YUBA CITYYUBA CITY

““Update Existing Flood Update Existing Flood Inundation Mapping”Inundation Mapping”

Related to:Related to:““Flood Hazard Mitigation Flood Hazard Mitigation

Plan”Plan”

Introductions:Introductions:

Thomas S. Plummer P.E., CFMPresident 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)

Yuba City Flood Inundation Mapping Yuba City Flood Inundation Mapping Proposal:Proposal:

Summary of Information to be presented: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

Storm Events for Inundation Studies: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.

Modeling Approach Options: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.

Modeling Approach Options: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).

CESI 1-D Modeling Tools: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

CESI 1-D Modeling Tools:CESI 1-D Modeling Tools:

• HEC1-VOLS Tool:

Model Results (Extracted):Model Results (Extracted):

• Inundation Mapping

Model Results (Extracted):Model Results (Extracted):

• Flood Depth TimingPRE-PROJECT (BEFORE)

Model Results (Extracted):Model Results (Extracted):

• Depth-Velocity Timing• Rule of 9 ( Depth * Velocity < 9 )• Human Depth-Velocity Safety Curve

Model Results (Extracted):Model Results (Extracted):

• Depth-Velocity Timing• Rule of 9 ( Depth * Velocity < 9 )• Human Depth-Velocity Safety Curve• Structural Depth-Velocity Safety Curve

Model Results (Extracted):Model Results (Extracted):

• Depth-Velocity Timing• Rule of 9 ( Depth * Velocity < 9 )• Human Depth-Velocity Safety Curve• Structural Depth-Velocity Safety Curve

Model Results (Extracted):Model Results (Extracted):

• Max/Min Values for Simulation Run• Velocity

Model Results (Extracted):Model Results (Extracted):

• Animations – Real Time Simulations• Velocity:

Model Results (Extracted):Model Results (Extracted):

• Animations – Real Time Simulations• Depth:

Model Results (Extracted):Model Results (Extracted):

• Animations – Real Time Simulations• Side By Side for Comparison:

Model Results (Extracted):Model Results (Extracted):

• Data Contained in GIS Files – Can Be Compared to Other Data for Other Purposes:

Model Results (Extracted):Model Results (Extracted):

• Flood Damage Assessment and Annualized Risk

Natomas Basin Development Projects:

Flood Risk Factors of Added Development:

Condition Current Build-outNo NILPP

Build-outWith NILPP

No of Structures At Risk from External Levee Breach

28,000 107,000 52,000(Single – Event

28,000 & 24,000)

Ave. Single Event Est. Damages

$5.3 B $24.3 B $4.4 B

Average Annualized Risk$/Year

$70M * $165M to $331M

* $76.2M to $152M

* Depends on Final Level of Improvements Implemented by SAFCA NLIP (between 100-year and 200-year assumed). Does not include Dev. Fee SAFCA Improvements. Est. database.

INPUT DATA OF VARYING RELIABILITYINPUT DATA OF VARYING RELIABILITY

NILPP HEC-RAS MODELNILPP HEC-RAS MODEL

22 20.25

19.5

19

17.75

17

16.75

16.5 15.25 14.25

13.5

13.221 12

11.25 9.75 8.75

7.25 6.75 6.25

4.75 3 2.5

1.754

20 19.6666*19.1333*18.5384*17.9565*17.4782*16.9* 15.3*

10

80 79.4* 79

78.5* 77.3703*

77

76.25* 75.15* 74.6* 74.1* 73.6* 73 72.2330*

71.875* 71.375* 70.75*

70 69.5* 69.

50 49

48.2* 47.3333*

46.6666*46

45 43.5*

43 42.25* 42

41.625* 41.25* 40.8333*40 39.5714*39.1428*38.7142*38.1428*37.6* 37.3* 36.4900*36.1225*35.0514*34.875* 34.375* 33.6518*33.3259*33 32.375*

31.2586*30.75* 30.25*

29.6* 29

79.21

78.50 78.00

77.50 77.00

76.50 76.00 75.50 75.00

74.50 74.00

73.25 72.50 72.00 71.50

70.926 70.25

69.50 69.00

68.50 66.75 66.25 65.75 65.25 64.75 64.25 63.75

63.25 61.50

Natomas Levee Break #1 (Southflow) Plan: 1) NATPRE4 2/24/2007 Legend

WS 03JUN2005 2300

Ground

Ineff

Bank Sta

Levee

Lat Struct

Ground

QUESTIONS?

YUBA CITYYUBA CITY

““Update Existing Flood Update Existing Flood Inundation Mapping”Inundation Mapping”

Related to:Related to:““Flood Hazard Mitigation Flood Hazard Mitigation

Plan”Plan”