Figure - available from: Journal of Chemistry
This content is subject to copyright. Terms and conditions apply.
In situ and ex situ water quality parameters of (a) pH, (b) DO, (c), turbidity, (d) TS, (e) BOD5, (f) COD, (g), TAN, and (h) TP at stations of downstream Bakun hydroelectric dam when the spillway was closed (dash line) and when it is opened (solid line) when the dam is in operation. Different letters indicate significant difference at p value ≤ 0.05 along the downstream river (uppercase—spillway closed; lowercase—spillway opened).
Source publication
Water quality in the downstream river of a hydroelectric dam may be affected by the structural design and operation. To date, little is known about the water quality downstream of the largest dam in Malaysia, the Bakun hydroelectric dam. Therefore, the objective of the study was to determine the water quality downstream of the dam when the spillway...
Citations
... This fact has already been mentioned in the literature and corroborates with the understanding of residents in Africa (Gyasi et al., 2018) and China (Rousseau, 2020) after the construction of HEDs. In other countries, studies show that HEDs negatively impact water quality in several parameters both downstream and upstream of the dam (Ling et al., 2016(Ling et al., , 2017Tomczyk et al., 2021) and the same is found in the Tocantins River (Oliveira, de et al., 2020). ...
Hydroelectric dams (HEDs) cause significant socio-environmental damage such as reduced fish diversity, population displacement and health problems. The fishers have extensive local ecological knowledge that can be used to improve understanding of the impacts of HEDs. Therefore, the objective of this study was to verify and evaluate the perceptions of fishers about the impacts caused by the HEDs in the Tocantins River. For this, 25 fishers were interviewed using a questionnaire with 22 questions. Data analyses were performed considering descriptive analysis of the responses. There was convergence in the responses of fishers who perceived the decrease in fish diversity after the construction of the HEDs, including fish of commercial interest, which is linked to a decrease in income and decreased food security for these families. In addition, the fishers noted symptoms that may be a consequence of mercury contamination, and diarrhea as a possible consequence of decreased water quality. Despite all these socio- environmental losses, the fishers report a lack of prior consultation, and low representativeness and transparency in the decision-making process that preceded the construction of HEDs. In general, the fishers perceived themselves as being strongly affected from the socio- environmental point of view and do not cite any benefits offered to the community from these projects.
... According to Central Pollution Control Board (CPCB) guidelines, the water quality of Malin River is classified as category E due to its turbidity levels, making it unsuitable for drinking, bathing, or irrigation. Ling et al. (2016) reported that the Malaysia Bakun hydroelectric dam downstream of the Balui River has caused an increase in turbidity values ranging from 40 to 74.5 NTU due to the dam's rapid water release. The accelerated flow of water causes soil erosion and resuspension of settled particles, which increases the amount of suspended solids in the water and raises its turbidity. ...
... These results are consistent with Ahmed et al. (2012), which reported a pH range of 7.6 to 8.2 for the Kshipra River's water quality. Ling et al. (2016) found the pH level in Malaysia's Balui River to be between 6 and 7.7. Simeon et al. (2019) recorded the pH of Silver River to be between 7.06 and 7.14. ...
... Ahmed et al. (2012) reported that DO values in the Kshipra River ranged from 0 to 5 mg/L. Ling et al. (2016) found that DO readings downstream of the Balui River in Malaysia, below the Bakun hydroelectric dam, ranged from 4.3 to 9.3 mg/L. The spillway from the dam significantly increased DO downstream. ...
