noaa / NATIONAL OCEANIC AND

ATMOSPHERIC ADMINISTRATION

National Environmental Satellite,

Data, and Information Service

NOAA Technical Memorandum NESDIS NGDC-25

DIGITAL ELEVATION MODEL OF CENTRAL OREGON COAST:

PROCEDURES, DATA SOURCES AND ANALYSIS 

K.S. Carignan 

L.A.Taylor

B.W. Eakins

R.R. Warnken

E. Lim

P.R. Medley

National Geophysical Data Center

Marine Geology and Geophysics Division

Boulder, Colorado

March 2009

UNITED STATES

DEPARTMENT OF COMMERCE

Gary Locke

Secretary

NATIONAL OCEANIC AND

ATMOSPHERIC ADMINISTRATION

Dr. Jane Lubchenco

Under Secretary for Oceans

and Atmosphere/Administrator

National Environmental Satellite,

Data, and Information Service

Mary E. Kicza

Assistant Administrator

NOAA Technical Memorandum NESDIS NGDC-25

DIGITAL ELEVATION MODEL OF CENTRAL OREGON COAST:

PROCEDURES, DATA SOURCES AND ANALYSIS

Kelly S. Carignan1

Lisa A. Taylor2

Barry W. Eakins1

Robin R. Warnken2

Elliot Lim1

Pamela R. Medley1

1Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder

2

NOAA, National Geophysical Data Center, Boulder, Colorado 

National Geophysical Data Center

Marine Geology and Geophysics Division 

Boulder, Colorado

March 2009
Carignan et. al, 2009

ii

NOTICE

Mention of a commercial company or product does not constitute an endorsement by the 

NOAA National Environmental Satellite, Data, and Information Service. Use of information 

from this publication concerning proprietary products or the test of such products for publicity

or advertising purposes is not authorized. 

Corresponding project 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/tsunami/inundation.html

Also available from the National Technical Information Service (NTIS)

(http://www.ntis.gov)
Digital Elevation Model of Central Oregon Coast

iii

Contents

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

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

3. Methodology ......................................................................................................................................3

3.1 Data Sources and Processing ......................................................................................................4

3.1.1 Shoreline................................................................................................................5

3.1.2 Bathymetry ............................................................................................................7

3.1.3 Topography..........................................................................................................19

3.2 Establishing Common Datums .................................................................................................28

3.2.1 Vertical datum transformations ...........................................................................28

3.2.2 Horizontal datum transformations.......................................................................28

3.3 Digital Elevation Model Development .....................................................................................29

3.3.1 Verifying consistency between datasets..............................................................29

3.3.2 Smoothing of bathymetric data ...........................................................................29

3.3.3 Gridding the data with MB-System.....................................................................31

3.4 Quality Assessment of the DEM...............................................................................................32

3.4.1 Horizontal accuracy.............................................................................................32

3.4.2 Vertical accuracy .................................................................................................32

3.4.3 Slope maps and 3-D perspectives........................................................................33

3.4.4	 Comparison with source data files.......................................................................34

3.4.5 Comparison with NGS geodetic monuments......................................................35

4. Summary and Conclusions...............................................................................................................37

5. Acknowledgments............................................................................................................................37

6. References........................................................................................................................................37

7. Data Processing Software ................................................................................................................38

List of Figures

Figure 1. Shaded-relief image of the Central Oregon Coast DEM ............................................................1

Figure 2. Landsat 7 i-cubed satellite image of the Central Oregon Coast DEM boundary........................2

Figure 3. Source and coverage of datasets used to compile the Central Oregon Coast DEM ...................4

Figure 4. Digital coastline datasets used in developing a coastline for the Central Oregon 

Coast DEM ..........................................................................................................................5

Figure 5. Spatial coverage of bathymetric datasets used to compile the Central Oregon 

Coast DEM ..........................................................................................................................8

Figure 6. Digital NOS hydrographic survey coverage in the Central Oregon Coast region....................10

Figure 7. Spatial coverage of USACE hydrographic channel line and offshore surveys for 

Depoe Bay and Yaquina River...........................................................................................12

Figure 8. Spatial coverage of USACE hydrographic channel line and offshore surveys for 

Siuslaw River.....................................................................................................................13

Figure 9. Spatial coverage of USACE hydrographic channel line and offshore surveys for 

Umpqua River....................................................................................................................13

