GLOBAL TIMBER CONFERENCE 2017

The Conference

6 to 8 November 2017
Pullman , Kuching , Sarawak Malaysia

Innovation & Market Driven Strategies: Keys to Sustainable Growth 

Timber; flexible, structurally strong and being the lowest embodied carbon of any commercially available commodity; contributes $600 billion to the global economy and that translates to 1% of global total GDP. According to the World Bank’s forecast, the global demand for timber will quadruple by 2050. The market foresees major changes in the regional supply of and demand for wood fiber over the next two decades which will impact both international markets and other producers around the globe. 

Southeast Asia itself has extensive tropical hardwood resources and wood processing industries, and is a major supplier of hardwood logs and woodchips. It is also a primary supplier of pulp, plywood and furniture to the global markets. Given Southeast Asia’s key role in the global hardwood markets, trends occurring in this region disproportionately impact global trade flows. 

The second edition of the Global Timber Conference 2017 (GTC 2017) is once again back to gather 300 odd regional policy makers, experts and captains of the industry from over 20 countries in Sarawak; under the selected theme ‘Innovation & Market Driven Strategies: Keys to Sustainable Growth’ to discuss and deliberate on strategies in lifting the timber and timber-products industry.

For further information log on website :
http://globaltimberconference.com/

PANELS & FURNITURE : GROUP OF WOOD MAGAZINES

ABOUT US

Panels & Furniture Group is Asia’s premium business journal for the global timber industry. We cover current affairs and macro-economic trends in the sector in Southeast Asia, China, the Middle East and North Africa (MENA). With eyes on global market movements our analyses gives you an Asian perspective.

Our readership is made up of management-level executives from the regional solid wood, flooring, furniture, doors and windows, wood-based panels, and woodworking machinery sector.

Architects, builders, designers, and engineers will also find this an invaluable resource on timber as a material in building, construction and interior design.

Some of the topics we cover:

NEWS
Be informed on developments in the wood and wood-based products sector at a glance, including new appointments, market trends and statistics, product highlights, and newly commissioned projects.

PANELS and FURNITURE MANUFACTURING
Know about activities, latest techniques, acquisitions, business developments in the market place for panels and furniture production.

ENVIRONMENTAL FOCUS
Understand environmental issues such as sustainability, certification, legality, and government regulations in forestry around the world, and what it means for your business.

SOLID WOOD and ENGINEERED WOOD
Understand the business of logs and lumber, as essential for design, furniture and structural elements.

Engineered wood such as glue-laminated timber, laminated veneer lumber and cross-laminated timber are harnessed for its strength and durability as a structural element. Every issue, a column is dedicated to understanding how this product is developing in Asia.

INDUSTRY INSIGHT
Once in a while, we get good stuff from our connections with industry leaders. When they offer their experiences and expertise, it becomes precious insight which we share exclusively with you.

IN PERSON (Exclusive interviews)
We get up close and cosy with a key decision-maker or market mover, who share their thoughts and opinions.

THOUGHT LEADERSHIP

SURFACE & DESIGNContributing editor Kenn Busch scouts out the best and newest surfaces, materials and design.

GLOBAL WOOD RESOURCES 
Michael Hermens shares observations on what’s happening in the global timber trade.

WOOD CLINICMr Shim addresses readers’ common problems in furniture production.

MALAYSIAN MDF MANUFACTURERS’ ASSOCIATIONPeter Fitch, Chairman of the MMMA, checks in on what’s happening in the wood-based panel products sector in Southeast Asia.

EVENT PREVIEW and REVIEW
Trade fairs, open houses, conferences, roundtable talks, workshops, and seminars are excellent platforms for trade and networking. This section provides fast and easy updates on the panel and furniture industries’ major get-togethers.

For further information log on website :
http://www.panelsfurnitureasia.com/en/about-us

Airborne Fungi in Wood and Wood Based Board Factories

Author

Hüseyin Sivrikaya, Ömer Kara

First Published June 10, 2009 Others

Article Information

Volume: 18 issue: 3, page(s): 265-269

Article first published online: June 10, 2009;Issue published: June 1, 2009 

https://doi.org/10.1177/1420326X09103018

Hüseyin Sivrikaya

Bartin University, Department of Forest Products Engineering, h_sivrikaya@yahoo.com

Ömer Kara

Bartin University, Department of Forestry

Abstract

This study was a comparative investigation of the isolation and identification of airborne fungi between wood processing and melamine coated board processing factories. Isolation of airborne fungi was performed in four small sized enterprises engaged in wood processing and melamine coated board processing, located in the West Black Sea region of Turkey. Petri dishes containing Rose-Bengal streptomycin agar were exposed to air in the plants for 15 minutes. The highest fungal colony counts were observed in plant D, where the average value was 72 cfu per plate. Penicillium was the most widespread species identified in all the plants. Aspergillus fumigatus, which has major importance among the airborne fungi because it can cause health problems for workers, was only isolated in plant A.

For further details log on website :
http://journals.sagepub.com/doi/pdf/10.1177/1420326X09103018

Time-Resolved Optical Spectroscopy of Wood

Author

C. D'Andrea*, A. Farina, D. Comelli, ...

First Published May 1, 2008 Research Article

Article Information

Volume: 62 issue: 5, page(s): 569-574

Article first published online: May 1, 2008;Issue published: May 1, 2008
Received: September 06, 2007; Accepted: February 11, 2008

https://doi.org/10.1366/000370208784344424

C. D'Andrea*, A. Farina, D. Comelli, A. Pifferi, P. Taroni, G. Valentini, R. Cubeddu, L. Zoia, M. Orlandi, A. Kienle

CNR-INFM and CNR-IFN, Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy (C.D., A.F., D.C., A.P., P.T., G.V., R.C.); Università Milano-Bicocca, Dipartimento di Scienze dell'Ambiente e del Territorio, Piazza della Scienza 1, 20126 Milano, Italy (L.Z., M.O.); and Institut für Lasertechnologien in der Medizin und Meßtechnik, Helmholtzstr. 12, D-89081 Ulm, Germany (A.K.)

Corresponding Author: * Author to whom correspondence should be sent. E-mail: cosimo.dandrea@mail.polimi.it

Abstract

We have proposed and experimentally demonstrated that picosecond time-resolved optical spectroscopy in the visible/near-infrared (NIR) region (700–1040 nm) is a useful technique for noninvasive characterization of wood. This technique has been demonstrated on both softwood and hardwood samples treated in different ways simulating the aging process suffered by waterlogged woods. In all the cases, alterations of absorption and scattering spectra were observed, revealing changes of chemical and structural composition.

For further details log on website :
http://journals.sagepub.com/doi/pdf/10.1366/000370208784344424

Mechanical properties of some Swedish hard wood species

Author

S-I Gustafsson

First Published July 1, 2001 Research Article

Article Information

Volume: 215 issue: 3, page(s): 125-131

Issue published: July 1, 2001 

https://doi.org/10.1243/1464420011544969

S-I Gustafsson¹

¹IKP/Wood Science and Technology, Institute of Technology S581 83 Linkóping, Sweden

Abstract

A large part of Sweden is located within the Taiga Area and hence most of the wood species growing there are included in the division of Coniferales. This has also led to major research activities on the needle-leaved types in the Pinaceae family. There are, however, many broad-leaved trees, but because of their relatively low economic importance only a few researchers have had the opportunity to study such woods. For certain branches of the Swedish wood manufacturing industry the Angiosperms are of vital importance, e.g. the furniture factories. In this paper the mechanical properties of two Swedish hard wood genera, namely Betula and Alnus, are revealed. These findings are also compared with those found in the literature.