The current study aimed to assess the health of the Malin River situated in Najibabad city, India by analyzing several physicochemical parameters. The main objective was to evaluate the impact of industrial and domestic wastewater on the river's health. The study was conducted over six months, from January to June 2023, at four different locations along the river. To calculate the water quality index (WQI), the data was further processed, and Pearson correlation was utilized. Except for site 1, most of the analyzed physicochemical parameters exceeded the Bureau of Indian Standards (BIS) limit, as indicated by the results. The utilization of river Malin water for irrigation, laundry, and vegetable cleaning may pose a health hazard to the public due to high contamination levels at the points where industrial (site 2) and domestic (site 3) effluents continuously mix with the river water. The water quality at all locations is deemed unsuitable for consumption due to a WQI score greater than 100. There are strong positive correlations between total dissolved solids (TDS) and other studied parameters, except for dissolved oxygen (DO), chemical oxygen demand (COD), biochemical oxygen demand (BOD), and turbidity. This suggests the presence of inorganic pollutants concerning organic pollutants. Wastewater treatment facilities are necessary along river coasts to conserve river flora and fauna, as well as water quality, to safeguard human and river health.
... A smaller number of studies also consider how mitigating low dissolved oxygen from hypolimnetic reservoir releases can affect downstream nutrient export (Carey et al. 2022) and biological communities (Bednarek and Hart 2005). Reductions in downstream pH due to hypolimnetic release have been noted in other systems (on the order of ~ 0.4 units; Wang et al. 2015, Ling et al. 2016. To our knowledge, this is the first paper to demonstrate a link between shifting reservoir outflow pH and downstream nutrient (P) availability. ...
Reservoirs often bury phosphorus (P), leading to seasonal or persistent reductions in P supply to downstream rivers. Here we ask if observed variation in the chemistry of dam release waters stimulates downstream sediment P release and biological activity in an arid, oligotrophic system, the Colorado River below Lake Powell, Arizona, USA. We use bottle incubations to simulate a range of observed pH (6–8.8) and oxygen (0–9.4 mg L⁻¹) levels, with the hypothesis that either oxygen concentrations or pH regulates P release from sediments to the water column. We found support for pH-mediated P release from calcite across the three sites we sampled. The magnitude of this effect was lower in bottles filled with tailwater sediment, but at downriver sites low pH resulted in declining water column dissolved inorganic nitrogen:soluble reactive P (DIN:SRP) ratios, which dropped below the Redfield ratio of 16:1, increasing water column total protein production, and down-regulating alkaline phosphatase production. Additional 7-day incubations showed that tributary storm inputs can temporarily elevate riverine P availability from < 1.5 µg L⁻¹ total dissolved P (TDP) pre-storm to 6.7 µg L⁻¹ TDP post storm. Taken together, our lab incubation and long-term observational results highlight the importance of pH, and ultimately reservoir management and storm dynamics, in regulating P availability and biological processes both now and into the future.
... These pressures have led to dramatic ecological changes, such as alterations in the hydrological parameters, urbanization, water pollution, and habitat degradation [1,4,5]. Consequently, there is an urgent need for managers to develop innovative methods to better understand and assess the ecological status of these types of ecosystems [6,7]. ...
This study aimed to evaluate the effects of the Martil River rehabilitation project and
recently constructed dam infrastructures to reduce flood risks and to promote local socio-economic development on the ecological integrity of the river. The assessment focused on changes in fluvial landforms over time and the evaluation of aquatic ecosystems based on six physicochemical parameters (temperature, pH, electrical conductivity, dissolved oxygen, biochemical oxygen demand, and chemical oxygen demand), morpho-hydrological variables (stream width, water depth, and current speed), habitat indices (QBR, IHF, and MQI), and macroinvertebrate assemblages of EPT, OCH, and Chironomidae (Diptera) at five stations from autumn 2015 to spring 2018 (prior to and during the rehabilitation actions). The results showed that the river rehabilitation project led to profound
changes in Martil River’s ecosystem and water quality over time. Physicochemical and habitat measurements at the rehabilitated sites revealed a major change in macroinvertebrate communities due to changes in fluvial landforms in relation to flow-sediment regimes. As a result, some typical species of lentic habitats disappeared, while alien, opportunistic, and lotic species appeared.
... The Sarawak Corridor of Renewable Energy (SCORE) aims to generate renewable energy with 12 mega-dams and fuel industrial growth. Although Sarawak already has three operational dams and plans for at least six more, very little work has been done to investigate their effects on downstream rivers and their ecosystems Ling, Soo, Heng, et al., 2016;Sim et al., 2016;Wera et al., 2019). In the tropics, the impact of dams is compounded by land cover change and climate change which can also alter river conditions, so such studies are needed as a matter of priority. ...
