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Across the globe, water sources are managed to supply energy, drinking water, grow food, and control floods. To meet our increasing needs, water planners are struggling to secure adequate supplies. However, with progressive policies to guide careful planning and management, human needs for water can be met while maintaining freshwater ecosystem health.
In recent decades, scientists have amassed considerable evidence that naturally-varying water flows are essential to the health and sustainability of freshwater ecosystems.
Environmental flows refer to the quality, quantity and timing of water flows required to sustain healthy freshwater ecosystems and the benefits they provide to human communities. Integrating environmental flow considerations into water management results in healthier freshwater ecosystems that benefit nature and people.
The Nature Conservancy provides global leadership in environmental flow science and management, and informs policies to protect and restore rivers for nature and for people.
Providing Support
To help others implement environmental flows, Conservancy staff work in partnership with government agencies, multilateral institutions, water management agencies, the hydropower industry, the scientific community, and other non-governmental organizations around the world. Recently, scientists, water managers and others signed the Brisbane Declaration, calling for the global protection and restoration of environmental flows.
We have developed tools and methodologies for application at individual projects as well as approaches that work at a river basin or regional scale. Conservancy scientists provide training in these methods, while continuing to develop and refine new approaches for protecting freshwater habitats.
Ecological Limits of Hydrologic Alteration (ELOHA):
- A scientifically robust and flexible framework for assessing environmental flow needs across large regions, such as a states, provinces, major river basins, or entire countries.
- Helps scientists understand the ecological ramifications of human-induced alterations in river flows over a large geographic region.
- Information gathered through ELOHA allows water managers and stakeholders to develop environmental flow targets for rivers without requiring detailed, site-specific hydrologic or biological information for each river.
- Compared to river-by-river approaches, ELOHA can be rapid, cost effective, and practical to implement.
Ecologically Sustainable Water Management (ESWM):
- A six step framework that determines how to meet people’s water needs by storing, diverting and releasing water in a manner that either sustains or restores a river’s ecological integrity.
- Begins with understanding which aspects of river flow are necessary to sustain or restore the river’s integrity, assesses how human activities influence water flow, and then identifies areas of incompatibility between human and ecosystem water needs.
- These investigations provide a foundation for taking the next steps, including searching for solutions that resolve incompatibilities, conducting water management experiments to test new approaches, and designing and implementing an adaptive management plan that improves water management for the long term.
Multi-Stakeholder Approach:
- By working together, stakeholders, scientists and engineers can integrate environmental flow considerations into their river management plans.
- To start this process, stakeholders define goals for river ecosystem health and then work with river scientists to translate these goals into specific, quantified environmental flow recommendations.
- Through this process, participants gain a clear understanding of the environmental flows that must be included in the management plan, and how it will support the stated goals for the ecosystem given technical, financial and social constraints.
Software:
- Indicators of Hydrologic Alteration (IHA) is a free software program developed by Conservancy scientists, which provides useful information for developing environmental flow recommendations and understanding the impacts of human activities on water flows.
- IHA can display statistical information about water flow changes and trends in multiple formats, such as comparing the water flow in a particular river between pre-dam and post-dam periods.
- Water resource managers, hydrologists, engineers, ecologists, researchers and policy makers around the world use it to evaluate present practices and to guide decisions regarding proposed water management scenarios.
For more information and access to these products, please visit the practitioner pages.
Nature picture credits (top to bottom, left to right): Photo © Mark Godfrey (waterfall); Photo © Dick Dewey (salmon on Eel River).
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