For further details log on website :
http://journals.sagepub.com/doi/pdf/10.1243/1464420011544969

Feasibility of Using Heat Treated Wood in Wood/Thermoplastic Composites

Author

Alireza Kaboorani, Mehdi Faezipour, Ghanbar Ebrahimi

First Published November 1, 2008 Research Article

Article Information

Volume: 27 issue: 16-17, page(s): 1689-1699

Article first published online: November 1, 2008;Issue published: November 1, 2008 

https://doi.org/10.1177/0731684407084207

Alireza Kaboorani

Department of Wood and Paper Technology, Faculty of Natural Recourses University of Tehran, Karaj, Iran, kaboorani@gmail.com

Mehdi Faezipour

Department of Wood and Paper Technology, Faculty of Natural Recourses University of Tehran, Karaj, Iran

Ghanbar Ebrahimi

Department of Wood and Paper Technology, Faculty of Natural Recourses University of Tehran, Karaj, Iran

Abstract

Using wood and other natural fibers with thermoplastic materials is always associated with a problem: poor compatibility between wood fibers and thermoplastic matrix. This paper deals with the mentioned problem and tries to solve, or at least ease, it through pre-heat treatment of woodprior to blending of wood fibers with other components of composites. In this study, wood pre-heat treated at different temperatures (175, 190 and 205°C) was used at various loadings (25 and 50%) with high density polyethylene (HDPE) and polypropylene-maleic anhydride copolymer (MAPP) to produce composites. The composite properties, including mechanical performance and morphological character, were investigated. The results of this study show that pre-heat treatment temperature and coupling agent content did not impact the composite properties at 25% woodcontent. Adding treated wood at 50% level to the composites enhanced the mechanical properties in comparison with untreated wood. The degree of the enhancement depended on pre-heat treatment temperature. Using wood treated at 190°C resulted in composites with the highest modulus of rupture (MOR) and tensile strength. In terms of modulus of elasticity (MOE), composites having wood treated at 205°C showed the highest MOE in both tensile and flexural tests. Adding 2% coupling agent caused an improvement in modulus of rupture (MOR) and tensile strength. An increase in wood content from 25 to 50% deceased strain at maximum load drastically. Morphological study showed that the mode of fracture is a function of wood and coupling agent content, and pre-heat treatment temperature.

For further details log on website :
http://journals.sagepub.com/doi/pdf/10.1177/0731684407084207

Seasonal Changes and Spatial Variation in Water Quality of a Large Young Tropical Reservoir and Its Downstream River

Journal of Chemistry
Volume 2017 (2017), Article ID 8153246, 16 pages
https://doi.org/10.1155/2017/8153246

Author

Teck-Yee Ling,1 Norliza Gerunsin,2 Chen-Lin Soo,1 Lee Nyanti,1 Siong-FongSim,1 and Jongkar Grinang3

1Faculty of Resource Science and Technology, Universiti Malaysia Sarawak, 94300 Kota Samarahan, Sarawak, Malaysia
2Universiti Teknologi MARA, Kota Samarahan Campus, Jalan Meranek, 94300 Kota Samarahan, Sarawak, Malaysia
3Institute of Biodiversity and Environmental Conservation, Universiti Malaysia Sarawak, 94300 Kota Samarahan, Sarawak, Malaysia

Correspondence should be addressed to Teck-Yee Ling

Received 18 January 2017; Revised 18 May 2017; Accepted 19 June 2017; Published 26 July 2017

Academic Editor: Wenshan Guo

Copyright © 2017 Teck-Yee Ling et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

This study examined the water quality of the large young tropical Bakun hydroelectric reservoir in Sarawak, Malaysia, and the influence of the outflow on the downstream river during wet and dry seasons. Water quality was determined at five stations in the reservoir at three different depths and one downstream station. The results show that seasons impacted the water quality of the Bakun Reservoir, particularly in the deeper water column. Significantly lower turbidity, SRP, and TP were found during the wet season. At 3–6 m, the oxygen content fell below 5 mg/L and hypoxia was also recorded. Low -N, -N, and SRP and high BOD5, OKN, and TP were observed in the reservoir indicating organic pollution. Active logging activities and the dam construction upstream resulted in water quality deterioration. The outflow decreased the temperature, DO, and pH and increased the turbidity and TSS downstream. Elevated organic matter and nutrients downstream are attributable to domestic discharge along the river. This study shows that the downstream river was affected by the discharge through the turbines, the spillway operations, and domestic waste. Therefore, all these factors should be taken into consideration in the downstream river management for the health of the aquatic organisms.

1. Introduction

The creation of a large-scale dam and its associated reservoir often has significant negative impacts on the hydrological, biological, and chemical processes of the reservoir, upstream, and downstream of the dam [1–9]. The Bakun hydroelectric dam, which was impounded from 2010 to 2012 on the Balui River in Malaysia, produced these effects. The dam which is one of the tallest concrete rock filled dams (205 m) in the world created a reservoir covering a surface area of 695 km2. A few pre- and postimpoundment studies on the physicochemical parameters of the Bakun Dam reservoir have been performed [10–12]. However, the reservoir water quality is likely changing as the reservoir is receiving loads of pollutants from adjacent anthropogenic activities during its operation [13, 14]. Water quality deterioration is a common problem in reservoirs surrounded with anthropogenic activities receiving high loads of suspended solids, organic matter, and nutrients [15, 16].

The water quality of reservoirs has been observed to vary seasonally in tandem with changes in temperature and rainfall [17–19]. The low and high precipitation during dry and wet seasons in a tropical country like Malaysia can greatly change the water quality of the reservoir. The high precipitation during the wet season can either decrease the pollutant concentration by dilution or deteriorate the reservoir water quality due to increased surface runoff from anthropogenic activities. Reference [20] demonstrated that the levels of total phosphorus in Batang Ai Reservoir during the rainy season and high water levels were lower than those observed during the dry season and low water levels. Besides, high volume of inflow following heavy rainfall promotes mixing and disturbs stratification in the reservoir. The increase of bottom dissolved oxygen level in the well-mixed reservoir inhibits the release of nutrients from sediments causing a rapid reduction of phytoplankton concentration in the reservoir [17].

On the other hand, the reservoir outflow has a great influence on the downstream river. Studies have shown that the downstream river is subjected to major environmental impacts which range from downstream morphology changes to loss of biodiversity of the ecosystem [1, 5, 7, 8, 21]. The reservoir outflow is often controlled by the electrical demand and operation cost, independent of ecological considerations in the downstream river. Differences in structure and operation scheme of a dam may result in differences in water quality downstream. Recently, [22] demonstrated that the physicochemical characteristics of the river downstream of the Bakun Dam changed when the spillway was opened.

