YUBA CITY “Update Existing Flood Inundation Mapping” Related to: “Flood Hazard Mitigation Plan”

1. YUBA CITY “Update Existing Flood Inundation Mapping” Related to: “Flood Hazard Mitigation Plan”

2. Introductions: Thomas S. Plummer P.E., CFM President and Founder of Civil Engineering Solutions, Inc. (Northern Director of Floodplain Management Association) Terry Paxton, P.E. Project Manager (Formerly with the City of Sacramento)

3. Yuba City Flood Inundation Mapping Proposal:

4. Summary of Information to be presented: • Storm Events for Inundation Studies • 100-Year Current Standard for FEMA • 200-year (State Plan, Legislation relating to levees) • Many Local Agencies would like to achieve 500-year or better ultimate protection from Regional Flood Events. • Modeling Approach Options • 1 Dimensional Modeling • 2 Dimensional Modeling • Information that can be extracted from the Models • Inundation Mapping • Flood Depth Timing • Depth-Velocity Timing • Animations – Real Time Simulations • Flood Damage Assessment and Annualized Risk • GIS files

5. Storm Events for Inundation Studies: • 100-Year • Most Common Flood Mapping Available • Current Standard for FEMA • Standard Project Flood • 1957 State Plan • Similar to 200-year Event • 200-year • Current Legislation will require 200-year flood mapping in Levee Protected areas (Central Valley Plan of Flood Protection AB-5/SB-5) • 500-year or Greater • Many Local Agencies would like to achieve 500-year or better ultimate protection from Regional Flood Events.

6. Modeling Approach Options: • 2 Dimensional Modeling • Software such as FLOW2D, FESWMS, MIKE-FLOOD • Usually, sediment transport and other geomorphic processes can be analyzed directly in software. • But, requires a lot of information, model setup time, and model monitoring time. • Length of time needed to perform calculations, can reduce ability to test options, calibrate models, and try scenarios. • Models superior results where lateral flows, and sheet flows are expected, and where system area confinement is to be tested. • Generally modeling software will directly use standard DTM and GIS formats for input, and output. • Animations can be performed produced directly in Software.

7. Modeling Approach Options: • 1 Dimensional Modeling • Most commonly performed in HEC-RAS for Riverine Models. Sometimes SWMM (EPA or XPSWMM) is used where conduit flows are deemed to be significant. GEO-RAS can be useful, but often requires similar setup requirements as 2-D modeling. • Approximates Lateral conditions with weir equations. • Model setup and run times are very short. More information can be extracted from the models is Georectification of data is possible (as in HEC-RAS). • Reduced model Run Time increases options for multiple scenarios. • Generally, output information has to be manually converted to useable formats such as GIS/ and Pictoral. • Animation production is limited within software (< HEC-RAS 3.3) • CESI Has built an in-house software suite for dealing with Geo-rectification and extraction of data from 1-dimensional modeling software (HEC-RAS & SWMM).

8. CESI 1-D Modeling Tools: • CESI Originally Founded as a Software Firm (CS DRAINAGE STUDIO, CS UTILITY SUITE, CS EARTHWORK) • Cross Section Cutting tool for generating Geo-Rectified Cross Sections in HEC-RAS. (ACAD Script) • HEC1-VOLS Tool: • Exploits the HEC-RAS “SDF” export tool to Generate GIS, JPEG (rectified) output of analysis results for any time during the simulation. • Works with GIS Engine “Global Mapper” software via scripting to generate output. • Lots of Other Features

9. CESI 1-D Modeling Tools: • HEC1-VOLS Tool:

10. Model Results (Extracted): • Inundation Mapping

11. Model Results (Extracted): • Flood Depth Timing PRE-PROJECT (BEFORE)

12. Model Results (Extracted): • Depth-Velocity Timing • Rule of 9 ( Depth * Velocity < 9 ) • Human Depth-Velocity Safety Curve

13. Model Results (Extracted): • Depth-Velocity Timing • Rule of 9 ( Depth * Velocity < 9 ) • Human Depth-Velocity Safety Curve • Structural Depth-Velocity Safety Curve

14. Model Results (Extracted): • Depth-Velocity Timing • Rule of 9 ( Depth * Velocity < 9 ) • Human Depth-Velocity Safety Curve • Structural Depth-Velocity Safety Curve

15. Model Results (Extracted): • Max/Min Values for Simulation Run • Velocity

16. Model Results (Extracted): • Animations – Real Time Simulations • Velocity:

17. Model Results (Extracted): • Animations – Real Time Simulations • Depth:

18. Model Results (Extracted): • Animations – Real Time Simulations • Side By Side for Comparison:

19. Model Results (Extracted): • Data Contained in GIS Files – Can Be Compared to Other Data for Other Purposes:

20. Model Results (Extracted): • Flood Damage Assessment and Annualized Risk

21. INPUT DATA OF VARYING RELIABILITY

22. NILPP HEC-RAS MODEL

23. QUESTIONS? YUBA CITY “Update Existing Flood Inundation Mapping” Related to: “Flood Hazard Mitigation Plan”