Figure 10.	 Spatial coverage of multibeam swath sonar files from NGDC multibeam database................15

Figure 11. Revelle multibeam survey colored by elevation.......................................................................16

Figure 12. Spatial coverage of PMEL/OSU bathymetric data for Alsea Bay ............................................17

Figure 13. Spatial coverage of ORDFW multibeam surveys.....................................................................18

Figure 14. Spatial coverage of topographic datasets used in the Central Oregon Coast DEM..................20

Figure 15. Comparison of NED topographic data and aerial photo of Yaquina Harbor ............................21

Figure 16. Comparison of pre and post processed CSC LiDAR data ........................................................22

Figure 17. Detail image of preliminary DEM at Placer Lake ....................................................................23

Figure 18. Aerial photo of Placer Lake from Google Earth.......................................................................24

Figure 19.	 Quick Terrain Modeler image of final DEM at Placer Lake.....................................................24

Figure 20. Spatial coverage of extracted ENC land elevation data............................................................25
Carignan et. al, 2009

iv

Figure 21. Aerial photo of Yaquina River jetties........................................................................................26

Figure 22. Aerial photo of Siuslaw River jetties........................................................................................26

Figure 23. NGDC digitized coastal features at Yaquina River...................................................................27

Figure 24. NGDC digitized coastal features at Siuslaw River...................................................................27

Figure 25. Preliminary bathymetric surface showing NOS survey H04753..............................................29

Figure 26. Histogram of the differences between NOS hydrographic survey H08040 and the 

1 arc-second pre-surfaced bathymetric grid ......................................................................30

Figure 27. Comparison of NED and SRTM contour lines.........................................................................32

Figure 28. Slope map of the Central Oregon Coast DEM..........................................................................33

Figure 29. Perspective view of the Central Oregon Coast DEM ...............................................................34

Figure 30. Histogram of the differences between a section of the CSC ALACE LiDAR survey

 and the Central Oregon Coast DEM.................................................................................34

Figure 31. Histogram of the differences between NGS monuments and Central Oregon 

Coast DEM ........................................................................................................................35

Figure 32. Location of NGS geodetic monuments and the NOAA tide station used in 

Central Oregon Coast DEM...............................................................................................36

List of Tables

Table 1.	 PMEL specifications for the Central Oregon Coast DEM..........................................................3

Table 2. Shoreline datasets used in the Central Oregon Coast DEM .......................................................5

Table 3. Digital nautical charts available in the Central Oregon Coast region.........................................6

Table 4. Bathymetric datasets used in compiling the Central Oregon Coast DEM..................................7

Table 5. Digital NOS hydrographic surveys used in compiling the Central Oregon Coast DEM............9

Table 6. USACE surveys used in compiling the Central Oregon Coast DEM.......................................11

Table 7. Multibeam surveys from the NGDC database used in compiling the Central Oregon 

Coast DEM ........................................................................................................................14

Table 8. Topographic datasets used in compiling the Central Oregon Coast DEM ...............................19

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

Central Oregon Coast region .............................................................................................28

Table 10. Data hierarchy used to assign gridding weight in MB-System.................................................31
Digital Elevation Model of Central Oregon Coast:

Procedures, Data Sources and Analysis

1. Introduction

In September 2008, the National Geophysical Data Center (NGDC), an office of the National Oceanic and

Atmospheric Administration (NOAA), developed an integrated bathymetric–topographic digital elevation model 

(DEM) of Central Oregon Coast (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) developed by PMEL for the NOAA Tsunami Warning Centers. This report provides a 

summary of the data sources and methodology used in developing the Central Oregon Coast DEM.

1. The Central Oregon Coast 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 Waldport, Oregon (44°25.80′ N, 

124°3.60′ W; Fig. 2) 1/3 arc-second of latitude is equivalent to 10.29 meters; 1/3 arc-second of longitude equals 7.37 meters.

Figure 1. Shaded-relief image of the Central Oregon Coast DEM. 

Contour interval is 50 meters in water and 100 meters on land. Image 

is in Mercator projection.
Carignan et. al, 2009

2

2. Study Area

The Central Oregon Coast DEM covers the coastal area of Oregon from Cascade Head south to the Umpqua 

River (Fig. 2). As part of the Cascadia Subduction Zone, the Oregon coast is subject to a variety of geologic hazards 

including landslides, earthquakes, volcanoes, and tsunamis. The major coastal communities located within the Central 

Oregon Coast DEM boundary are Lincoln City located north of Siletz Bay, Newport on the north side of Yaquina Bay, 

Waldport on the south side of Alsea Bay, and Florence at the Siuslaw River.

