Construction Of Large Dams Research Articles

Ecological perspectives of endemic fish species under cascade hydropower development

Wang Y, Wang Q, Zhang W, Wang N, Cong N, Kattel G, Qi Y, Yao W. 2024. Ecological perspectives of endemic fish species under cascade hydropower development. Lake Reserv Manag. XXX–XXX. The upstream Lancang River basin (in Tibet) offers rich hydropower resources together with some of the most delicate freshwater fish species diversity in the world. However, a large dam construction scheme throughout the basin has threatened the fish species diversity and ecology. Our study focuses on the extent to which hydropower construction in the basin influences the river’s ecological status, including the aquatic environment, fish migration, and fish spawning sites. We surveyed the water quality, fish distribution, and fish spawning sites and estimated the fish spawning capacity in the basin. Our results indicate that the water quality prior to dam construction would meet China’s water standards. However, water quality would decline significantly following dam construction, exacerbating the rate of loss of 7 of the protected endemic fish species, as well as threatening the habitat of several other fish species. Our analysis shows a loss trend of fish populations and spawning capacity after damming the river. Cascade dams constructed in the upstream Lancang River basin would obstruct natural migration of fish and inundate their spawning sites, causing reproductive failure and population decline. Based on our analysis, and eco-hydraulic engineering principles, we recommend several ecological protection measures and management options in the upstream Lancang River basin, including the construction of artificial fish ladders, the implementation of ecological regulation, and a fish strategy that will reduce the negative effect of cascade dam constructions.

THE WATER CRISIS LOOMS LARGE IN PAKISTAN WHICH MAY FACE ABSOLUTE SCARCITY

Pakistan has the fourth-highest rate of water use in the world, as reported by the IMF (International Monetary Fund), and is the 3rd greatest water-stress country in the world.Water can be scarce for many reasons: water supply is very low compared to demand, infrastructure is inadequate, and institutions fail to balance every person’s daily needs. Water scarcity is a global problem, with the most badly and worse affected communities. In this thesis we can measure Pakistan’s water scarcity with the four main indicators. The four main indicators can be measured in a country’s water scarcity: The Water Poverty Index, Water Resources Vulnerability Index, the Falkenmark indicator, and Physical and Economic Water Scarcity Indicators. Currently, Pakistan is one of the countries where demand of water exceeds over available water supply with the giving of these 4 indicators. There are many reasons for Pakistan’s water scarcity, being increased populace, citified and computerization, climate change, unsatisfactory warehouse, residues in the existing tank, corrupt system efficiency, irrigational problem and traditional methods of farming, and insufficient finance. The possible alternatives to overcome these issues are the construction of small and large dams where possible, the construction proper irrigation system, improving the surface water governance with suitable pricing, controlling the increase in population, improving transportation, changing the existing harvesting patterns by accepting low delta crops and using saline groundwater, in conjunction with independently with salt accepting crops. Nevertheless, a unified approach is required to optimally use water resources.

Trends of forest cover and prospects of Great Ethiopian Renaissance Dam (GERD) to Ethiopia and the downstream countries

The need for forest products, agricultural expansion, and dependency on biomass for the household energy source has largely influenced Ethiopia’s forest resources. Consequently, the country lost its forest resources to less than 6% until the millennium. In this study, quantitative and qualitative historical data analysis was employed to understand the socioeconomic benefits of large dam construction to Ethiopia and downstream countries. Moreover, remotely sensed data was also used to analyze the trends of vegetation cover change in the Nile catchment since the commencement of the dam; focusing on areas where there are high settlement and urban areas. It was identified that Ethiopia has one of the lowest electricity consumption per capita in Africa; about 91% of the source of household energy supply depends on fuelwood today and more than 55.7% of the population does not have access to electricity. The normalized difference vegetation index result shows an increment of vegetation area in the Nile catchment and a reduction of no vegetation area from 2011–2021 by 37.1%; which is directly related to the protection of the dam catchment for its sustainability in the last decade. The hydroelectric dam construction has prospects of multi-benefit to Ethiopia and downstream countries either through the direct benefit of hydropower energy production, related socioeconomic values, and reducing risks of destructive flood from Ethiopian highlands. Generally, it explains the reason why to not say ‘No’ to the reservoir as it is an ever more vital tool for fulfilling growing energy demand and supporting ecological stability.

