Protecting and Enhancing Ecosystem Services the Role of Wetlands and Watershed Management in Flood Attenuation Dr. Mark Gloutney Director Regional

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1 Protecting and Enhancing Ecosystem Services the Role of Wetlands and Watershed Management in Flood Attenuation Dr. Mark Gloutney Director Regional Operations Eastern Canada April

2 Changes in Storm Events

3 Hardening of Landscape

4 Hardening of Landscape Wetland loss: Settled Areas Canada: 65% of wetlands Ontario: Lost 1.4M ha of wetland since 1800 or 72% of wetlands

5 Hardening of Landscape

6 Loss of Environmental Resilience Flooding and drought Water quality Increasing costs to society

7 Flood Attenuation Study Assumption that wetlands help control flooding but how effective are they? How much can they reduce flooding? Where do they limit flooding the most? And what is the economic value? Research will help answer these questions and determine the role and value of wetlands in southern Ontario

8 Project Overview Research is being carried out in the Credit River watershed, in partnership with Credit Valley Conservation

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10 Project Overview Hydrologic modelling to determine the capacity of wetlands to store water during storm event scenarios, and assess the impact of wetland loss and future restoration efforts Results will feed into an economic analysis to quantify the value of flood mitigation services provided by wetlands

11 Literature Review Balance of academic literature confirms that wetlands can help mitigate flooding: Wetland drainage in the Canadian Prairies has led to an increase of up to 350% in flood peak flow (Pomeroy et al, 2014) A 5.7 acre wetland can retain the natural runoff from a 410 acre watershed (Godschalk et al, 1999)

12 Literature Review Estimates of the economic value of flood mitigation provided by wetlands include: $380 million per year in the Greenbelt (Wilson 2008) $157 million per year in the Lake Simcoe Watershed (Wilson 2008) $16 million per year in the Credit River Watershed (Kennedy and Wilson 2009)

13 Keys to Modelling Wetlands Wetland modelling is an emerging field Wetland water balances (long term) Flood retention & detention (short term/event-based) Connectivity to the groundwater system Integrated systems require an integrated approach

14 Modelling Scenarios All 7 scenarios will be modelled under 7 rainfall intensities (2yr, 5yr, 10yr, 25yr, 50yr, 100yr, Ontario s record maximum) 1. A baseline scenario using existing wetland extent Wetland Restoration Scenario: 2. Loss of all geographically isolated/headwater wetlands 3. Loss of all riparian/riverine/lowland/floodplain wetlands 4. Loss of all Non-Provincially Significant Wetlands (PSWs) 5. Projected near-term loss using CVC Natural Heritage System % Wetland Loss Wetland Restoration Scenario: 7. Restored wetlands at all CVC planned restoration sites

15 Hydrologic/Economic Interface Phase 2 Phase 3 Hydrologic Modelling Hydrologic / Economic Interface Economic Assessment Develop Business Case Objective 1 & 2 Determine landscape based wetland characteristics and functions that influence downstream flood depth Organization of key hydrological outputs that impacts economic considerations Flood depths and duration by a range of flood return periods Understanding of wetlands influence flood depths for each assess return period Objective 3 Estimate the avoided damage costs associated with each modeled flood return period Objective 4 Utilize information to develop a business case for wetland protection and restoration

16 Economic Assessment Phase 3 Economic Assessment Objective 3 Estimate the avoided damage costs associated with each modelled flood scenario Develop Business Case Objective 4 Utilize information to develop a business case for wetland protection and restoration

17 Additional Ecological Goods and Service Provided by Wetlands GHG mitigation Ontario work Water quality Black creek

18 Investigating carbon storage and accumulation rates of wetlands within the agricultural landscape of southern Ontario: Dr Irena Creed Carbon stores increased from upland portions of the wetland basins to the wetland basin centre. Wetland drainage releases in the range of Mg C ha -1. Wetland restoration increased the rate of C sequestration with rates increasing over first 20 years.

19 The Impacts of Wetland Loss in the Lake Simcoe Watershed: Dr Wanhong Yang Wetlands prevent P from entering Lake Simcoe, and are critical to meeting the Lake s P reduction objectives phosphorus removal benefits provided by the Black River wetlands save local municipalities $292,661 annually Further loss of wetlands will significantly diminish the benefits of financial investment in improving Lake Simcoe s water quality If 25% of remaining wetlands were lost, the additional phosphorus input into the Lake would be equivalent to the phosphorus currently removed by the Sutton WPCP

20 Increasing Environmental Resilience Part of the solution to building greater environmental resilience includes a focused effort to conserve existing wetlands and strategically restore lost or degraded wetlands