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Results of Cameron Parish DFIRM appeal

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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)




                                                               1
        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

                                       2
ABFE




       3
DFIRM




        4
   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

                                        5
CAMERON PARISH AREA




                      6
         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




                                          7
ADCIRC / LIDAR COMPARISON:
    LITTLE CHENIER


                          MAX ELEVATION:
                            2.22 FEET




         Rev 12-15-2008                    8
ADCIRC / LIDAR COMPARISON:
    LITTLE CHENIER

                          MAX ELEVATION:
                            +10 FEET




         Rev 12-15-2008                    9
          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          10
LIDAR COMPARISON




                       LARGE INTERPOLATIONS
                       OMIT MAJOR TERRAIN
                       FEATURES




      Rev 12-15-2008                          11
   LIDAR / SURVEY COMPARISON
 THE FOLLOWING SLIDES ILLUSTRATE THE
  DISCREPANCIES BETWEEN LIDAR
  TOPOGRAPHIC DATA AND LGH & ASSCS
  GPS SURVEYED TOPOGRAPHIC DATA




                  Rev 12-15-2008        12
LIDAR / SURVEY COMPARISON




          Rev 12-15-2008    13
MODEL ERRORS




    Rev 12-15-2008   14
          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        15
         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   16
      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        17
STARTING POINT SHIFT: AREA BETWEEN
    HOLLY BEACH AND CAMERON


   COMMAND

   STATION DISTANCE
   FROM BEGINNING

   ELEVATION


   VEG TYPE




                      Rev 12-15-2008   18
    STARTING POINT SHIFT:
SOUTHEASTERN MOST TRANSECT




           Rev 12-15-2008    19
       OF vs VH 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            20
OF vs VH COMMAND LINE




         Rev 12-15-2008   21
      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         22
OF vs IF COMMAND LINE


                          SHOULD BE MODELED
                          AS IF COMMAND LINE
                            RATHER THAN OF




         Rev 12-15-2008                        23
      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     24
Rev 12-15-2008   25
         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           26
VEG MAPS: WEST CAMERON PARISH



                                       HACKBERRY




                                              CALCASIEU
                                                LAKE

                                                              CREOLE
                                                   CAMERON

                                HOLLY BEACH
      JOHNSON BAYOU                                          OAKGROVE
                             GULF OF MEXICO

                      Rev 12-15-2008                                    27
       CORRECTED WHAFIS
          SIMULATIONS
o ALL TRANSECTS WERE MODIFIED AND
  RECOMPUTED BY LGH BASED ON THE
  FOLLOWING INPUT MODIFICATIONS:
  o STARTING POINT PLACED IN PROPER
    POSITION
  o PROPER COMMAND LINES INSERTED IN
    INPUT FILES
  o CORRECTED ELEVATIONS
  o CORRECTED VEGETATION PROPERTIES


                 Rev 12-15-2008        28
CORRECTED WHAFIS
   SIMULATIONS


       A ZONES ACHIEVED WITH
       PROPER STARTING POINT,
     ELEVATIONS, COMMAND LINES,
      AND DEFAULT VALUE FOR Cd




       Rev 12-15-2008             29
A ZONES: CAMERON




            A ZONES INCREASE
            DRAMATICALLY AS
              Cd INCREASES




      Rev 12-15-2008           30
           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        31
ABFE




Rev 12-15-2008   32
LGH REVISED




   Rev 12-15-2008   33
DFIRM




        34
LGH REVISED




   Rev 12-15-2008   35

				
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