Figure 2. NASA World Wind i-cubed Landsat 7 image of Central Oregon Coast; DEM boundary shown in red (http://worldwind.arc.nasa.gov/).
Digital Elevation Model of Central Oregon Coast

3

3. Methodology

The Central Oregon Coast DEM was constructed to meet PMEL specifications (Table 1), based on input

requirements for the development of Reference Inundation Models (RIMs) and Standby Inundation Models (SIMs) 

(V. Titov, pers. comm.) in support of NOAA’s Tsunami Warning Centers use of SIFT to provide real-time tsunami 

forecasts in an operational environment. The best available digital data were obtained by NGDC and shifted to common 

horizontal and vertical datums: North America Datum 1983 (NAD 83) and Mean High Water (MHW), respectively, for 

modeling of maximum flooding2. Data processing and evaluation, and DEM assembly and assessment are described 

in the following subsections.

Table 1: PMEL specifications for the Central Oregon Coast DEM.

Grid Area Central Oregon Coast

Coverage Area 123.81o to 124.63o W; 43.70o to 45.14o N

Coordinate System Geographic decimal degrees

Horizontal Datum World Geodetic System 1984 (WGS 84)

Vertical Datum Mean High Water (MHW)

Vertical Units Meters

Cell Size 1/3 arc-second

Grid Format ESRI Arc ASCII grid

2. The horizontal difference between the North American Datum of 1983 (NAD 83) and World Geodetic System of 1984 (WGS 84) geographic 

horizontal datums is approximately one meter across the contiguous U.S., which is significantly less than the cell size of the DEM. Most GIS applications treat the two datums as identical, so do not actually transform data between them, and the error introduced by not converting between 

the datums is insignificant for our purposes. NAD 83 is restricted to North America, while WGS 84 is a global datum. As tsunamis may originate

most anywhere around the world, tsunami modelers require a global datum, such as WGS 84 geographic, for their DEMs so that they can model the 

wave’s passage across ocean basins. This DEM is identified as having a WGS 84 geographic horizontal datum even though the underlying elevation

data were typically transformed to NAD 83 geographic. At the scale of the DEM, WGS 84 and NAD 83 geographic are identical and may be used 

interchangeably.
Carignan et. al, 2009

4

3.1 Data Sources and Processing

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

local agencies including: NOAA’s National Ocean Service (NOS), Office of Coast Survey (OCS), Coastal Services

Center (CSC), and Pacific Marine Environmental Laboratory (PMEL); the U.S. Geological Survey (USGS); the U.S.

Army Corps of Engineers (USACE); and the Oregon Department of Fish and Wildlife (ORDFW). Safe Software’s 

(http://www.safe.com/) FME data translation tool package was used to shift datasets to NAD 83 horizontal datum and 

to convert them into ESRI (http://www.esri.com/)ArcGIS shape files3. The shape files were then displayed withArcGIS

to assess data quality and manually edit datasets. Vertical datum transformations to MHW were accomplished using 

FME and ArcGIS, based upon data from the NOAA tide stations. Applied Imagery’s Quick Terrain Modeler software 

(http://www.appliedimagery.com/) was used for editing data and to evaluate processing and gridding techniques.

3. FME uses the North American Datum Conversion Utility (NADCON; http://www.ngs.noaa.gov/TOOLS/Nadcon/Nadcon.html) developed by 

NOAA’s National Geodetic Survey (NGS) to convert data from NAD 27 to NAD 83. NADCON is the U.S. Federal Standard for NAD 27 to NAD 

83 datum transformations.

Figure 3. Source and coverage of datasets used 

to compile the Central Oregon Coast DEM.
Digital Elevation Model of Central Oregon Coast

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3.1.1 Shoreline

Coastline datasets of the Central Oregon coastal region were obtained from NOAA’s Office of Coast Survey

as Electronic Navigational Charts and from the high resolution bathymetric–topographic DEMs of Port Orford and 

Garibaldi, Oregon created by NGDC (Table 2; Fig. 4). The NOAA National Shoreline from the National Geodetic 

Survey (NGS) was evaluated but not used in the Central Oregon Coast DEM.

 Table 2: Shoreline dataset used in the Central Oregon Coast DEM.

