Larry Voice

Risk Analysis – FEMA Region VIApril 12, 2010

HEC Software and FEMA SubmittalsEWRI Workshop – HEC Users Conference

Risk MAP

Overview

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� Flood Hazard Analysis

� Overview of Map Changes

� Accepted Model List

� Guidance

�Common submittal challenges

� Technical Issues With Models

� Submittal Completeness

�Map Modernization to Risk MAP

Risk MAP

Flood Hazard Analysis Revisions

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� Failing to keep pace with the changing and

dynamic nature of watersheds ultimately leads to

unwise decisions that place homeowners and

communities at increased risk of flooding.

Risk MAP

Flood Hazard Analysis Revisions

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� If your community’s FIRM panels require update:

� Letters of Map Change

� Letters of Map Amendment (LOMA)

� Letters of Map Revision (LOMR)

� Physical Map Revision

� Appeals/Protests

� Restudy

�Revisions to the FIRM panels require technical

supporting data

� Hydrologic Modeling

� Hydraulic Modeling

Risk MAPConsequences of Incomplete/Incorrect Submittals

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� Incomplete/Incorrect Submittals

� Increase chances submittal will be rejected

� Increase time to receive change

� For CLOMR and LOMR

� FEMA will notify requester and community within

60 days if more data required

� FEMA provides a LOMR or CLOMR or other

written determination within 90 days from the last

piece of information received

�May lead to additional fees

Risk MAP

Accepted Model List : Hydrology

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�Single Event

� HEC-1 (Versions 4.0.1 and up)

� HEC-HMS (Versions 1.1 and up)

�Continuous Event

� HEC-HMS (Versions 3.0 and up)

http://www.fema.gov/plan/prevent/fhm/en_hydro.shtm

Risk MAP

Accepted Model List : Statistical

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� For Gage Analysis

� HEC FFA (Version 3.1)

� Flood Frequency Analysis

� Bulletin 17B analysis

http://www.fema.gov/plan/

prevent/fhm/en_stat.shtm

Risk MAP

Accepted Model List : Hydraulics

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�One-Dimensional Steady Flow

� HEC-2 (Version 4.6.2)

� HEC-RAS (Versions 3.1.1 and up)

�One Dimensional Unsteady Flow

� HEC-RAS (Versions 3.1.1 and up)

� UNET (Version 4.0)

� Two-Dimensional Steady/Unsteady Flow Models

� TABS-RMA2 (Version 4.3)

� TABS-RMA4 (Version 4.5)

http://www.fema.gov/plan/prevent/fhm/en_hydra.shtm

Risk MAP

Accepted Models

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http://www.fema.gov/plan/prevent/fhm/en_modl.shtm

Risk MAP

Common Submittal Challenges

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�Common Technical Issues With Models

� Ineffective Flows

� Split Flows

� X-Sections

� Model Calibration

� Tie-Ins

� Floodways

�Other Common Submittal Issues

� All Necessary Models Not Included

� Topographic Data

� Notices to Affected Landowners

Risk MAP

Common Technical Issues

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� Ineffective Flow Not Considered at Upstream and

Downstream Faces of Bridges and Culverts

� Split Flows Incorrectly Modeled

� Separate x-sections needed for each channel

� Discharges should be adjusted through iterative process

� X-Sections

� Too Far Apart

� Frequently See X-Section 2000 or 4000 feet apart

� For some applications this is fine, but not for FEMA

flood insurance studies

� X-Sections Do Not Contain Flow

� X-Sections Not Surveyed

Risk MAP

Common Technical Issues

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�Model Calibration

� Model are should be calibrated if practical

� Hydrology is usually calibrated.

� Hydraulics are rarely calibrated.

� Don’t adjust parameters to values outside of normal range

� Need to investigate why model is giving poor results

Risk MAP

Common Technical Issues

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� Tie-Ins

� Models must tie into the effective BFE within 0.50’

� Match within 0.10’ preferred.

� Must tie in visibly, using available topography as a guide.

� A 90°bend at the property line is not acceptable

� Model far enough to achieve both tie ins, regardless of how

long the model must be.

