DIGITAL ELEVATION MODEL OF KAWAIHAE, HAWAII

noaa / NATIONAL OCEANIC AND

ATMOSPHERIC ADMINISTRATION

National Environmental Satellite,

Data, and Information Service

NOAA Technical Memorandum NESDIS NGDC-15

DIGITAL ELEVATION MODEL OF KAWAIHAE, HAWAII:

PROCEDURES, DATA SOURCES AND ANALYSIS 

L.A.Taylor

B.W. Eakins

K.S. Carignan

R.R. Warnken

T. Sazonova

D.C. Schoolcraft

National Geophysical Data Center

Marine Geology and Geophysics Division

Boulder, Colorado

January 2008


DIGITAL ELEVATION MODEL OF KAWAIHAE, HAWAII

UNITED STATES

DEPARTMENT OF COMMERCE

Carlos M. Gutierrez

Secretary

NATIONAL OCEANIC AND

ATMOSPHERIC ADMINISTRATION

VADM Conrad C. Lautenbacher, Jr.

Under Secretary for Oceans

and Atmosphere/Administrator

National Environmental Satellite,

Data, and Information Service

Mary E. Kicza

Assistant Administrator

NOAA Technical Memorandum NESDIS NGDC-15

DIGITAL ELEVATION MODEL OF KAWAIHAE, HAWAII:

PROCEDURES, DATA SOURCES AND ANALYSIS

Lisa A. Taylor1

Barry W. Eakins2

Kelly S. Carignan2

Robin R. Warnken1

Tatiana Sazonova2

David C. Schoolcraft1

1NOAA, National Geophysical Data Center, Boulder, Colorado

2

Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder 

National Geophysical Data Center

Marine Geology and Geophysics Division 

Boulder, Colorado

January 2008
ii

Taylor et al., 2008

NOTICE

Menton of a commercal company or product does not consttute an endorsement by the 

NOAA Natonal Envronmental Satellte, Data, and Informaton Servce. Use of nformaton 

from ths publcaton concernng propretary products or the test of such products for publcty

or advertsng purposes s not authorzed. 

Corresponding author contact:

Lsa A. Taylor

NOAA, Natonal Geophyscal Data Center

Marne Geology and Geophyscs Dvson

35 Broadway, E/GC 3

Boulder, Colorado 80305

Phone: 303-497-6767

Fax: 303-497-653

E-mal: Lsa.A.Taylor@noaa.gov

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

Also avalable from the Natonal Techncal Informaton Servce (NTIS)

(http://www.nts.gov)
iii

DIGITAL ELEVATION MODEL OF KAWAIHAE, HAWAII

Contents

1. Introduction........................................................................................................................................1

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

3. Methodology ......................................................................................................................................2

3.1 Data Sources and Processing ......................................................................................................3

3.1.1 Shoreline................................................................................................................4

3.1.2 Bathymetry ............................................................................................................4

3.1.3 Topography............................................................................................................9

3.2 Establishing Common Datums .................................................................................................11

3.2.1 Vertical datum transformations ...........................................................................11

3.2.2 Horizontal datum transformations.......................................................................11

3.3 Digital Elevation Model Development .....................................................................................11

3.3.1 Verifying consistency between datasets..............................................................11

3.3.2 Gridding of multibeam bathymetric data ............................................................11

3.3.3 Smoothing of bathymetric data ...........................................................................12

3.3.4 Gridding the data with MB-System.....................................................................12

3.4 Quality Assessment of the DEM...............................................................................................12

3.4.1 Horizontal accuracy.............................................................................................12

3.4.2 Vertical accuracy .................................................................................................12

3.4.3 Slope maps and 3-D perspectives........................................................................13

3.4.4	 Comparison with source data files.......................................................................14

3.4.5 Comparison with NGS geodetic monuments......................................................15

4. Summary and Conclusions...............................................................................................................16

5. Acknowledgments............................................................................................................................17

6. References........................................................................................................................................17

7. Data Processing Software ................................................................................................................17

List of Figures

Figure 1. Shaded relief image of the Kawaihae DEM ...............................................................................1