Tropical river ecosystems are being increasingly modified by the accelerated construction of hydropower dams. Dams are known to have detrimental effects on downstream flows and sediment transport, with long-lasting implications for fluvial processes, habitats and ecosystems. The tropics are also experiencing high rates of deforestation and forest degradation. These types of land use change can alter components of the hydrological cycle through the modification of terrain characteristics, evapotranspiration and fine sediment runoff. Moreover, predictions of increased temperatures and changes in precipitation in tropical regions may further modify the hydrological cycle and, in turn, river flows. The state of Sarawak, Malaysia, is witnessing the construction of 12 mega-dams as part of the Sarawak Corridor of Renewable Energy. The compounding effects of these dams, land use change and climate change pose a significant threat to the hydrology and overall functioning of rivers in Sarawak, but this threat has received little scientific attention. Baleh river was chosen as the study site because it is a typical Malaysian river surrounded by intact forest and its catchment is a headwater region with clear hydropower potential that will soon be realized. Thus, it is an area which can provide highly valuable new information on how large dams interact with landcover and climate change to alter river dynamics. This study therefore aimed to assess how damming, land cover and climate change interact and influence runoff of water and sediment in the River Baleh, a naturally forested tropical catchment in Sarawak. It incorporates two main components: (i) long-term land cover change assessment, and (ii) hydrological modelling of the impacts of the dam, climate and land cover change on flows and sediment loads in the Baleh. The land cover change assessment involved processing multi-temporal satellite images in Google Earth Engine (GEE) and carrying out supervised classification in ArcGIS. Besides providing empirical data on the magnitude and nature of land cover change across the Baleh catchment, the classified image outputs from this component formed input data for the second component - the catchment hydrological modelling. For the hydrological modelling, the Soil and Water Assessment Tool (SWAT) was used to simulate discharge and fine sediment loads for the whole of the catchment. The model was calibrated and validated using observed flow data. The performance of SWAT on daily and monthly time-steps was good (NSE > 0.62). Baseline conditions in the catchment were established with SWAT before running the future climate, land cover and dam scenarios; baseline models runs used the most recent five-year period. The future scenarios modelled the influence of land cover change with both low and high deforestation rates as well as climate models that involved increased temperature and decreased rainfall. Two operational scenarios were devised for the dam: a non-hydropower regime simply balancing dam outflow and inflows, to maintain lake levels and avoid dam spilling, while a hydropower regime was created which involved the dam operating at specific percentages of its capacity over the course of the year. Analysis of satellite images indicated that there has been very minimal land cover change in the Baleh catchment over the last two decades (<2% reduction in forest cover) but a significant expansion of logging roads; these roads may promote future deforestation. SWAT models suggested that even high deforestation rates (loss of 5% per year) will not cause major hydrological changes in the Baleh River, but the models indicated dramatic increases in sediment yield from sub-catchments and, in turn, increases in the total amount of sediment exported by the catchment (up to 736% increase by 2050, compared to baseline). Modelling of climate scenarios suggested a counter-acting effect, with predicted lower rainfall and high temperature decreasing flow and sediment loads. SWAT simulations suggest that the dam will have a greater impact on flow and sediment loads in the Baleh catchment than the future land cover and climate change scenarios that were modelled. The presence of the dam has the greatest impact on flow and sediment at the dam site, reducing sediment loads by approximately 95% and reducing discharge variability. Simulations suggest that impacts on flow are still evident almost 100 km downstream, despite tributary inputs. Impacts on sediment loads at the catchment outlet are more difficult to understand, because of how the river might adjust to cumulative alterations in flow, competence and supply over decadal timescales. Preliminary analysis for the first five years of dam operation suggests that sediment yield at the basin outlet may differ from baseline much less than it does at the dam site but further work on this is needed, particularly because of the sensitivity to exact dam operational regimes (which at present are unclear). The high sediment yield from the upper sub-catchments has implications for the operation of the Baleh dam due to siltation, but the large size of the reservoir means that even by 2050 its storage capacity will have been reduced by only around 5%. Overall, this study demonstrates how models such as SWAT can be used to provide insights into the complex interacting effects of anthropogenic stressors in tropical catchments. It is recommended that a period of 10-30 years is used for SWAT studies of the downstream effects of dams, to capture the sequences of transient states which will evolve in response to altered flow regimes and sediment supply. The traits of tropical rivers such as the Baleh (high discharge and sediment loads relative to catchment area) and the numerous tributaries create the potential for more rapid downstream ‘recovery’ than in other hydroclimatic settings, but this is confounded by ongoing climate and land cover changes which modify boundary conditions. Modelling assessments of the type presented here should be complemented by empirical studies of fluvial adjustment, to fully understand the habitat and ecological changes that follow impoundment.