The effect of the gravity on the earthquake performance of roller compacted concrete dams

Roller compacted concrete (RCC) is a dry concrete mixture often utilized in the construction of large dams. The interlayer of the RCC dam, which is the weakest plane of the structure, can easily fail under hydraulic shear load, geological impact, earthquake force and environmental impact. In this study linear and performance analyzes were carried out for eight different scenarios for foundation effect, gravity effect and empty and full reservoir situations. In analyses, the earthquake response and performance of the Akçakoca RCC Dam, taking into account the interaction between the dam and the water. The reservoir water behavior is simulated using the Eulerian-Lagrangian coupled (CEL) approach with finite elements modeling. Linear analyses reveal that hydrodynamic pressure leads to increased displacements and principal stresses. The earthquake performance evaluation of the Akçakoca RCC dam indicates that critical concrete damages are expected based on linear time-history analyses conducted for both empty and full reservoir scenarios. Besides, according to this study, gravity effect clearly increases the earthquake performance of the dam.

Poverty-Food Insecurity Nexus in the Post-Construction Context of a Large Hydropower Dam in the Brazilian Amazon.

Within the 2030 Sustainable Development Agenda, large hydropower dams are positioned as a sustainable energy source, notwithstanding their adverse impacts on societies and ecosystems. This study contributed to ongoing discussions about the persistence of critical social issues, even after the investments of large amounts of resources in areas impacted by the construction of large hydropower dams. Our study focused on food insecurity and evaluated this issue in the city of Altamira in the Brazilian Amazon, which has been profoundly socially and economically impacted by the construction, between 2011 and 2015, of Brazil's second-largest dam, namely, Belo Monte. A survey in Altamira city featured a 500-household random sample. Structural equation modeling showed conditioning factors of 60% of the population experiencing varying food insecurity degrees. Poverty, female-led households, lower education, youth, and unemployment were strongly linked to higher food insecurity. Crowded, officially impacted, and resettled households also faced heightened food insecurity. Our findings underscore the food insecurity conditions in the region impacted by the Belo Monte dam, emphasizing the need to take into account this crucial issue while planning and implementing hydropower dams.

Anthropogenic Changes in Land Use Impact the Emergence and Transmission of Infectious Diseases

Human interventions in natural landscapes have promoted rapid and profound transformations in the environment, generating great impacts at different levels, including on human and animal health. Actions such as deforestation for logging, intensive agriculture, construction of large hydroelectric dams, pastures for cattle, mining, and construction of roads that favor human access to remote areas have promoted habitat destruction, changes in trophic chains due to nutritional factors, loss of biodiversity, changes in the natural balance of vectors, mammals, hosts and pathogen reservoirs, and closer human contact with wildlife. Another important impact related to changes in land use is forest and habitat fragmentation. According to different investigations, anthropogenic actions causing changes in land use are potential inducers of emergence/reemergence and increased transmission of infectious diseases in the world, including those with pandemic potential. Most of these diseases are classified as zoonoses and many are arboviruses. Deforestation and agricultural intensification seem to be the events that most influence the incidence of zoonoses. Changes in land use may also favor a species jump to a zoonotic pathogen, making it a potential threat to humanity if it acquires an efficient capacity for inter-human transmission. Here, we summarize important evidence on how anthropogenic changes in land use influence the emergence and transmission of infectious diseases to humans.

A Half-Century of Human Impact on Nan River Runoff and Sediment Load Supplied to the Chao Phraya River

The construction of large dams in the upper tributary basin of the Chao Phraya River (CPR) has been linked to a significant decrease in sediment load in the CPR system, estimated between 75–85%. This study, utilizing historical and recent river flow and sediment data from 1922 to 2019, examines the impact of three major dams constructed in the Nan River basin (the Sirikit, Naresuan, and Khwae Noi dams) on river runoff and sediment loads in the CPR. The investigation employed the Mann–Kendall (MK) test and the double mass curve (DMC) for analysis. Findings indicate that the Nan River is a major contributor to the CPR, accounting for around 40% of the runoff and 57% of the total sediment load (TSL). The Naresuan diversion dam’s water regulation was found to significantly reduce annual runoff and TSL downstream of the dam. Despite an initial increase in sediment load at the CPR headwater (C.2) post the construction of the Sirikit dam, attributed to expanded irrigation downstream and channel improvements in the lower Nan River, the operation of the three dams eventually led to a 31% reduction in sediment load at C.2 compared to pre-construction levels.