Figure 2. Volcanoes of the Island of Hawaii ..............................................................................................2

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

Figure 4. Digital NOS hydrographic survey coverage in the Kawaihae region.........................................6

Figure 5. Screen grab of multibeam sonar surveys in the Kawaihae region..............................................7

Figure 6. Spatial coverage of JALBTCX SHOALS bathymetric LiDAR surveys in the Kawaihae 

region ...................................................................................................................................8

Figure 7. Color image of the NED DEM in the vicinity of the Kohala Volcano .....................................10

Figure 8. Aerial photo of Waipio and Waimanu Valleys shown in Figure 7 ............................................10

Figure 9. Slope map of the Kawaihae DEM ............................................................................................13

Figure 10. Perspective view from the west of the Kawaihae DEM ...........................................................14

Figure 11.	 Histogram of the differences between one file of the NED data and the Kawaihae DEM.......14

Figure 12. Histogram of the differences between NOS survey #H09015 and the Kawaihae DEM. .........15

Figure 13. Histogram of the differences between NGS geodetic monument elevations and the 

Kawaihae DEM .................................................................................................................15

Figure 14. Location of NGS monuments and NOAA tide stations in the Kawaihae region......................16

List of Tables

Table 1.	 PMEL specifications for the Kawaihae, Hawaii DEM ...............................................................2

Table 2. Shoreline dataset used in compiling the Kawaihae DEM...........................................................4

Table 3. Bathymetric datasets used in compiling the Kawaihae DEM.....................................................4

Table 4. Digital NOS hydrographic surveys used in compiling the Kawaihae DEM ..............................5

Table 5. Multibeam sonar surveys used in compiling the Kawaihae DEM..............................................7
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Taylor et al., 2008

Table 6. Topographic dataset used in compiling the Kawaihae DEM......................................................9

Table 7. Relationship between Mean High Water and other vertical datums in the Kawaihae 

region .................................................................................................................................11

Table 8. Data hierarchy used to assign gridding weight in MB-System.................................................12


DIGITAL ELEVATION MODEL OF KAWAIHAE, HAWAII

Digital Elevation Model of Kawaihae, Hawaii:

Procedures, Data Sources and Analysis

1. Introduction

In August 2007, the National Geophysical Data Center (NGDC), an office of the National Oceanic and

Atmospheric Administration (NOAA), developed a bathymetric–topographic digital elevation model (DEM) of 

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

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

of Splitting Tsunami) 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 Kawaihae DEM.

Figure 1. Shaded relief image of the Kawaihae DEM. Contour interval is 100 meters.

. The Kawaihae 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 Kawaihae, Hawaii (20°2.4′ N, 155°49.9′

W) 1/3 arc-second of latitude is equivalent to 10.25 meters; 1/3 arc-second of longitude equals 9.69 meters.


Taylor et al., 2008

2. Study Area

The Kawaihae DEM covers the northwestern coastal region centered on the western coast of the island of 

Hawaii, Hawaii. The islands of Hawaii have been created by shield-building volcanoes, whose low-viscosity lava 

flows often reach the coast. The Island of Hawaii lies over or just north of the Hawaiian hot spot and is composed of

five volcanoes (Fig. 2): Kohala, Hualalai, Mauna Kea, Mauna Loa, and Kilauea; the extinct Mahukona Volcano (Fig.

1) lies west of Kawaihae and is completely submerged, Loihi, the youngest volcano, lies south of the island and has yet 

to reach the sea surface. The island has 428 km of general coastline and is known locally and abroad as the Big Island. 

The western side of the Big Island lies in the lee of Mauna Loa (4,205 m), the largest volcano on Earth (measuring 

from the sea floor), which has formed in the last 600,000–1,000,000 yrs, rising almost 9 km from the sea floor. The

leeward climate is extraordinarily dry with 25 cm annual rainfall, resulting in minimal stream erosion on the Hawaii

lavas of western Kohala, and on the lavas of Mauna Kea, Mauna Loa, and Hualalai, south along the coast respectively. 

Kawaihae Harbor is a deep draft harbor on the Big Island and is fronted by a system of offshore fringing reefs. Several 

sand beaches exist at the south end of Kawaihae Bay, derived from eroded coral that was dredged during construction 

of the harbor. 

