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Lonnie G. Harper & Associates, Inc. Results of Cameron Parish DFIRM appeal. Lonnie G. Harper, PE & PLS (LGH) David Minton, PE (LGH) Dr. Joseph Suhayda (Coastal Oceanographic Consultant) Dr. Roy Dokka (LSU C4G) Dr. Eddie Lyons (McNeese State University). Key Parish concerns.

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Results of Cameron Parish DFIRM appeal

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Lonnie g harper associates inc

Lonnie G. Harper & Associates, Inc.

Results of Cameron Parish DFIRM appeal

Lonnie G. Harper, PE & PLS (LGH)

David Minton, PE (LGH)

Dr. Joseph Suhayda (Coastal Oceanographic Consultant)

Dr. Roy Dokka (LSU C4G)

Dr. Eddie Lyons (McNeese State University)


Key parish concerns

Key Parish concerns

  • THE PRELIMINARY DFIRMs RESULT IN A SIGNIFICANT CONVERSION OF A ZONES TO V ZONES IN CAMERON PARISH

  • BUILDING WITHIN V ZONES RESULTS IN INCREASED CONSTRUCTION COSTS

  • FEDERAL ASSISTANCE IS UNAVAILABLE IN V ZONES


Results of cameron parish dfirm appeal

ABFE


Dfirm

DFIRM


Technical issues storm surge

TECHNICAL ISSUES: Storm Surge

  • CALIBRATION ERRORS ARE PRESENT ASSOCIATED WITH THE HINDCAST FOR HURRICANE RITA: ERRORS IN PREDICTED HIGH-WATER MARKS (HWM) COMPARED TO MEASURED HWM AS GREAT AS+/- 4.5 FEET

  • AN EXAMINATION OF THE PRELIMINARY ADCIRC GRID HAS REVEALED MAJOR CHENIER RIDGES, LEVEES, MANMADE FEATURES, AND OTHER TOPOGRAPHIC DATA WERE OMITTED FROM THE MODEL


Results of cameron parish dfirm appeal

CAMERON PARISH AREA


Topographic data

TOPOGRAPHIC DATA

  • LGH COMPLETED A REVIEW OF MUCH OF THE TOPOGRAPHIC DATA USED FOR FIS

  • FIELD SURVEY DATA HAS BEEN GATHERED FOR COMPARISON TO ADCIRC AND LIDAR

    • ADCIRC VS. LIDAR

    • WHAFIS VS. LIDAR

    • LIDAR VS. SURVEY ELEVATIONS


Adcirc lidar comparison little chenier

Adcirc / lidar comparison:LITTLE CHENIER

MAX ELEVATION:

2.22 FEET

Rev 12-15-2008


Adcirc lidar comparison little chenier1

Adcirc / lidar comparison:LITTLE CHENIER

MAX ELEVATION:

+10 FEET

Rev 12-15-2008


Lidar concerns

LIDAR CONCERNS

  • LIDAR NAVD88 (2004.65) WAS REPORTEDLY USED AS THE VERTICAL DATUM

  • THE SPARSENESS OF FEMA’S TOPOGRAPHIC DATA USED IN THEIR WHAFIS MODEL OMITS MAJOR TERRAIN FEATURES

  • FOLLOWING SLIDES ILLUSTRATE DIFFERENCES BETWEEN ELEVATIONS FROM FEMA’S WHAFIS MODEL AND ELEVATIONS EXTRACTED FROM LIDAR NAVD88 (2004.65)

Rev 12-15-2008


Lidar comparison

LIDAR COMPARISON

LARGE INTERPOLATIONS

OMIT MAJOR TERRAIN FEATURES

Rev 12-15-2008


Lidar survey comparison

LIDAR / SURVEY comparison

  • THE FOLLOWING SLIDES ILLUSTRATE THE DISCREPANCIES BETWEEN LIDAR TOPOGRAPHIC DATA AND LGH & ASSCS GPS SURVEYED TOPOGRAPHIC DATA

Rev 12-15-2008


Lidar survey comparison1

LIDAR / SURVEY comparison

Rev 12-15-2008


Model errors

MODEL ERRORS

Rev 12-15-2008


Whafis errors

WHAFIS ERRORS

  • STARTING POINT TYPICALLY BEGINS 500 FEET IN GULF OF MEXICO

  • DUNE (DU) COMMAND LINE USED TO MODEL STRUCTURES SUCH AS LEVEES OR SEAWALLS OMITTED FROM THE WHAFIS MODEL

  • WHAFIS TERRAIN DATA DOES NOT REFLECT ACTUAL CONDITIONS

    • OVERWATER FETCH (OF) VS. INLAND FETCH (IF) AND VEGETATION HEADER (VH)

Rev 12-15-2008


Whafis errors1

WHAFIS ERRORS

  • A ZONE AREAS AS DEFINED BY WHAFIS ARE OMITTED FROM DFIRMs

  • IMPROPER DEFINITION OF DRAG COEFFICIENT FOR VEGETATION HEADER COMMAND LINES

Rev 12-15-2008


Starting point shift

STARTING POINT SHIFT

  • EVERY WHAFIS TRANSECT (104) HAS BEEN SHIFTED SOUTH RESULTING IN THE STARTING POINT OF EACH TRANSECT BEING OVER THE OPEN WATER OF THE GULF OF MEXICO