Where have all the sediments gone? Reservoir silting and sedimentary justice in the lower Ebro River

At the intersection of natural and social sciences, interest in river sedimentary fluxes and their alteration by human activities is increasing in the context of general retreat of delta formations. Since the 1950s, the construction of large dams in the main course of rivers has produced, among other impacts, a radical decrease in sedimentary fluxes — a key factor in the worldwide sedimentary crisis. While sediment accumulates in reservoirs, the resulting sediment scarcity downstream contributes to land subsidence and coastal erosion, endangering livelihoods in low lying areas such as river deltas. Focusing on the case of the Ebro River and delta (Spain), this article builds on Katherine Dawson's notion of sedimentary justice to examine the articulation of a social demand to mobilise the sediments trapped in reservoirs to counter delta subsidence and coastal erosion. Using a historical perspective and paying attention to matters of both sediment quantity and quality, we show how this demand has developed hand in hand with the emergence of a scientific interpretation of the Ebro delta's origins that emphasises non-human forces and the importance of sedimentary fluxes before human interferences. Activists have taken up this argument to demand the restoration of sedimentary fluxes, exposing corporate hydropower interests and insisting on the mobilisation of sediment trapped in reservoirs. Overall, by scrutinizing the power relations embedded in the immobilization of river sediments, this article contributes to recent work that integrates the materiality of sediment to the hydrosocial framework of analysis and argues that sedimentary justice provides new avenues to incorporate the non-human world to the literature on environmental and water justice.

River definitions reciprocally define us

AbstractThis article explores different definitions of river, and in doing so, considers how our efforts to define rivers illuminate aspects of the human condition. Through an exploration of our definitions of river, through the human imagination, in poetry, music, and human's actions, this article considers how our nature is reflected back by rivers—how we in turn are defined by rivers—such as their role in determining borders, movement, escape, the locations of cities, trade, communication, and in the shaping of cultures and societies. This article specifically highlights three definitions of river using examples predominately from North America. River as boundary, exploring how in the reaches of some river basins, rivers act not only as a border, or boundary between two nations or cultures, but also as a line of demarcation between the known and unknown landscapes and the tamed and untamed lands. The definition of river as pathway includes exploration of how the Mississippi River served as a natural highway for people escaping slavery to travel North and reach Underground Railroad routes toward freedom, while also forcibly moving hundreds of thousands of enslaved people in the United States from the Upper South to the Lower South as they were “sold down the river.” Third, this article examines how rivers have been defined as a resource through examples, such as the US government and Bonneville Power Administration's (BPA) efforts, to encourage support of large dam construction and water development projects by hiring Woody Guthrie in 1941 to write songs that would prompt public support for the water projects. Through this discussion of three river definitions, the article considers how rivers have been conceptualized over time and how those different knowledges inform our understanding and treatment of rivers. The article argues that it is vital to include knowledge from across scales, time, boundaries, and ways of knowing in order to improve the protection of rivers and their ecosystems. If we do not, we will continue to lose freshwater biodiversity, wetland and riverine habitat, and their immeasurable qualities that inspire life and imagination at a staggering rate.

Flood pulses and fish species coexistence in tropical rivers - a theoretical food web model

AbstractFreshwater fish diversity reaches its zenith in large tropical rivers. Although the origins of this diversity have been relatively well studied, the mechanisms that maintain high fish diversity in tropical rivers remain largely unknown. It has been hypothesized that the annual flood pulse, a perennial feature of many lowland rivers in the tropics, reduces competitive exclusion and consequently promotes species coexistence. During the high-water season, superabundant allochthonous resources and relatively low fish density may reduce intra- and interspecific competition. During the low-water season on the other hand, resource availability is low and predation pressure high, offsetting competitive differences between species and controlling fish population sizes. Here, we tested the potential role of these mechanisms for species coexistence using a food web model where fish species exhibit strong differences in competition strength and compete for finite resources. We simulated fish interactions when a regular flood pulse was either present or absent. We found that extinction rates in the simulations without an annual flood pulse were consistently higher when compared to those with a flood pulse, indicating more species could coexist when a regular annual flood pulse is present. If the flood pulse is a relevant mechanism for fish species coexistence, as our model results suggest, then flood pulse changes could result in species extinctions and lower fish diversity. Deforestation, climate change, and the construction of large hydropower dams are current drivers of hydrological change across the tropics, increasing the urgency to understand the role of natural flooding regimes for the maintenance of tropical freshwater fish diversity.