... Other studies indicate an ambiguous influence of hydropower plants on the shaping of the values of water quality indicators -in some, there was an improvement downstream hydropower plants (Malaysia; Ling et al. 2016 [49]), and in some, deterioration of water quality (Brazil; de Olivera et al. 2021 [50]), and other studies do not provide a clear answer regarding the impact of hydropower plants on water quality (China; Luo et al. 2019 [51], Poland; Tomczyk et al. 2021 [52]). The differences in the values of the indices fluctuated in the cited studies ranging from -69.09% to +24.25% downstream hydropower plants compared to the points upstream the hydropower plants. ...
Water is the basis for the life of organisms and is used for various purposes, especially in agriculture, industry, municipal, and energy production. Assessing water quality in terms of its various uses is not without significance. This study investigates the water quality within two small hydropower plants in an urban area from natural, social and economic perspectives. Wrocław I and Wrocław II hydropower plants on the Odra River in Poland were selected as case studies. This study presents the results of four-year research (2017-2020) for points located upstream and downstream of the intake. The following elements were assessed: physicochemical status, trophic status, assessment of fish living conditions, and water quality indices. The results show that hydropower plants improved the average physicochemical status of BOD5 (by 6.19% comparing the results downstream and upstream of the hydropower plant), dissolved oxygen (3.85%), PO4-P (3.31%), and electrical conductivity (0.52%), however, they worsened in the case of the pH (by 2.63%) and NO3-N (by 1.83%). Water near the study cases is classified as mesotrophic or eutrophic. The conditions for the existence of salmonids and cyprinids were not met due to the increased concentrations of NO2 and BOD5 values. In the case of salmonids, also due to the temperature and dissolved oxygen concentration. The water quality indices differed and indicated the quality from poor to good, depending on the classification. This study provides important insights for policymakers regarding the impacts of small hydropower plants on water quality in urban areas.
... Changes in water physico-chemical variables also varied with dam operational schemes, as highlighted in previous studies (Aristi et al., 2014;Kamidis et al., 2021;Ling et al., 2016). Irrigation dams considerably reduced the nutrient and TSS concentrations downstream. ...
