SummaryMore than 100 hydropower dams have already been built in the Amazon basin and numerous proposals for further dam constructions are under consideration. The accumulated negative environmental effects of built and proposed dams, if constructed, will trigger massive hydrophysical and biotic disturbances that will impact the Amazon basin's floodplains, estuary, and sediment plume. By introducing a Dam Environmental Vulnerability Index (DEVI) we quantify the current and potential impacts of dams in the basin. The scale of foreseeable environmental degradation indicates the need for collective action among nations and states to avoid cumulative, far-field impacts. We suggest institutional innovations to assess and avoid the likely impoverishment of Amazon rivers.
Background: Competition for freshwater between cities and agriculture is projected to grow due to rapid urbanization, particularly in the Global South. Water reallocation from rural to urban regions has become a common strategy to meet freshwater needs in growing cities. Conceptual issues and associated measurement problems have impeded efforts to compare and learn from global experiences. This review examines the status and trends of water reallocation from rural to urban regions based on academic literature and policy documents.Methods: We conduct a systematic literature review to establish the global reallocation database (GRaD). This process yielded 97 published studies (academic and policy) on rural-to-urban reallocation. We introduce the concept of reallocation 'dyads' as the unit of analysis to describe the pair of a recipient (urban) and donor (rural) region. A coding framework was developed iteratively to classify the drivers, processes and outcomes of water reallocation from a political economy perspective.Results: The systematic review identified 69 urban agglomerations receiving water through 103 reallocation projects (dyads). Together these reallocation dyads involve approximately 16 billion m 3 of water per year moving almost 13 000 kilometres to urban recipient regions with an estimated 2015 population of 383 million. Documented water reallocation dyads are concentrated in North America and Asia with the latter constituting the majority of dyads implemented since 2000.Synthesis: The analysis illustrates how supply and demand interact to drive water reallocation projects, which can take many forms, although collective negotiation and administrative decisions are most prevalent. Yet it also reveals potential biases and gaps in coverage for parts of the Global South (particularly in South America and Africa), where reallocation (a) can involve informal processes that are difficult to track and (b) receives limited coverage by the English-language literature covered by the review. Data regarding the impacts on the donor region and compensation are also limited, constraining evidence to assess whether a water reallocation project is truly effective, equitable and sustainable. We identify frameworks and metrics for assessing reallocation projects and navigating the associated trade-offs by drawing on the concept of benefit sharing.
Competition for freshwater resources is intensifying water scarcity and its impacts on people, economies, and the environment, posing a growing challenge for sustainable development. Meeting these challenges will require incentives to encourage sustainable water use. Prior calls to shift from supply-driven solutions to a soft path of demand management (pricing, markets, behavioral changes) have encountered stubborn obstacles. We undertake a multi-scale assessment of water reallocation and investment in water conservation technologies to understand their potential and limits for addressing different drivers of water scarcity. Our model identifies what drives water scarcity at the subbasin scale, and examines two prominent responses to these drivers. Our analysis distinguishes different types of water scarcity based on the demands for water and their timing, creating nine (9) categories of water competition, which can overlap. Water demand within agriculture contributes to scarcity in 94% of the basins experiencing scarcity, concentrated in central USA, Spain, and India. Urbanization has led to competition between cities and agriculture in 1,596 of 3,057 subbasins (52%). We examine how different institutional mechanisms (incentive-based water reallocation) and technologies (investment in water conservation technologies) can address these different types of water scarcity. This study builds on several local and high-resolution models demonstrating the potential to increase the economic efficiency (and marginal productivity) of water use. The gap between potential and implementation is high, however. Efforts to bridge this gap in priority geographies can link modelling advances with the design of pathways that combine incentives with robust water accounting, caps on water extraction, and enforcement capacity at multiple scales.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.