Evaluating hydrological alterations and recommending minimum flow release from the Ujjani dam to improve the Bhima River ecosystem health.

Numerous anthropogenic activities like the construction of large dams, storages, and barrages changed the watershed characteristics impacting ecosystem health. In this study, the hydrological alterations (HAs) that have occurred in the Bhima River due to the construction of the Ujjani dam were analyzed. The hydraulic analysis is also performed to determine the hydraulic parameter and recommend the lowest flow release from the dam for improving ecosystem health. Fifty-eight years of data starting from the year 1960 to 2018 were gathered at Yadgir station, which is located downstream of the Ujjani dam. The data were divided into pre- and post-construction river flow discharge. To check for the change in the river flow regime for the post-dam construction period, HA was calculated using Flow Health Software (FHS). The results demonstrate that the dam impoundment reduces high flows primarily by storing flood flow for water supply, irrigation, etc. The velocity and depth provided by the environmental design flow for a flow health (FH) score of 0.62 give a very good habitat to fishes. A minimum release of 24.8 m3/s from the dam is recommended. This study will help policymakers mitigate the impacts of degrading ecosystem health of the Bhima River.

Spatial-temporal evolution of sediment transport in the upper Yangtze River Basin considering the cumulative impacts of mega reservoirs

The intensive construction of large dams in the upper Yangtze River Basin (UYRB) has formed large-scale cascade reservoirs and obviously altered the flow regime and sediment transport of the basin. However, few studies have quantitatively described the cumulative impact of these reservoirs on sediment interception. In this study, a flow and sediment transport model that fully considers the operation processes of 24 mega reservoirs in the UYRB was established, and the spatial and temporal variations in sedimentation from 2011 to 2080 were elucidated, assuming repeated series of daily input flow discharge and sediment concentration during 2011–2020 and monthly water operation levels of 24 reservoirs during 2018–2021 as boundary conditions. The results showed an annual average sedimentation of more than 300 Mt in the UYRB during 2011–2060, which falls to 270 Mt in the period 2061–2080, and more than 80% of the sedimentation occurs in the flood season. Nearly 80% of the total sedimentation during 2010–2080 was observed in the mainstream reservoirs, especially the four mega reservoirs in the lower Jinsha River and the Three Gorges Reservoir (TGR), which accounted for 31.9% and 22.7% of the total sedimentation, respectively. The proportion of sedimentation in mainstream reservoirs will further increase with increasing operation periods. Most reservoirs in the UYRB will not reach sedimentation equilibrium by 2080, except for reservoirs in the Min River Basin. The ratio of siltation capacity to average annual sediment yield determines the percentage of residual siltation capacity of each reservoir. The operation of the cascade reservoirs in 2013–2020 had no more immediate impact on the middle and lower Yangtze River than that in 2003–2012, when the TGR started impoundment. However, the joint operation of these cascade reservoirs has changed the spatial distribution of sedimentation in the UYRB, and will lead to prolonged impacts on downstream channel erosion.

Modelling spatiotemporal tendencies of climate types by Markov chain approach : A case study in Sanliurfa province in the south-eastern of Turkey

