Environmental flows defined using the Savannah Process explicitly ignore all real or perceived constraints to their immediate implementation, including those that are physical, legal, social, political, or financial.
Nicknamed the “Savannah Process” for the river where it was first applied, the process described in Richter et al. (2006) is designed to be science-based, deeply interdisciplinary, adaptive, and flexible enough to be customized based on available time and resources. The Savannah Process involves the following five basic steps (Figure 2):
1. Orientation Meeting – This is the kickoff of the Savannah Process, bringing together diverse scientists and representatives from all key agencies and organizations
with water management interests in the basin. The remaining steps (Steps 2-5), expected timeline, products, costs, and roles and responsibilities are outlined and discussed. Orientation meetings have involved between 40 and 100 people.
2. Literature Review and Summary Report – A small team of scientists is tasked with: (a) conducting an extensive review of existing published research and gray literature related to flow-ecology relationships in the river and similar rivers in the region; and (b) synthesizing this information into a “summary report” designed to inform the environmental flow workshop (Step 3). This team has a designated lead, typically consists of 5-10 scientists, and needs to be diverse in its expertise. For example, a team might consist of a hydrologist or fluvial geomorphologist, fish and mussel experts, and riparian and estuarine ecologists. Drafts of both the literature review and summary report are distributed for comment to all who attended the orientation meeting, with comments addressed and the reports redistributed a month prior to the flow workshop.
3. Environmental Flow Workshop – This facilitated workshop, which is typically an intensive 2-3 day event, produces two very important products. The first is a unified set of environmental flow recommendations that give consideration to river, floodplain, and – where appropriate – estuarine systems, and encompass requirements for low flows, high flow pulses, and floods for different year types (e.g., climatically dry, average, and wet years). Each of the environmental flow components that make up the recommendations are quantified (flow magnitude, duration, timing, frequency, and rates of change) and explicitly stated in terms of the ecological processes that are hypothesized to support (Figure 3). The second product is a prioritized list of information gaps to help guide research and monitoring efforts. These flow workshops have involved between 35 and 90 people.
|20,000-40,000 cfs: 2-3 days, 1/month (Jan-May)
- Provide predator-free habitat for birds
- Disperse tree seeds
- Transport fish larvae
- Flush woody debris from floodplain to channel
- Floodplain access for fish
- Fish passage past NSBLD
|Figure 3. A portion of the environmental flow recommendation for the Savannah River. The magnitude, duration, and frequency of this controlled flood are quantified, as are the ecological processes that will be supported by the flow event.
4. Environmental Flow Implementation – This involves modifying reservoir operations or other water management practices to create river flows as called for in the workshop recommendations (Step 3). In terms of implementation, defined environmental flows tend to fall into one of three categories: (a) those that can be implemented immediately without significant conflict, (b) those that require study – typically involving computer modeling – to assess the implications of their implementation, and (c) those with significant social and/or economic implications that require long-term planning and likely substantial investment to implement.
5. Monitoring and Research – As noted above, a list of priorities for monitoring and research is one of the important products emerging from the flow workshop (Step 3). Each of the environmental flow components that comprise the recommendations is linked to specific ecological processes. They are, in effect, hypotheses that are tested through coordinated reservoir operations and monitoring. These hypotheses and the scientific knowledge gaps identified and ranked during the workshop provide a foundation for setting formal monitoring and research priorities.
The time and cost for this process varies. To date, environmental flows have been defined (Steps 1-3 completed) at six of the nine SRP sites, taking a total of six to 12 months and costing between $40,000 and $90,000. Environmental flows have been partially implemented (Step 4) at five of these sites, along with different degrees of associated monitoring and research (Step 5). Implementation involves planning, such as storing water earlier in the year, but it is also responsive to specific circumstances such as large rainfall events. Most of the engineer-scientist teams meet quarterly to discuss and coordinate reservoir releases and monitoring for the upcoming season. Estimated costs for monitoring and research at SRP sites range from a low of less than $10,000 to more than $150,000 per year. Sites at the higher end of this range are those where more intensive fieldwork was conducted to support computer model development.
Environmental flows defined using the Savannah Process explicitly ignore all real or perceived constraints to their immediate implementation, including those that
are physical, legal, social, political, or financial. The purpose of the process is to define the river flows that are necessary to maintain long-term ecosystem health. Any necessary tradeoffs between this goal and other expectations for water management are made elsewhere. This approach to defining environmental flows has: (1) helped advance understanding of the ecosystem processes that will not be supported by different management options, and (2) highlighted opportunities to align ecosystem restoration or protection with other more traditional human demands for water such as improving flood control or hydropower generation.
In collaborating to move through the Savannah Process, water managers and scientists establish working relationships that are mutually beneficial. At each of the SRP sites where environmental flows have been defined and are being implemented, formal and informal conversations now occur between these groups on a quarterly, monthly, or even weekly basis. The engineers benefit from having real-time access to experts who can provide constructive guidance on how to meet multiple management objectives in the most ecologically beneficial (or at least benign) way. The scientists benefit by engaging the water managers – those who control river flows – as partners in research. As a collective, they are positioned to run experiments to determine how different flow conditions relate to ecosystem health and the goods and services humans derive from healthy ecosystems. This relationship is ongoing and allows for experimentation not only around a single event or for a single year, but for a long series of years. This directly supports adaptive management and serves to advance river science.
Finally, the Savannah Process has begun to see application beyond the SRP and the United States. The process is currently being used to define environmental flows for municipal water supplies involving dams and ground water extraction in places such as the Rivanna River in Virginia and the Verde River in Arizona. The process is also being applied in China and Honduras, the latter of which is faced with a dearth of scientific information and is relying heavily on indigenous knowledge. It is in part this flexibility that has gained the process a growing acceptance. Moreover, it is the pairing of engineers and scientists through the process that will lead to improved management, advances in science, and better protection and restoration of rivers globally.
Richter, B.D., A.T. Warner, J.L. Meyer, and K. Lutz. 2006. A Collaborative and Adaptive Process for Developing Environmental Flow Recommendations. River Research and Applications 22:297-318.
Andrew Warner is a Senior Advisor for Water Management with The Nature Conservancy’s Sustainable Waters Program. He also is the Conservancy’s National Coordinator on the Sustainable Rivers Project, a national collaboration between TNC and the U.S. Army Corps of Engineers. Andy has 18 years of experience in the environmental and conservation fields on projects and policy relating to water, water quality, and floodplain management. In his current position, Andy works with government agencies, academic institutions, and private organizations to identify and implement innovative water management strategies that meet human demands while maintaining healthy ecosystems. Andy received a Master of Science in Watershed Science from Colorado State University and a Bachelor of Science in Water Resources from Ohio University.