Wetlands, Flood Control and Ecosystem Services in the Smith Creek Drainage Basin: A Case Study in Saskatchewan. John K. Pattison-Williams, PhD, PAg

Transcription

1 Wetlands, Flood Control and Ecosystem Services in the Smith Creek Drainage Basin: A Case Study in Saskatchewan John K. Pattison-Williams, PhD, PAg NAWMP 14 November 2018

2 Introduction and Problem Wetland loss How to value them? Theory vs Pragmatism Business Case Approach

3 Smith Creek the Problem Loss of wetland ecosystems Flooding across the Prairie Pothole Region Unseeded acres Nutrient export Infrastructure damage Significant financial resources have been required to compensate for these damages

4 Background: Wetland Evaluation Research An assessment of the lost ecological goods and services that are associated with wetland drainage in the watershed.

5 Research Questions Do wetland ecosystems in this area present a viable financial option to mitigate the impact of flood events in Saskatchewan specifically, and the Canadian PPR in general? Is wetland conservation an economically viable solution to address a suite of environmental issues in Saskatchewan specifically, and the Canadian PPR in general?

6 Research Location: Prairie Pothole Region

7 Research Location: Smith Creek

8 Methodology Multidisciplinary Modelling Wetland Area Biophysical: Hydrology and Nutrient Economic Biophysical Benefits Assertion of Financial Value Financial Cost Calculation Step 1: Flooding Return on Investment Step 2: Social Return on Investment Comparison of Scenarios

9 Methodology: Loss and Restoration Scenarios Scenarios Rest100 Rest25 Rest5 Existing Loss5 Loss25 Loss100 Description Restoration of 100% of the historic wetland area Restoration of 25% of the historic wetland area Restoration of 5% of the historic wetland area Retention of the existing wetland area 5% Loss of existing wetland area 25% Loss of existing wetland area 100% Loss of existing wetland area

10 Methodology: Calculations PV = T TC t i (1 + r) t t= 1 TC is the total cost (or benefit) r is the discount rate t is the time period summed over the total time period T. > 1 means good investment

11 Cost Determination Opportunity Cost: $88.01 per ha (GOS) Restoration Cost: $13,585 per ha (DUC) Initial, one time expenditure Maintenance Future management Total Cost = Opportunity + Restoration

12 Results: Flooding Return on Investment A revised model (Pomeroy et al., 2014) was used to simulate the snow regimes on and the streamflow runoff from five sub-basins and the main basin of Smith Creek for six years ( ). Annual discharge and peak daily stream-flow have a high sensitivity to wetland drainage in years that were not preceded by exceptionally wet conditions Financial values of these flood control benefits specific to the Smith Creek basin are not available. Brander et al. (2013) calculated a mean flood control provision of CAD$ per hectare of wetland in agricultural landscapes of Canada

13 Results: Flooding Return on Investment Scenario Ha Change Change in Benefit (Total ha x $/ha) $/yr Total Benefit (Total ha x $/ha) $/yr Rest100 8,804 2,236 Rest50 7,685 1,117 Rest25 7, ,942 2,456, ,626 2,144, ,911 1,982,712 Existing 6, Loss25 4,926 (1,642) Loss50 3,277 (3,291) Loss100 0 (6,568) 1,832,800 (458,301) 1,374,500 (918,217) 914,584 (1,832,800) 0 *based upon a CAD$ benefit per hectare of intact wetland (Brander et al., 2013)

14 Flooding Return on Investment SROI Ratio Retention Rest25 Rest50 Rest100 Initial Years Years

15 Results: Flooding In all wetland conservation scenarios, the flood reduction benefits of wetlands cover the costs of retention. Retention of existing wetlands provides the highest return on investment of 3.17 The ratio becomes smaller in the restoration scenarios due to high restoration costs assumed to occur in the first year. When considering longer time horizons (10 and 30 years) the flood control benefits of these wetlands approaches, and in some cases surpasses, the costs of restoration.

