Digital Elevation Model for Biloxi, Mississippi:

Procedures, Data Sources and Analysis

Prepared for the Pacific Marine Environmental Laboratory (PMEL) NOAA Center for Tsunami

Research by the NOAA National Geophysical Data Center (NGDC)

March 29, 2007

Taylor, L.A., B.W. Eakins, K.S. Carignan, R.R. Warnken, T. Sazonova, and D.C. Schoolcraft

NOAA, National Geophysical Data Center, Boulder, Colorado

Corresponding author contact:

Lisa A. Taylor

NOAA, National Geophysical Data Center

Marine Geology and Geophysics Division

325 Broadway, E/GC 3

Boulder, Colorado 80305

Phone: 303-497-6767

Fax: 303-497-6513

E-mail: Lisa.A.Taylor@noaa.gov

http://www.ngdc.noaa.gov/mgg/inundation/
DIGITAL ELEVATION MODEL FOR BILOXI, MISSISSIPPI 2

CONTENTS

1. Introduction ............................................................................................................................................. 4

2. Study Area............................................................................................................................................... 5

3. Methodology ........................................................................................................................................... 5

3.1 Data Sources and Processing.......................................................................................................... 6

3.1.1 Shoreline.................................................................................................................... 7

3.1.2 Bathymetry.............................................................................................................. 12

3.1.3 Topography ............................................................................................................. 18

3.1.4 Topography–Bathymetry ....................................................................................... 25

3.2 Establishing Common Datums..................................................................................................... 27

3.2.1 Vertical datum transformations ............................................................................. 27

3.2.2 Horizontal datum transformations......................................................................... 27

3.3 Digital Elevation Model Development........................................................................................ 28

3.3.1 Verifying consistency between datasets................................................................ 28

3.3.2 Smoothing of bathymetric data.............................................................................. 28

3.3.3 Gridding the data with MB-System....................................................................... 29

3.4 Quality Assessment of the DEM.................................................................................................. 30

3.4.1 Horizontal accuracy................................................................................................ 30

3.4.2 Vertical accuracy .................................................................................................... 30

3.4.3 Slope maps and 3-D perspectives.......................................................................... 30

3.4.4 Comparison with source data files......................................................................... 32

3.4.5 Comparison with NGS geodetic monuments........................................................ 33

4. Summary and Conclusions................................................................................................................... 35

5. Acknowledgments ................................................................................................................................ 35

6. References............................................................................................................................................. 35

7. Data Processing Software..................................................................................................................... 35

LIST OF FIGURES

Figure 1. Color image of the Biloxi, Mississippi DEM................................................................................ 4

Figure 2. Barrier islands in Mississippi Sound.............................................................................................. 5

Figure 3. Source and coverage of datasets used to compile the Biloxi DEM ............................................. 6

Figure 4. NOAA Electronic Navigational Charts available in the Biloxi region........................................ 8

Figure 5. Detail of coastline datasets available for Biloxi DEM at Biloxi Bay .......................................... 9

Figure 6. Digital coastline segments used to create a ‘combined coastline’ for the Biloxi region .......... 10

Figure 7. Chandeleur Island Chain morphology, pre-2005 and post-Katrina ........................................... 11

Figure 8. Digital NOS hydrographic survey coverage in the Biloxi region .............................................. 14

Figure 9. Location of USACE survey data within dredged shipping channels in the Biloxi region ....... 15

Figure 10. ENC sounding data used in the Biloxi DEM............................................................................... 16

Figure 11. Detailed view of RNC #11371 at Karako Bay ............................................................................ 17

Figure 12. Source and coverage of topographic datasets used in building the Biloxi DEM...................... 19

Figure 13. Color image of the NED DEM..................................................................................................... 20

Figure 14. Color image of Harrison County DEM........................................................................................ 21

Figure 15. Spatial coverage of CSC topographic LiDAR datasets for the Biloxi DEM ............................ 22

Figure 16. CSC LiDAR merged post-Katrina dataset showing a “hill” at Bayou Casotte........................ 23

Figure 17. Images of RNC #11373 and NED data at Bayou Casotte .......................................................... 23

Figure 18. Chevron Refinery at Bayou Casotte............................................................................................. 24

Figure 19. Spatial coverage of topographic/ bathymetric datasets used in Biloxi DEM............................ 25

Figure 20. Slope map of the Biloxi DEM...................................................................................................... 31

Figure 21. Histogram: post-Katrina JALBTCX LiDAR survey and the Biloxi DEM ............................... 32

Figure 22. Histogram: NOS hydrographic survey and the Biloxi DEM...................................................... 32

Figure 23. Histogram: NGS geodetic monument elevations and the Biloxi DEM.................................... 33

Figure 24. Location of NGS monuments and NOAA tide stations in the Biloxi region ............................ 34
DIGITAL ELEVATION MODEL FOR BILOXI, MISSISSIPPI 3

LIST OF TABLES

Table 1. PMEL specifications for the Biloxi, Mississippi DEM ................................................................ 5

Table 2. Shoreline datasets used in compiling the Biloxi DEM................................................................. 7

Table 3. NOAA nautical charts in the Biloxi, Mississippi region .............................................................. 7

Table 4. Bathymetric datasets used in compiling the Biloxi DEM .......................................................... 12

Table 5. Digital NOS hydrographic surveys used in compiling the Biloxi DEM ................................... 12

Table 6. USACE bathymetric surveys used in compiling the Biloxi DEM............................................. 15

Table 7. Topographic datasets used in compiling the Biloxi, Mississippi DEM..................................... 18

Table 8. Combined topographic–bathymetric datasets used in compiling the Biloxi DEM................... 25

Table 9. Relationship between Mean High Water and other vertical datums in the Biloxi

region...................................................................................................................................... 27

Table 10. Data hierarchy used to assign gridding weight in MB-System.................................................. 29
DIGITAL ELEVATION MODEL FOR BILOXI, MISSISSIPPI 4

Digital Elevation Model for Biloxi, Mississippi:

Procedures, Data Sources and Analysis

1. INTRODUCTION

The National Geophysical Data Center (NGDC), an office of the National Oceanic and Atmospheric

Administration (NOAA), has developed a bathymetric–topographic digital elevation model (DEM) centered on

Biloxi, Mississippi (Fig. 1) for the Pacific Marine Environmental Laboratory (PMEL) NOAA Center for Tsunami

Research (http://nctr.pmel.noaa.gov/). The 1/3 arc-second1 coastal DEM will be used as input for the Method of

Splitting Tsunami (MOST) model developed by PMEL to simulate tsunami generation, propagation and inundation.

The DEM was generated from diverse digital datasets in the region (grid boundary and sources shown in Fig. 3) and

will be used for tsunami inundation modeling, as part of the tsunami forecast system SIFT (Short-term Inundation

Forecasting for Tsunamis) currently being developed by PMEL for the NOAA Tsunami Warning Centers. This

report provides a summary of the data sources and methodology used in developing the Biloxi DEM.

