Use of Conceptual Ecosystem Model to Structure Environmental Flow Assessment

Transcription

1 Use of Conceptual Ecosystem Model to Structure Environmental Flow Assessment Dr. Andrea Bradford & Andy Beaton Latornell Conservation Symposium November 20 th 2014 Nottawasaga, Ontario

2 Outline What are Environmental Flows (E-flows)? Current State of the Science Need for Provincial Guidance Recommended Process and Approaches 2

3 What are E-flows?.quantity, timing and quality of water flows required to sustain freshwater and estuarine ecosystems and the human livelihoods... (Brisbane Declaration, 2007) 3

4 What are E-flows? Small Floods An ecological model was developed for each site based on site attributes Large Pre- Floods settlemen t Current High Flow Pulse Low Flows (Insert hydrograph of EFC s) Extreme Low Flows 4

5 What are E-flows? An ecological model was developed for each site based on site attributes Water Level Presettlement Current High Flow Pulse Shape physical (Insert habitat hydrograph within of EFC s) channel 5

6 What are E-flows? An ecological model was developed for each site based on site attributes Presettlement Current Water Level (Insert hydrograph of EFC s) Low Flows Connectivity to different habitats 6 (Black et al., 2005)

7 7 University of Guelph What are E-flows? Natural Flow Regime Paradigm: Aquatic ecosystem has adapted to natural flow regime Maintain natural flow regime maintain aquatic ecosystem Abitibi River Missing important flow components that have important ecosystem function

8 State of the Science: Recognition of reality of current state of freshwater ecosystems (invasive species, climate change etc.) hybrid, emerging, novel ecosystems as reference designer e-flows used to meet specific ecosystem objectives ``Building blocks`` for specific ecosystem objectives

9 State of the Science: Recognition of ecosystem complexity uncertainty of flow-ecological response relationships Recognition of need to integrate of socio-political decisions with science (a) Threshold based on scientific conclusion Threshold based on socio-political decision Obvious breakpoint No obvious breakpoint

10 E-flows in Ontario to Date: E-flows embedded in many Ontario guidelines and policies Permit to Take Water Manual (2005) Lake Simcoe Protection Plan (2009) Water Budget Guidelines (2011) Ontario Low Water Response (2010) 10

11 E-flows in Ontario to Date: Conservation Ontario (2005) Credit CA (2012) MNRF Science (2013) Lake Simcoe CA (2010-Present) Working towards more detailed guidance for Southern Ontario context 11

12 12 University of Guelph Target Setting vs. Scenario Based Assessment Developing a target environmental flow regime requires a decision on the desired future state And, what if questions are inevitable as new demands for land and water resources arise An approach that accommodates consideration of many scenarios, and their flow alterations and ecological consequences, may better support decision-making

13 13 University of Guelph What should come first? The ecological functions may be identified and then the water needs to support these functions determined Or, alterations in the hydrologic regime may be determined and then the ecological responses to these alterations predicted. Both approaches depend on an understanding of the functional links between all aspects of the hydrology and ecology the ecohydrology - of the aquatic ecosystem.

14 14 University of Guelph Process: Phase 1 Context Setting / Conceptual (Hydroecological) Model Development Phase 2 E-flow Analysis / Quantification Phase 3 Integration / Synthesis Phase 4 Monitoring / Adaptation

15 Context Setting / Conceptual Model : Stream classification (hydrologic stream type, geomorphic) Assessment of degree of alteration from the natural regime Conceptual ecohydrology model 15

16 Conceptual Model Development: Scale Biotic and Human Needs (Functions) Variables that limit function(s) Flowrelated processes governing variable Non-flow related processes affecting variable Flow regime (temporal aspects) Macro/ Segment Meso / Site / Local Step 1 Step 2 Step 3 Step 4 Step 5 Use of flow response guilds as knowledge becomes available Zaghal,

17 17 University of Guelph Example hypotheses: ecological responses to flow alteration (after Poff et al. 2010): Extreme low flow - Depletion will lead to rapid loss of diversity and biomass in invertebrates and fish due to declines in wetted riffle habitat, lowered residual pool area/depth, loss of connectivity and poor water quality Baseflows - Depletion will lead to Augmentation may lead to High flows (within channel) - Increased frequency and duration will lead to Decreased frequency of substrate disturbing flow events will lead to

18 18 University of Guelph Phase 2: E-Flow Analysis / Quantification Convergence of approaches in e-flow frameworks Bottom-up approaches demanding to implement, vulnerable to knowledge gaps (potential to omit critical flow characteristics) Top-down approach challenge to determine acceptable deviations beyond the natural range of variability of system simple rules are not ecologically based and can be misleading, but support whole ecosystem protection, helping bridge gaps in specific needs addressed from bottom-up.

19 19 University of Guelph Phase 3: Integration / Synthesis Analysis completed can be used to develop different forms of specifications that are suitable for the range of water resources management activities typical of a developing (or developed) watershed Ecologically acceptable annual hydrograph informs seasonal water management (or management over a several year period). E flow assessment process can yield ecologically acceptable hydrographs for average, wet and dry years.

20 20 University of Guelph Phase 3: Integration / Synthesis The hydrographs for average, wet and dry years, which occur with an ecologically acceptable frequency, can be integrated to establish a flow duration curve (Petts, 2009). The FDC is most suitable for long-term water resources management and planning. Where reservoirs exist, flow releases may be used to maintain specific functions; local, operational rules can incorporate information from e-flow analysis Minimum flow limit is not a target - it is better described as threshold of concern, which requires action (e.g. cease to pump) to limit ecological or other impacts.

21 21 University of Guelph Phase 4: Monitoring and Adaptation Thresholds of Potential Concern (Rogers and Biggs, 1999) Specific ecological end-points which represent hypotheses of the limits of acceptable change in ecosystem structure (form) and function Suite of ecosystem indicators

22 22 University of Guelph Phase 4: Monitoring and Adaptation Decisions on water management will be made with or without scientific input. It is preferable to contribute on the basis of the best available knowledge; adhere to the precautionary principle where uncertainties are high; learn by doing; and practice adaptive management (King and Brown, 2006)

23 23 University of Guelph Research There is an urgent need to determine the variability of key abiotic parameters over a range of spatial scales, to measure and model the effects of these variations upon biota, habitats and ecosystems, to understand the time scales and mechanisms of ecosystem response to hydrological change, and to advance models for healthy rivers in developed catchment contexts. (Petts, 2009)

24 24 University of Guelph Conclusion In Southern Ontario there are many interacting stressors and managing the cumulative effects is a major challenge. Nevertheless, there are opportunities to return the landscape, flow regime, stream corridors and their land - water linkages to a healthier, more functional state. Healthier, more functional ecosystems are expected to be more resilient (capable of responding and adjusting to disturbance).

25 Thank You!