North Bay Watershed Association May 6 th , 2011 Rick Jorgensen, Winzler & Kelly

1. North Bay Watershed Association May 6th, 2011 Rick Jorgensen, Winzler & Kelly Carlos Diaz, Winzler & Kelly

2. Presentation Overview Introduction to 2 Case Studies Discussion of Status Quo Value Added by New Modeling Approach Salvador Creek Case Study City of Sonoma Case Study Open Forum for Questions

3. Two Case Study Applications Flood Reduction Analysis, Salvador Creek, City of Napa Alternatives Analysis aimed at identifying flood reduction solutions for the City Storm Drain Master Plan, City of Sonoma Master Plan and CIP Development Both applications represent first time this modeling approach has been used in North America!

4. Historic Modeling Approaches Flood Reduction Analysis Typically restricted to 1-D channel hydraulics (HEC-RAS) Maybe 1-D channel coupled to 2-D floodplain SD system not considered Storm Drain Master Planning Typically 1-D storm drain model only (StormCAD) or hydraulic calculations Downstream tailwater conditions taken from design storm and/or 100-year FEMA models

5. The New Approach • MIKE FLOOD

6. Value Added by New Approach Flood Reduction Analysis Storm drain system provides detention and attenuation Storm drain system can cause as much flooding as channel in some cases Improved representation of flooding extent, timing and duration of flooding Ability to visualize flooding and flood reduction due to improvements Ability to quantify benefits and costs of alternatives

7. Value Added by New Approach Storm Drain Master Planning If it pops, where does it go? Ability to visualize extent of flooding, identify priorities, and impacts of improvements Ability to visualize transfer opportunities and benefits/drawbacks Ability to better represent flooding of structures Potential for savings on CIP projects - using a constant DS boundary condition can be conservative and doesn’t consider timing of peaks

8. Value Added by New Approach Big Picture Clients get 2 significant products – channel and SD system models Dynamically linked – able to analyze impacts to other systems from changes in one system Ability to visualize – a picture’s worth a thousand words

9. Flood Reduction Analysis, Salvador Creek Highly urbanized watershed (~5,000 acres) with historical flooding Modeling has evolved over the years Initially tasked by FCWCD to analyze 4 alternatives Detention basins Floodwalls Bypass channel Flapgates Next steps include additional pipes <30” diameter and additional bypass alternatives

10. 2005/2006 Napa River Flooding

12. Recent Salvador Creek Flooding

13. Historical Modeling The players Napa County Resources Conservation District City of Napa Napa County Flood Control and Water Conservation District Modeling has evolved over the years on Salvador Creek Original HEC models since 1999 Unsteady MIKE 11 modeling started in 2001 MIKE FLOOD in 2005/2006 W&K inherited MIKE FLOOD model in 2008 and updated hydrology and added storm drain system

14. New MIKE Model – Salvador Movie

15. Model Development - MIKE URBAN

16. MIKE URBAN

17. MIKE URBAN

18. MIKE URBAN

19. Final Calibration

20. MU/MF Baseline Flood

21. Alternative 1 – Upland Detention

23. Alternative 3 – Floodwalls With Flapgates

25. Next Phase – Bypass Options

26. Storm Drain Master Plan, City of Sonoma Considers pipes larger than 24-in diameter ~11.3 miles of pipe Four watersheds – Nathanson Creek, Fryer Creek, Sonoma Creek, and Schell Creek, 1st application of all three MIKE models for SDMP purposes and CIP project development

27. New MIKE Model – Sonoma Movie

28. Sonoma Watershed Map

29. SDMP Model Development Aerial/LIDAR Channel Cross Section Field Surveys City GIS and Manhole Dipping Old FEMA models

30. CIP Development Process Baseline for Assessment - SCWA Flood Control Design Criteria Analyzing model results for compliance with criteria Identifying channel improvements Identifying storm drain system improvements

31. SCWA FCDC Criteria Storm Drain System with drainage < 1 sq. mile – minor waterway 1 foot freeboard requirement at 10 year design storm Surface routes shall be available to handle 100-year flows with no inundation of structures Fryer Creek ~ 2 sq. miles – secondary waterway 25-year event with 1.5 feet of freeboard 100-year event with no inundation of structures Nathanson Creek > 4 sq. miles – major waterway 100-year event within channel banks

32. Sonoma Baseline Model Results

33. Channel Improvement Model Results

34. CIP Project Model Results

35. Summary 2 case study applications of MIKE model Improved representation of flooding extent, timing and duration of flooding from dynamic model Ability to visualize flooding and flood reduction due to improvements Ability to quantify benefits and costs of alternatives Potential for savings on CIP projects - using a constant DS boundary condition can be conservative and doesn’t consider timing of peaks

36. Questions?