Figure 1. Color image of the Biloxi, Mississippi DEM.

 1. The Biloxi DEM is built upon a grid of cells that are square in geographic coordinates (latitude and longitude), however, the cells are not

square when converted to projected coordinate systems, such as UTM zones (in meters). At the latitude of Biloxi, Mississippi (30°24′ N, 88°53.3′

W) 1/3 arc-second of latitude is equivalent to 10.26 meters; 1/3 arc-second of longitude equals 8.90 meters.
DIGITAL ELEVATION MODEL FOR BILOXI, MISSISSIPPI 5

2. STUDY AREA

The Biloxi DEM covers the coastal region surrounding Biloxi, Mississippi, including the communities of

Gulfport and Pascagoula (Fig. 1), as well as the offshore areas of the Mississippi Sound, Chandeleur Sound, and the

Gulf Islands. The Chandeleur Islands (e.g., Fig 2) have undergone coastal erosion and changes in sediment

deposition that have modified the shoreline in the geologically short time span of 150 years.

More recently, the 2005 hurricane season severely impacted the landscape and economy of the Mississippi

Gulf Coast region. Hurricanes Arlene, Cindy, Dennis, and Katrina made landfall in the area between June and

August 2005, dramatically changing the shape of the coastline.

Figure 2. Barrier Islands in Mississippi Sound

(http://pubs.usgs.gov/of/2005/1151/images/fig1LG.jpg).

3. METHODOLOGY

The Biloxi DEM was developed to meet PMEL specifications (Table 1), based on input requirements for

the MOST inundation model. The best available digital data were obtained by NGDC and shifted to common

horizontal and vertical datums: World Geodetic System 1984 (WGS84) and Mean High Water (MHW), for

modeling of “worst-case scenario” flooding, respectively. Data processing and evaluation, and DEM assembly and

assessment are described in the following subsections.

Table 1: PMEL specifications for the Biloxi, Mississippi DEM.

Grid Area Biloxi, Mississippi

Coverage Area 88.3o to 89.3o W; 29.7o to 30.6o N

Coordinate System Geographic decimal degrees

Horizontal Datum World Geodetic System 1984 (WGS84)

Vertical Datum Mean High Water (MHW)

Vertical Units Meters

Grid Spacing 1/3 arc-second

Grid Format ESRI ASCII raster grid
DIGITAL ELEVATION MODEL FOR BILOXI, MISSISSIPPI 6

3.1 Data Sources and Processing

Shoreline, bathymetric, topographic and combined topographic–bathymetric digital datasets (Fig. 3) were

obtained from several U.S. federal and state agencies, including: NOAA’s National Ocean Service (NOS) and

Coastal Services Center (CSC); the U.S. Geological Survey (USGS); the U.S Army Corps of Engineers (USACE);

the Mississippi Office of Geology (MOG), Coastal Geology and Energy Division; and the Mississippi Automated

Resource Information System (MARIS). Safe Software’s (http://www.safe.com/) FME data translation tool package

was used to shift datasets to WGS84 horizontal datum and to convert them into ESRI (http://www.esri.com/)

ArcGIS shape files. The shape files were then displayed with ArcGIS to assess data quality and manually edit

datasets; NGDC’s GEODAS software (http://www.ngdc.noaa.gov/mgg/geodas/) was used to manually edit large xyz

datasets. Vertical datum transformations to MHW were also accomplished using FME, based upon data from local

NOAA Biloxi tidal stations. VDatum model software (http://nauticalcharts.noaa.gov/csdl/vdatum.htm) was not

available for this area.

Figure 3. Source and coverage of datasets used to compile the Biloxi DEM.
DIGITAL ELEVATION MODEL FOR BILOXI, MISSISSIPPI 7

3.1.1 Shoreline

Two digital coastline datasets of the Biloxi region were analyzed for inclusion in the Biloxi DEM: OCS

Electronic Navigational Charts and the Mississippi Office of Geology (MOG), Coastal Geology and Energy

Division High Water shoreline (Table 2).

Table 2: Shoreline datasets used in compiling the Biloxi DEM.

Source Year Data Type Spatial

Resolution

Original Horizontal

Datum/Coordinate

System

Original Vertical

Datum URL

OCS Electronic

Navigation

Charts (ENC)

2002 to 2004 extracted

coastline

Digitized

from

1:250,000 to

1:456,394

scale charts

WGS84 MHW http://chartmaker.ncd.n

oaa.gov/

Mississippi

Office of 

Geology (MOG),

Coastal Geology

and Energy

Division

1986 to 2002

MS High

water 

shoreline

~ 5 meters WGS84 “High water 

shoreline”

http://geology.deq.state.

ms.us/coastal/Shoreline

s-GPS.htm

1) NOAA Office of Coast Survey electronic navigational charts

Thirteen NOAA nautical charts within the Biloxi DEM region were downloaded from the NOAA OCS

website (http://chartmaker.ncd.noaa.gov/). All of the nautical charts are available in raster nautical chart

(RNC) format—georeferenced map imagery, which are frequently updated—with eight also available as

Electronic Navigational Charts (ENCs)—digital GIS chart components (Table 3 and Fig. 4). The NOAA

Coastal Services Center’s ‘Electronic Navigational Chart Data Handler for ArcView’ extension

(http://www.csc.noaa.gov/products/enc/) was used to import the ENCs into ArcGIS. The ENCs include

coastline data files (MHW), which were compared with the other coastline datasets, high-resolution coastal

LiDAR data, topographic data, and NOS hydrographic soundings. The ENCs also include soundings

(extracted from NOS hydrographic surveys) and land elevations.

Two of the ENCs (#11360 and #11366) were used in conjunction with the MOG coastline dataset to

build a ‘combined coastline’ (Fig. 6). Coastline files extracted from lower resolution ENCs #11360 and

#11366 were used instead of the higher resolution ENC #11363 and #11371 through #11375, as the data

more closely matched recent LiDAR data in areas with high rates of coastal change. Editing all of the ENC

coastline data was necessary to capture detail in areas where recent bathymetric survey data existed.

Nautical charts in RNC format were used to evaluate other coastline, bathymetric and topographic datasets

and for digitization of coastal features not represented in any digital coastline dataset.

Table 3: NOAA Electronic navigational charts in the Biloxi, Mississippi region.

