178 research outputs found
Water quality of Bakun Hydroelectric Dam Reservoir, Sarawak, Malaysia, during the construction of Murum dam / Lee Nyanti, Teck-Yee Ling and Theresa Muan
No full textSince Bakun Hydroelectric Reservoir was filled, there has not been any published literature on its water quality. A previous study conducted during its filling stage showed that the DO level dropped very rapidly and the water was
turbid. Since water quality was expected to improve over time, this study was carried out. Six stations and 3 depths at each station were investigated. Results show that dissolved oxygen at 0.5 m depth ranged from 6.25 to 7.02 mg/L but the water was anoxic at 15 m and 30 m depths. pH at 0.5 m depth in the reservoir ranged from 7.37 to 7.73 and decreased with depth to acidic condition. In the
reservoir, turbidity at the subsurface were 0 NTU but at 15 m depth, it ranged from 19.5-105.4 NTU. BOD5 were higher at 15 m and 30 m than 0.5 m depth. There was some improvement of water quality for stations in the reservoir compared to the previous study, especially in terms of pH and DO, but turbidity was still high at deeper regions. Stations in the Murum River and its downstream showed extremely high turbidity attributed to the construction of the Murum Dam. Thus, the river was not suitable for sensitive aquatic organisms
Water quality of rivers that flow into bakun hydroelectric dam reservoir, Sarawak, Malaysia / Teck-Yee Ling, Lee Nyanti and Annestasia Simbut John Masion
Get PDFAfter Bakun Dam was filled to its full supply level 2 years ago, little is known about the water quality of the rivers that flow into the reservoir. After the impoundment, sections of rivers of Batang Balui were submerged. Those rivers are still important for aquatic organisms and they will affect the reservoir water quality. A previous study showed that one of the rivers to the south of the dam has high dissolved oxygen and high turbidity which affected the turbidity in the reservoir. Therefore, the objective of this study was to determine the water quality of some of the other rivers. Results show that all the five rivers
are well-aerated with dissolved oxygen of above 7 mg/L. However, the Belepeh River had very high total suspended solids and turbidity when it was raining and it falls in Class III of INWQS. In contrast, turbidity values of the other four rivers complied with Class II standard. In terms of BOD5 when it rained, all the rivers fall in Class III except for the Bulo River which complied with Class II. There is a need to reduce the inflow of sediments into the Belepeh River to provide suitable environment for sensitive aquatic species
Water quality of rivers that flow into Bakun Hydroelectric Dam Reservor, Sarawak, Malaysia
No full textAfter Bakun Dam was filled to its full supply level 2 years ago, little is known about the water quality of the rivers that flow into the reservoir. After the impoundment, sections of rivers of Batang Balui were submerged. Those rivers are still important for aquatic organisms and they will affect the reservoir water quality. A previous study showed that one of the rivers to the south of the dam has high dissolved oxygen and high turbidity which affected the turbidity in the reservoir. Therefore, the objective of this study was to determine the water quality of some of the other rivers. Results show that all the five rivers are well-aerated with dissolved oxygen of above 7 mg/L. However, the Belepeh River had very high total suspended solids and turbidity when it was raining and it falls in Class III of INWQS. In contrast, turbidity values of the other four rivers complied with Class II standard. In terms of BOD5 Keywords: Balui RiverBelepeh RiverWat RiverNa RiverBulo River. , when it rained, all the rivers fall in Class III except for the Bulo River which complied with Class II. There is a need to reduce the inflow of sediments into the Belepeh River to provide suitable environment for sensitive aquatic species
Physicochemical parameters of Bakun reservoir in Belaga, Sarawak, Malaysia, 13 months after reaching full supply level
No full textDetermining the water quality of Bakun Reservoir 13 months after it operates at full supply level is crucial for better understanding of changes in the physicochemical parameters, which may enable the prediction of its effects on the survival of aquatic life in the reservoir. This study determined 13 physicochemical parameters at six stations within the reservoir at fixed depths. The results showed that the minimum 5 mg/L of dissolved oxygen (DO) required for sensitive aquatic organisms was recorded at 6 m depth. However, DO was not detectable at depths exceeding 7 m. The water was acidic at depths of more than 10 m. Turbidity and total suspended solids increased corresponding with depth. Inorganic nitrogen were predominantly in the form of ammonia-nitrogen, creating an unhealthy environment for aquatic life. Concentration of Chl-a was significantly higher at the subsurface water than 30 m depth in four out of six stations. The present study shows changes in water quality as compared to the pre-impounded period and 15 months after the filling phase, in particular, stratification of dissolved oxygen, thermocline conditions and alkalinity. The changes varied according to the distance from the dam and may have been influenced by existing land developments within the area such as the construction of the Murum Hydroelectric Dam, oil palm plantations and timber concessionares. Though the water quality might have deteriorated, further study is needed to determine if this condition will prolong