Rivers and streams have suffered multiple transformations to attend the increasing water demands worldwide. Among these, dams and reservoirs cause some of the most severe ecological impacts on rivers, altering the river flow and thermal regimens, nutrient and sediment fluxes, and network connectivity. However, in the context of the different dam purposes and operational schemes, knowledge of the ecological impacts on the riverine biota is still limited. In this study, our main goal was to assess dam-related effects (e.g. hydrological and thermal alteration, water quality changes) on river biological communities and identify key ecological responses associated to flow regulation. To achieve this, diatom, macroinvertebrate, and fish communities were surveyed in control (n = 8) and impacted (n = 11) streams (i.e. downstream of irrigation or hydropower dams) along three consecutive years. The study design aimed at minimising the environmental variability among control and impacts using previously established hydrological classifications. This allowed focusing primarily on the effects of dam operation schemes. In addition to traditional biotic indices based on the composition and structure of these communities, we assessed community-level responses using trait-based analyses with multivariate and fourth-corner analyses. The ecological changes varied with dam purpose and, in general, favoured disturbance-tolerant traits. Common biotic indices did not consistently respond to dam uses; trait-based analyses, in contrast, provided a more detailed picture of the dam-related effects on the studied river communities, with macroinvertebrate traits showing the strongest correlations to dam-related hydrological and physico-chemical variables, followed by diatoms and fish. Changes in the biological communities downstream of irrigation dams were mostly related to the inversion of the seasonal flow regimes (e.g. increases in the summer flows and magnitude of low flow extremes; decreases in the winter flows and in the frequency and magnitude of extreme high flow events) and the reduction of nutrient concentration. These changes favoured planktonic diatoms, macroinvertebrates with short life cycles and small body sizes, and fish feeding on the water column. Hydropower dams elevated significantly the rate of flow change and water temperature, favouring low profile adnate diatoms, multivoltine and passively dispersed macroinvertebrates, and scrapers. The key relationships identified in our study are useful to underpin river biodiversity conservation strategies and to set future research directions aiming at reducing the negative effects of dam operation schemes.
... Third, water physicochemical properties (P < 0.001, r = − 0.265) had a negative direct effect on the Mt-IBI. Previous studies showed that cascade dams affect water physicochemical properties, such as dissolved oxygen, temperature, and pH (Daniels and Danner, 2020;Ling et al., 2016). The final SEM illustrated that water physicochemical properties did have an ecological effect, but not one sufficient to drive river ecological status. ...
Cascade dams have exerted significant effects on river ecosystems. To quantitatively assess dam-induced effects on river ecological status, a novel multi-species interaction-based index of biotic integrity (Mt-IBI) was developed. Benthic microbiota was selected as a bio-indicator for its sensitivity to the environmental disturbance. An environmental DNA metabarcoding tool was used to identify microbiota (bacteria, protozoan, and metazoan). The Mt-IBI was applied to assess the ecological status of the Hanjiang River, a representative dam-affected river in China. Fifteen sampling sites along the Hanjiang River were sampled in June 2018. Seven core metrics were screened from a total of 364 candidate metrics to calculate the value of the Mt-IBI. The Mt-IBI of the Hanjiang River ranged from 1.90 to 6.39, with a mean value of 4.02. The mean values of Mt-IBI at the reservoir and riverine side of dams were 2.11 and 3.81, respectively. The downstream reach without dam constructions had the highest mean Mt-IBI (5.79). Thus, the continuity of the river was strongly related to the Mt-IBI. Structural equation models (SEMs) were further established to identify the dominant environmental variables in the dam-affected river. The SEMs indicated that flow velocity (coefficient 0.749) was the most important determinant of ecological status in the Hanjiang River. Water organic matter also played a vital role in determining the ecological status of the Hanjiang River, and exerted the strongest direct effect (P < 0.001, r = 0.712). The reliability of SEMs was verified by building a support vector regression model (R² = 0.8141). This study can provide new tools for ecological assessment and diagnosis, and provide a new perspective for the management of cascade dams.
... The presented results for UWQI are consistent with the results for reservoir hydropower plants: Michalice in Poland , Bakun in Malaysia (Ling et al. 2016) and Gongguoqiao in China (Luo et al. 2019). In these cases, better water quality was noted, expressed by the water quality index below the hydrotechnical structures. ...