Chart

Number

Title Edition Date Scale Available

Format

Used in

Combined

Coastline

11360 Cape St. George to Mississippi Passes 7th 2006 1:456,394 ENC yes

11363 Chandeleur and Breton Sounds 40th 2005 1:80,000 ENC

11366 Approaches to Mississippi River 7th 2007 1:250,000 ENC yes

11371 Lake Borgne and Approaches Cat Island to Point Aux

Herbes

2nd 2007 1:80,000 ENC

11372 Dog Keys Pass to Waveland 21st 2006 1:40,000 ENC

11373 Mississippi Sound and Approaches Dauphin Island to

Cat Island

8th 2007 1:80,000 ENC

11374 Dauphin Island Alabama to Horn Island Mississippi 12th 2006 1:40,000 ENC

11375 Pascagoula Harbor Mississippi 10th 2007 1:20,000 ENC
DIGITAL ELEVATION MODEL FOR BILOXI, MISSISSIPPI 8

Figure 4. NOAA Electronic Navigational Charts available in the Biloxi region.

ENCs #11360 and #11366 provide coverage for the majority of the DEM area.
DIGITAL ELEVATION MODEL FOR BILOXI, MISSISSIPPI 9

2) Mississippi Office of Geology, Mississippi High Water Shoreline

The Mississippi Office of Geology (MOG), Coastal Geology and Energy Division has developed a

High Water shoreline for use in coastal morphology studies and to provide a baseline dataset for

monitoring yearly shoreline changes. The primary data were collected in the field using backpack GPS

receivers while walking the high tide line. Orthophotos were also digitized and combined with the GPS

data to form complete coastal coverage2.

The MOG shoreline was manually edited using ESRI ArcMap to eliminate features such as piers and

docks. A comparison of the MOG shoreline with other coastline datasets available for the Mississippi

mainland is illustrated in Figure 5. The NGA and NGS datasets show bridge features, which were not

present in the MOG shoreline.

Figure 5. Detail of coastline datasets available for Biloxi Bay.

 2 GPS Data were collected in the field with backpack GPS receivers while walking the high tide line. GPS data post processed using base station

data from MOG base stations in Biloxi and Jackson. Shoreline vectors were cleaned to remove hanging nodes and manually corrected to remove

clusters and errant data points. Shoreline loops were also removed. Areas where survey parties met were joined by removing redundant sections

or nodes. Jagged shorelines sections, a result of data errors, were simplified where possible. OrthoImagery was used to supplement the GPS data

and complete the shoreline. This data is not as accurate as the GPS data. Ortho Image Data: shoreline digitized from aerial photo using ArcGIS.

All data cleaned to insure topological correctness. Polylines were split in segments less than 100 m in length for attributing. Dangles and

overshoots removed in process of line splitting. Shoreline is not continuous in all locations. Attribute data were conflated from previous sources

and from data created by the Mississippi Office of Geology. Previous source data were used as is. Created data were visually checked using map

analysis and orthoimagery. [Extracted from metadata]
DIGITAL ELEVATION MODEL FOR BILOXI, MISSISSIPPI 10

To obtain the best digital MHW coastline, NGDC combined the MOG High Waterline and ENC coastlines

into a ‘combined coastline’ (Fig. 6). Where overlap occurred between coastline datasets, the dataset with the most

detail and consistency with topographic, bathymetric and topographic–bathymetric datasets was used. This

combined coastline was manually adjusted along the Gulf coast, using ESRI ArcMap to match the JALBTCX highresolution coastal LiDAR data, particularly the late 2005 post-Hurricane Katrina survey. For areas where coastline

data were unavailable or grossly inaccurate in the Katrina-impacted Chandeleur Island region (e.g., Fig 7), NGDC

manually digitized a MHW coastline based on zero elevation data from both CSC topographic and JALBTCX

bathymetric/topographic datasets.

The combined coastline was converted to point data for use as a coastal buffer in the bathymetric presurfacing algorithm (see Section 3.3.2), to ensure that interpolated bathymetric values reached “zero” at the coast. It

was also used to clip USGS NED topographic DEMs, which contain elevation values, typically zero, over the open

ocean (Section 3.1.3).

Figure 6. Digital coastline segments used to create a ‘combined coastline’ for the Biloxi region.
DIGITAL ELEVATION MODEL FOR BILOXI, MISSISSIPPI 11

Figure 7. Changes in coastal morphology of the Chandeleur Island Chain pre- and post-Katrina

(http://coastal.er.usgs.gov/hurricanes/katrina/photo-comparisons/chandeleur.html#set5).
DIGITAL ELEVATION MODEL FOR BILOXI, MISSISSIPPI 12

3.1.2 Bathymetry

Bathymetric datasets used in the compilation of the Biloxi DEM include 48 NOS hydrographic surveys, 25

USACE surveys of dredged shipping channels, and OCS ENC extracted soundings in the Chandeleur Sound region

(Table 4).

Table 4: Bathymetric datasets used in compiling the Biloxi DEM.

Source Year Data Type Spatial Resolution

Original

Horizontal

Datum/Coordinate

System

Original

Vertical Datum URL

USACE

2005

to

2007

Bathymetric

surveys

Profiles 75 to 300 m

long, 5 to 150 m

apart with < 1 m

point spacing

NAD83 State

Plane Mississippi

East (feet)

MLLW

(meters)

NOS

1917

to

1989

Hydrographic

survey

soundings

Ranges from 10 m

to 1 km (varies with

scale of survey,

depth, traffic, and

probability of 

obstructions)

NAD27, NAD83

geographic

MLLW or 

MLW (meters)

http://www.ngdc.noaa.gov/mgg/bathy

metry/hydro.html

OCS 2006

extracted

ENC 

soundings

200 to 2500 m point

spacing

WGS84

geographic

MLLW

(meters)

1) NOS hydrographic survey data

A total of 48 NOS hydrographic surveys conducted between 1917 and 1989 were utilized in

developing the Biloxi DEM (Table 5; Fig. 8). The hydrographic survey data were originally vertically

referenced to Mean Lower Low Water (MLLW) or Mean Low Water (MLW) and horizontally referenced

to either NAD27 or NAD83 geographic datums.

All surveys were extracted from NGDC’s online NOS hydrographic database

(http://www.ngdc.noaa.gov/mgg/bathymetry/hydro.html) in their original, digitized datums (Table 5). The

data were then converted to WGS84 and MHW using FME software, an integrated collection of spatial

extract, transform, and load tools for data transformation (http://www.safe.com). The surveys were

subsequently clipped to a polygon 0.05 degree (~5%) larger than the Biloxi DEM area to support data

interpolation along grid edges.

After converting all NOS survey data to MHW (see Section 3.2.1), the data were displayed in ESRI

ArcMap and reviewed for digitizing errors against scanned original survey smooth sheets and compared to

the USACE multibeam and coastal LiDAR data, NED topographic data, the combined coastline, RNCs,

and Google Earth satellite imagery. Data point spacing for the NOS surveys varied by collection date. In

general, earlier surveys had greater point spacing than more recent surveys.

Table 5: Digital NOS hydrographic surveys used in compiling the Biloxi DEM.

