The legacy of large dams and their effects on the water-land nexus

Abstract

Large dams trigger controversial effectsMan-made river dams and reservoirs have increasingly been constructed to modify free-flowing rivers to benefit society through hydropower generation, irrigation, and other water supplies, navigation, and flood prevention. However, this ongoing global boom (Zarfl et al. 2015) also triggers harmful outcomes to local, directly affected stakeholder groups, and the environment. Particularly, profound social impacts of involuntary resettlement need alleviating measures and room for remembrance. Restoring vital characteristics of aquatic ecosystems after artificial reservoir establishment, to any possible degree, may contribute to higher welfare and sustainability.Large reservoirs cause both particularly large positive and negative effects on society, the economy, and the environment. In Brazil, reservoirs were initially constructed for the primary purpose of hydroelectricity generation, to prevent flooding, and to provide irrigation capacities in the dryer parts of the country. However, an increasing number of users and usages have increased the pressure on stored and flowing water. Their requirements differ in terms of river discharge, water quality, and reservoir levels, most often reducing the options of the water users downstream. The resolution of conflicts over water allocation and management has been legally supported by the Brazilian Water Act since 1997, which introduced the paradigm of multiple and equally important water uses.Several of these water uses are closely linked to land-use practices, particularly irrigated agriculture. By law, domestic supply for the river basin's residents sets a priority for water consumption during pronounced water scarcity. In terms of accessibility and water quality, water abstraction for domestic supply is being affected by water levels. Domestic water supply is also directly linked to water pollution through dilution of untreated wastewater in the river or reservoir. The intertwined and often divergent necessities and externalities of water and land use call for a coordinated management and governance approach to mitigate conflicts. Yet many of * Marianna Siegmund-Schultze m.siegmund-schultze@tu-berlin.de Maria do Carmo Sobral msobral@ufpe.br Márcia M. G. Alcoforado de Moraesthe natural and societal processes underlying these conflicts have not been sufficiently understood. Climate change causes additional burdens on river basins. While a general rainfall reduction has not been confirmed by climate simulations in the semi-arid regions of Brazil (increasing as well as decreasing climate model simulations have been proposed), rising temperature projections are more certain. These conditions will impact the growth of cultivated crops and natural vegetation, as well as increase heat stress on domestic and wild animals. The subsequent change of habitats will ultimately affect the provision of ecosystem services.The INNOVATE project (Interplay among multiple uses of water reservoirs via in novative coupling of aquatic and terrestrial ecosys...

Management of Tropical River Basins and Reservoirs under Water Stress: Experiences from Northeast Brazil

“…An evaluation of the environmental impacts of the 30-year-old Itaparica Reservoir (actually called Luiz Gonzaga Reservoir) in the São Francisco river has been the focus of a research program [12,[16][17][18]. The São Francisco River has a length of 3160 km and is the 25th largest river worldwide, stretching from Minas Gerais in the rainy Southwest of Brazil, to the dry zone of Northeast Brazil.…”

Interdisciplinary Reservoir Management—A Tool for Sustainable Water Resources Management

“…The social surrounding is linked in a myriad of ways to most processes within and around the reservoir, connected e.g., to the land use, the social fabric and the governance, from the first planning stages to the implemented infrastructure. Social impacts of reservoirs therefore occur in a complex setting of time, space and value spheres [8][9][10]19,[143][144][145][146][147][148]. The land use in the upstream catchment area influences amongst others erosion processes, the resulting sediment yield and the amount of sediments which reach rivers and reservoirs (see Section 3.1), nutrient input, e.g., from agricultural uses [149] or sewage treatment plants, but also hydrological aspects [22,150,151].…”

Water Reservoirs as a Driver of Anthropogenic Changes in Landscape and Transport Networks: The Czech Republic Experience

“…The continuous supply of water to a company cannot be ensured without accumulation in reservoirs. Human-made rivers, dams, and reservoirs have increasingly been constructed to modify free-flowing rivers to benefit society through hydropower generation, irrigation, other water supplies, navigation, and flood prevention [8]. Dams and reservoirs play an important role in controlling and managing water resources.…”

“…Another topic is the prediction of future landscape development pathways in the vicinity of reservoirs, based on the past land-use change trajectories [44]. The construction of reservoirs is controversial because of the potential negative impacts on not only the land-use change but also the population, economy, industry, and agriculture [8,45].…”