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Charlottesville, VA, United States

Richter B.D.,Global Freshwater Program | Postel S.,Global Water Policy Project | Revenga C.,The Nature Conservancy | Scudder T.,California Institute of Technology | And 3 more authors.
Water Alternatives

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. Source

Fingerman K.R.,University of California at Berkeley | Berndes G.,Chalmers University of Technology | Orr S.,International Freshwater Team | Richter B.D.,Global Freshwater Program | Vugteveen P.,International Union for Conservation of Nature
Biofuels, Bioproducts and Biorefining

Bioenergy expansion can significantly impact water resources in the region in which it occurs. Investment, policy, and resource management decisions related to bioenergy should therefore take this critical consideration into account. Water resource impacts can defy easy quantification because water consumption varies spatially and temporally, different water sources are not necessarily commensurable, and impact depends on the state of the resource base that is drawn upon. This perspective offers an assessment framework that operators and policy-makers can use in evaluating projects to avoid or mitigate detrimental effects. We adapt water footprint (WF) and life cycle assessment (LCA) techniques to the bioenergy context, describing comprehensive life cycle inventory (LCI) approaches that account for blue and green water use as well as for pollution effects, varying sources, coproduct allocation, and spatial heterogeneity. Impact assessment requires that characterization (weighting) factors be derived so that consumption values can be summed and compared across resources and locations. We recommend that characterization draw on metrics of water stress, accounting for environmental flow requirements, climatic variability, and non-linearity of water stress effects. Finally, we describe some location-specific impacts of concern that may not be revealed through common analytical approaches and may warrant closer consideration. © 2011 Society of Chemical Industry and John Wiley & Sons, Ltd Copyright © 2011 Society of Chemical Industry and John Wiley & Sons, Ltd. Source

Jager H.I.,Oak Ridge National Laboratory | Efroymson R.A.,Oak Ridge National Laboratory | Opperman J.J.,Global Freshwater Program | Kelly M.R.,University of Tennessee at Knoxville | Kelly M.R.,Ohio State University
Renewable and Sustainable Energy Reviews

What is the best way to arrange dams within river basins to benefit society? Recent interest in this question has grown in response to the worldwide trend toward developing hydropower as a source of renewable energy in Asia and South America, and the movement toward removing unnecessary dams in the US. Environmental and energy sustainability are important practical concerns, and yet river development has rarely been planned with the goal of providing society with a portfolio of ecosystem services into the future. We organized a review and synthesis of the growing research in sustainable river basin design around four spatial decisions: Is it better to build fewer mainstem dams or more tributary dams? Should dams be clustered or distributed among distant subbasins? Where should dams be placed along a river? At what spatial scale should decisions be made? The following design principles for increasing ecological sustainability emerged from our review: (i) concentrate dams within a subset of tributary watersheds and avoid downstream mainstems of rivers, (ii) disperse freshwater reserves among the remaining tributary catchments, (iii) ensure that habitat provided between dams will support reproduction and retain offspring, and (iv) formulate spatial decision problems at the scale of large river basins. Based on our review, we discuss trade-offs between hydropower and ecological objectives when planning river basin development. We hope that future testing and refinement of principles extracted from our review will define a path toward sustainable river basin design. Source

Vigerstol K.,Global Freshwater Program
Journal / American Water Works Association

Primary and secondary effects of a water sustainability risk assessment are discussed. Primary and secondary effects are defined as physical effects on the hydrologic system resulting from unsustainable water use within the risk assessment framework. Comparison of the latest hydrologic data with the sustainability boundaries of the water bodies within the area of influence will help determine whether cumulative water use is stressing the system sufficiently for primary effects to occur. The latest average monthly flows or water levels that fall outside the sustainability boundaries indicate that the system is affected by this use. Primary effects are those that can be measured within the hydrologic system and are directly connected to water use in the area of influence. The sustainability risk assessment framework also defines secondary effects as the ecologic, social, and economic effects related to unsustainable water use. Source

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