Survey ID Year Scale Original vertical datum Original horizontal datum

D00077 1988 20,000 Mean Lower Low water NAD83

D00078 1984/87 40,000 Mean Lower Low water NAD27

D00079 1988 20,000 Mean Lower Low water NAD83

F00077 1948/88 40,000 Mean Low Water NAD27

F00314 1988 20,000 Mean Lower Low water NAD83

F00315 1988 20,000 Mean Lower Low water NAD83

F00324 1989 20,000 Mean Lower Low water NAD83

F00329 1989 20,000 Mean Lower Low water NAD83

F00335 1989 20,000 Mean Lower Low water NAD83
DIGITAL ELEVATION MODEL FOR BILOXI, MISSISSIPPI 13

H04000 1917 40,000 Mean Low Water undetermined

H04021 1917 40,000 Mean Low Water undetermined

H04171 1920 80,000 Mean Low Water undetermined

H04212 1921/22 80,000 Mean Low Water undetermined

H04219 1922 80,000 Mean Low Water undetermined

H04223 1922 80,000 Mean Low Water undetermined

H06550 1940 80,000 Mean Low Water NAD27

H06552 1940 40,000 Mean Low Water NAD27

H06688 1941 40,000 Mean Low Water NAD27

H08643 1961/62 10,000 Mean Low Water NAD27

H08644 1961/64 10,000 Mean Low Water NAD27

H08645 1961/62 10,000 Mean Low Water NAD27

H08646 1961/62 10,000 Mean Low Water NAD27

H08647 1961/62 20,000 Mean Low Water NAD27

H08648 1961/62 20,000 Mean Low Water NAD27

H08649 1962 10,000 Mean Low Water NAD27

H08650 1962 10,000 Mean Low Water NAD27

H08651 1962 10,000 Mean Low Water NAD27

H08652 1962 10,000 Mean Low Water NAD27

H08922 1966/68 10,000 Mean Low Water NAD27

H08923 1966/68 10,000 Mean Low Water NAD27

H08924 1967/68 20,000 Mean Low Water NAD27

H08925 1967/68 10,000 Mean Low Water NAD27

H08970 1968 10,000 Mean Low Water NAD27

H08971 1968 20,000 Mean Low Water NAD27

H09004 1968/69 20,000 Mean Low Water NAD27

H09028 1970/71 20,000 Mean Low Water NAD27

H09103A 1970 20,000 Mean Low Water undetermined

H09103B 1970 20,000 Mean Low Water undetermined

H09118 1970/75 20,000 Mean Low Water NAD27

H09156 1970/71 10,000 Mean Low Water NAD27

H09177 1970/71 10,000 Mean Low Water NAD27

H09200 1971 20,000 Mean Low Water NAD27

H10113 1983 40,000 Mean Lower Low water NAD27

H10206 1985 40,000 Mean Lower Low water NAD27

H10208 1985 20,000 Mean Lower Low water NAD27

H10247 1987 20,000 Mean Lower Low water NAD83

H10261 1987 20,000 Mean Lower Low water NAD27
DIGITAL ELEVATION MODEL FOR BILOXI, MISSISSIPPI 14

Figure 8. Digital NOS hydrographic survey coverage in the Biloxi region. DEM boundary shown in red, combined coastline shown in gray.
DIGITAL ELEVATION MODEL FOR BILOXI, MISSISSIPPI 15

2) USACE surveys of dredged shipping channels

Twenty five USACE bathymetric surveys of dredged shipping channels in the Mississippi Sound (Fig.

9) were provided to NGDC by Matt Tate, USACE Mobile District, Irvington Site Office. All data were

originally in NAD83 Mississippi State Plane East coordinates, and MLLW vertical datum (Table 6).

Surveys consist of parallel, across-channel profiles, spaced 5 to 125 meters apart, with point soundings less

than 1 meter apart. Two surveys (GA121306HIGH and GA121306LOW) were edited in ArcMap to remove

soundings inconsistent with neighboring soundings and nautical chart data. NGDC created soundings

along the axis of the Gulf Port shipping channel to insure its representation in the DEM.

Figure 9. Location of USACE survey data within dredged shipping channels in the Biloxi region.

Table 6: USACE bathymetric surveys used in compiling the Biloxi DEM.

Region Original horizontal

datum

Original vertical

datum Spatial Resolution

Biloxi NAD83 State Plane

Mississippi East (feet) MLLW Profiles ~100 m long, spaced 125 m apart, with <1 mpoint spacing

Gulfport NAD83 State Plane

Mississippi East (feet) MLLW Profiles ~200 m long, spaced 150 m apart, with <1 mpoint spacing

Pascagoula NAD83 State Plane

Mississippi East (feet) MLLW Profiles ~125 to 250 m long, spaced 25 to 125 m apart,with <1 m point spacing

Pass Christian NAD83 State Plane

Mississippi East (feet) MLLW Profiles ~75 to 300 m long, spaced 5 to 25 m apart,with <1 m point spacing
DIGITAL ELEVATION MODEL FOR BILOXI, MISSISSIPPI 16

3) Office of Coast Survey Electronic Nautical Chart extracted soundings

Two of the available ENCs for the Biloxi DEM were used to provide bathymetric sounding coverage

in the Chandeleur Sound region where NOS surveys were either non existent or provided sparse data

coverage (Fig. 10). ENCs #11363 and #11371 were downloaded from the OCS website

(http://chartmaker.ncd.noaa.gov/MCD/enc/index.htm) in S-57 format and imported to a coverage using

ArcCatalog. Elevations were converted from MLLW to MHW, and values greater than zero were deleted.

The data were then clipped using ArcCatalog to remove points more than 2.5 minutes outside the DEM

boundary. Figure 11 illustrates the unusual morphology of pitting on the seabed identified in ENC#11371.

Figure 10. Soundings taken from ENCs #11363 and #11371shown in green and blue, respectively. Biloxi DEM boundary shown in

red, combined coastline shown in black. Arrow indicates Karako Bay shown in Figure 11.
DIGITAL ELEVATION MODEL FOR BILOXI, MISSISSIPPI 17

Figure 11. Small depressions on the sea bed of Karako Bay identified in ENC#1137.

Numbers in red are elevation values transformed to MHW in meters.
DIGITAL ELEVATION MODEL FOR BILOXI, MISSISSIPPI 18

3.1.3 Topography

Topographic datasets in the Biloxi region were obtained from the U.S. Geological Survey, Mississippi

Automated Resource Information System (MARIS), and NOAA Coastal Services Center (CSC) (Fig.12). The U.S.

Army Corps of Engineers provided NGDC with a coastal Mississippi DEM that was not processed to bare earth; it

was not used in building the Biloxi DEM.

Table 7: Topographic datasets used in compiling the Biloxi DEM.