16 Results: Social Return on Investment Phosphorous. If 25% of wetlands were lost, there would be a resultant 550 kg (11%) increase in the annual total phosphorous (TP) loading to the basin; this quantity would increase to 6910 kg (145%) under complete loss. Alternatively, restoring all wetlands in the basin would retain an additional 290 kg of TP in 25% restoration to 2540 kg under full restoration Nitrogen. Wetland restoration scenarios increase the total nitrogen (TN) retention capacity from existing levels by 12,610 kg under full restoration, and decrease loading retention of TN by 18,610 kg under complete wetland loss. Recreation: high degree of local variation such as proximity to urban areas, numbers of waterfowl, demographics of the local population, etc. Considered CAD$19.60 per hectare annually Carbon. wetlands in the PPR contain on average 205 t of carbon per hectare, and when they are drained 89 t are lost to the atmosphere. It takes many years for restored wetlands to become carbon sinks. Conservative approach and estimate that loss scenarios lead to a onetime release of 326 t of CO2e per hectare; the retention scenario will retain a conservative 3.25 t of CO2e per hectare. Based upon the CAD$20 per tonne carbon tax.

17 Results: Social Return on Investment Scenario Wetland area Phosphorous Removal Nitrogen Removal Tourism and Recreation Carbon Storage Total ha Change $/yr $/yr $/yr $/yr $/yr Rest100 11,237 3, ,920 4,520,742 2,838, ,557 Rest50 8, ,920 1,799,947 1,266, ,621 Rest25 7, ,920 1,728,218 1,156, ,262 Retention 7, ,920 1,286, , ,733 Loss25 7, , , ,717 96,543 Loss50 5,693 1, , , ,918 64,239 Loss , ,958,287 3,644,047 3,451,069 2,618,337 1,510,583 1,188,045 0

18 Results: Social Return on Investment SROI Ratio Retention Rest25 Rest50 Rest100 Initial Years Years

19 Unabated Wetland and ES Loss 10,000, ,000,000 CAD Dollars -20,000,000-30,000,000-40,000,000-50,000,000-60,000,000 Existing Loss25 Loss50 Loss100 Total Benefit 4,451,137 2,885,083 2,102,629 - Lost Benefit - -12,380,995-24,016,517-47,701,678

20 Results Comparison Flood Returns Social Returns SROI Ratio SROI Ratio Retention Rest25 Rest50 Rest100 - Retention Rest25 Rest50 Rest100 Initial Initial Years Years Years Years

21 Conclusions We present a financial case for the retention and restoration of wetland ecosystems in the Smith Creek basin and, by extension, similar prairie basins in southern Saskatchewan and the Canadian PPR Investment in wetland conservation provides a positive SROI: every CAD$1 invested in retention yields CAD$7.70 in flood control, nutrient removal, recreation, flood control and carbon sequestration; and every CAD$1 invested in 25% restoration of lost wetlands yields CAD$3.22 over a 10-year time frame. Having wetlands on the landscape mitigates major environmental concerns in the province, such as flooding and water quality, which are having significant impacts on the residents of the province and downstream jurisdictions. Wetland conservation can assist the Government of Saskatchewan meet the objectives in the Plan for Growth.

22 Next Steps More research is necessary to understand the variability of benefit estimates associated with TP, TN and water quantity. Expectation among conservationists that stakeholders will increasingly demand the protection of these resources for economic and quality of life reasons. Further exploration of the myriad of issues involved such as perspectives between upstream and downstream users, power dynamics between rural and urban perspectives and concerns of private and public property rights. Time for a tune-up? Profitability mapping and new economics models

23 Acknowledgements Funding from BHP Billiton, Prairie Habitat Joint Venture and Ducks Unlimited Canada. Lyle Boychuk, Trevor Plews, Ian Glass, Wanhong Yang and Longbo Liu for biophysical information. The Canada Research Chairs program and the Canada Excellence Research Chair in Water Security also supported aspects of this research. Photo Credit: Marilylle Soveran

24 Questions?