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Lost in Development's Shadow: The Downstream Human Consequences of Dams

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Brian D. Richter at The Nature Conservancy
Brian D. Richter
Sandra Postel
Sandra Postel
Revenga Carmen
Revenga Carmen
Revenga Carmen
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Scudder Thayer
Scudder Thayer
Scudder Thayer
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The World Commission on Dams (WCD) report documented a number of social and environmental problems observed in dam development projects. The WCD gave particular emphasis to the challenges of properly resettling populations physically displaced by dams, and estimated the total number of people directly displaced at 40-80 million. Less attention has been given, however, to populations living downstream of dams whose livelihoods have been affected by dam-induced alterations of river flows. By substantially changing natural flow patterns and blocking movements of fish and other animals, large dams can severely disrupt natural riverine production systems – especially fisheries, flood-recession agriculture and dry-season grazing. We offer here the first global estimate of the number of river-dependent people potentially affected by dam-induced changes in river flows and other ecosystem conditions. Our conservative estimate of 472 million river-dependent people living downstream of large dams along impacted river reaches lends urgency to the need for more comprehensive assessments of dam costs and benefits, as well as to the social inequities between dam beneficiaries and those potentially disadvantaged by dam projects. We conclude with three key steps in dam development processes that could substantially alleviate the damaging downstream impacts of dams.
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... Dam-release flooding remains a specific form of flooding that is under-studied. Approximately 472 million people globally live downstream of large dams whose livelihoods depend on these dams [14]. Dam attenuation effects have been reported to reduce total flood susceptibility by 9%, protecting 590 million people globally from flood exposure [15]. ...
... According to global modelling studies, dams ameliorate flood risk, but locally, they can increase flooding intensity and frequency [22]. Dam releases from spills usually cause flooding downstream [14] but their impacts on livelihoods are context-dependent. More specific evidence from local case studies on livelihood impacts is thus important to inform dam design and management sensitive to specific contexts. ...
A qualitative study of lived experience and life courses following dam release flooding in Northern Ghanaian communities: Implications for damage and loss assessment
Article
Full-text available
Background Dams provide water for industrial, agricultural, and domestic use, particularly in arid regions. However, controlled dam releases due to heavy rainfall may affect downstream communities’ livelihoods and life courses such long-term impacts may be omitted from damage and loss assessments. This study aims to assess the lived experiences and long-term consequences of dam release flooding for downstream populations, comparing these with the typical scope of a damage and loss assessment (DaLA). Methods This research was conducted in two flood-prone districts in the White Volta basin, Ghana, subject to dam spillage. Four Focus Group Discussions (FGDs) with community opinion headers, household heads, chiefs, local politicians, and institutional staff were conducted and analysed, alongside semi-structured interviews with twelve opinion leaders and disaster-related institutions. Results Flood-affected communities struggled to attract partners for marriage due to stigmatisation from flooding impacts. Women outside flooded areas rejected male members’ marriage proposals, while communities offered young girls for marriage to wealthy men for greater financial security. Out-migration of female members to seek better livelihoods frequently led to divorce, subsequently affecting children’s education and well-being. Participants reported long-term trauma from flood-related contact with dangerous wildlife, travel disruption, disease risk, livelihood loss, and accidents. Such life course events and long-term trauma would be omitted from a DaLA exercise. Conclusion Beyond its immediate impacts, flooding undermines family relationships and marriage, impairing children’s education and traumatises affected communities. We recommend livelihood diversification programmes, psychological support and family counselling to address these long-term impacts, with expansion of DaLA’s scope to underpin such support.
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... Generally, construction of dams in rivers has negative social and environmental effects as well. According to Richter et al. (2010), industrial-scale agricultural developments or urban centers have typically benefited from dam construction, while populations dependent on rivers downstream have frequently faced difficult changes to their livelihoods, loss of food security, and other negative effects on their physical, cultural, and spiritual well-being. In most instances, river flows altered by construction of dams have often disrupted and destroyed downstream habitat for aquatic species, as well as fishing, cropping, and grazing systems that rely on these river systems. ...
... In most instances, river flows altered by construction of dams have often disrupted and destroyed downstream habitat for aquatic species, as well as fishing, cropping, and grazing systems that rely on these river systems. While populations relying on rivers downstream may have gained to some extent from improved irrigation options and flood protection offered by dams, detrimental effects are considerably more prevalent and typically outweigh the advantages to downstream people, resulting in a decline of their incomes and livelihoods (Richter et al., 2010). s0125 Deforestation p0335 Deforestation continues to be a major challenge to the freshwater biodiversity found in West Africa (Kamdem- Toham and Teugels, 1999;Kouassi et al., 2021). ...