Source Year Data Type Spatial

Resolution

Original Horizontal

Datum/Coordinate

System

Original

Vertical

Datum

URL

USGS/NED 1998 to

2000 DEM 1/3 arcsecond NAD83 NAVD88(meters)

http://seamless.usgs.

gov/

USGS/SRTM 2004 DEM ~ 30 meters WGS84

assumed

Mean Sea

Level

http://seamless.usgs.

gov/

Mississippi

Automated

Resource

Information System

(MARIS)

1964 to

1996 county DEM 10 meters NAD83 NGVD29(feet)

http://www.maris.sta

te.ms.us/Htm/Downl

oadData/DEM.html

CSC/Mississippi

LiDAR for Harrison

County

2004 coastal LiDAR 5 meters NAD83 NAVD88

(meters)

http://www.csc.noaa

.gov/lidar

CSC/Mississippi

LiDAR post-Katrina

merged flood

2005 bare earth

coastal LiDAR 5 meters NAD83 NAVD88(meters)

http://www.csc.noaa

.gov/lidar

CSC/Mississippi

LiDAR for Jackson

and Hancock

Counties

2005 coastal LiDAR 5 meters NAD83 NAVD88

(meters)

http://www.csc.noaa

.gov/lidar
DIGITAL ELEVATION MODEL FOR BILOXI, MISSISSIPPI 19

Figure 12. Source and coverage of topographic datasets used in building the Biloxi DEM.
DIGITAL ELEVATION MODEL FOR BILOXI, MISSISSIPPI 20

1) USGS NED topography

The U.S. Geological Survey (USGS) National Elevation Dataset (NED; http://ned.usgs.gov/) provided

complete 1/3 arc-second coverage of the Biloxi region3. Data are in NAD83 geographic coordinates and

NGVD88 vertical datum (meters), and are available for download as raster DEMs. The extracted bare-earth

elevations have a vertical accuracy of +/- 7 to 15 meters depending on source data resolution. See the

USGS Seamless web site for specific source information (http://seamless.usgs.gov/). The dataset was

derived from USGS quadrangle maps and aerial photographs based on topographic surveys; it has been

revised using data collected in 1998 and 2000. The DEMs include zero values over the ocean, which were

clipped to the combined coastline.

Figure 13. NED topographic data for the northeastern section of the DEM showing lineations in data.

The lineated section was clipped from the final DEM.

The NED data for the northeastern section of the Biloxi DEM includes anomalous lineations that were

clipped from the dataset using ArcCatalog. The NED data were used exclusively in the eastern section of

the DEM located in Alabama and for the western Chandeleur Sound region as no LiDAR data were

available in those regions.

 3. The USGS National Elevation Dataset (NED) has been developed by merging the highest-resolution, best quality elevation data available

across the United States into a seamless raster format. NED is the result of the maturation of the USGS effort to provide 1:24,000-scale Digital

Elevation Model (DEM) data for the conterminous U.S. and 1:63,360-scale DEM data for Georgia. The dataset provides seamless coverage of the

United States, HI, AK, and the island territories. NED has a consistent projection (Geographic), resolution (1 arc second), and elevation units

(meters). The horizontal datum is NAD83, except for AK, which is NAD27. The vertical datum is NAVD88, except for AK, which is NGVD29.

NED is a living dataset that is updated bimonthly to incorporate the "best available" DEM data. As more 1/3 arc second (10 m) data covers the

U.S., then this will also be a seamless dataset. [Extracted from USGS NED website]
DIGITAL ELEVATION MODEL FOR BILOXI, MISSISSIPPI 21

2) Mississippi Automated Resource Information System DEMs

The MARIS data consist of two 10-meter resolution DEMs within Harrison and Jackson counties.

These DEMs were generated from 1:24,000 USGS topographic maps and are available on the MARIS

website (http://www.maris.state.ms.us/Htm/DownloadData/DEM.html).

NGDC clipped the MARIS DEMs to the combined coastline and converted the resulting DEM to

points, using ArcCatalog tools. Elevation values in the area of the barrier islands were anomalous; they

were removed using ArcMap (Fig. 14). The remaining data were included in the final DEM where NED

data were eliminated and where LiDAR data were unavailable.

Figure 14. Color image of the MARIS Harrison County DEM in the north eastern part of the Biloxi region. Note the

detail view of Cat Island showing an example of the poor data quality around the barrier islands.
DIGITAL ELEVATION MODEL FOR BILOXI, MISSISSIPPI 22

3) CSC Coastal LiDAR

NOAA’s Coastal Services Center provided coastal LiDAR datasets that were 95% processed to bareearth for Harrison, and Jackson and Hancock counties, as well as a post-Katrina Merged Flood4 dataset that

covered all three counties. Anomalous elevations below zero, located on land, were eliminated by filtering

the data using FME.

The post-Katrina Merged Flood dataset is processed to bare-earth; however Figures 16, 17, and 18

illustrate discrepancies between the LiDAR data and other topographic datasets that could not be rectified

by NGDC.

Figure 15. Spatial coverage of the CSC topographic LiDAR datasets for the Biloxi DEM.

 4 Pre- and post-hurricane Katrina LiDAR datasets of Hancock, Harrison, and Jackson Counties, MS, were merged into a seamless coverage by

URS. The pre-Katrina LiDAR data was collected by EarthData International at a 5-meter posting density during the period of February 25 to

March 30, 2005. Woolpert and USACE collected the post-Katina LiDAR data. Woolpert acquired 1-meter posting density data of Coastal

Mississippi between the dates of September 19 and October 9, 2005. USACE collected 1-meter posting density LiDAR of the Mississippi barrier

islands over the same time period. Each dataset was clipped at the approximate location of the debris line. Data south of the debris line was

removed from the Mississippi LiDAR dataset. Data north of the debris line was removed from the post-Katrina LiDAR dataset. The postKatrina LiDAR dataset was then imported into the seamless Mississippi LiDAR dataset creating a merged seamless coverage. [Extracted form

metadata.]
DIGITAL ELEVATION MODEL FOR BILOXI, MISSISSIPPI 23

Figure 16. CSC LiDAR merged post-Katrina dataset showing a ~40 meter “hill” at Bayou Casotte. It is an actual feature that was retained in

the Biloxi DEM..

Figure 17. A. Image of RNC #11373 at Bayou Casotte.

B. Image of NED data at Bayou Casotte, showing no expression of large hill in LiDAR data.
DIGITAL ELEVATION MODEL FOR BILOXI, MISSISSIPPI 24

Figure 18. Chevron Refinery at Bayou Casotte. Image from USGS

(http://coastal.er.usgs.gov/hurricanes/katrina/quickphotos/pascagoula/).

3) NASA Shuttle Radar Topography Mission

The NASA Shuttle Radar Topography Mission (SRTM) obtained elevation data on a near-global scale

to generate the most complete high-resolution digital topographic database of Earth5. The SRTM consisted

of a specially modified radar system that flew onboard the Space Shuttle Endeavour during an 11-day

mission in February of 2000. Data from this mission have been processed into 1 degree × 1 degree tiles that

have been edited to define the coastline, and are available from the USGS Seamless web site

(http://seamless.usgs.gov/) as raster DEMs. The data have not been processed to bare earth, but meet

absolute horizontal and vertical accuracies of 20 and 16 meters, respectively.