Identification of spatiotemporal tendencies of climate types may help water managers mitigate the negative impacts of droughts on water-demanding sectors. The primary objective of this study was to figure out the spatiotemporal tendencies of climatetypes in Sanliurfa province by using Erinc’s aridity index (EDI). To that end, long-term (1965-2018) annual precipitation and average annual maximum temperature series of meteorological stations were obtained and utilized to calculate the EDI series on a yearly basis. The EDI series of each station was divided into three periods, non-overlapping and successive, i.e., P1 (1965-1981), P2 (1982-1999) and P3 (2000-2018). Outliers were detected, andremoved from the EDI series; missing data were completed by regression analysis. The Markov transition probability matrix of the climate classes for the three periods was estimated for each station. Maps of the initial probability vectors and steady-state probabilities for the three periods of each climate class were generated by the inverse distance-weighted technique. Hypsometric curves for each climate class, as well as period, were developed and areal coverage of occurrence probabilities (OP) was determined. Results indicated that, as time progressed, the areal extent of severe-arid and arid climatic classes continued consistently to spread from the south to the north. Areas of semi-arid climate type showed a slight tendency towards the arid-climate type. Construction of large dams in the region could not prevent the shifts in the climate in favour of developing arid zones. The humid climate class is likely to vanish away in the future. Research led us to conclude that the expansion of the aridzone from south to northhas been alarming in terms of the adequacy of water resources. It is strongly recommended that spatiotemporal climate change studies should be periodically conducted in tandem with forest management practices for the region.

In situ experimental study on mechanical properties of interlayer in roller compacted concrete (RCC) dam

Roller compacted concrete (RCC) is a kind of dry concrete widely used in the construction of large dams. As the weakest plane of the structure, the interlayer of the RCC dam is easy to deteriorate under the action of hydraulic shear load, geological action and environmental influence. Therefore, in this study, in combination with actual engineering, in-situ tests were carried out to study the shear properties of RCC interlayers under different cementing material treatments, different surface roughness, different exposure time and different stress. In addition, the failure modes were classified and analyzed, and the factors affecting the angle and depth of the plane undulation in the failed surface of RCC were summarized. The result shows that the shear strength of the RCC interlayer increases with the increase of normal stress. The increase of surface roughness results in better interlayer bonding and higher shear strength. After mortar treatment, the shear strength, cohesion and friction angle of the RCC layers are higher than those of the mortar treatment. The strength parameters of the RCC layer treated with cementing material are improved to a certain extent compared with that of the untreated layer. With the increase of layer exposure time, the interlayer strength parameters decreased gradually. The change of cementation between layers and the bite force of aggregate under different conditions is an important reason for the change of mechanical properties between layers of RCC. The experimental results are expected to enhance the understanding of the construction of hydraulic dams.

A Policy Review on Sustainability and the Three Gorges Dam in China

The construction of large dams has become a controversial environmental issue around the world. The Three Gorges Dam on the Yangtze River in China is by far the largest hydroelectric power plant in the world. Supporters of the project argue that it would help control catastrophic flooding along the Yangtze River, provide much-needed electricity to the central region of China along the river, and enhance the economic advantage of the interior. The most important role is for the dam to act as an important power station and reservoir in the middle and lower reaches of the Yangtze River, as it will not only solve natural disasters, such as floods and mudslides, but also promote economic development in the middle and lower reaches of the Yangtze River through power generation. The dam is also intended to protect millions of people from periodic flooding along the Yangtze River, although there has been debate about its effectiveness. However, the dam has also caused damage to ecological and wildlife habitats, archaeological and cultural sites, and the displacement of millions of people.

Development of Hydropower and the Environmental Impacts of Hydroelectric Dam Construction in China

The need to mitigate climate change and reduce carbon emissions has resulted in an increasing demand for the transition from fossil fuels to renewable sources of energy. Hydropower, in particular, has emerged as a prominent and extensively developed source of renewable energy in recent decades. This specific renewable energy harnesses the kinetic energy of falling or fast-flowing water to generate electricity. Despite being a dependable, adaptable, and cost-effective energy source, previous studies have highlighted the detrimental ecological effects of hydropower, ranging from altered land use to the disruption of natural habitats in the vicinity of dams. The main purpose of this study is two-fold. First, the change of renewable energy, particularly hydropower, is evaluated from 2000 to 2020 in China and globally, highlighting the leading role of hydropower in renewable energy generation. Second, this study aims to investigate the environmental influences of large hydroelectric dam construction and perform a case study of the Three Gorges Dam in China. The Pearson's linear correlation analysis was utilized to identify the association between hydropower and climate, and biodiversity, individually. Although dam construction can boost hydroelectricity generation, it can also have adverse effects on the regional climate and result in substantial depletion of biodiversity. This study will shed light on potentially reliable strategies to optimize the advantages of hydropower and minimize the negative environmental impacts of large-scale dam construction.