Rivers of West Africa
Chapter
  • Nov 2024
The West Africa is characterized by varied climatic zones and habitat types, which include the dry Sahel, grassland, and savannah. Related to these habitat types is the highly variable rainfall patterns, which contribute significantly to the region's river dynamics. The large and permanent rivers are found south of the Sahel region. Many of the major rivers of this region such as the Senegal, Gambia, Niger, Volta, and Chad Rivers support rich diversity of plant and animal life. They are transboundary and provide ecosystem services across different countries. This chapter provides a brief review of West African rivers, paying close attention to their associated climate, physiography, biogeography, as well as their geomorphology and hydrology. The chapter finishes by discussing the major threats to rivers of West Africa and some of the conservation initiatives undertaken by different nations and organizations in an effort to ameliorate the threats faced by these rivers. Most of these conservation interventions are focused on large rivers, and it will appear that smaller rivers are not being extended the same attention.
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... Essa tendência é amplificada por fenômenos climáticos extremos, como chuvas intensas, que intensificam a pressão sobre as estruturas, e pela ausência de manutenções preventivas ou modernizações adequadas. Internacionalmente, a construção e operação de barragens têm sido alvo de debates sobre impactos transfronteiriços, disputas geopolíticas e gestão de recursos hídricos (Beck;Claassen;Hundt, 2012;Richter et al., 2010;Tilt;Braun;He, 2009). No Brasil, a relevância do tema é reforçada pela necessidade de políticas que equilibrem desenvolvimento econômico, sustentabilidade ambiental e justiça social. ...
CAPACITAÇÃO DE PROFISSIONAIS ENVOLVIDOS EM SEGURANÇA DE BARRAGENS, SEGUNDO O NOVO MARCO LEGAL
Article
Full-text available
  • Jan 2025
Este estudo analisou a capacitação de profissionais e comunidades potencialmente afetadas por falhas em barragens, com foco no novo marco regulatório brasileiro. O trabalho examinou a evolução dos programas de treinamento, especialmente após o desastre de Brumadinho, em 2019. A metodologia incluiu levantamento bibliográfico, estudo de caso e análise comparativa com programas internacionais, como o modelo da Federal Emergency Management Agency dos Estados Unidos. Os resultados revelaram que, embora existam avanços normativos, persistem deficiências em abordagens preventivas e treinamentos comunitários. Observou-se que 96% dos estudos analisados priorizam aspectos técnicos, negligenciando a preparação social e educacional das comunidades vulneráveis. A análise destacou a necessidade de integrar planos de ação de emergência com capacitações e simulações práticas para fortalecer a resiliência local. As propostas incluem a adoção de ciclos contínuos de treinamento, baseados no modelo Homeland Security Exercise and Evaluation Program , bem como o fortalecimento das políticas de compliance e governança. Recomendou-se a criação de equipes internas dedicadas à gestão das barragens e o desenvolvimento de plataformas digitais para disseminação de informações e monitoramento em tempo real. Conclui-se que a implementação de estratégias proativas, aliadas à modernização das práticas de gestão e capacitação, é essencial para reduzir vulnerabilidades e mitigar os impactos de desastres. O estudo fornece diretrizes aplicáveis tanto para empreendedores quanto para gestores públicos, contribuindo para a segurança e sustentabilidade ambiental.
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... Commercially important species populations, such as salmon, are impacted by the resulting loss of habitat, and the introduction of competitors and predators (Havel et al., 2005). Human populations living along, or around fragmented rivers can suffer from dam safety issues or community uprooting (Duda and Bellmore, 2022;Richter et al., 2010). ...
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... It is not enough to focus solely on the project's financial worthwhile planning or executing its development. We also need to consider how the project will affect the local community not to mention wildlife as well as the environment [8]. ...
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... Many dams store practically the entire sediment load of the drainage basin [Richter 2010]. The shape of the channel, floodplain, and coastal delta is affected by the decrease in sediment load in rivers downstream of dams. ...