Source Year Data Type Spatial 

Resolution

Original Horizontal 

Datum/Coordinate 

System

Original Vertical 

Datum URL

OCS ENC 

extracted 

shoreline

2008 vector

1:185,238 

to 

1:191,730

WGS 84 geographic 

(meters) Mean High Water

http://chartmaker.

ncd.noaa.gov/

MCD/enc/index.

htm

NGDC Port 

Orford and 

Garibaldi DEM 

coastlines

2007 vector WGS 84 geographic Mean High Water

http://www.

ngdc.noaa.gov/

mgg/inundation/

tsunami/

Figure 4. Digital coastline datasets used for developing a coastline for the Central Oregon Coast DEM.
Carignan et. al, 2009

6

1) OCS Electronic Navigational Charts

 Two electronic navigational charts (ENCs) were available for the Central Oregon Coast area (Table 3) 

and downloaded from the NOAA’s Office of Coast Survey website (http://chartmaker.ncd.noaa.gov/MCD/

enc/index.htm). The coastline data were extracted from the ENC S-57 format to vector line shapefiles using

FME and merged using the ArcCatalog merge tool. The ENC coastline dataset covers the entire DEM area. 

Table 3: Digital nautical chart data available in the Central Oregon Coast region.

Chart Title Edition Edition Date Format Scale

18520 Yaquina Head to Columbia River – Netarts Bay 10 (ENC) 2008 ENC and RNC 1:185,238

18561 Approaches to Yaquina Bay 12 2003 RNC 1:50,000

18580 Cape Blanco the Yaquina Head 6 (ENC) 2008 ENC and RNC 1:191,730

18581 Yaquina Bay and River 17 2002 RNC 1:10,000

18583 Siuslaw River 39 2005 RNC 1:20,000

18584 Umpqua River – Pacific Ocean to Reedsport 48 2007 RNC 1:20,000

18587 Coos Bay 70 2005 RNC 1:20,000

2) NGDC Port Orford and Garibaldi DEM coastlines

Both the northern and southern Central Oregon Coast DEM boundaries overlap DEMs previously 

developed by NGDC. Coastlines from these existing DEMs for Garibaldi and Port Orford were clipped to the 

Central Oregon Coast boundary and merged using the ArcCatalog ‘merge’ tool.

The coastline datasets were merged using ArcCatalog into a ‘combined’ coastline and visually compared to Google 

Earth satellite imagery (http://earth.google.com/userguide/v4/#imagery_dates), USGS topographic maps available on 

NASA World Wind (http://worldwind.arc.nasa.gov/index.html), and USACE aerial photos to ensure features such as 

jetties and breakwaters were present in the ‘combined’ coastline. Coastal features were added using ArcMap editing 

tools. To represent the most recent topographic data, the ‘combined’ coastline was adjusted to match the NOAA 

Coastal Services Center 2002 ALACE LiDAR dataset along the coast. In bays and along rivers where LiDAR was 

not available, the ‘combined’ coastline was adjusted to ensure recent USACE hydrographic surveys were located 

in channels. Further modifications were made using RNCs and NED topographic data to reflect shoreline locations

accurately.
Digital Elevation Model of Central Oregon Coast

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3.1.2 Bathymetry

Bathymetric datasets used in the compilation of the Central Oregon Coast DEM include 35 NOS hydrographic 

surveys; 24 USACE hydrographic channel line surveys; 12 multibeam swath sonar surveys downloaded from the 

NGDC multibeam sonar database; 2 multibeam sonar surveys from the Oregon Department of Fish and Wildlife, 

Marine Resources Program (ORDFW); and a hydrographic survey of Alsea Bay conducted by Oregon State University 

and provided by NOAA/PMEL (Table 4; Fig. 5).

Table 4: Bathymetric datasets used in compiling the Central Oregon Coast DEM.