Figure 2. The volcanoes of the Island of Hawaii (image from http://geopubs.wr.usgs.gov/i-map/i2809/).

3. Methodology

The Kawaihae 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 Kawaihae, Hawaii DEM.

Grid Area Kawaihae, Hawaii

Coverage Area 155.6o to 156.25o W; 19.4o to 20.4o 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 OF KAWAIHAE, HAWAII

3.1 Data Sources and Processing

Shoreline, bathymetric, and topographic digital datasets (Fig. 3) were obtained from several U.S. federal 

agencies, including: NOAA’s National Ocean Service (NOS), the U.S. Army Corps of Engineers (USACE); and the 

U.S. Geological Survey (USGS). The data were collected by numerous methods, in different terrestrial environments, 

and at various scales and resolutions. Datasets were assessed for quality and accuracy both within each dataset, 

and between datasets to ensure consistency and gradual topographic transitioning along the edges of datasets. Safe 

Software’s (http://www.safe.com/) FME data translation tool package was used to shift datasets to WGS84 horizontal 

datum and to convert 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 accomplished 

using FME, based upon data from a NOAA tide station at Kawaihae Hawaii, as no VDatum model software (http://

nauticalcharts.noaa.gov/csdl/vdatum.htm) was available for this area.

Figure 3. Source and coverage of datasets used to compile the Kawaihae DEM.
Taylor et al., 2008

3.1.1 Shoreline

One digital coastline dataset of Hawaii Island was used in building the Kawaihae DEM: the United States 

Geological Survey Hawaii Island 7.5 minute Quads-Derived Shoreline (Table 2). 

Table 2. Shoreline dataset used in compiling the Kawaihae DEM.

Source Year Data Type Spatial Resolution Original Horizontal Datum/

Coordinate System

Original Vertical 

Datum

USGS 2004 

Vector shoreline 

derived from 

USGS quads

~ 1:24,000 NAD83 UTM Zone 5 Inferred MHW

1) USGS Hawaii Island 7.5 minute Quads-Derived Shoreline 

The Hawaii (Big Island) coastline is an unclassified vector dataset generated by the United States Geological

Survey in 1998. The shoreline is referenced to MHW and constructed from digitized 7.5 minutes USGS quads. 

The Hawaii coastline is mostly consistent with the NED topographic data and JALBTCX SHOALS 

bathymetric LiDAR surveys. The coastline was converted to point data for use as a coastal buffer for the bathymetric 

pre-surfacing 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). 

3.1.2 Bathymetry

Bathymetric datasets used in the compilation of the Kawaihae DEM include 28 NOS hydrographic surveys, 

13 multibeam sonar surveys, and JALBTCX SHOALS bathymetric LiDAR surveys along the coast (Table 3).

Table 3. Bathymetric datasets used in compiling the Kawaihae DEM.

Source Year Data Type Spatial Resolution

Original Horizontal 

Datum/Coordinate 

System

Original 

Vertical 

Datum

URL

 NOS 1932 to 

1987

Hydrographic 

survey 

soundings

Ranges from 10 

m to 1 km (varies 

with scale of survey, 

depth, traffic, and

probability of 

obstructions)

Early Hawaiian Island, 

Old Hawaiian, or 

NAD83 geographic

MLLW http://www.ngdc.noaa.gov/

mgg/bathymetry/hydro.html

NGDC 1986 

- 2002

Multibeam 

sonar ~ 3% of water depth WGS84 geographic MSL

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

mgg/bathymetry/multibeam.

html

USACE 2001 SHOALS 

LiDAR ~ 5 to 10 meters WGS84 geographic MLLW

http://shoals.sam.usace.army.

mil/hawaii/pages/Hawaii_

Data.htm

NGDC 2006

Digitized 

soundings in 

Nonokohau 

and Kawaihae 

harbors

~5-10 meters WGS84 geographic MLLW

1) NOS hydrographic survey data

A total of 28 NOS hydrographic surveys conducted between 1932 and 1987 were utilized in developing 

the Kawaihae DEM (Table 4; Fig. 5). The hydrographic survey data were originally vertically referenced to 

Mean Lower Low Water (MLLW) and horizontally referenced to Early Hawaiian Island, Old Hawaiian, or 

NAD83 geographic datums.