The aim of the article was the analysis of the physicochemical quality of water within the hydropower plant on the Ślęza River in Wrocław (south-west Poland) in the context of the European Union's classification of water quality, as well as an assessment of the potential impact of hydropower plants on this quality. The study uses the results of monthly tests from three measurement points within the hydropower plant on the Ślęza River in the city of Wrocław (points upstream and downstream the hydropower plant and the reference point), from the period June 2018 to May 2020. The analyses covered 10 physicochemical parameters, i.e.: pH, electrical conductivity (EC), water temperature, turbidity, NH4-N, NO3-N, NO2-N, total phosphorus, dissolved oxygen and BOD5. The conducted analysis showed that the hydropower plant has no clear influence on the physicochemical quality of the water in the Ślęza River, other interactions present in the catchment area are more important. From the effects visible in the results, a decrease in the amplitudes of water temperature downstream the hydropower plant compared to the other points was noted, as well as a lower median of its value (statistically significant changes). An additional noticeable effect was the increase in water oxygenation below the damming, but it was not statistically significant. It has been shown that the physicochemical condition of water at the tested points does not meet the assumed standards for 8 out of 9 parameters (except for water temperature). The largest exceedances of the limit values concerned NO2-N (up to 923% of the norm), and the most consistent, almost constantly occurring-EC (23 out of 24 months). The reason for the high NO2-N content was most probably surface runoff from the fields and the re-suspension of sediments rich in nutrients, while in the case of EC, its high values result from the specificity of the catchment area.
... It was proved that the dam affected site 3 downstream the dam which caused decreasing values of magnesium concentrations which may be related to the presence of sulphates in this site, after the discharge of water from the reservoirbottom via the opening of dam spillways 49 , which resulted in the reaction of sulphur compounds with magnesium and magnesium precipitation and reduced their values in the water column in Hindiya Dam reservoir 50 . While, the higher average of magnesium concentrations was on site 1 (upstream the dam) might be related to this site received wastewater from a local wastewater sources 51 . ...
... While, the high average was recorded on site 3 compared with other sites might be due to that this site was under dam impact by influxes of hypolimentic layer during opening of spillways of the dam. This layer was rich with phosphate that came from decomposition processes of organics and phytoplankton damage 49 . Our findings agreed with researcher such as Ling et al. 49 when investigated Bakun Dam in Malaysia. ...
... This layer was rich with phosphate that came from decomposition processes of organics and phytoplankton damage 49 . Our findings agreed with researcher such as Ling et al. 49 when investigated Bakun Dam in Malaysia. Also, Adesakin et al. 55 when they investigated Opa Reservoir in Nigeria. ...
Five sites were chosen to the north of Babil Governorate in order to identify the limnological features and the impact of the Hindiya Dam during 2019. Site2 was located near the dam to reflect the ecological features of this site, whereas other sites, S1 was located at the upstream of the dam as a control site. Moreover, the two other sites S3 and S4 were located down the dam. The results of the study showed a close correlation between air and water temperature at all sites. Also there were significant differences in average of thirteen out of eighteen water parameters.Water temperature, total alkalinity, bicarbonate, DO, POS, TH and Mg +2 ions decreased from 22.76˚C, 203.33 mg/L, 146.75 mg/L, 8.8 mg/L, 100.023%, 438 mg/L, 35.55mg/L, respectively on S2 to 22.66 ˚C, 200.28 mg/L, 145.58 mg/L, 8.35 mg/L, 95.45%, 422.66 mg/L, 28.81 mg/L, respectively at site below the dam. While, turbidity, TSS, Ca +2 , SO 2 +4 , NO 3-2 and PO 4-2 increased from 13.32 NTU, 23.08 mg/L, 116.89 mg/L, 107.5 mg/L, 1.027 mg/L and 0.019 mg/L, respectively on S2 to 26.574 NTU, 26.83 mg/L, 119.23 mg/L, 137.5 mg/L, 1.145 mg/L and 0.032 mg/L, respectively at the site below the dam. However, no apparent dam effect was reported in EC, S, TDS, pH values at Euphrates River. No significant differences of all characteristics were found among sites except, turbidity, TSS, Mg +2 , SO +4 and PO 4-2. It can be considered that the Euphrates River is very hard, oligohaline, slightly alkaline, well ventilated and clear to turbid. In addition, the turbidity and TSS values exceeded permissible limits of water quality for aquatic life in most samples especially in site below the dam. However, the river was considered by BOD 5 to be doubtful in its cleanliness water. Calcium, magnesium, nitrate and phosphate values in this study were within permissible limits.