The environmental impact of dam construction in a wetland area. A case study Boukhroufa (El Taref) Algeria
Article
  • Oct 2024
This article presents an approach to the assessment of the environmental impact of a dam construction for agricultural use in the Boutheldja region. This region's environment is rich in natural resources and forms a part of the El Kala National Park (P.N.E.K). It was designated a wetland of international importance under the Ramsar convention by UNESCO in 1983 and later declared a biosphere reserve in 1990. It is among the most significant aquatic areas in this region (contains about 40% of surface water resources). The physical characteristics of the watershed support the construction of the dam, although there could be a number of unfavorable effects: upstream-including soil erosion and reservoir sedimentation, reduced storage capacity, lower water quality and loss of productivity of flooded area; downstream-removal of silt from downstream flows, loss of fertilising functions, changes in water quality, changes in productivity, reduction in natural floods, loss of access to resources and ecological disturbance. Such processes will have an impact on an ecosystem so fragile. Although Boukhroufa dam provides significant benefits to the city, such as controlling stream regime, preventing floods, and supplying agricultural water from stored water, it also has significant negative effects on the surrounding watershed ecosystem.
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... It has been estimated that dams impact approximately 48 % of global river water volume (Grill et al. 2015) and that reservoirs contribute to a 7.3 % increase in the Earth's naturally occurring surface freshwater (Lehner et al. 2011). The effects of dams extend beyond the reservoir and can be demonstrated both upstream and downstream (Ligon et al. 1995;Richter et al. 2010) in aquatic and riparian biotopes (Poff & Zimmerman 2010). Dams alter habitat characteristics by fragmenting the river continuum and severely modifying river flow, resulting in lower peak flows, changed flooding regimes, reduced inundation, and reduced transport of particles (Ligon et al. 1995;Poff et al. 1997;Nilsson et al. 2005;Brenna et al. 2021). ...
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Big Meadow Bog: A Lost Backyard
Chapter
  • Jan 2025
Big Meadow Bog provided berries and game and medicinal plants for the first people, the Mi’kmaw, and continued to do so for the first settlers. Their livelihoods and island economy were based on the coastal fishery but the Meadow was part of life and tradition. Paths from the village of Westport ran the length of the Meadow leading to berry picking areas, pools with duck, and the beach at the south end of the wetland complex. The Meadow continued to function as a “commons” for people to harvest berries and hunt until it was ditched in 1958. The ditching lowered the water table and altered the ecosystem so that shrubs and brambles grew up making a barrier that separated the village from the Meadow. The bog vegetation was lost and the pools were drained. We argue that when the hydrology of a wetland is fundamentally altered, the traditional uses of that wetland by local people are also lost. The margin, the “lagg”, of Big Meadow Bog was a key habitat for the Endangered Eastern Mountain Avens, Geum peckii. Conservation concern and the recovery efforts aimed at this plant provided the rationale for the wetland restoration discussed throughout this book. This restoration effort and the boardwalk from the village into the bog have reconnected the village with this lost backyard and have renewed an appreciation of the Meadow and a sense of pride in its globally rare Avens.
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Understanding Environmental Factors Influencing Vegetation Cover Downstream of Dams
Article
  • Nov 2024
Environmental assessment and management of dams are essential for understanding and mitigating their impact on downstream vegetation in arid and semi-arid regions. These regions pose challenges due to water scarcity and extreme climatic conditions. This study uses remote sensing technology to investigate the complex relationships between downstream vegetation changes before and after dam construction and various environmental factors, including land surface temperature, soil moisture, soil salinity, groundwater, runoff water, temperature, and precipitation. This study is notable for its comprehensive parameters and methods, providing unique insight into the direct and indirect impacts of dam construction on vegetation dynamics across diverse climatic regions. The examination encompasses four case studies, including Hali and Baish in Saudi Arabia and Lakes Argyle and Julius in Australia. This analysis utilizes satellite imagery and reanalyzed data, which allow consideration of a long time scale without any restrictions. A moderated mediation analysis explores the direct and indirect associations between downstream flows, environmental factors, and vegetation. Additionally, factor analysis using Principal Component Analysis (PCA) and Two-Step Clustering analysis is utilized to gain deeper insights into the underlying correlations and groupings within the dataset. The research findings highlight the significant roles of runoff, groundwater, soil salinity, and other environmental factors in influencing vegetation before and after dam construction in arid and semi-arid regions. Before dam construction in Hali and Baish, soil salinity, precipitation, and groundwater were key factors for vegetation, with runoff directly affecting arid areas. After construction, soil salinity and groundwater remained crucial, but runoff's direct impact ceased. In semi-arid regions like Lake Argyle and Julius, soil moisture, soil salinity, precipitation, and groundwater remained important, with runoff affecting vegetation cover. The study emphasizes the need to consider these factors, along with the use of remote sensing technology, in ecological and land management studies, noting that factors influencing vegetation dynamics changed significantly before and after dam construction.