Data point spacing for the NOS surveys varied by collection date. In general, earlier surveys had greater 

point spacing than more recent surveys. All surveys were extracted from NGDC’s online NOS hydrographic 

database (http://www.ngdc.noaa.gov/mgg/bathymetry/hydro.html) in their original, digitized vertical datum 
DIGITAL ELEVATION MODEL OF KAWAIHAE, HAWAII

and NAD83 horizontal datum (Table 4). 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 (~10%) larger than the 

Kawaihae 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 

topographic NED data, JALBTCX SHOALS LiDAR bathymetric data, the Hawaii coastline, NOAA nautical 

charts, and Google Earth satellite imagery.

Table 4. Digital NOS hydrographic surveys used in compiling the Kawaihae DEM.

NOS Survey 

ID

Year of 

Survey Survey Scale Original Vertical Datum Original Horizontal Datum

H05339 1932 100,000 mean lower low water early Hawaiian island datum

H09017 1968 10,000 mean lower low water early Hawaiian island datum

H09019 1968 10,000 mean lower low water early Hawaiian island datum

H09015 1969 40,000 mean lower low water early Hawaiian island datum

H09016 1969 80,000 mean lower low water early Hawaiian island datum

H09129 1970 40,000 mean lower low water early Hawaiian island datum

H09131 1970 10,000 mean lower low water early Hawaiian island datum

H09132 1970 10,000 mean lower low water old Hawaiian datum

H09234 1971 5,000 mean lower low water old Hawaiian datum

H09235 1971 5,000 mean lower low water old Hawaiian datum

H09308A 1972 5,000 mean lower low water old Hawaiian datum

H09308B 1972 5,000 mean lower low water old Hawaiian datum

H09334 1972 10,000 mean lower low water old Hawaiian datum

H09335 1972 10,000 mean lower low water early Hawaiian island datum

H09339 1972 80,000 mean lower low water early Hawaiian island datum

H09346 1972 10,000 mean lower low water old Hawaiian datum

H09361B 1973 5,000 mean lower low water old Hawaiian datum

H09816 1979 10,000 mean lower low water early Hawaiian island datum

H09974 1981 80,000 mean lower low water old Hawaiian datum

H09975 1981 20,000 mean lower low water old Hawaiian datum

H09983 1981 20,000 mean lower low water old Hawaiian datum

H09985 1981 80,000 mean lower low water early Hawaiian island datum

B00090 1986 50,000 mean lower low water NAD83

B00101 1987 50,000 mean lower low water NAD83

H09018 1968/70 10,000 mean lower low water early Hawaiian island datum

H09237 1971/72 10,000 mean lower low water old Hawaiian datum

H09336A 1972/73 5,000 mean lower low water early Hawaiian island datum

H09307 1972/74 10,000 mean lower low water early Hawaiian island datum
Taylor et al., 2008

Figure 4. Digital NOS hydrographic survey coverage in the Kawaihae region. DEM boundary in red, USGS coastline in gray.
DIGITAL ELEVATION MODEL OF KAWAIHAE, HAWAII

2) NGDC multibeam sonar surveys

Various oceanographic institutions have conducted high-resolution multibeam swath sonar surveys 

around the Hawaiian Islands in the period from 1987 through 2002 including NOAA, University of Rhode 

Island, Scripps Institute of Oceanography, Monterey Bay Aquarium Research Institute, and Japan Agency for 

Marine-Earth Science and Technology. The multibeam data are archived and disseminated by NGDC, with 

13 surveys falling within the Kawaihae DEM boundary (Table 5, Fig. 6). Data were referenced to WGS84 

and MSL and were gridded using MB-System [section 3.3.2].

Table 5. Multibeam sonar surveys used in compiling the Kawaihae DEM.