Examining Disruptions of Social Systems due to Large Dam Projects in the North East

The vulnerability of the tribals to lose more than the commodity value of land due to large dam projects in the North East has not been given due attention both in policy space and empirical research. Also, the question of whether the living standards of the already displaced tribals have improved after dam construction has not been treated with rigour. The paper tries to disaggregate the social disruption effects of large dam construction along the lines of gender, religious identity and ethnic conflicts and question the conventional economics of resettlement. The study examines the claimed effects (and benefits) of large dams on tribal communities made in non-empirical papers and government documents using available real-world examples from the north-east. The study also validates the findings from the literature through a sentiment analysis of newspaper articles and a public opinion survey of dams in the north-east. This crossexamination is expected to serve as a foundation for further empirical research.

Causes & effects of upstream-downstream flow regime alteration over Catchment-Estuary-Coastal systems

The construction of large dams along rivers has significantly changed the natural flow regime, reducing the inflow into many lakes and terminal wetlands. However, the question of the impact of dam operation on downstream estuarine wetlands has less been taken into account. Spatio-temporal flow regime alteration in the Mond River shows the complexity of drivers affecting the estuary-coastal system named the Mond-Protected Area in southern Iran. To this end, we applied river impact (RI) and Indicator of hydrological alteration (IHA) methods on monthly and daily river flow data across the basin. Based on the river impact method, a “drastic” impact below two in-operation (Tangab and Salman Farsi) dams, with RI values of 0.02 and 0.08, diminish to a ‘severe’ impact with RI value of 0.35 at the last gauge (Ghantareh) on the main corridor of the Mond river due to the addition of flow from a large mid-basin (about 20,254 km2). Furthermore, the degree of hydrological alteration (daily flow analysis) at mid-stream (e.g., Dehram gauges) was similar to the unregulated upstream tributaries (e.g., Hanifaghan gauges). The remote sensing analysis in the Mond Protected Area showed the prevailing impact of sea-level rise in the Persian Gulf with the inundation of the coastal area and a shift of vegetation in a landward direction which complied with standardized precipitation index (SPI) values as a meteorological drought indicator. Thus, the consequence of climate change (e.g., sea-level rise, draught) has a higher impact on the protected area than the upstream river regulation and land-use change in the Mond basin. The holistic approach and the catchment-level study allowed us to see the complexity of the drivers influencing the estuary-coastal system.

Risk and Security Management: Stakeholder Project Failures Illuminated by an IED occurrence at a Hydro-Power Construction Project in Pakistan

Risk and security management is an important aspect of construction activities, especially in countries where the level of security is challenging. This paper is focused on evaluating the impacts of risk/security measures resulting from stakeholder failures related to explosives mismanagement and security events, over an 18-month period, on a large, complex Dam project in a remote area in Pakistan. In July 2021, an incident occurred that had huge ramifications for the risk/security management of a large dam construction site. A qualitative methodology was utilised, where content analysis was conducted on project documentary evidence and where the research design targeted a closed population of 12 - Engineer supervisors/managers to explore their personal opinions. The outcomes indicated that the Employer, the Engineer, WB group and contractors engage in destructive managerial behaviour considered primarily to reduce project performance and create unsafe project situations that were systemically induced. Further, stakeholders are not managing explosives or the security situation underpinning poor project physical progress, leading to consistent project failure issues.

A feasibility study of operating a low static pressure head micro pelton turbine based on water hammer phenomenon

Small hydropower has received a great interest in recent years as a source of renewable energy with low investment costs for providing electricity worldwide. Small hydropower does not require construction of large dams compared to the large hydropower stations. The aim of the present study is to provide: (1) detailed performance measurements on a micro Pelton turbine model, (2) detailed measurements on a modified small scale ram pump system based on the principle of water hammer phenomenon, and (3) propose a new hydraulic system to operate the micro Pelton turbine model at the best efficiency point, but at a very low static pressure head of water. A simplified mathematical model was developed and its results were satisfactory and in line with the theory of the Pelton turbine, verifying similarity and repeatability of the model for estimating the turbine performance. The operating conditions (net head and flowrate) of the experimental 10W micro Pelton turbine model with a single nozzle are 20 m of water and 33.01 l/min. Integrating the proposed hydraulic system with the base Pelton turbine model shows that the best efficiency point is reached at a total flow rate of 33 l/min and at only 2.5 m pressure head.