Environmental Flows: State of the Science and Principles of Bes Practice Insert Image Credit Mark Godfrey Brian Richter Co-Director, Global Freshwater Program
Key Factors in River Ecosystem Health Connectivity Physical Habitat Species Interactions Food Sources Water Quality Flow Regime
Freshwater Ecosystem Health Physical Habitat Water Quality Connectivity Energy Supply Species Interactions Flow Regime Ecological Integrity Ecosystem Services
From Rivers for Life: Managing Water for People and Nature by Sandra Postel and Brian Richter, Island Press
Flow as a Master Variable River Flow Regime (lows, high pulses, floods) Physical Habitat Water Quality Connectivity Food Sources Species Interactions Ecological Integrity Ecosystem Services
Flow Alteration and Loss of Ecosystem Services
Flow Alteration and Loss of Ecosystem Services
Flow Alteration and Loss of Ecosystem Services
Ecosystem Goods & Services
Definition of Environmental Flows Environmental flows describe the quantity, timing, and quality of water flows required to sustain freshwater and estuarine ecosystems and the human livelihoods and well-being that depend on these ecosystems. How much, and at what times, must water be released from the dam to sustain ecosystem health and services? Source: The Brisbane Declaration, International RiverSymposium, September 2007
Maintaining Natural Flow Patterns From Rivers for Life: Managing Water for People and Nature by Sandra Postel and Brian Richter, Island Press (adapted from Tharme and King 1998)
Establishment of links between flow events, channel hydraulics & biophysical components Lower shrub Upper shrub/tree Sedge 15 Moss Wetbank Drybank Aquatic Water depth (m) 10 5 0 Inter-annual flood events 1:2 y flood 1:5 y flood wet-season low flow range dry-season low flow range 0 50 100 150 Cross-channel distance (m)
The Big Question How much flow alteration (e.g., from hydropower operations) is too much?
Environmental Flow Building Blocks Savannah River, below Thurmond Dam (River-Floodplain) Floods High Flow Pulses 50,000-70,000 cfs; 2 weeks, avg every 2 yrs Maintain channel habitats Create floodplain topographic relief Provide fish access to the floodplain control invasive species Maintain wetlands and fill oxbows and sloughs Enhance nutrient cycling & improve water clarity Disperse tree seeds >30,000 cfs;5 pulses, >2 days with 2 events of 2 week duration (March and early April) 20,000-40,000 cfs; 2-3 days, 1/month 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 navigation dam <13,000 cfs; 3 successive years, every 10-20 years Floodplain tree recruitment Details: 20,000-40,000 cfs; 2-3 days, 1/month Hypotheses: 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 navigation dam 8,000-12,000 cfs; Exchange water with oxbows Low Flows Key Wet Year Avg Year Dry Year >8,000 cfs Larval drift for pelagic spawners <5,000 cfs Adequate floodplain drainage Create shallow water habitat for small-bodied fish 3,000 cfs; 3 successive years every 10-20 years Floodplain tree recruitment JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
E-Flow implementation: Savannah River, Georgia
Ecosystem Monitoring & Adaptive Management
Traditional Ecological Knowledge
Pimienta (Mayo 20, 2007) MITCH!!! Mucho lodo, mala para machacas y otros, buscan caños, no pican en el río, pero los caños son buenos (Jun, Jul y Oct 2006). Duración 1-3 meses Un nivel que no afecta a los peces Agosto Sep/ Dic - Ene 2006). Nivel mínimo invier (Ago, 2006). El máximo nivel para los peces. Limpia el canal. Duración 1 semana (Jul y Oct. 2006) Cuyameles, tepemechines inician movimientos (20 Mayo 2007)
Inundacion Figure 1. Recomendaciones para los caudales ambientales, Rio Patuca 800-2000 cms; 12 dias, cada ano Sediment transport Maintain channel form and habitats (including for navigation) Create floodplain topography Provide fish access to the floodplain Disperse tree seeds Pulsos early humedo pulsos pequenos; 2 pulsos cada ano entre 125 and 170 cms, 7 dias Migration/spawning cue for fish, other aquatic species and reptiles Tree germination Create sandy beaches for reptiles mid humedo pulsos 4 pulsos cada ano entre 200 and 900 cms 7 dias Fish migration and access to habitat late humedo pulsos pequenos; 2 pulsos cada ano entre 125 and 170 cms, 7 dias Fish migration and access to habitat Low Flows Decline from 70 to 40 cms Maintain levels for transportation Adult fish feeding and egg development Increase from 40 to 100 cms Reduce gold extraction Adult fish feeding and egg development 100 cms Maintain sandy banks for reptiles Decline from 100 to 70 cms Maintain sandy banks for reptiles JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