As a young reservoir in a tropical country, changes continue to occur in the reservoir and it is important to monitor the water quality in order to evaluate its suitability for secondary purposes such as aquaculture and recreation. The knowledge of the seasonal variation of the reservoir’s water quality is important for dam operation and management decision. The impact of the dam on the water quality of its downstream river during the wet and dry seasons remains unknown. Hence, the aim of this study was to assess the water quality of the Bakun Reservoir and the influence of its outflow on the water quality of the downstream river during wet and dry seasons.

2. Materials and Methods

2.1. Study Area and Sampling Stations

The present study was conducted at Bakun Reservoir and its downstream river in Sarawak, Malaysia, as illustrated in Figure 1. The Bakun hydroelectric dam was built across the Batang Balui with a total of eight installed turbines and a spillway weir located at 209 m above sea level. The reservoir covers mainly the Balui River that is fed by three major tributaries, namely, the Murum River, Linau River, and Bahau River. A total of five stations were selected at the Bakun Reservoir and one station was selected at the downstream river. Stations 1 and 2 were located at the Batang Balui and Linau River, respectively. Stations 3 and 4 were located at the Murum River where the upstream Murum hydroelectric dam was under ongoing construction during the time of sampling. Station 5 was located in the proximity of the Bakun hydroelectric dam and downstream of active logging activities while Station 6 was located at the downstream river approximately 4.3 km from the dam.

Figure 1: The study area and sampling stations in the present study.

Sampling was conducted in February and September 2014 corresponding to the wet and dry seasons in Sarawak (Table 1). There was no rain recorded during the two and three weeks prior to the first and second samplings, respectively. The water level during the second sampling in the dry season was approximately 7 m lower than the water level during the wet season. The water release during hydropower generation is drawn from the top 10 m of the reservoir using selective withdrawal intake structures. Occasionally, additional water is released from the spillway with intake at a depth of approximately 15 m. At the end of the spillway, the water hits the concrete barrier before entering Balui River downstream. Sampling was conducted during electrical power generation where the downstream river received the water discharged from the reservoir after the water passed through the turbines. During the first sampling, additional water was discharged from the spillway at a rate of 501 m3/s in addition to the turbine outflow (536 m3/s). The spillway was closed during the second sampling; hence, Station 6 was receiving solely the turbine outflow at a rate of 730 m3/s.

Table 1: The details of the sampling location and sampling regime in the present study.

2.2. Field Collection and Laboratory Analysis

Depth profiles of temperature and dissolved oxygen (DO) were measured using a YSI 6820 V2 multiparameter water quality sonde during the first sampling in February 2014. The pH and turbidity were measured at 0 m, 10 m, and 20 m depths in Bakun Reservoir in both samplings by using a pH meter (EcoScan, Eutech) and a turbidity meter (Martini Instruments, Mi415), respectively. Triplicate water samples were collected at 0 m, 10 m, and 20 m depths in Bakun Reservoir (Stations 1 to 5) using a Van Dorn water sampler whereas triplicate water samples were collected at 0 m depth at the downstream river of the dam (Station 6). The depth of the reservoir was measured using a portable depth sounder (Speedtech). All sampling bottles were acid-washed, cleaned, and dried before use. Water samples were acidified to pH < 2 for total phosphorus (TP) analysis. All samples were placed in an ice box and transported to the laboratory for further analysis [23].

All the analyses were conducted according to standard methods [23, 24]. Chlorophyll a (Chl a) was determined from adequate samples filtered through 0.45 μm glass fiber filter (Whatman GF/F) and extracted for 24 h using 90% (v/v) acetone. The absorbance was read using a DR 2800 spectrophotometer and concentration of Chl a was calculated according to [25]. Total suspended solid (TSS) was calculated as the difference between the initial and final weights of the 0.45 μm glass fiber filter (Whatman GF/F), after filtration of an adequate sample volume and drying at 105°C. Five-day biochemical oxygen demand (BOD5) was determined as the difference between the initial and five-day DO content, after five-day-long incubation of the sample. The initial DO content was determined in the field and increased by vigorous aeration if the DO value was low. -N and -N levels were determined by the diazotization method (low range) and the cadmium reduction method, respectively, after filtering through a 0.45 μm glass fiber filter (Whatman GF/F). Organic Kjeldahl nitrogen (OKN) was determined by the Macro-Kjeldahl Method where ammonia was removed from the water sample before digestion and distillation, followed by Nessler’s method. SRP was determined by the colorimetric ascorbic acid method after filtering through a 0.45 μm glass fiber filter (Whatman GF/F). TP was determined by the ascorbic acid method after persulfate digestion of samples. The estimated detection limits of -N, -N, and SRP were 0.005 mg/L -N, 0.01 mg/L -N, and 0.02 mg/L , respectively.

Quality control steps were taken throughout the study. Sample bottles and glassware were washed using phosphate-free detergent followed by the standard acid wash procedure. Sample preparation and storage were performed according to the standard methods [23]. Triplicate blank water that was free of the analytes of interest was used in the same procedure for each of the aforementioned analyses.

2.3. Statistical Analysis

Comparison of water quality parameters between the stations and the depths in the Bakun hydroelectric reservoir was conducted using one-way ANOVA and Tukey’s pairwise comparisons with 5% significance level. Student’s -test was used to compare the water quality of the reservoir between the wet and dry seasons. Pearson’s correlation analysis was performed to determine the relationship among all the parameters in the reservoir during each season. The water quality of the downstream river between the wet and dry seasons and the results between the intake point of the dam and the downstream river were compared using Student’s -test. Cluster analysis (CA) was used to investigate the grouping of the sampling stations with different depths by using the water quality parameters collected in the reservoir and the downstream river. -score standardization of the variables and Ward’s method using Euclidean distances as a measure of similarity were used. All the statistical analyses were carried out by using the Statistical Package for the Social Sciences (SPSS Version 22, SPSS Inc., 1995).

3. Results and Discussion

3.1. Water Quality of Bakun Reservoir

Figure 2 illustrates the vertical stratification in Bakun Reservoir, indicating poor water mixing in the reservoir. Among the five sampling stations in the Bakun Reservoir, Station 2, which is located at Linau River, is stratified into three distinct layers of different temperatures. The thermocline layer observed at 3 m to 7 m separates the epilimnion (≈30.5°C) and hypolimnion (≈25.5°C) at Station 2. Similarly, [10, 11] reported that the thermocline started at a depth of 4-5 m and between 6 m and 9 m in Bakun Reservoir during the filling phase and 13 months after reaching the full-supply level, respectively. Thermal stratification in reservoirs has been widely reported in tropical and subtropical reservoirs [19, 26–28]. The temperature gradient within the thermocline layer in the Bakun Reservoir is in agreement with the range of thermal stratification of 0.5°C to 5°C for a tropical reservoir [29].

Figure 2: Depth profile of temperature and DO in Bakun Reservoir in February 2014.

