[en] The application of environmental isotope as a tracer in water resources studies is presented. The main objectives of this paper are to investigate the distribution and origin of water resources involved in the study. Isotope technique is a useful tool in determining the groundwater recharge sources, ages of water bodies, interaction between surface water and groundwater, source of groundwater contamination, degree of mixing and for estimating subsurface residence time. The environmental isotopes, particularly stables isotopes of water (¹⁸O and ²H) are measured using Continuous Flow Isotope Ratio Mass Spectrometer (CF-IRMS). Oxygen and hydrogen isotope compositions are reported as delta (δ) and denoted as % or per mill, a variation which is relative to a known standard (Vienna Standard Mean Ocean Water, VSMOW). This study has successfully demonstrated the ability of isotope technique in delineating the water resources. The findings that are obtained from this study would greatly assist local water authorities or related agencies to manage their water resources for the socio-economic benefit of the region. (author)

No abstract available

[en] Timely water distribution is of prime importance to the MADA irrigation scheme especially during dry season planting. To measure the transit time for various sections of the water conduit. I-131 was employed. At low discharge (600 Cu sec), the water from Pedu took 45 hours to reach Pelubang, which is 67 km downstream. At Pelubang the conduit splits into two. A discharge of 400 Cu sec flows through the North canal and reaches the sea, 50 km downstream, after about another 134 hours. While during high discharge (4000 Cu sec), it took nearly 26 hours to reach Pelubang and another 32 hours to reach the sea. Though not carried out during the same period, with 1700 Cu sec of water discharge at Pelubang through South Canal, it took about 80 hours to reach secondary canal SCD1 (58 km downstream) that is at the end of the distribution line. Generally there is a decrease in speed as the water flows from Pedu Dam downstream. (Author)

[en] This paper described the preparation procedure of fluorescent sand tracer. The materials that used in this experiment were beach sand, Rhodamine-B, Araldite CY-245, hardener Hy-248, toluene and ethyl alcohol. Three solutions were prepared at certain formula i.e. solution A (Rhodamine-B + ethyl alcohol + toluene), solution B (Araldite + ethyl alcohol + toluene) and solution C (Hardener + ethyl alcohol + toluene) in order to produce the fluorescent sand. These solutions were mixed together with sand and blended slowly until the surface of the sand grain dried. Fluorescent monitor and UV cabinet viewer were used to measure and monitor the intensity of fluorescent sand. Results show that various intensity of fluorescent sand can be obtained depending on the formulation. Laboratory test has been carried out purposely to identify the suitable sand for the field test. (Author)

[en] Observations of salinity, temperature, suspended sediment concentration (SSC) and tidal current velocity were made in the lower and along the longitudinal axis of Sungai Selangor estuary over neap-spring cycles. The variations of these parameters at the measurement stations and along the channel are presented to illustrate the water and sediment dynamics in the estuary. The results shows that the Sungai Selangor estuary changes from a partially-mixed type during neaps to a well-mixed one during springs, promoted by stronger tidal energy during the higher tidal ranges. The strong neap density stratification is also promoted by the high river discharges during the measurement period. Maximum concentration of suspended sediment (> 2000 mg/l) occurs during maximum current velocities both during flood and ebb. The maximum salinity was achieved during high water slack but the salt water was totally flushed out of estuary during low water springs. The longitudinal axis measurement indicates that a partially-developed zone of turbidity maximum with a sediment concentration over 1000 mg/l was observed at the limit of salt water intrusion in salinity range less than 1 ppt. Tidal pumping as oppose to the estuarine circulation is the more dominant factor in the maximum formation as the salt water is totally excluded at low water. (Author)

[en] A study on the sediment size distribution and determination of sediment density profile in the selected area of Muda dam catchment area, Kedah is presented. The objective of the study was to establish a base line data of the input sedimentation with regards to the effects of development within the catchment in the future. Three main sampling locations were identified namely at Sungai Teliang, Sungai Muda and Muda reservoir. Measurement of sediment thickness was performed by using nuclear gauges i.e. direct transmission and backscattering methods. Results showed that the grain size distribution of sediment ranges from gravel to clay sizes. In the reservoir and downstream of the river, most of the samples studied consisting of fine sediment i.e silt and clay sizes (<63,um). However, sediment distribution in the upstream section of Sungai Teliang mainly consist of fine to coarse sand. Sediment density profiles in the reservoir showed little changes, whereas bed sediment profiles in the river cross-sectional areas exhibit some changes. The results also showed that thickness of bedload sediment were different from one location to another, in which the thickness may achieve up to 0.75 metre in some areas. Based on the sediment distribution profile analysis, the study site could be divided into two parts comprising of dynamic area (region) covering selected locations along the river and deposited sediment in the reservoir. Basic information derived from this study may provide as one of the important inputs for the MADA reservoir management authority in monitoring, supervising y and identifying rate and source of sediment in the catchment area

No abstract available

[en] The direct CO₂ absorption method is a fast and economical sample preparation compared to benzene synthesis for ¹⁴C dating in hydrological study. This paper explains sequentially the CO₂ extraction and absorption process using the setup line unit that was recently assembled in the Environmental Tracer Application Group (e-TAG) laboratory. The setup line unit comprises of two main sections, the CO₂ extraction unit and the CO₂ absorption unit. The CO₂ extraction unit comprises of three sub-sections, reaction unit, moisture trap unit and CO₂ storage unit. The CO₂ absorption unit includes three sub-sections, CO₂ storage, flow control and the absorption units. A vacuum pump unit is directly attached to the setup line to generate the required vacuum condition for the process (author)

[en] This study describes the development and experimental application of two types of suspended sediment gauges by using nuclear technique. A radioactive source Am-241 and radiation detecting system are used to measure suspended sediment concentration in this experiment. The distance between the radioactive source and detecting probe was set at 22.5 cm, while the diameter of the collimated source was 7.0 mm. From the experiment, the factor of measuring error has been analysed and a calibration curve of the count-rate and sediment concentration has been established. The range of measurement of the gauge is about 0 - 2.34 u g/cc, high enough for most equatorial stream flow. New suspended sediment gauge system also being proposed for shallow and deep water

No abstract available