  • THIS HAS RESULTED IN STATIONS, WITH COMMAND LINES MODELING VEGETATION (VH OR VE), BEING LOCATED OVER OPEN WATER

Rev 12-15-2008


Starting point shift area between holly beach and cameron

STARTING POINT SHIFT: AREA BETWEEN HOLLY BEACH AND CAMERON

COMMAND

STATION DISTANCE

FROM BEGINNING

ELEVATION

VEG TYPE

Rev 12-15-2008


Starting point shift southeastern most transect

STARTING POINT SHIFT: SOUTHEASTERN MOST TRANSECT

Rev 12-15-2008


Of vs vh command line

OF vsvh command line

  • THERE ARE MANY INSTANCES OF OVERWATER FETCH (OF) COMMAND LINES BEING USED WHERE VEGETATION HEADER (VH) COMMAND LINE SHOULD BE USED. THIS, IN EFFECT, CAUSES A LAKE TO MODELED IN REGIONS WHERE EMERGENT LAND EXISTS

  • ONE EXAMPLE IS THE SOUTHERN END OF TRANSECT 17, LOCATED IN THE JOHNSON BAYOU AREA

Rev 12-15-2008


Of vs vh command line1

OF vs VH COMMAND LINE

Rev 12-15-2008


Of vs if command line

OF vs IF COMMAND LINE

  • OF (OVERWATER FETCH) COMMAND LINE IS USED FOR WATER WITH DEPTHS GREATER THAN 10 FEET, SUCH AS LAKES OR BAYS

  • IF (INLAND FETCH) COMMAND LINE IS FOR SHELTERED WATER WITH A DEPTH OF LESS THAN 10 FEET

Rev 12-15-2008


Of vs if command line1

OF vs IF COMMAND LINE

SHOULD BE MODELED

AS IF COMMAND LINE

RATHER THAN OF

Rev 12-15-2008


Wave model validation

Wave Model Validation

  • LGH INSTALLED SENSORS THROUGHOUT CAMERON PARISH FOR HURRICANE IKE

    • 7 UNITS AT 0.5 SECOND INTERVALS

    • 4 UNITS AT 2 SECOND INTERVALS

  • LGH CREATED A WAVE HEIGHT TO WATER DEPTH RATIO FROM ACTUAL FIELD DATA FROM HURRICANE IKE

Rev 12-15-2008


Results of cameron parish dfirm appeal

Rev 12-15-2008


Vegetation maps

VEGETATION MAPS

  • ONLY ONE TYPE OF VEGETATION (SPARTINA PATENS) WAS USED IN FEMA’S WHAFIS MODEL

  • CAMERON PARISH CONTAINS AT LEAST FIVE (5) DIFFERENT TYPES OF TERRAIN:

    • FRESHWATER MARSH

    • INTERMEDIATE MARSH

    • BRACKISH MARSH

    • SALTWATER MARSH

    • OTHER (EMERGENT TERRAIN USUALLY FOUND ON CHENIER RIDGES)

Rev 12-15-2008


Veg maps west cameron parish

VEG MAPS: WEST CAMERON PARISH

HACKBERRY

CALCASIEU

LAKE

CREOLE

CAMERON

HOLLY BEACH

JOHNSONBAYOU

OAKGROVE

GULF OF MEXICO

Rev 12-15-2008


Corrected whafis simulations

CORRECTED WHAFIS SIMULATIONS

  • ALL TRANSECTS WERE MODIFIED AND RECOMPUTED BY LGH BASED ON THE FOLLOWING INPUT MODIFICATIONS:

    • STARTING POINT PLACED IN PROPER POSITION

    • PROPER COMMAND LINES INSERTED IN INPUT FILES

    • CORRECTED ELEVATIONS

    • CORRECTED VEGETATION PROPERTIES

Rev 12-15-2008


Corrected whafis simulations1

CORRECTED WHAFIS SIMULATIONS

A ZONES ACHIEVED WITH

PROPER STARTING POINT,

ELEVATIONS, COMMAND LINES,

AND DEFAULT VALUE FOR Cd

Rev 12-15-2008


A zones cameron

A ZONES: CAMERON

A ZONES INCREASE

DRAMATICALLY AS

Cd INCREASES

Rev 12-15-2008


Summary

SUMMARY

  • LOW RESOLUTION OF TOPOGRAPHIC DATA IN ALL MODELS

  • POOR CALIBRATION OF SURGE MODEL

  • IMPROPER APPLICATION OF INPUT DATA

  • INCONSISTENT ELEVATION DATA BETWEEN MODELS

  • OMISSION OF INPUT DATA

  • USE OF REGIONAL SURGE MODEL FOR A SMALL GEOGRAPHIC AREA WITH UNUSUAL TOPOGRAPHIC FEATURES MAY YIELD QUESTIONABLE SWEL RESULTS

Rev 12-15-2008


Results of cameron parish dfirm appeal

ABFE

Rev 12-15-2008


Lgh revised

LGH Revised

Rev 12-15-2008


Dfirm1

DFIRM


Lgh revised1

LGH Revised

Rev 12-15-2008


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