Dissolved oxygen was relatively consistent in the surface water of the Bakun Reservoir, with a mean value of 7.22 mg/L. The DO level started to decrease rapidly from a depth of 2 m to less than 0.2 mg/L at a depth of 4 m at Station 1 which is located at Batang Balui. The DO level at Stations 2, 3, and 5 started to decrease rapidly from the depth of around 3 m whereas the DO level at Station 4 started to decrease from 5 m depth. In other words, the healthy level of DO content above 5 mg/L was only observed at the water column above 3–6 m in Bakun Reservoir. Similarly, [26] showed that oxygen depletion is a common phenomenon in the hypolimnia of Indonesian lakes and reservoirs with different oxycline depths. The authors attributed the shallow oxycline depth and thick anoxic layer in the Cirata Reservoir to the weak wind-induced mixing and high organic loads that lead to rapid decomposition and oxygen depletion in the reservoir. On the other hand, the DO concentration never fell below 2 mg/L in Qiandaohu Lake, China, where the DO depth profiles were closely linked to the water temperature depth profiles [19]. The decrease of DO with depth is commonly observed in reservoirs as photosynthesis increases oxygen level in the surface water while respiration of bacteria decomposing dead organic matter consumes all the dissolved oxygen in the bottom water column coupled with insufficient exchange with oxygenated surface water [30]. However, a slight increase of DO content was observed at the water column of the Bakun Reservoir between 12 m and 20 m which is most likely due to the additional water discharged from the spillway where the water intake was at a depth of approximately 15 m. The rapid water movement due to the additional water withdrawal at the particular water column promotes the mixing of the low DO water with a large volume of oxygenated colder water inflow from tributaries around the reservoir [14]. This phenomenon was not observed in the study in [11] where the DO content was reported as undetectable from a depth of 7 m up to a depth of 30 m as the reservoir water was not discharged from the spillway during this study.

The pH value of the Bakun Reservoir ranged from 4.93 ± 0.06 to 8.06 ± 0.05 during the wet season with the lowest and highest pH value being observed at Station 5 and Station 2, respectively. On the other hand, the pH value of the Bakun Reservoir is relatively consistent during the dry season with a mean value of 7.30. Vertical distribution of pH values in Bakun Reservoir differed between the wet and dry seasons although this was not significantly different (p value > 0.05) (Table 2). During the dry season, the pH value of the Bakun Reservoir decreased as depth increased up to a depth of 10 m and remained at a similar value up to a depth of 20 m as illustrated in Figure 3. The vertical distribution of pH values during the dry season in the present study is in good agreement with the previous study in the Bakun Reservoir [11] and the Batang Ai Reservoir [31] where the pH value of the reservoir water decreased as depth increased. However, the pH value tends to increase with depth when the surface pH value is low as demonstrated by Stations 3 and 5 during the wet season. The results showed that the low pH value at the surface water was diluted by the reservoir water with higher pH value as depth increased. The dilution in the water column improved the pH at Station 3 from 6.3 to 6.8. However, despite the dilution in the water column, Station 5, which was the closest station to the dam, still showed pH values of less than 6.5 mg/L. On the other hand, when the pH value was high (>7), the pH value decreased as depth increased which is similar to vertical pH distribution during the dry season. The surface pH value was classified as Class I but was changed to Class II as depth increased according to the National Water Quality Standard (NWQS) for Malaysia [32] during the dry season. During the wet season, the pH values of the Bakun Reservoir were classified as Class I except for Stations 3 and 5. The surface water at Station 3 was classified as Class II while the extremely low surface pH value of 4.9 at Station 5 exceeded the NWQS. Besides, the pH values at Station 5 at depths of 10 m and 20 m were classified as Classes II and III, respectively.

Table 2: Mean difference of water quality parameters of the Bakun Reservoir during the wet season and dry season conducted in February and September 2014, respectively ().

Figure 3: The distribution of pH and turbidity at three different depths (0, 10, and 20 m) of Bakun Reservoir in February (a) and September (b) 2014.

Table 3 shows that no significant correlation (p value > 0.05) was found between the pH value of the Bakun Reservoir and the other parameters during the wet season suggesting that the pH value of the Bakun Reservoir, particularly Stations 3 and 5, was mainly influenced by the low pH surface runoff from the anthropogenic activities in the surrounding area. Stations 3 and 5 were located downstream of the construction site of the Murum hydroelectric dam and active logging activities. The decomposition of organic matter derived from anthropogenic activity acidified the upstream rivers that flow into the reservoir and caused the acidification at the stations. On the other hand, during the dry season, the pH value of the Bakun Reservoir was significantly positively correlated with Chl a and SRP but negatively correlated with turbidity and TP (p value ≤ 0.05) as shown in Table 4. The relationship revealed that the pH value of the Bakun Reservoir was regulated by the process of photosynthesis and decomposition of organic matter in the reservoir during the dry season. Photosynthesis increases pH value in the surface water but the rate decreases with depth due to light limitation in the water column [33, 34].

Table 3: Correlation of water quality parameters of the Bakun Reservoir during the wet season ().

Table 4: Correlation of water quality parameters of the Bakun Reservoir during the dry season ().

The surface turbidity value of the Bakun Reservoir was low (<6 FNU) and increased significantly (p value ≤ 0.05) as depth increased at all stations which agrees with the previous study on the reservoir [10, 11]. The turbidity value increased up to 131.33 FNU and 263.67 FNU at a depth of 20 m during the wet season and dry season, respectively. The surface turbidity value in the Bakun Reservoir was classified as Class I during both trips except for Station 3 during the wet season which was classified as Class II. The turbidity value exceeded the NWQS as depth increased where the turbidity value was more than 50 FNU. The turbidity value was significantly higher (p value ≤ 0.05) at Stations 3 and 4 which are located at Murum River. Figure 3 illustrates that the turbidity value at Station 4 increased linearly during both trips while the turbidity value at Station 3 increased linearly during the wet season. The turbidity value at Station 3 increased up to 261.3 FNU at a depth of 10 m and became stagnant up to a depth of 20 m during the dry season. The significant positive correlation between turbidity and TSS (p value ≤ 0.05) suggested that the turbidity resulted from the suspended solids in the water column. The land clearing coupled with the construction at the upstream area of the Murum River accelerated the soil erosion and sedimentation and the resulting suspended solids were transported into the reservoir during surface runoff and were deposited at the bottom of the reservoir. The high turbidity value which increased with depth was most likely due to the settling and resuspension of settled solids. The turbidity value at Station 3 was recorded up to 1000 FNU at a depth of 15 m and 30 m in the year 2013 [13]. The present study did demonstrate an improvement in the water turbidity over time although the value still exceeded the standard. Turbidity was also significantly positively correlated with OKN (p value ≤ 0.05) during the dry season. Many pollutants are attaching to the particles; thus, an increase in particles in the reservoir results in an increase in OKN in the present study.

