plants, and many water resources projects. In the
last decades, extensive theoretical and experimental investigations of the branching open channels
have been carried out to understand the characteristics of this branching flow, varying from case
studies to theoretical and experimental investigations. The objectives of this paper are to review and
summarise the relevant literatures regarding branching channel flow. These literatures were reviewed
based on flow characteristics, physical characteristics, and modeling of the branching flow.
Investigations of the flow into branching channel show that the branching discharge depends on many
interlinked parameters. It increases with the decreasing of the main channel flow velocity and Froude
number at the upstream of the branch channel junction. Also it increases with the increasing of the
branch channel bed slope. In subcritical flow, water depth in the branch channel is always lower than
the main channel water depth. The flow diversion to the branch channel leads to an increase of water
depth at the downstream of the main channel. From the review, it is important to highlight that most
of the study concentrated on flow characteristics in a right angle branch channel with a rigid boundary.
Investigations on different branching angles with movable bed have still to be explored.
Tripoli coastal aquifer, Libya, which is located in a densely urbanised area, is the primary source of water supply in Tripoli city. In the last few decades and due to population growth, more than 100 wells have been drilled in Tripoli aquifer for the purpose of increasing pumping to meet demand on groundwater. The urbanisation at the Tripoli upper aquifer system has reduced the recharge rates and affected the groundwater storage. In this study, changes in groundwater dynamics in Tripoli’s unconfined aquifers were simulated using MODFLOW-2005 code. The model was calibrated and validated using measured and simulated values. Statistical tests such as coefficient of determination, R2 mean error, mean absolute error, and the root mean square error were computed and found to be 0.97, 0.31, 1.70 and 2.32 respectively. The simulation will assist in the assessment of the long term saline water intrusion. Calibrated transient groundwater flow models for the years 2020 – 2100 indicated that this case is likely to occur along pumping profiles with high pumping rates. Simulation results show that the groundwater levels will decline and exceed 12 m in the Southern area while in the Northern area near the coastal line, depletion is continuous and more than 70 wells will face saline water intrusion by the year 2100. Doubling the pumping rate from the wells will accelerate the drop in the groundwater levels and about 98% of the wells will be subjected to high salinity level by 2100. The salinity levels in these wells will make the groundwater unfit for human consumption.