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Influência da operação da UHE de Foz do Chapecó (SC) nos níveis do Rio Uruguai no Salto do Yucumã, Parque Estadual do Turvo (RS)
Article
Full-text available
  • Oct 2024
A instalação e operação de uma Usina Hidrelétrica (UHE) podem causar diversos impactos ambientais, os quais podem ser agravados de acordo com as condições ambientais locais. Este estudo, teve por objetivo identificar e descrever o padrão de escoamento fluvial resultante da operação da UHE Foz do Chapecó (SC) no Rio Uruguai, no trecho compreendido entre a usina e os Saltos do Yucumã (localizados no Parque Estadual do Turvo-PET, RS). Para isso, foram coletadas informações pluviométricas e fluviométricas das estações de Foz do Chapecó Jusante, Iraí, Itapiranga e da estação de monitoramento experimental instalada nos Saltos do Yucumã, durante o período de 18/02/2018 a 11/03/2018. A análise de dados fluviométricos e pluviométricos coletados permitiu identificar que a onda de cheia (níveis máximos) demora, em média, 17:22 h para se propagar entre a UHE Jusante e os Saltos do Yucumã (PET), levando 2:28 h horas até Iraí (eleva em média 268,4 cm), mais 11:30 h até Itapiranga (eleva em média 142,47 cm) e outras 3:24 h até o Salto do Yucumã (eleva em média 245,52 cm). A velocidade de ascensão dos níveis atinge 45,50 cm h-1 no Salto do Yucumã, o que decorre da geomorfologia do canal assemelhando o comportamento ao observado na zona de descarga da UHE. As características desse escoamento tornam a região um local de elevada fragilidade ambiental sendo necessário o acompanhamento do processo hidrológico e a identificação dos impactos ambientais que decorrentes das oscilações sub-horárias dos níveis do Rio Uruguai nos Saltos do Yucumã.
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Assessing Environmental Flow Requirements and Trade-Offs for the Lower Zambezi River and Delta, Mozambique
Article
Full-text available
  • Jul 2010
The Zambezi Delta is vital to Mozambique's national economy and is a Wetland of International Importance. Large dams in the Zambezi catchment have substantially altered the magnitude, timing, duration, and frequency of flooding events in the delta, resulting in adverse ecological and socio-economic changes. We evaluated conflicts/trade-offs among various water uses and the potential for improving delta conditions through environmental flow releases from Cahora Bassa Dam, using the downstream response to imposed flow transformations (Brown, C.A. and Joubert, A., 2003. Using multicriteria analysis to develop environmental flow scenarios for rivers targeted for water resource development. Water SA, 29 (4), 365–374; King, J.M., Brown, C.A., and Sabet, H., 2003. A scenario-based holistic approach to environmental flow assessments for regulated rivers. Rivers Research and Applications, 19 (5–6), 619–640) model. Five variations in low flows, 18 alternatives for annual floods, and one extreme (1:5 year) flood were considered for a range of uses/concerns, including commercial and small-scale agriculture, estuarine ecology, coastal and freshwater fisheries, livestock, large mammals, waterbirds, vegetation, invasive species, natural resources, water quality, navigation, and groundwater recharge. The study revealed minimal trade-offs among different uses with regard to reinstating environmental flows. The majority of user-representatives perceive reinstatement of the annual flood to be beneficial and the perceived benefits increase with increased magnitude and prolonged duration, provided the timing of the annual flood occurs during the normal wet season. Simulation modelling of the Zambezi system dam operation indicates that these environmental flow releases can be realized within the constraints of firm power commitments and total energy demand. Of the 18 annual flood change levels considered, 7 can be generated with a firm power reliability >95% and hydropower reductions of
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Indirect Economic Impacts of Dams
Chapter
Full-text available
  • Oct 2012
Dam projects generate a vast array of economic impacts—both in the region where they are located, and at inter-regional, national and even global levels. These impacts are generally evaluated in terms of additional output of agricultural commodities, hydropower, navigation, fishing, tourism, recreation, prevention of droughts and reduction in flood damages, and are referred to as direct impacts.
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Can hydropower be sustainable?
Article
Full-text available
  • Oct 2007
A lot of hydro power companies are now planning and constructing a hydro power dams as an alternative source of energy. Among companies that planned and constructed hydro power dams are the China Three gorges Power Corporation (CTGPC) of which declared another four set of dams project of the which the two of four dams will be located on the upper mainstem of the Yangtze, known as the Jinsha Jiang to provides a capacity of 36,000MW, two times the original design capacity of Three Gorges. A joint venture, Jinshajiang Hydropower Development Corporation that are planned to raised eight more dams on the Jinsha Jiang to produce a capacity of 20,000MW as well as Ertan Hydropower Development Company that propose for a 21 dam that will produce a total capacity of 25,000MW3. Although, this hydro power has low emissions of greenhouse gases and capable of meeting pressing energy demands with current technology, this dams can cause serious downstream impacts, as well. To address this issues, a higher standard of hydro power is needed of which is carefully planned and operated in order to achieve much energy benefit within boundaries consistent with the protection of natural freshwater ecosystems and its valuable social benefits.