The surface Chl a concentration ranged from 0.62 ± 0.21 µg/L to 2.30 ± 0.81 µg/L and from 0.64 ± 0.02 µg/L to 5.87 ± 0.99 µg/L in the Bakun Reservoir during the wet and dry seasons, respectively. The vertical distribution of Chl a in the Bakun Reservoir shows that Chl a decreased with depth or remained at similar concentrations in the water column (Figure 4). Sufficient light availability on the surface water promoted the growth of phytoplankton leading to the highest concentration of Chl a in the surface water whereas light limitation as depth increased reduced the growth of the phytoplankton in the present study. However, in studies such as [27], the Chl a concentration exhibited a different trend where the Chl a concentration was the highest at a depth of 10 m compared to the surface water. The authors attributed this observation to the unfavorable high temperature and irradiance in the surface water for the phytoplankton. Nevertheless, the authors reported that the Chl a concentration was the lowest at a depth of 30 m due to the light limitation in the reservoir.

Figure 4: The distribution of Chl a, TSS, and BOD5 at three different depths (0, 10, and 20 m) of Bakun Reservoir in February (a) and September (b) 2014.

Previously, the highest concentration of 7.25 µg/L of Chl a was reported in the surface water of Bakun Reservoir [11] whereas the Chl a concentration was reported up to 4.58 mg/m3 [35] and 6.02 mg/m3 [28] in the surface water of the Batang Ai Reservoir. The high Chl a in the Batang Ai Reservoir was attributed to the cage culture activities in the reservoir [35] whereas the high Chl a concentration in the present study was most likely due to the nutrient availability from the anthropogenic activities in the adjacent area. In the present study, Chl a was significantly positively correlated with SRP during the dry season (p value ≤ 0.05). The positive correlation between Chl a and SRP reveals that the growth of phytoplankton in the Bakun Reservoir was not limited by the phosphorus.

All surface TSS values in Bakun Reservoir were classified as Class I which is less than 25 mg/L. The surface TSS concentration in the present study was lower than the previously reported surface TSS concentration (66.7–100.0 mg/L) in the year 2013 [11]. The improvement of TSS concentration demonstrated the settling of the suspended solids in the reservoir over time. The old Batang Ai Reservoir also contained low TSS values which are less than 25 mg/L even at a depth of 30 m [35]. The vertical distribution of TSS exhibited a similar trend with turbidity where the TSS value increased significantly (p value ≤ 0.05) as depth increased in the present study. Figure 4 shows that Station 3 contained the highest TSS concentration as depth increased during the dry season, followed by Station 4 where both stations were located at the Murum River. The extremely high TSS concentrations at Stations 3 and 4 revealed the impact of the land clearing and dam construction upstream of the river that carries eroded soil particles into the reservoir.

Surface BOD5 concentration at the Bakun Reservoir ranged from 3.24 ± 0.19 mg/L to 4.30 ± 0.15 mg/L and from 3.47 ± 0.06 mg/L to 4.43 ± 0.06 mg/L during the wet and dry seasons, respectively. Table 2 shows that Stations 3 and 5 often contained significantly higher BOD5 concentrations (p value ≤ 0.05) at the three different depths of the water column. The high BOD5 concentrations at the two stations downstream of the construction of the Murum hydroelectric dam and logging activities show organic matter loading from the anthropogenic activities into the reservoir. BOD5 concentrations decreased to a value of 2.23 mg/L at a depth of 20 m at Station 1, classified as Class II. Other than that, BOD5 concentrations in the Bakun Reservoir were classified as Class III. In contrast to the TSS concentration, the surface BOD5 concentration in the present study was higher than the surface BOD5 concentration (<2 mg/L) in the year 2013 [13]. The elevated BOD5 concentration in the reservoir indicates high loading and accumulation of organic matter in the Bakun Reservoir over time. However, the present surface BOD5 concentration was lower than the BOD5 concentration in the Batang Ai Reservoir where up to 12 mg/L of BOD5 concentration was reported [35].

The -N concentration was low in the Bakun Reservoir. The surface -N concentrations were not significantly different (p value > 0.05) among the stations during the wet season with a mean of 0.003 mg/L. During the dry season, the highest value of surface -N was observed at Station 4 (0.008 ± 0.001 mg/L) followed by Station 3 (0.007 ± 0.001 mg/L) which were significantly higher (p value ≤ 0.05) than other stations (≈0.002 mg/L). Similarly, the surface -N concentration was generally low in the Bakun Reservoir, ranging from 0.014 ± 0.006 mg/L to 0.037 ± 0.001 mg/L during the wet season. The mean concentration of surface -N in the Bakun Reservoir during the dry season was 0.008 mg/L except at Station 4 which exhibited a peak of 0.022 ± 0.011 mg/L. The highest concentrations of -N in the reservoir were observed at Station 2 at a depth of 20 m (0.050 mg/L) and Station 4 (0.059 mg/L) during the wet and dry seasons, respectively. Comparisons of the results with NWQS indicated that -N and -N in the Bakun Reservoir were classified as Class I. Surface OKN concentrations of the Bakun Reservoir ranged from 0.32 ± 0.01 mg/L to 0.42 ± 0.01 mg/L and from 0.29 ± 0.01 mg/L to 0.35 ± 0.01 mg/L during the wet and dry seasons, respectively. Significantly high concentrations of OKN (p value ≤ 0.05) were observed at Stations 4 and 5 during the wet and dry seasons which are predominantly from the surface runoff from the anthropogenic activities as mentioned above. Similar to the BOD5 concentration, no obvious trend was observed in the vertical distribution of OKN concentrations in the Bakun Reservoir (Figure 5).

Figure 5: The distribution of -N, -N, and OKN at three different depths (0, 10, and 20 m) of Bakun Reservoir in February (a) and September (b) 2014.

The -N concentration in the present study is within the range of -N (0.0003–0.0083 mg/L) reported in the year 2013 [11] and lower than the -N concentration (0.001–0.053 mg/L) in the Batang Ai Reservoir [35]. On the other hand, the -N concentration in the present study is within the range of -N (0.01–0.06 mg/L) in the Batang Ai Reservoir [35] but the -N concentrations in Station 2 during the wet season and Station 4 during the dry season were higher than the range of -N (0.003–0.027 mg/L) reported in the Bakun Reservoir in the year 2013 [11]. -N was significantly positively correlated with TP and BOD5 (p value ≤ 0.05), and OKN was significantly positively correlated with -N (p value ≤ 0.05) during the wet season. The relationship indicated the active decomposition and nitrification process in the reservoir. The relatively higher -N concentration in the reservoir compared to the year 2013 indicated that nitrogen in the reservoir is being converted to -N which is less toxic to aquatic organisms in the reservoir.

The concentration of SRP was low and relatively consistent in the Bakun Reservoir during the wet season with a mean value of 8.6 µg/L. The highest concentration of SRP (13.2 µg/L) was observed at Station 1 at a depth of 20 m. The SRP concentration was significantly higher during the dry season in the Bakun Reservoir (p value ≤ 0.05) with a mean value of 37.9 µg/L. The lowest and the highest concentrations of surface SRP were observed at Station 4 (17.4 ± 1.8 µg/L) and Station 5 (107.5 ± 3.1 µg/L), respectively, and significantly differed (p value ≤ 0.05) from other stations in the reservoir. Figure 6 illustrates that most stations in the Bakun Reservoir exhibited similar vertical distributions of SRP concentration during the dry season except for Station 4. The SRP concentration significantly decreased (p value ≤ 0.05) as depth increased in the Bakun Reservoir except at Station 4 where the surface SRP concentration was significantly lower (p value ≤ 0.05) than the SRP concentration at depths of 10 m and 20 m. Reference [26] reported that phosphate was lower in hypolimnion (>2.5 µM) compared to the surface water (0.05–0.23 µM) in the Cirata Reservoir which could be caused by enhanced loading from the sediment in the anoxic condition. The SRP concentration in the present study was lower than the SRP concentration in the year 2013 where the highest SRP concentration was 652.2 µg/L [11].

