Bryan Tolson 1 Masoud Asadzadeh Saman Razavi 1. Assistant Professor

1. Restoring Water Levels on Lakes Michigan-Huron: Impact AnalysisIUGLS Study Board MeetingWindsor, ONNov 30, 2010 Bryan Tolson1 Masoud Asadzadeh Saman Razavi 1. Assistant Professor Department of Civil and Environmental Engineering

2. Introduction • Purpose is to assess the impacts of “restoring” Lake MH levels by 10 cm to 50 cm • x-cm restoration here is defined as a permanent structural change to the St. Clair River that raises the long term average of Lake MH by x-cm • The actual structural change is not specified and thus the actual hydraulic impacts are not assessed here • Instead, we assume that reducing the conveyance of the St. Clair River as simulated in the co-ordinated routing model (CGLRRM) is roughly representative of system-wide restoration impacts of some actual structural change to reduce St. Clair River conveyance

3. Quantifying Restoration • Equation below describes the conveyance of the St. Clair River in CGLRRM • We simulate the system with the Equation coefficients set to describe the current conveyance regime of the river • to simulate system under restoration, we manipulate a coefficient in Equation to reduce conveyance of the river • primarily, we consider ymSC QSC = KSC((MH+SC)/2-ymSC)aSC (MH-SC)bSC-IW ymSC: Mean Channel Bottom Elevation of St. Clair River With the default value of 167.00 m Base case: ymSC= 167.00 m

4. Quantifying Restoration Restoration impacts are assessed with CGLRRM+1958DD down to Montreal (Jetty1) simulating 109 years of lake levels based on 1900-2008 (historical) residual NBS QSC = KSC((MH+SC)/2-ymSC)aSC (MH-SC)bSC-IW Increase ymSC from 167.00 so that the long-term average MH lake level increases by 10, 25, 40, and 50 cm Restoration average is calculated over the final 55 years of the simulation ( ‘equilibrium’ is reached … MH stops filling) In a sensitivity analysis, we will repeat with KSC (function of mean channel cross-section area and roughness) rather than ymSC 4

5. Outline of Restoration Scenarios # levels [4] [2] [2] [3] [2] • factors we will vary to define scenarios include: • 10 cm, 25 cm, 40 cm, 50 cm restoration targets • static versus dynamic behaviour of Lake Superior • one-time (instantaneous) versus staged restoration • vary initial lake levels/NBS inflows to estimate worst-case downstream restoration impacts (Lake Erie  1930s, 1960s) • restoration via the ymSC versus the KSC coefficient • we do not evaluate impacts of all 4x2x2x3x2 = 96 combinations of factor levels • we only evaluate impacts for some of these

6. Outline of Restoration Scenarios • Unless otherwise noted, you can assume the following factor levels for all restoration results: • 10 cm, 25 cm, 40 cm or 50 cm restoration target (will be specified in all results) • static behaviour of Lake Superior • one-time (instantaneous) restoration at start of year 1 in simulation (year 1900 initial lake levels) • restoration via the ymSC (bottom level) coefficient

7. Restoration Scenarios • Static Plan 77A for Superior releases: • Run 77A for the base case where ymSC = 167.00 m • Take the outflow of lake Superior • Study the effect of adjusting ymSC on Midlakes by simulating only Midlakes with static inflow to MH (outflow of Lake Superior constant at the base case) • Dynamic 77A: • Study the effect of adjusting ymSC on Superior and Midlakes (Lake Superior with plan 77A as well as Midlakes) • here Lake Superior levels (through Plan 77A) are allowed to respond to restoration • Static 77A deemed most representative of trying to restore Lake MH levels without changing/degrading Lake Superior levels

8. RESULTS for STATIC 77A • Upstream Effects of Restoration • Downstream Effects of Restoration

9. Lakes Michigan Huron Response to 1-TIME Restoration

11. 50 cm

12. 1-Time MH Restoration – STATIC 77A Long-Term Upstream Effects • more extreme flooding more frequently on Lake MH due to restoration

13. RESULTS for STATIC 77A • Upstream Effects of Restoration • Downstream Effects of Restoration 13

14. St. Clair River Response to1-TIME Restoration

15. Lake St. Clair Response to1-TIME Restoration

18. Long-term Impacts Downstream of Lake St. Clair • Results again for Lake St. Clair • All further downstream long term impacts look very much the same (0-2% increase in frequency for 50 cm restoration) • focus attention on short-term impacts downstream

19. Detroit River Response to1-TIME Restoration

20. Lake Erie Response to1-TIME Restoration

21. Niagara River + Welland Canal Response to 1-TIME Restoration

22. Lake Ontario (Plan 58DD*) Response to1-TIME Restoration

23. Lake Ontario Outflow Response to 1-TIME Restoration

24. Montreal Jetty1 Level Response to1-TIME Restoration

25. 1-Time Restoration – STATIC 77A Short-Term Downstream Effects Short-term impacts limited to ~10 yrs, max. impacts within year 1 How are most extreme base case levels exacerbated

26. Mitigating Short-term Downstream Impacts of Restoration

27. Staged vs 1-Time Restoration • Short-term downstream impacts of restoration can be minimized by spreading them out (staging) over time • essentially this means filling Lake MH more slowly • We evaluate a staged 25 cm restoration case and compare to 1-time restoration (same principle applies to any restoration scenario) • Staged restoration scenario evaluated: • 5 stages of restoration • each restoring 5 cm to Lake MH • each spaced in time by 5 years • thus, 20 yrs between start and end of physical restoration changes

28. Lakes Michigan Huron Response to 1-Time vs. STAGED Restoration • Staged restoration accomplishes same thing as 1-time restoration in the long term

29. St. Clair River Response to 1Time vs. STAGED Restoration

30. Lake St. Clair Response to 1Time vs. STAGED Restoration

31. Detroit River Response to 1Time vs. STAGED Restoration

32. Lake Erie Response to STAGED Restoration

33. Niagara River + Welland Canal Response to STAGED Restoration

34. Lake Ontario Response to STAGED Restoration

35. Lake Ontario Outflow Response to STAGED Restoration

36. Jetty1 Response to STAGED Restoration

37. Staged Restoration Summary Findings • 25 cm staged restoration can almost completely mitigate the negative downstream impacts of a one-time restoration • similar concept applies to any other selected level of restoration • exact mitigation extent is of course dependent on being able to stage whatever structural channel changes are selected • minimal downstream impact restoration (staging) takes longer (25 yrs instead of 10 yrs in this example) 37

38. Sensitivity of Short-term Restoration Impacts to Initial Lake Levels/NBS variability • Purpose here is assess worst case short-term downstream impacts due to a poorly-timed project [Worst case impacts upstream are in the long-term and so timing a project to start during a high water period will not be worse - all we would show is that it would be better to start project during high water period] • How are impacts exacerbated if physical restoration changes are completed just before period of very low Lake Erie levels? • Based on observed Lake Erie levels, there are two points in historical record to consider …

39. Simulated Lake Erie Level under Base Case “1960s” start “1930s” start

40. Starting the 10cm Restoration in Dry Period of the 30’s

47. Starting the 10cm Restoration in Dry Period in 60’s