Survey ID Year Source

AII8L11 1987 U. of Rhode Island

B00090 1986 NOAA

B00101 1987 NOAA

CRGN04WT 1987 SIO

DRFT13RR 2002 SIO

KR2001 2001 JAMSTEC

Kohala 1998 MBARI

Mahukona 1998 MBARI

NECR05RR 2000 SIO

TUNE03WT 1991 SIO

TUNE04WT 1991 SIO

YK1999 2002 JAMSTEC

YK2002 2002 JAMSTEC

Figure 5. Screen grab of multibeam sonar surveys in the Kawaihae region, from NGDC ArcIMS interface (http://map.ngdc.noaa.gov/website/

mgg/multibeam/viewer.htm).
Taylor et al., 2008

3) JALBTX SHOALS LiDAR surveys

Near coastal bathymetric LiDAR data (Fig. 6) were collected by the U.S. Army Corps of Engineers Joint 

Airborne LiDAR Bathymetry Technical Center of Expertise (JALBTCX), using the SHOALS (Scanning 

Hydrographic Operational Airborne LiDAR Survey) system, which consists of an airborne laser transmitter/

receiver capable of measuring 400 soundings per second. The system operates from a deHavilland DHC6 Twin Otter flying at altitudes between 200 and 400 meters with a ground speed of about 100 knots. The

SHOALS system also includes a ground-based data processing system for calculating accurate horizontal 

position and water depth. The positional accuracy of the data is +3 meters horizontally, and +0.15 meters 

vertically. The dataset was originally referenced to MLLW and WGS84 geographic.

Positive elevation values were present in the data, reflecting subaerial returns, and were excised by

NGDC prior to building the Kawaihae DEM. Some anomalous values were also present in bathymetric 

regions, which were deleted.

Figure 6. Spatial coverage of JALBTCX SHOALS bathymetric LiDAR surveys in the Kawaihae region.

4) NGDC Honokohau and Kawaihae harbors

As no bathymetry was available for Honokohau and Kawaihae harbors NGDC digitized soundings 

for the harbors from two NOAA Raster Nautical Charts (#19330 and #19327). Original soundings were in 

fathoms at MLLW.
DIGITAL ELEVATION MODEL OF KAWAIHAE, HAWAII

3.1.3 Topography

One topographic dataset in the Kawaihae region was obtained from the U.S. Geological Survey and used in 

building the Kawaihae DEM (Table 6; Fig. 7). 

Table 6. Topographic dataset used in compiling the Kawaihae DEM.

Source Year Data Type Spatial 

Resolution

Original Horizontal 

Datum/Coordinate System

Original 

Vertical Datum URL

USGS 2001 NED DEM 1/3 arcsecond NAD83 geographic Inferred Mean 

Sea Level http://ned.usgs.gov/

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 Kawaihae region. 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 was revised using data 

collected in 1999 and 2004.

The NED data included “zero” elevation values over the open ocean, which were removed from the 

dataset before gridding. Non-zero values still remained over the open ocean, which were visually inspected 

and compared with NOAA nautical charts, the USGS coastline, and Google Earth satellite imagery. ESRI 

Arc Catalog was used to clip the data to the USGS coastline. 

The NAVD88 vertical datum is established only for the North American mainland and has not been 

surveyed for Hawaii. The NED DEMs are therefore inferred to represent elevations relative to Mean Sea 

Level.

. 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]
10

Taylor et al., 2008

Figure 7. Color image of the NED DEM in the vicinity of the Kohala Volcano.

Figure 8. Aerial photo of Waipio and Waimanu Valleys shown in Figure 7. The deeply incised canyons formed by erosion following landslide 

collapse [Smith et al., 2001]. (Photo was taken by P. Mouginis-Mark, http://satftp.soest.hawaii.edu/space/hawaii/nav/ap.kohala.html).
11

DIGITAL ELEVATION MODEL OF KAWAIHAE, HAWAII

3.2 Establishing Common Datums

3.2.1 Vertical datum transformations

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

of vertical datums including Mean Lower Low Water (MLLW), Mean Sea Level (MSL), and North American Vertical 

Datum of 1988 (NAVD88). All datasets were transformed to MHW to provide the worst-case scenario for inundation 

modeling, using values measured at the NOAA tidal station at Kawaihae, Hawaii (#1617433; Table 7).