Figure 6: The distribution of SRP and TP at three different depths (0, 10, and 20 m) of Bakun Reservoir in February (a) and September (b) 2014.

Surface TP of the Bakun Reservoir ranged from 78.2 ± 3.6 µg/L to 136.9 ± 9.6 µg/L and from 135.6 ± 19.3 µg/L to 244.9 ± 11.1 µg/L during the wet and dry seasons, respectively. Similar to the SRP, TP concentration was significantly higher during the dry season (p value ≤ 0.05) in the Bakun Reservoir. This shows that high precipitation during the wet season and the elevated reservoir water volume diluted both SRP and TP substantially in the reservoir. A similar observation where TP showed lower concentrations during the rainy season and high water level (24.90–38.59 µg/L) than the dry season and low water level (45.94–67.28 µg/L) was reported in the Batang Ai Reservoir [20]. The present TP concentration in the Bakun Reservoir was higher than the TP concentration in the Batang Ai Reservoir during both seasons. Figure 6 illustrates that the vertical distribution of TP concentration is relatively consistent in the Bakun Reservoir but shows an opposite trend between the wet and dry seasons. The TP concentration was the lowest at the depth of 10 m during the wet season but became the highest during the dry season. Station 3 contained significantly higher TP concentrations at 0 m, 10 m, and 20 m (p value ≤ 0.05) in the reservoir during the wet season, suggesting that the phosphorus originates from the surface runoff from the Murum Dam construction. The intensity of the impact increased substantially during the wet season as more phosphorus is washed down into the reservoir. In the present study, SRP concentrations complied with the 200 µg/L standard in accordance with the NWQS [32] during both trips. The TP concentration complied with the NWQS during the wet season but was noncompliant with the standard when the TP concentration increased substantially during the dry season.

3.2. Water Quality of the Downstream River of the Bakun Hydroelectric Dam

Table 5 summarizes the in situ and ex situ water quality of the downstream river of the Bakun Dam during the wet and dry seasons. The result demonstrated that the reservoir water has altered the surface water temperature of the downstream river. When the cooler reservoir water at a depth of 10 m is released into the downstream river, it decreased approximately 4°C to 5°C of the surface water temperature of its downstream river. The mean value of DO in the downstream river was 9.40 mg/L and 2.59 mg/L during the wet and dry seasons and was classified as Class I and Class IV, respectively. Both DO values in the downstream river were higher than the DO value of the reservoir water at a depth of 10 m (<1 mg/L), particularly the DO content during the wet season because the spillway of the dam was open and additional water was discharged from the spillway during the sampling. The strong water current from the spillway coupled with the water flow from the turbines promotes aeration and increases the DO content substantially. On the other hand, the DO content was low when the spillway was not open during the sampling in the dry season. When the oxygen-deprived reservoir water was released into the downstream river without additional aeration, it decreased the oxygen level of the downstream river below the minimum requirement of 5 mg/L for sensitive aquatic organisms.

Table 5: Summary of the mean and standard deviation of the in situ and ex situ water quality parameters in the downstream river of the Bakun Dam (Station 6) and the mean difference of the parameters between the wet and dry seasons ().

Low pH values (≈6.1) were observed at the downstream river and classified as Class II according to NWQS [32]. Table 6 shows that there was no significant difference in pH value between Station 6 and the dam intake point at 10 m for both seasons (p value > 0.05) revealing that the low pH in the downstream river is due to the low pH of the reservoir water that was released into the downstream river after passing through the turbines. The pH value of the downstream river was relatively lower than the pH value of tributaries that flow into the Bakun Reservoir (6.8–7.8) [14]. The turbidity value in the downstream river of the dam was high and exceeded the standard guideline of 50 FNU in Malaysia [32]. The turbidity values were also significantly higher (p value > 0.05) than the reservoir water during both seasons. When water is discharged from the spillway in addition to turbine outflow, resuspension of deposited sediments under the high flow rate increases the suspended solids downstream. The turbidity value (77.00 ± 1.00 FNU) during the wet season was significantly lower (p value > 0.05) than the dry season (113.67 ± 0.58 FNU) which is most probably due to more dilution from the tributaries along the downstream river during the wet season. Similar to the turbidity value, the TSS concentration during the wet season was significantly lower than the dry season (p value ≤ 0.05) and was classified as Class II and Class III, respectively. Both values were also significantly higher than the TSS concentration (p value ≤ 0.05) at the intake point.

Table 6: Mean difference of in situ and ex situ water quality parameters between the intake point of the dam at 10 m (Station 5) and its downstream river (Station 6) during wet and dry seasons ().

There was no significant difference in Chl a between the wet and dry seasons (p value > 0.05) in the downstream river with a mean value of 0.58 µg/L. The Chl a concentration was significantly higher (p value ≤ 0.05) than the intake point during the wet season but it was similar to the Chl a concentration at surface reservoir water (0.64 µg/L). There was no significant difference in Chl a between downstream river and the intake point (p value > 0.05) during the dry season. The mean value of BOD5 in the downstream river was 5.70 mg/L and 3.10 mg/L during the wet and dry seasons and was classified as Class III. The BOD5 concentration during the wet season was significantly higher than the dry season (p value ≤ 0.05). Besides, the downstream BOD5 concentration was significantly higher than the BOD5 concentration at the intake point (p value ≤ 0.05) during the wet season whereas the BOD5 concentration was significantly lower than the BOD5 concentration at the intake point (p value ≤ 0.05) during the dry season. The higher downstream BOD5 concentration during the wet season indicates that the high BOD5 concentration is most likely attributed to other domestic discharge and runoff in addition to the reservoir water. Several longhouses and villages located along the downstream river may have contributed substantial organic matter to the downstream river.

-N and -N concentrations were also low in the downstream river, similar to the reservoir water, and were classified as Class I according to NWQS [32]. Significantly higher -N concentration (p value ≤ 0.05) was found during the wet season whereas no significant difference of -N concentration was found between the wet and dry seasons (p value > 0.05). The downstream -N concentration was also significantly higher than the reservoir -N concentration at the intake point. There was no significant difference in OKN between the wet and dry seasons (p value > 0.05) in the downstream river with a mean value of 0.39 mg/L. OKN was significantly higher (p value ≤ 0.05) at the downstream river than the OKN concentration at intake point. The higher downstream -N and OKN concentrations besides BOD5demonstrated the organic pollutant contribution from adjacent domestic discharge and runoff in the downstream river.