� Duplicate effective, corrected effective, existing, and

proposed conditions model should agree at a common cross-

section near the limits of your models.

� Otherwise - probably have not a satisfactory tie in.

Risk MAP

Tie-Ins

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620

625

630

635

640

645

M

REVISED AREA

EFFECTIVE 100-YEAR PROFILE

AS-BUILT 100-YEAR PROFILE

TIE-IN POINT

TIE-IN POINT

25.5 26.0 26.5 27.0 27.5 28.0 28.5 29.0 29.5 30.0

STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH CREEK

Risk MAP

Floodways

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�Observe equal conveyance reduction criteria (Method

4)

�Rerun floodway with final limits set using Method 1 to

ensure a hydraulically smooth floodway boundary

�Use correct maximum floodway surcharges

� Floodway must be contained within SFHA

� Floodway can not be within the channel banks or

inside levees

�Retain existing floodway where possible

Risk MAP

Incorrect Hydraulic Model Submittal

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� If the effective model will be changed via the

LOMR process a number of models are required

to be submitted.

� Effective Model

� Duplicate Effective – Recreation of the Effective Model

� Corrected Effective – Corrections to Effective Model

� Existing Conditions – Additional XS, updated flow,

structures not previously included

� Proposed or As-Built Hydraulics.

Risk MAPCommon Issues With Topographic Workmaps

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�No contours provided

� Too few cross sections used or shown on map

�Physical features shown but not modeled (or vice

versa)

� Floodplain or Floodway Incorrectly Drawn

� 1% annual chance floodplain is delineated inside floodway

� Floodplain boundaries not consistent BFE

� Floodplain delineation inconsistent with topography

� Floodway width not consistent with information

shown in model or Floodway Data Table

Risk MAP

Notifications

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�Community acknowledgement for ALL affected

communities

�A letter stating all communities affected by

floodway changes will adopt and enforce the new

floodway

�Evidence of property owner notification for any

increase in WSEL, SFHA or any change in the

floodway delineation

Risk MAP

Additional Guidance And Tools

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�Guidelines and specifications for Flood Hazard

Mapping Partners

� Volume 2: Map Revisions and Amendments

� Appendix C: Riverine Analysis and Mapping

�Procedure Memorandums

http://www.fema.gov/plan/prevent/fhm/gs_memos.shtm

�Check-2 and Check-RAS

http://www.fema.gov/plan/prevent/fhm/frm_soft.shtm

�What’s New In Flood Hazard Mapping

http://www.fema.gov/plan/prevent/fhm/wn_main.shtm

Risk MAP

Final Thought

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�Ongoing MT-2 Applications In Region 6:

� Arkansas 10

� Louisiana 3

� New Mexico 10

� Oklahoma 22

� Texas 166

Risk MAP

Map Modernization to Risk MAP

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� Map Modernization used increasingly-

available technology to increase the quality,

reliability, and availability of flood hazard

maps and data

� It focused on digitizing maps to provide

timely, accurate information to community

planners

Risk MAP further enhances the maps, involves communities during the assessment and planning stages, and guides and encourages them to

communicate risk to their constituents

Risk MAP

Through collaboration with State, Local, and Tribal entities, Risk MAP will deliver quality data that increases public awareness and leads to action that reduces risk to life and property.

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Risk Mapping, Assessment, & PlanningRisk Mapping, Assessment, & Planning

Risk MAP

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Risk MAP: Project PlanningRisk MAP: Project Planning

Quality Data – Topographic information is needed to produce studies in Risk MAP

Awareness and Understanding of Local and State

needs – CNMS

Review of National HAZUS Level 1 Run – Forecasted

for April 2010

Review of current Mitigation Plans for potential

projects, review grant opportunities

Risk MAP

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Risk MAP: Project PlanningRisk MAP: Project Planning

� Focus Areas 2010

• Coastal, Levee and Other Engineering

• Funding will be based on “Trifecta”

� Risk + Need + Elevation Data

� Focus Areas 2011

• Funding will be based on “Superfecta”

� Risk + Need + Elevation Data

� AND Partner Contribution

Risk MAP