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Sinking Deltas due to Human Activities
Article
Full-text available
Many of the world’s largest deltas are densely populated and heavily farmed. Yet many of their inhabitants are becoming increasingly vulnerable to flooding and conversions of their land to open ocean. The vulnerability is a result of sediment compaction from the removal of oil, gas and water from the delta’s underlying sediments, the trapping of sediment in reservoirs upstream and floodplain engineering in combination with rising global sea level. Here we present an assessment of 33 deltas chosen to represent the world’s deltas. We find that in the past decade, 85% of the deltas experienced severe flooding, resulting in the temporary submergence of 260,000 km2. We conservatively estimate that the delta surface area vulnerable to flooding could increase by 50% under the current projected values for sea-level rise in the twenty-first century. This figure could increase if the capture of sediment upstream persists and continues to prevent the growth and buffering of the deltas.
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The value of water: Floodplain versus large-scale irrigation benefits in Northern Nigeria
Article
  • Sep 1998
Many African river floodplains are disappearing or being modified as the result of water management activities, in particular large-scale irrigation schemes. Often any resulting impact on downstream wetland benefits is ignored. By combining hydrological and economic analyses we simulate different scenarios for large-scale irrigation schemes in the Hadejia-Jama'are River Basin in northern Nigeria. We compare the agricultural, fishing and fuelwood benefits lost through reduced flooding downstream against the gains from increased irrigation production upstream. Our analysis suggests that the irrigation benefits can only partially replace the lost benefits from reduced floodplain inundation. Given that several upstream irrigation schemes are completed or currently under construction, our simulations show that the introduction of regulated flood releases is the best hope of minimizing further losses of floodplain benefits. Further expansion of large-scale irrigation within the river basin should also be avoided.
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The Downstream Impacts of Dam Construction: A Case Study from Nigeria
Article
  • Jan 1985
The Bakolori Dam was built in the mid-1970s on the River Sokoto in Northwest Nigeria to supply a 30 000 ha irrigation scheme. The dam reduced the magnitude of the wet season floods which supported an extensive and sophisticated agricultural system and a fishery on which a population of some 50 000 people depended. Reduced flooding caused a shift from rice to lower value millet and sorghum crops in the wet season, and a significant reduction in the extent of dry season cultivation. Fish populations apparently declined, and fishing decreased. Estimates of the consequent loss of production show how a more complete economic appraisal of the scheme at Bakolori would have been less favourable than the calculation upon which it was approved. Downstream effects of dam projects are rarely considered in project appraisal. Some reasons for this are discussed, and opportunities for remedial development in the flood-plain are outlined.
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Livelihood functions of Inland fisheries: Policy implications in developing countries
Article
  • Aug 2005
An improved analytical framework and typology of fishers are provided to improve understanding of the diverse livelihood functions of inland fishing in development policy making. Inland fisheries make an important but often neglected contribution to rural livelihoods in developing countries. A holistic and widely applicable analysis of the possible livelihood functions of such fisheries is presented, focusing on fishing as one activity within diverse livelihoods. Four different livelihood strategies are identified, involving fishing as: (i) a primary livelihood of last resort, (ii) part of a diversified semi-subsistence livelihood, (iii) a specialist occupation and (iv) part of a diversified accumulation strategy. The policy implications of these strategies are found to be differentiated and poorly represented in practice by socio-economic analysis that either undfervalues fisheries or treats them solely as livelihoods of last resort and by traditional approaches to fisheries management centred on stock conservation. The need for a more diverse and flexible range of measures, tailored to local priorities and conditions and ensuring that poor people can access the benefits of inland fisheries whilst achieving conservation objectives, is identified.
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The Need and Justification for Maintaining Transboundary Flood Regimes: The Africa Case
Article
  • Jan 1991
  • NAT RESOUR J
In this article the author argues the need for a new approach to African river basin development whereby dams combine hydropower generation with the release of a controlled flood, synchronized with reservoir drawdown, for the benefit of riverine populations and eco-systems. Annual flood regimes have sustained the economies of mil-lions of African producers for centuries without environmental degradation. Not only are those producers dependent on annual flood regimes, but their productivity, with associated multiplier effects, could be significantly increased by low resource development strat-egies, including the improved water management that controlled flooding would provide.
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