1) Bathymetric data

The NOS hydrographic and JALBTCX SHOALS LiDAR surveys were transformed from MLLW 

to MHW, using FME software, by adding a tide-station derived constant offset of -0.5 m (Table 7). The 

multibeam sonar data were referenced to MSL and were shifted by adding a constant offset of -0.217 m. 

2) Topographic data

The USGS NED 1/3 arc-second DEM is referenced to NAVD88, which is not defined in Hawaii; this

dataset was inferred to be referenced to MSL. Conversion to MHW, using FME software, was accomplished 

by adding a tide-station derived constant offset of -0.217 m (Table 7). 

Table 7. Relationship between Mean High Water and other vertical datums in the Kawaihae region.*

Vertical datum Difference to MHW

MSL+ -0.217

MLW -0.446

MLLW -0.5

* Datum relationships measured at tide station #1617433, Kawaihae, Hawaii. +

 Topographic data referenced to Local Tidal datum or NAVD88 inferred to be equivalent to MSL.

3.2.2 Horizontal datum transformations

Datasets used to compile the Kawaihae DEM were originally referenced to NAD83 geographic, NAD83 

UTM Zone 5, 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.

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:

•	 Data values over the open ocean in the NED. The DEM required automated clipping to the USGS coastline.

•	 Noise present in the multibeam data which was resolved by eliminating data within survey. 

•	 Offsets between older, low-resolution NOS surveys and newer recent high-resolution multibeam sonar data. 

NOS soundings in areas covered by multibeam sonar data were deleted.

3.3.2 Gridding of multibeam bathymetric data

MB-System (http://www.ldeo.columbia.edu/res/pi/MB-System/) was used to grid the multibeam sonar data 

files. MB-System is an NSF-funded share-ware software application specifically designed to manipulate submarine
12

Taylor et al., 2008

multibeam sonar data. The MB-System tool ‘mbgrid’ applied a tight spline tension to the swath sonar data, and 

interpolated values for nearby cells without data. The resulting 1 arc-second ASCII grid was brought into ArcGIS for 

evaluation and conversion from MSL to MHW, and exported as xyz data for surfacing of all of the bathymetric data.

3.3.3 Smoothing of bathymetric data

The NOS hydrographic surveys are generally sparse at the resolution of the 1/3 arc-second Kawaihae DEM: 

in deep water, the NOS survey data have point spacings up to 900 m 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 multibeam grid and JALBTCX 

SHOALS LiDAR survey data into a single file, along with points extracted from the Hawaii 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 (~10%) larger than the Kawaihae 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 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 an xyz file for use in the final gridding process (see Table 8).

3.3.4 Gridding the data with MB-System

MB-System was used to create the 1/3 arc-second Kawaihae DEM. 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 8. Greatest weight was given to the highresolution topographic NED DEM. Least weight was given to the pre-surfaced 1 arc-second bathymetric grid. 

Table 8. Data hierarchy used to assign gridding weight in MB-System.

Dataset Relative Gridding Weight

JALBTCX SHOALS coastal bathymetric LiDAR 100

Multibeam grid 100

USGS NED topographic DEM 1000

NOS hydrographic surveys: bathymetric soundings 100

Pre-surfaced bathymetric 1 arc-second grid 1

3.4 Quality Assessment of the DEM

3.4.1. Horizontal accuracy

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

the datasets used to determine corresponding DEM cell values. NED topography is accurate to within about 15 

meters. Bathymetric features are resolved only to within a few tens of meters in deep-water areas. Shallow, nearcoastal regions have an accuracy approaching that of subaerial topographic features. Positional accuracy is limited by 

the sparseness of deep-water soundings and one potentially large positional uncertainty of pre-satellite navigated (e.g., 

GPS) NOS hydrographic surveys. 