Mainstreaming E-Flows into Hydropower Projects Water and Power Magazine articles World Bank Technical Note Federal water laws, e.g., South Africa
Seven Principles of Best Practice 1. Fully engage stakeholders in every aspect of e-flow assessment and decision-making. Use an open, inclusive, transparent stakeholder process to identify ecosystem-related values and needs. Give these values due consideration when assessing tradeoffs in dam siting, design, and operations. Stakeholders must be involved in defining e-flow needs and in negotiating which aspects of e-flow recommendations will be implemented (i.e., selection of implementation scenarios).
Seven Principles of Best Practice (continued) 2. Identify opportunities for e-flow integration at a regional scale Optimizing water management to generate hydropower and sustain ecosystem health and social benefits is best achieved at a regional scale. This involves identifying rivers that must be permanently protected from dam development to ensure that broader social and environmental goals are met, as not all of the impacts of dams on ecosystem values and services can be mitigated through design and operations. Regional planning and dam siting are by far the most effective ways to avoid unacceptable impacts.
Seven Principles of Best Practice (continued) 3. Define e-flow needs using a holistic approach, utilizing the best available knowledge and tools E-flows need to be defined by inter-disciplinary teams of natural, physical, and social scientists supplemented with traditional ecological knowledge E-flows need to encompass a broad range of conditions ranging from low flows to floods to support the health of the whole ecosystem and ecosystem-related values, not just minimum flows or individual species E-flow assessments should utilize the large and diverse toolbox of analysis methods and tools that are now available for e-flow assessment. The methods chosen should be tailored to the specific uncertainties and priorities identified by the stakeholders, and should match the level of information, resources, time available and certainty required. Use available information, professional judgment and traditional ecological knowledge to complete an e-flow assessment. A lack of data is not an acceptable excuse for not integrating ecosystem values and requisite e-flow components into hydropower schemes.
Seven Principles of Best Practice (continued) 4. Assess e-flow needs before designing the dam s structural features. Complete e-flow assessment before designing a dam s structural features (e.g., turbine & outlet sizes) or operating plan. It is always far easier and less costly to integrate early, rather than to retrofit later.
Seven Principles of Best Practice (continued) 5. For existing dams, seek to integrate e-flow needs and implement opportunistically. Explicitly identify those components of e-flow recommendations can be implemented immediately by fully integrating e-flow objectives into regular operations. Other e-flow components may need to await more favorable structural, political, social, or economic enabling conditions. Integrating e-flows into hydropower schemes is not an all or nothing decision. Seek innovative solutions to address multiple objectives. Collaboration with other water management sectors including flood control, floodplain management, and water supply may improve the socioeconomic or technical feasibility of implementing e-flows.
Seven Principles of Best Practice (continued) 6. Be clear about desired outcomes and the flows necessary to achieve them, and monitor outcomes during implementation. Explicitly identify ecological and social indicators and their linkage to specific e-flow conditions that can be used to evaluate the effectiveness of e-flow management. Carefully document baseline conditions, monitor the outcomes of e-flow implementation, and adjust e-flow management accordingly (adaptive ecosystem management)
Seven Principles of Best Practice (continued) 7. Invest in local capacity-building. Use every e-flow assessment as an opportunity to teach and build capacity in the local region. The better that local scientists, engineers, and stakeholders understand the concept of e-flows, the more likely they are to be successful in implementing them over the long term.