The SRTM data were used for a small area in the southern most section of the Chandeleur Island chain

(Fig 3). No other topographic data were available for this area.

 5. The SRTM data sets result from a collaborative effort by the National Aeronautics and Space Administration (NASA) and the National

Geospatial-Intelligence Agency (NGA – previously known as the National Imagery and Mapping Agency, or NIMA), as well as the participation

of the German and Italian space agencies, to generate a near-global digital elevation model (DEM) of the Earth using radar interferometry. The

SRTM instrument consisted of the Spaceborne Imaging Radar-C (SIR-C) hardware set modified with a Space Station-derived mast and additional

antennae to form an interferometer with a 60 meter long baseline. A description of the SRTM mission can be found in Farr and Kobrick (2000).

Synthetic aperture radars are side-looking instruments and acquire data along continuous swaths. The SRTM swaths extended from about 30

degrees off-nadir to about 58 degrees off-nadir from an altitude of 233 km, and thus were about 225 km wide. During the data flight the

instrument was operated at all times the orbiter was over land and about 1000 individual swaths were acquired over the ten days of mapping

operations. Length of the acquired swaths range from a few hundred to several thousand km. Each individual data acquisition is referred to as a

"data take." SRTM was the primary (and pretty much only) payload on the STS-99 mission of the Space Shuttle Endeavour, which launched

February 11, 2000 and flew for 11 days. Following several hours for instrument deployment, activation and checkout, systematic interferometric

data were collected for 222.4 consecutive hours. The instrument operated almost flawlessly and imaged 99.96% of the targeted landmass at least

one time, 94.59% at least twice and about 50% at least three or more times. The goal was to image each terrain segment at least twice from

different angles (on ascending, or north-going, and descending orbit passes) to fill in areas shadowed from the radar beam by terrain. This

'targeted landmass' consisted of all land between 56 degrees south and 60 degrees north latitude, which comprises almost exactly 80% of Earth’s

total landmass. [Extracted from SRTM online documentation]
DIGITAL ELEVATION MODEL FOR BILOXI, MISSISSIPPI 25

3.1.4 Topography–Bathymetry

Combined topographic–bathymetric surveys of coastal Mississippi were performed in 2004 and 2005—

post-Hurricanes Dennis and Katrina—by the Joint Airborne LiDAR Bathymetry Technical Center of Expertise

(JALBTCX) (Table 8; Fig. 19). The data were collected using the CHARTS (Compact Hydrographic Airborne

Rapid Total Survey) system to depict elevations above and below water along the immediate coastal zone

6

. The

surveys generally extend from 200 to 2500 meters inland and up to 150 meters over the water. Data points are

spaced approximately every 5 meters, and have an accuracy better than 3.0 meters horizontally and 0.3 meters

vertically. The dataset covers much of the barrier island chain with the exception of the islands to the west of

Chandeleur Sound; it covers the mainland excluding Harrison County.

Table 8. Combined topographic–bathymetric datasets used in compiling the Biloxi DEM.

Source Year Data Type Spatial

Resolution

Original Horizontal Datum/Coordinate

System

Original Vertical

Datum

JALBTCX USACE

2004 Topo/Bathy

project

2004 LiDAR 5 meters NAD83 geographic NAVD88 (meters)

JALBTCX USACE

2005 post-Katrina

Topo/Bathy project

2005 LiDAR 5 meters NAD83 geographic NAVD88 (meters)

Figure 19. Spatial coverage of topographic- bathymetric datasets utilized in Biloxi DEM development.

 6. These data were collected using a SHOALS-1000T system. It is owned and operated by Fugro Pelagos performing contract survey services for

the US Army Corps of Engineers. The system collects topographic lidar data at 10 kHz and hydrographic data at 1 kHz. The system also collects

RGB imagery at 1Hz. Aircraft position, velocity and acceleration information are collected through a combination of Novatel and POS A/V

equipment. Raw data are collected and transferred to the office for downloading and processing in SHOALS GCS software. GPS data are

processed using POSPac software and the results are combined with the lidar data to produce 3-D positions for each lidar shot. These data are

edited using Fledermaus software to remove anomalous data from the dataset. The edited data are unloaded from SHOALS GCS, converted from

ellipsoid to orthometric heights, based on the GEOID03 model, and split into geographic tiles covering approximately 5km each. [Extracted from

metadata]
DIGITAL ELEVATION MODEL FOR BILOXI, MISSISSIPPI 26

1) Post-Katrina 2005 JALBTCX LiDAR survey

This dataset consists of a bathymetric–topographic LiDAR survey covering 70 kilometers of the

coastal region from the eastern DEM boundary at San Souci Beach, Alabama to Deer Island at Biloxi,

Mississippi; the Gulf Islands National Seashore’s barrier islands; and the central section of the Chandeleur

Island chain. Post-Hurricane Katrina elevations were collected above and below water along the immediate

coastal zone. The survey has a spatial resolution of 5 meters and covers the shoreline with an approximate

width of 2,000 meters. Very little bathymetric information exists in the data, and the shoreline can not be

easily extracted from this dataset due to the near shore noise.

2) 2004 JALBTCX LiDAR survey

This dataset consists of a bathymetric–topographic coastal LiDAR survey covering Ship Island, Horn

Island, Petit Bois Island, Dauphin Island, and Deer Island. The survey has a spatial resolution of 5 meters

and consists primarily of topographic data. NGDC used this dataset for the areas not covered by the postHurricane Katrina dataset.
DIGITAL ELEVATION MODEL FOR BILOXI, MISSISSIPPI 27

3.2 Establishing Common Datums

3.2.1 Vertical datum transformations

Datasets used in the compilation and evaluation of the Biloxi DEM were originally referenced to a number

of vertical datums including Mean Lower Low Water (MLLW), Mean Low Water (MLW), Mean Sea Level,

National Geodetic Vertical Datum of 1929 (NGVD29), and North American Vertical Datum of 1988 (NAVD88).

All datasets were transformed to MHW to provide the worst-case scenario for inundation modeling. Units were

converted from feet to meters.

1) Bathymetric data

The NOS hydrographic surveys, the extracted ENC soundings, and the USACE surveys were

transformed from MLLW or MLW to MHW, using FME software, by adding a constant offset determined

by averaging two Biloxi NOAA tidal stations (Table 9; Fig. 26).

2) Topographic data

The USGS NED 1/3 arc-second DEM and the CSC LiDAR data were originally referenced to

NAVD88. The SRTM data were assumed to be referenced to MSL. The DEMs provided by MARIS were

referenced to NGVD29. Conversion to MHW, using FME software, was accomplished by adding tidestation derived constant offsets (Table 9).