Assessment of water quality of Batang Rajang at Pelagus area, Sarawak, Malaysia
No full textThis study was carried out to examine the water quality of Batang Rajang at Pelagus area, Sarawak, Malaysia. Water
quality was determined at 12 stations along Batang Rajang and its tributaries in terms of in-situ and ex-situ water
quality parameters. The results showed that most stations at main river were categorized as slightly polluted while
most tributaries were clean according to the Water Quality Index. The river is suffering from organic pollution where
almost all stations along the river contained high chemical oxygen demand (? 43.1 mg/L) and total ammonia nitrogen
(? 0.520 mg/L) and were classified as Class III and IV at most of the stations. High suspended solids (218.3 mg/L) and
low dissolved oxygen (4.6 mg/L) were observed at the main river. The low dissolved oxygen content from the Bakun
dam upstream of the study area has an impact on the river particularly during dry season where DO dropped below the
minimum required for sensitive aquatic organisms. As seven tributaries are within Class II indicating healthy freshwater
ecosystems, they should be conserved as habitats for sensitive aquatic organisms. Conversely, proper management need
to be initiated in particular, Sungai Merit tributary and the main river where DO were below the minimum required for
sensitive aquatic organisms
Impact of different land uses on the Escherichia coli concentrations, physical and chemical water quality parameters in a tropical stream
No full textRural streams are important source of water for the nearby communities. However, bacterial contamination from agriculture and human settlement may render the water unsuitable for drinking and body contact recreation. Hence, the objective of this study was to determine the impact of different land uses such as animal farming and human settlement on E. coli concentrations in the Serin River, a tropical stream. Samplings were conducted at 9 stations from September 2009 to March 2010. Results showed that E. coli concentrations ranged from 2,000-6,900,000 CFU/100 mL with E. coli concentrations in fish aquaculture water exceeding the WHO standard. Animal and crop farming stations showed the highest E. coli concentrations in the tributaries. Re-suspension from stream sediment and non-point sources such as runoff contributed to the high concentrations observed in the main river. Multiple linear regressions indicated that total suspended solids and
dissolved oxygen were significant water quality parameters and they explained 68.1% of the total E. coli variations observed
Modeling Escherichia Coli Concentration in Surface Runoff: the ECOLI Model.
Get PDFA biological model, ECOLI, is developed that is capable of continuously simulating E. coli concentration in surface runoff from agricultural land applied with manure. The model was calibrated and validated by using data from field-scale studies at Franklinton, Louisiana. During validation the model was interfaced with GLEAMS-SWT model to obtain the necessary hydrologic and erosion variables as input to the ECOLI model. The ECOLI model was found to perform best when simulating runoff concentration following the first application of waste. For reapplication of waste within 50 days, the trend of decrease over time was well-simulated but simulated E. coli concentrations were lower than the observed concentrations. The correlation coefficient of the simulated E. coli concentration versus the observed concentration was found to be 0.85. The regression intercept is significantly different from zero. The regression slope is 1.06 and is not significantly different from 1.0. The ECOLI model is not recommended for reapplied waste until more research is done on the effect of applied waste on subsequent E. coli density and decay. The ECOLI model is also not recommended for use in simulating fecal coliform concentration unless methods of enumerating fecal coliforms that exclude false positive counts are used. Two experiments were carried out to investigate E. coli adsorption in soil-water system of Tangi Silt Loam and Commerce Clay Loam. The adsorption of E. coli in Tangi Silt Loam was found to be significantly lower than that of Commerce Clay Loam. The distribution coefficient of loose adsorption of E. coli in Tangi soil water system was found to be significantly lower than that of tight adsorption. The distribution coefficient of loose adsorption of E. coli in Commerce soil-water system was found to be significantly higher than that of tight adsorption. Soil with higher clay content was found to adsorb significantly more E. coli than soil with lowerer clay content. Together with literature data, a high correlation (R2 = 0.89) was found between adsorption and clay content. Significant correlation (R2 = 0.67) was found between distribution coefficient and clay content. The relationships developed may be used in modeling purposes
Residual Aluminium in Drinking Water Supplies In Relation To Peatland Catchment Areas In Mukah, Sarawak
Get PDFGrouted sleeve connections of circular hollow steel members under large deformation cyclic loading
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