SRP and TP concentrations in the downstream river exhibited a similar trend where the concentration during the wet season was significantly lower than during the dry season (p value ≤ 0.05). The downstream SRP concentration complied with the 200 µg/L standard in accordance with the NWQS [32] in both trips. On the other hand, the downstream TP concentration also complied with the NWQS during the wet season but changed to noncompliance with the standard when the TP concentration increased substantially during the dry season. The TP concentration was found to be significantly higher (p value ≤ 0.05) at the downstream river than the TP concentration at the intake point. The high TP and low SRP concentration indicate that phosphorus concentration mainly consisted of organic phosphorus in the present study. The higher downstream TP concentration further confirms the organic pollutant contribution from the adjacent domestic discharge.

3.3. Cluster Analysis

Figure 7 demonstrates that the water quality in the reservoir can be grouped into three clusters according to the season and the water depth of the reservoir. Cluster 1 and Cluster 2 are mostly made up of sampling stations at depths of 10 m and 20 m conducted during the dry season and wet season, respectively, indicating that the dry and wet seasons have an influence on the deeper water column of the reservoir. The surface water quality of the downstream river during the dry (Case32) and wet (Case16) seasons was also grouped to Clusters 1 and 2, respectively, as it was influenced by the deeper reservoir water discharged into the river. On the other hand, surface water quality of the reservoir except at Station 5 (Case13) during the wet season was not influenced by the season where the surface water quality of the Bakun Reservoir during both seasons was categorized as Cluster 3. This phenomenon is the most apparent based on the turbidity and TSS in the reservoir. The surface turbidity and TSS values during the wet and dry seasons were relatively similar with a mean value of 3.02 FNU and 3.66 FNU and 9.0 mg/L and 8.1 mg/L, respectively, but the turbidity (76.02 FNU versus 133.65 FNU) and TSS (60.7 mg/L versus 125.5 mg/L) values at a depth of 20 m during the wet season were around two times lower than during the dry season.

Figure 7: Clusters of the five sampling stations located in Bakun Reservoir at three different depths (0 m, 10 m, and 20 m) and one station located at its downstream river collected at 0 m during dry and wet seasons in Sarawak, Malaysia.

4. Conclusions

The Bakun hydroelectric reservoir is a thermally stratified reservoir with a temperature gradient of approximately 5°C within the thermocline layer. The thickness of the well oxygenated water was around 3–6 m of the surface water, whereas the oxygen content of most of the water body was below 5 mg/L or even in hypoxia. The Bakun Reservoir showed signs of organic pollution with high BOD5, OKN, and TP concentrations observed in the reservoir. Acidification was observed in parts of the reservoir, particularly downstream of active logging activities and the Murum hydroelectric dam construction during the wet season. The water quality of the reservoir was influenced by the wet and dry seasons particularly in the deeper water column. SRP and TP concentrations were discovered to be higher during the dry season in the reservoir. This result suggests the necessity of management and conservation of the reservoir to prevent further deterioration in the reservoir’s water quality where different water quality parameters should be targeted during different seasons. The present study also demonstrated that the water discharged from the Bakun Reservoir has a great impact on the water quality at the downstream river. The water released from the reservoir decreased the temperature, DO, and pH of the downstream river whereas turbidity and TSS concentration increased in the downstream river. Nevertheless, the water quality of the downstream river, particularly BOD5, OKN, and TP concentrations, was also influenced by adjacent anthropogenic activities such as household wastewater. This result suggests that the downstream river of the Bakun Reservoir was not solely impacted by the reservoir’s outflow. Therefore, all factors should be taken into account in decision-making of the management of the downstream river for the health of sensitive aquatic organisms.

Conflicts of Interest

The authors declare that there are no conflicts of interest regarding the publication of this paper.

Acknowledgments

The authors appreciate the financial support provided by the Malaysian Ministry of Higher Education through Grant no. FRGS/STWN01(04)/991/2013(32) and the facilities provided by Universiti Malaysia Sarawak.