3) Topographic–bathymetric data

Combined topographic–bathymetric coastal LiDAR survey data were transformed from NAVD88 to

MHW using FME software (Table 9).

Table 9. Relationship between Mean High Water and other vertical datums in the Biloxi region.*

Vertical datum Difference to MHW

NAVD88 -0.380

NGVD29 -0.4175

MSL -0.230

MLW -0.470

MLLW -0.502

* Datum relationships determined by averaging values from tide stations #8743735, Biloxi Bay and #8775557,

Gulfport.

3.2.2 Horizontal datum transformations

Datasets used to compile the Biloxi DEM were originally referenced to State Plane Mississippi North,

NAD27, NAD83 geographic, or WGS84 geographic horizontal datums. The relationships and transformational

equations between these horizontal datums are well established. All data were converted to a horizontal datum of

WGS84 using FME software.
DIGITAL ELEVATION MODEL FOR BILOXI, MISSISSIPPI 28

3.3 Digital Elevation Model Development

3.3.1 Verifying consistency between datasets

After horizontal and vertical transformations were applied, the resulting ESRI shape files were checked in

ESRI ArcMap for inter-dataset consistency. Problems and errors were identified and resolved before proceeding

with subsequent gridding steps. The evaluated and edited ESRI shape files were then converted to xyz files in

preparation for gridding. Problems included:

• Presence of man-made structures and river banks in most coastline datasets, which had to be removed.

• Inconsistencies between various coastline datasets and bathymetric, topographic and bathymetric–

topographic datasets. These inconsistencies are partly the result of differing resolution between datasets and

of morphologic change in the highly dynamic coastal zone such as the barrier islands area.

• Data values over the open ocean and rivers in the NED DEMs and LiDAR data. Each dataset required

automated clipping to the combined coastline.

• Digital, measured bathymetric values from NOS surveys date back over 70 years. More recent data, such as

USACE surveys in dredged shipping channels, differed from older, pre-dredging NOS data by as much as

10 meters. The older NOS survey data were excised where more recent bathymetric data exists.

3.3.2 Smoothing of bathymetric data

The NOS hydrographic surveys are generally sparse at the resolution of the 1/3 arc-second Biloxi DEM; in

deep water, the NOS survey data have point spacings up to 2 km apart. In order to reduce the effect of artifacts in the

form of lines of “pimples” in the DEM due to this low resolution dataset, and to provide effective interpolation into

the coastal zone, a 1 arc-second-spacing ‘pre-surface’ or grid was generated using GMT, an NSF-funded share-ware

software application designed to manipulate data for mapping purposes (http://gmt.soest.hawaii.edu/).

The NOS hydrographic point data, in xyz format, were combined with the USACE soundings and

JALBTCX bathymetric–topographic survey data into a single file, along with points extracted from the combined

coastline—to provide a “zero” buffer along the entire coastline. These point data were then median-averaged using

the GMT tool ‘blockmedian’ to create a 1 arc-second grid, 0.05 degrees (~5%) larger than the Biloxi DEM gridding

region. The GMT tool ‘surface’ then applied a tight spline tension to interpolate cells without data values. The GMT

grid created by ‘surface’ was converted into an ESRI Arc ASCII grid file, and clipped to the combined coastline (to

eliminate data interpolation into land areas). The resulting surface was compared with the original soundings to

ensure grid accuracy, converted to a shape file, and then exported as a xyz file for use in the final gridding process.
DIGITAL ELEVATION MODEL FOR BILOXI, MISSISSIPPI 29

3.3.3 Gridding the data with MB-System

MB-System (http://www.ldeo.columbia.edu/res/pi/MB-System/) was used to create the 1/3 arc-second

Biloxi DEM. MB-System is an NSF-funded share-ware software application specifically designed to manipulate

submarine multibeam sonar data, though it can utilize a wide variety of data types, including generic xyz data. The

MB-System tool ‘mbgrid’ applied a tight spline tension to the xyz data, and interpolated values for cells without

data. The data hierarchy used in the ‘mbgrid’ gridding algorithm, as relative gridding weights, is listed in Table 10.

Greatest weight was given to the high-resolution NOS multibeam and coastal LiDAR survey data. Least weight was

given to the pre-surfaced 1 arc-second NOS bathymetric grid. Gridding was performed in quadrants, each with a 5%

data overlap buffer. The resulting Arc ASCII grids were seamlessly merged in ArcCatalog to create the final 1/3 arcsecond Biloxi DEM.

Table 10. Data hierarchy used to assign gridding weight in MB-System.

Dataset Relative Gridding Weight

JALBTCX coastal lidar bathymetry–topography: post-Katrina 1

JALBTCX coastal lidar topography: merged flood 1000

Maris DEMs 1000

SRTM 1000

ENC soundings 100

USGS NED topographic DEM 10000

NOS hydrographic surveys: bathymetric soundings 100

Pre-surfaced bathymetric grid 10
DIGITAL ELEVATION MODEL FOR BILOXI, MISSISSIPPI 30

3.4 Quality Assessment of the DEM

3.4.1. Horizontal accuracy

The horizontal accuracy of topographic and bathymetric features in the Biloxi DEM is dependent upon the

datasets used to determine corresponding DEM cell values. Topographic features have an estimated accuracy of 1 to

15 meters: JALBTCX coastal LiDAR data have an accuracy of between 1 and 3 meters, NED topography is accurate

to within about 15 meters. Bathymetric features are resolved only to within a few hundred meters in deep-water

areas (i.e., the southeast corner of the DEM). Shallow, near-coastal regions, rivers, and dredged shipping channels

have an accuracy approaching that of subaerial topographic features. Positional accuracy is limited by the sparseness

of deep-water soundings, potentially large positional uncertainty of pre-satellite navigated (e.g., GPS) NOS

hydrographic surveys, and by the rapid morphologic change that occurs in this dynamic region.

3.4.2 Vertical accuracy

Vertical accuracy of elevation values for the Biloxi DEM is also highly dependent upon the source datasets

contributing to DEM cell values. Topographic areas have an estimated vertical accuracy between 0.15 for

JALBTCX coastal LiDAR data and up to 7 meters for NED topography. Bathymetric areas have an estimated

accuracy of between 0.1 meters and 5% of water depth (~1-2 meters in the southeast corner of the DEM). These

values were derived from the wide range of input data sounding measurements from the early 20th century to recent,

GPS-navigated sonar surveys. Gridding interpolation to determine values between sparse, poorly-located NOS

soundings degrades the vertical accuracy of elevations in deep water.