3.4.2 Vertical accuracy

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

datasets contributing to DEM cell values. Topographic areas have an estimated vertical accuracy to 7 meters (for 

NED topography). Bathymetric areas have an estimated accuracy of between 0.1 meters and 5% of water depth (220 

meters in the southwest corner of the DEM). Those 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. 
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DIGITAL ELEVATION MODEL OF KAWAIHAE, HAWAII

3.4.3 Slope maps and 3-D perspectives

ESRI ArcCatalog was used to generate a slope grid from the Kawaihae DEM to allow for visual inspection 

and identification of artificial slopes along boundaries between datasets (Fig. 9). The DEM was transformed to UTM

Zone 5 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 UTM-transformed DEM 

(Fig. 10) 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 1/3 arc-second Kawaihae DEM in 

its final version.

Figure 9. Slope map of the Kawaihae DEM. Flat-lying slopes are white; dark shading denotes steep 

slopes; USGS coastline in red.
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Taylor et al., 2008

Figure 10. Perspective view from the west of the Kawaihae DEM. USGS coastline in red; 

vertical exaggeration–times 3.

3.4.4	 Comparison with source data files

To ensure grid accuracy, the Kawaihae 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 one NED file

and the Kawaihae DEM is shown in Figure 11. Figure 12 shows a comparison between one NOS bathymetric survey 

and the Kawaihae DEM. Both show close agreement with the DEM, with the exception of areas where closely spaced 

values contribute to one elevation in the DEM. Significant discrepancies between some data values and the DEM

resulted in reevaluation of the source data, further data editing and building of a revised DEM.

Figure 11. Histogram of the differences between one file of the NED data and the Kawaihae DEM. The largest 

discrepancies resulted from the averaging of many closely spaced elevation values in regions of steep terrain.
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DIGITAL ELEVATION MODEL OF KAWAIHAE, HAWAII

Figure 12. Histogram of the differences between NOS survey #H09015 and the Kawaihae DEM.

3.4.5 Comparison with NGS geodetic monuments

The elevations of 128 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 Local Tidal datums, which is assumed to be equivalent to MSL. Elevations were shifted 

to MHW vertical datum (see Table 6) for comparison with the Kawaihae DEM (see Fig. 14 for monument locations). 

Differences between the Kawaihae DEM and the NGS geodetic monument elevations range from -24 to 2,189 meters, 

with a positive value indicating that the DEM elevation value is greater than the monument elevation (Fig. 13). The 

largest offset of 2,189 meters corresponds to the NGS geodetic monument located on the western side of the summit 

of mount Hualalai. The corresponding datasheet of this monument provides an elevation of 311 meters (local tidal 

datum), and the coordinates indicate that the monument is only 600 meters away from the summit at 2,520 meters. 

Thus, the datasheet for this NGS monument gives an incorrect elevation. Further examination of the monuments with 

the largest offset revealed that these monuments were located along the coastline on man-made structures.

Figure 13. Histogram of the differences between NGS geodetic monument elevations and the Kawaihae DEM. 
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Taylor et al., 2008

Figure 14. Location of NGS monuments and NOAA tide station in the Kawaihae region. Tide station #1617433 was used to 

convert between vertical datums; NGS monument elevations were used to evaluate the Kawaihae DEM.

4. Summary and Conclusions

A topographic–bathymetric digital elevation model of the Kawaihae, Hawaii 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 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 Kawaihae DEM, based on NGDC’s research and analysis, are listed below:

•	 Conduct topographic LiDAR surveys along the western coast of Hawaii.
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DIGITAL ELEVATION MODEL OF KAWAIHAE, HAWAII

5. Acknowledgments

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

The authors thank Chris Chamberlin and Vasily Titov (PMEL), and Jeff Lillycrop (USACE). The authors also thank 

Bill Virden for the help with acquiring and processing of the multibeam sonar surveys.

6. References

Smith, John R., K. Satake, J.K. Morgan, and P.W. Lipman, Submarine landslides and volcanic features on Kohala and 

Mauna Kea Volcanoes and the Hana Ridge, Hawaii, In: Takahashi, E., P.W., Lipman, M.O. Garcia, J. Naka, and 

S. Aramaki (Eds), Hawaiian Volcanoes: Deep Underwater Perspectives, Geophysical Monograph 128, American 

Geophysical Union, Washington, D.C., 11–28, 2002. 

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/

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/