References

1. M. W. Beck, A. H. Claassen, and P. J. Hundt, “Environmental and livelihood impacts of dams: common lessons across development gradients that challenge sustainability,” International Journal of River Basin Management, vol. 10, no. 1, pp. 73–92, 2012. View at Publisher · View at Google Scholar · View at Scopus
2. X. Li, S. Dong, Q. Zhao, and S. Liu, “Impacts of Manwan Dam construction on aquatic habitat and community in Middle Reach of Lancang River,” Procedia Environmental Sciences, vol. 2, no. 5, pp. 706–712, 2010. View at Publisher · View at Google Scholar
3. J. Li, S. Dong, S. Liu, Z. Yang, M. Peng, and C. Zhao, “Effects of cascading hydropower dams on the composition, biomass and biological integrity of phytoplankton assemblages in the middle Lancang-Mekong River,” Ecological Engineering, vol. 60, pp. 316–324, 2013. View at Publisher · View at Google Scholar · View at Scopus
4. D. D. A. Cunha and L. V. Ferreira, “Impacts of the Belo Monte hydroelectric dam construction on pioneer vegetation formations along the Xingu River, Pará State, Brazil,” Revista Brasileira de Botanica, vol. 35, no. 2, pp. 159–167, 2012. View at Google Scholar · View at Scopus
5. Q. G. Wang, Y. H. Du, Y. Su, and K. Q. Chen, “Environmental impact post-assessment of dam and reservoir projects: a review,” Procedia Environmental Sciences, vol. 13, pp. 1439–1443, 2012. View at Publisher · View at Google Scholar
6. G. L. Wei, Z. F. Yang, B. S. Cui et al., “Impact of dam construction on water quality and water self-purification capacity of the Lancang River, China,” Water Resources Management, vol. 23, no. 9, pp. 1763–1780, 2009. View at Publisher · View at Google Scholar · View at Scopus
7. Y. Yi, Z. Yang, and S. Zhang, “Ecological influence of dam construction and river-lake connectivity on migration fish habitat in the Yangtze River basin, China,” Procedia Environmental Sciences, vol. 2, no. 5, pp. 1942–1954, 2010. View at Publisher · View at Google Scholar
8. Q. Lin, “Influence of dams on river ecosystem and its countermeasures,” Journal of Water Resource and Protection, vol. 03, no. 01, pp. 60–66, 2011. View at Publisher · View at Google Scholar
9. W. L. Graf, “Downstream hydrologic and geomorphic effects of large dams on American rivers,” Geomorphology, vol. 79, no. 3-4, pp. 336–360, 2006. View at Publisher · View at Google Scholar · View at Scopus
10. L. Nyanti, T. Y. Ling, and J. Grinang, “Physico-chemical characteristics in the filling phase of Bakun hydroelectric reservoir,” vol. 2, pp. 92–101, Sarawak, Malaysia, 2012.
11. T.-Y. Ling, L. Nyanti, T. Muan, J. Grinang, S.-F. Sim, and A. Mujahid, “Physicochemical parameters of Bakun Reservoir in Belaga, Sarawak, Malaysia, 13 months after reaching full supply level,” Sains Malaysiana, vol. 45, no. 2, pp. 157–166, 2016. View at Google Scholar · View at Scopus
12. S. F. Sim, T. Y. Ling, L. Nyanti, N. Gerunsin, Y. E. Wong, and L. P. Kho, “Assessment of heavy metals in water, sediment, and fishes of a large tropical hydroelectric dam in Sarawak, Malaysia,” Journal of Chemistry, vol. 2016, Article ID 8923183, 10 pages, 2016. View at Publisher · View at Google Scholar
13. L. Nyanti, T. Y. Ling, and T. Muan, “Water quality of Bakun hydroelectric dam reservoir, the construction of Murum dam,” ESTEEM Academic Journal, vol. 11, no. 1, pp. 81–88, 2015. View at Google Scholar
14. T. Y. Ling, L. Nyanti, and A. S. Masion, “Water quality of rivers that flow into Bakun hydroelectric dam reservoir, Sarawak, Malaysia,” ESTEEM Academic Journal, vol. 11, no. 1, pp. 9–16, 2015. View at Google Scholar
15. V. Rossel and A. de la Fuente, “Assessing the link between environmental flow, hydropeaking operation and water quality of reservoirs,” Ecological Engineering, vol. 85, pp. 26–38, 2015. View at Publisher · View at Google Scholar · View at Scopus
16. T. da Costa Lobato, R. A. Hauser-Davis, T. F. de Oliveira et al., “Categorization of the trophic status of a hydroelectric power plant reservoir in the Brazilian Amazon by statistical analyses and fuzzy approaches,” Science of the Total Environment, vol. 506-507, pp. 613–620, 2015. View at Publisher · View at Google Scholar · View at Scopus
17. X. Li, T. Huang, W. Ma, X. Sun, and H. Zhang, “Effects of rainfall patterns on water quality in a stratified reservoir subject to eutrophication: Implications for management,” Science of the Total Environment, vol. 521-522, pp. 27–36, 2015. View at Publisher · View at Google Scholar · View at Scopus
18. M. Varol, B. Gökot, A. Bekleyen, and B. Şen, “Spatial and temporal variations in surface water quality of the dam reservoirs in the Tigris River basin, Turkey,” Catena, vol. 92, pp. 11–21, 2012. View at Publisher ·View at Google Scholar · View at Scopus
19. Y. Zhang, Z. Wu, M. Liu et al., “Dissolved oxygen stratification and response to thermal structure and long-term climate change in a large and deep subtropical reservoir (Lake Qiandaohu, China),” Water Research, vol. 75, pp. 249–258, 2015. View at Publisher · View at Google Scholar · View at Scopus
20. T. Y. Ling, T. Z. E. Lee, and L. Nyanti, “Phosphorus in batang ai hydroelectric dam Reservoir, Sarawak, Malaysia,” World Applied Sciences Journal, vol. 28, no. 10, pp. 1348–1354, 2013. View at Publisher · View at Google Scholar · View at Scopus
21. P. McCully, “Rivers no more: the environmental effects of dams,” in Silenced Rivers: The Ecology and Politics of Large Dams, P. McCully, Ed., pp. 29–64, Zed Books, London, UK, 1996. View at Google Scholar
22. T.-Y. Ling, C.-L. Soo, T. L.-E. Heng, L. Nyanti, S.-F. Sim, and J. Grinang, “Physicochemical characteristics of river water downstream of a large tropical hydroelectric dam,” Journal of Chemistry, vol. 2016, Article ID 7895234, 2016. View at Publisher · View at Google Scholar · View at Scopus
23. D. Jenkins, J. J. Connors, and A. E. Greenberg, Standard Methods for the Examination of Water and Wastewater, American Public Health Association, Washington, Wash, D.C,, USA, 21st edition edition, 205.
24. Hach, Hach Water Analysis Handbook, Hach Company, USA, 2015.
25. D. F. Goerlitz and E. Brown, “Methods for analysis of organic substances in water,” in Techniques of Water-Resources Investigations of The United States Geological Survey, R. L. Wershaw, M. J. Fishman, R. R. Grabbe, and L. E. Lowe, Eds., pp. 1–40, U. S. Geological Survey, United States, 1972. View at Google Scholar
26. Y. Hayami, K. Ohmori, K. Yoshino, and Y. S. Garno, “Observation of anoxic water mass in a tropical reservoir: the cirata reservoir in java, Indonesia,” Limnology, vol. 9, no. 1, pp. 81–87, 2008. View at Publisher · View at Google Scholar · View at Scopus
27. C. Ariyadej, P. Tansakul, and R. Tansakul, “Variation of phytoplankton biomass as chlorophyll a in banglang reservoir, yala province,” Songklanakarin Journal of Science and Technology, vol. 30, no. 2, pp. 159–166, 2008. View at Google Scholar · View at Scopus
28. T.-Y. Ling, L. Nyanti, C.-K. Leong, and Y.-M. Wong, “Comparison of water quality at different locations at Batang Ai Reservoir, Sarawak, Malaysia,” World Applied Sciences Journal, vol. 26, no. 11, pp. 1473–1481, 2013. View at Publisher · View at Google Scholar · View at Scopus
29. G. B. Sahoo and D. Luketina, “Modeling of bubble plume design and oxygen transfer for reservoir restoration,” Water Research, vol. 37, no. 2, pp. 393–401, 2003. View at Publisher · View at Google Scholar· View at Scopus
30. Y. Zhou, D. R. Obenour, D. Scavia, T. H. Johengen, and A. M. Michalak, “Spatial and temporal trends in Lake Erie hypoxia, 1987-2007,” Environmental Science and Technology, vol. 47, no. 2, pp. 899–905, 2013.View at Publisher · View at Google Scholar · View at Scopus
31. T. Y. Ling, D. P. Debbie, N. Lee, I. Norhadi, and J. J. E. Justin, “Water quality at Batang Ai Hydroelectric Reservoir (Sarawak, Malaysia) and implications for aquaculture,” vol. 2, pp. 23–30, 2012.
32. Department of Environment, Malaysia Environmental Quality Report 2014, Department of Environment, Kuala Lumpur, Malaysia, 2015.
33. T. R. Fisher, L. W. Harding Jr., D. W. Stanley, and L. G. Ward, “Phytoplankton, nutrients, and turbidity in the Chesapeake, Delaware, and Hudson estuaries,” Estuarine, Coastal and Shelf Science, vol. 27, no. 1, pp. 61–93, 1988. View at Publisher · View at Google Scholar · View at Scopus
34. P.-P. Shen, G. Li, L.-M. Huang, J.-L. Zhang, and Y.-H. Tan, “Spatio-temporal variability of phytoplankton assemblages in the Pearl River estuary, with special reference to the influence of turbidity and temperature,” Continental Shelf Research, vol. 31, no. 16, pp. 1672–1681, 2011. View at Publisher · View at Google Scholar · View at Scopus
35. L. Nyanti, K. M. Hiii, A. Sow, I. Norhadi, and T. Y. Ling, “Impacts of aquaculture at different depths and distances from cage culture sites in batang Ai hydroelectric dam reservoir, Sarawak, Malaysia,” World Applied Sciences Journal, vol. 19, no. 4, pp. 451–456, 2012. View at Publisher · View at Google Scholar ·View at Scopus

For further details log on website :
https://www.hindawi.com/journals/jchem/2017/8153246/