3.4.3 Slope maps and 3-D perspectives

ESRI ArcCatalog was used to generate a slope map from the Biloxi DEM to allow for visual inspection and

identification of artificial slopes along boundaries between datasets (e.g., Fig. 20). The DEM was transformed to

UTM Zone 16 coordinates (horizontal units in meters) in ArcCatalog for derivation of the slope grid; equivalent

horizontal and vertical units are required for effective slope analysis. Three-dimensional viewing of the UTMtransformed DEM was accomplished using ESRI ArcScene. Analysis of preliminary grids revealed suspect data

points, which were corrected before recompiling the DEM. Figure 1 shows a color image of the final version of the

1/3 arc-second Biloxi DEM.
DIGITAL ELEVATION MODEL FOR BILOXI, MISSISSIPPI 31

Figure 20. Slope map of the Biloxi DEM. Flat-lying slopes are white. Dark shading denotes steep

slopes; combined coastline in red.
DIGITAL ELEVATION MODEL FOR BILOXI, MISSISSIPPI 32

3.4.4 Comparison with source data files

To ensure grid accuracy, the Biloxi DEM was compared to select source data files. Files were chosen on

the basis of their contribution to the grid-cell values in their coverage areas (i.e., had the greatest weight and did not

significantly overlap other data files with comparable weight). A histogram of the difference between a postHurricane Katrina JALBTCX coastal bathymetric–topographic LiDAR survey file and the Biloxi DEM is shown in

Figure 21. A histogram of the difference between a NOS hydrographic survey file and the Biloxi DEM is shown in

Figure 22.

Figure 21. Histogram of the difference between one post-Katrina JALBTCX coastal bathymetric–topographic LiDAR

survey (438,007 points) and the Biloxi DEM.

Figure 22. Histogram of the difference between NOS hydrographic survey H010206 and the Biloxi DEM.
DIGITAL ELEVATION MODEL FOR BILOXI, MISSISSIPPI 33

3.4.5 Comparison with NGS geodetic monuments

The elevations of 63 NOAA NGS geodetic monuments were extracted from online shape files of

monument datasheets (http://www.ngs.noaa.gov/cgi-bin/datasheet.prl), which give monument positions in NAD83

(sub-mm accuracy) and elevations in NAVD88 (in meters). Elevations were shifted to MHW vertical datum (see

Table 9) for comparison with the Biloxi DEM (see Fig. 24 for monument locations). Differences between the Biloxi

DEM and the NGS geodetic monument elevations range from -12.3 to 27.9 meters, with a negative value indicating

that the monument elevation is less than the DEM (Fig. 23). Examination of the monuments with the largest positive

offsets from the DEM revealed that they lie within the East River Island region, alongside a highway, or atop a small

hill that is poorly resolved within the NED topographic DEM.

Figure 23. Histogram of the differences between NGS geodetic monument elevations and the Biloxi DEM.
DIGITAL ELEVATION MODEL FOR BILOXI, MISSISSIPPI 34

Figure 24. Location of NGS monuments and NOAA tide stations in the Biloxi region. Tide stations used to convert between

vertical datums; NGS monument elevations used to evaluate the DEM.
DIGITAL ELEVATION MODEL FOR BILOXI, MISSISSIPPI 35

4. SUMMARY AND CONCLUSIONS

A topographic–bathymetric digital elevation model of the Biloxi, Mississippi region, with cell spacing of

1/3 arc-second, was developed for the Pacific Marine Environmental Laboratory (PMEL) NOAA Center for

Tsunami Research. The best available digital data from U.S. federal and state agencies were obtained by NGDC,

shifted to common horizontal and vertical datums, and evaluated and edited before DEM generation. The data were

quality checked, processed and gridded using ESRI ArcGIS, FME, GMT, and MB-System software.

Recommendations to improve the Biloxi DEM, based on NGDC’s research and analysis, are listed below:

• Process coastal LiDAR data to bare earth.

• Obtain digital versions of several NOAA nautical charts that have not yet been digitized.

• Resurvey coastal areas impacted by Hurricane Katrina.

5. ACKNOWLEDGMENTS

The creation of the Biloxi DEM was funded by the NOAA, Pacific Marine Environmental Laboratory. The

authors thank Chris Chamberlin and Vasily Titov (PMEL), Jeff Lillycrop (USACE), Matt Tate (USACE Irvington

Site Office), and Cheryl Bosley (USACE Mobile District Office).

6. REFERENCES

Nautical Chart #11360, 7th Edition, 2006. Cape St. George to Mississippi Passes. Scale 1:456,394. U.S. Department

of Commerce, NOAA, National Ocean Service, Coast Survey.

Nautical Chart #11363, 40th Edition, 2005.Chandeleur and Breton Sounds. Scale 1:80,000. U.S. Department of

Commerce, NOAA, National Ocean Service, Coast Survey.

Nautical Chart #11366, 7th Edition, 2007. Approaches to Mississippi River. Scale 1:250,000. U.S. Department of

Commerce, NOAA, National Ocean Service, Coast Survey.

Nautical Chart #11371, 2nd Edition, 2006. Lake Borgne and Approaches Cat Island to Point Aux Herbes. Scale

1:80,000. U.S. Department of Commerce, NOAA, National Ocean Service, Coast Survey.

Nautical Chart #11372, 21st Edition, 2006. Dog Keys Pass to Waveland. Scale 1:40,000. U.S. Department of

Commerce, NOAA, National Ocean Service, Coast Survey.

Nautical Chart #11373, 8th Edition, 2007.Mississippi Sound and Approaches Dauphin Island to Cat Island. Scale

1:80,000. U.S. Department of Commerce, NOAA, National Ocean Service, Coast Survey.

Nautical Chart #11374, 12th Edition, 2006. Dauphin Island Ala. To Horn Island Miss.. Scale 1:40,000. U.S.

Department of Commerce, NOAA, National Ocean Service, Coast Survey.

Nautical Chart #11375, 10th Edition, 2007. Pascagoua Harbor Mississippi. Scale 1:20,000. U.S. Department of

Commerce, NOAA, National Ocean Service, Coast Survey.

7. DATA PROCESSING SOFTWARE

ArcGIS v. 9.2, developed and licensed by ESRI, Redlands, California, http://www.esri.com/

Electronic Navigational Chart Data Handler for ArcView, developed by NOAA Coastal Services Center,

http://www.csc.noaa.gov/products/enc/
DIGITAL ELEVATION MODEL FOR BILOXI, MISSISSIPPI 36

FME 2006 GB – Feature Manipulation Engine, developed and licensed by Safe Software, Vancouver, BC, Canada,

http://www.safe.com/

GEODAS v. 5 – Geophysical Data System, shareware developed and maintained by Dan Metzger, NOAA National

Geophysical Data Center, http://www.ngdc.noaa.gov/mgg/geodas/

GMT v. 4.1.4 – Generic Mapping Tools, shareware developed and maintained by Paul Wessel and Walter Smith,

funded by the National Science Foundation, http://gmt.soest.hawaii.edu/

MB-System v. 5.1.0, shareware developed and maintained by David W. Caress and Dale N. Chayes, funded by the

National Science Foundation, http://www.ldeo.columbia.edu/res/pi/MB-System/