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Lessons learnt and recommendations
Published in Ljiljana Spasic-Gril, Dams Safety and Society, 2023
The lifespan of any dam is as long as it is technically safe and operable. In view of the high damage potential of large storage dams, the safety must be assessed based on an integral safety concept, which includes the following elements: Structural safetySafety monitoringOperational safetyEmergency planning
Water Harvesting
Published in Sandeep Samantaray, Abinash Sahoo, Dillip K. Ghose, Watershed Management and Applications of AI, 2021
Sandeep Samantaray, Abinash Sahoo, Dillip K. Ghose
Over a period of time, sedimentation will decrease the capacity of the dam. Hence, during the planning procedure, the licence owner must take into consideration the capacity of dam for filling with silt and the measures needed to be undertaken for reducing the possibility of its occurrence. To stop huge volumes of sediment from entering a dam, certain erosion control and drainage measures must be undertaken for reducing the potential of sedimentation process. Once construction of the dam gets over, regular inspections and maintenance are required for ensuring good operational condition of the dam.
Floods: Riverine
Published in Yeqiao Wang, Wetlands and Habitats, 2020
William Saunders, Alison MacNeil, Edward Capone
The purpose of a dam is to retain or store water for any of several reasons, such as consumptive water supply, irrigation, flood control, energy generation, recreation, pollution and sediment control, and low flow augmentation. Many dams fulfill a combination of these functions.
A complex balance: assessing perspectives on decommissioning large dams to restore river ecosystems
Published in Water International, 2023
Joshua Matanzima, Teboho Mosuoe-Tsietsi
For proponents, there are at least four arguments in favour of decommissioning ageing or ‘unnecessary’ dams. These are public safety (the ageing dam infrastructure pose a safety risk), reducing maintenance costs, delaying reservoir sedimentation and environmental restoration (such as restoring river ecosystems; Duda & Bellmore, 2022; Hanks, 2020). The safety risks of large dams are mainly associated with dam failures, which may result from ‘excessive seepage (piping), cracking, overtopping, or structural failure’ linked to poor design or construction, lack of maintenance or operational mismanagement (Perera et al., 2021). Decommissioning minimizes dam failure risks because the water is discharged in low volumes, and in this way it is less likely to cause harm on the environment. Although dam failure may occur at any stage during the life of a dam, older dams (50 years or more) represent a higher risk to public safety, especially for downstream areas, more so when they are poorly maintained (Zhang et al., 2009). While the failure of dams generally has low probability, its associated consequences, which may be fatal, make it high risk, and should therefore not be tolerated (Bowles et al., 1999). Figure 4 shows recorded dam failure accidents from 1950 to 2019.
Bringing twentieth-century water projects into the twenty-first century: The case for revisiting dam operations in Alberta
Published in Canadian Water Resources Journal / Revue canadienne des ressources hydriques, 2018
Reed D. Benson, Stewart B. Rood
Environmental restoration of dammed rivers. In recent decades, science has produced a much clearer picture of the environmental impacts of dams on downstream rivers. Impacts of dam operations may include high fluctuations in daily flows, changes in water quality and temperature, alteration of natural seasonal flow patterns, scouring or down-cutting of the river channel, and negative impacts on native aquatic and riparian species caused by habitat loss (Collier et al. 2000). Recognizing these impacts, water policy scholars have called for changes in dam operating practices to improve water management and mitigate environmental impacts (Richter and Thomas 2007; Pittock and Hartmann 2011; Benson 2017). Much of the focus to date has been on hydropower projects, where operational changes have benefited downstream fish populations and other resources (Locke et al. 2008).
Effects of dams on riverine biogeochemical cycling and ecology
Published in Inland Waters, 2018
Fushun Wang, Stephen C. Maberly, Baoli Wang, Xia Liang
Modern dam construction began in 1900 and boomed from about 1950 with the use of concrete and innovation in excavation (Fig. 1). Currently, ∼70% of the world’s rivers are intercepted by dams (Kummu and Varis 2007), and in China, >80 000 reservoirs were constructed by the end of 2008, among which were >5000 dams higher than 30 m (http://www.chincold.org.cn). Dams are built to store water for various purposes. Accompanied with the rapid increase of dam construction (from 1948 to 2010), the global active storage capacity of reservoirs grew from about 200 to >5000 km3, >70% of the total global reservoir capacity (7000–8000 km3; Vörösmarty 1997, Zhou et al. 2016). The number of reservoirs will increase in the future with the restart of the hydropower loan project by the World Bank (World Bank 2009) and the motivation to increase renewable energy sources (Hermoso 2017).