Source Year Data Type Spatial Resolution

Original 

Horizontal Datum/

Coordinate System

Original 

Vertical 

Datum

URL

NOS

1927 

to 

1987

Hydrographic 

survey 

soundings

Ranges from 10 

m to 1 km (varies 

with scale of survey, 

depth, traffic, and

probability of 

obstructions)

NAD 27 or NAD 

83 geographic

Mean Lower 

Low Water

http://www.ngdc.noaa.

gov/mgg/bathymetry/

hydro.html

USACE

2005 

to 

2008

Hydrographic 

surveys

various, from 3 to 40 

meter point spacing

NAD 83 Oregon 

State Plane North 

(feet)

 Mean Lower 

Low Water

https://www.nwp.usace.

army.mil/op/nwh/

xyzcoastal.asp

NGDC 

1987 

to 

2003

Multibeam 

sonar swath 

files

raw MB files gridded

to 1/3 arc-second

WGS 84 

geographic

assumed 

Mean Sea 

Level

http://www.ngdc.noaa.

gov/mgg/bathymetry/

multibeam.html

PMEL/OSU 2002

Extracted 

bathymetric 

points

10 meters WGS 84 

geographic

Mean Sea 

Level

ORDFW 2003 

Multibeam 

sonar swath 

surveys

1 meter point data 

and 2 meter DEM

WGS 84 UTM 

Zone 10 North

Mean Lower 

Low Water
Carignan et. al, 2009

8

Figure 5. Spatial coverage of bathymetric datasets used to compile the DEM.
Digital Elevation Model of Central Oregon Coast

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1) NOS hydrographic survey data

A total of 35 NOS hydrographic surveys conducted between 1927 and 1987 were available for use 

in developing the Central Oregon Coast DEM. The hydrographic survey data were originally vertically 

referenced to Mean Lower Low Water (MLLW) and horizontally referenced to either NAD 1913, NAD 27, 

or NAD 83 datums if the datum was known and recorded (Table 5; Fig. 6).

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) referenced to NAD 83. The surveys were 

subsequently clipped to a polygon 0.05 degree (~5%) larger than the Central Oregon Coast DEM area to 

support data interpolation along grid edges. 

After converting all NOS survey data to MHW, the data were displayed in ESRI ArcMap and reviewed 

for digitizing errors against scanned original survey smooth sheets and edited as necessary. The surveys 

were also compared to the topographic and other bathymetric datasets, the ‘combined’ coastline, and NOS 

raster nautical charts (RNCs). The surveys were clipped to remove soundings that overlap the more recent 

multibeam surveys, USACE surveys, and where soundings from older surveys have been superseded by 

more recent NOS surveys.

Table 5: Digital NOS hydrographic surveys used in compiling the Central Oregon Coast DEM.

Survey ID Scale Date Digital Data Horizontal 

Datum

Vertical 

Datum

Original 

Horizontal Datum

H04746 20,000 1927 NAD 27 MLLW NAD1913

H04747 20,000 1927 NAD 27 MLLW NAD1913

H04748 20,000 1927 NAD 27 MLLW NAD1913

H04749 20,000 1927 NAD 27 MLLW NAD1913

H04753 120,000 1927 NAD 27 MLLW NAD1913

H04754 80,000 1927 NAD 27 MLLW NAD 27

H04756 40,000 1927 NAD 27 MLLW NAD1913

H04757 120,000 1927 NAD 27 MLLW NAD1913

H04758 80,000 1927 NAD 27 MLLW NAD 27

H04878 20,000 1928 NAD 27 MLLW NAD1913

H04879 20,000 1928 NAD 27 MLLW NAD1913

H04880 20,000 1928 NAD 27 MLLW NAD1913

H04881 20,000 1928 NAD 27 MLLW NAD1913

H04882 40,000 1928 NAD 27 MLLW NAD1913

H04883 40,000 1928 NAD 27 MLLW NAD1913

H04884 20,000 1928 NAD 27 MLLW NAD1913

H04885 20,000 1928 NAD 27 MLLW NAD1913

H04888 120,000 1928 NAD 27 MLLW NAD1913

H04889 120,000 1928 NAD 27 MLLW NAD1913

H04890 40,000 1928 NAD 27 MLLW NAD1913

H04894 40,000 1928 NAD 27 MLLW NAD1913

H04895 80,000 1928 NAD 27 MLLW NAD 27

H04896a 80,000 1928 NAD 27 MLLW NAD 27

H07896 5,000 1952 NAD 27 MLLW NAD 27

H08039 5,000 1953 NAD 27 MLLW NAD 27

H08040 10,000 1953 NAD 27 MLLW NAD 27

H08041 10,000 1953 NAD 27 MLLW NAD 27

H09238 10,000 1971 NAD 27 MLLW NAD 27

H09239 10,000 1971 NAD 27 MLLW NAD 27

H09240 2,500 1971 NAD 27 MLLW NAD 27
Carignan et. al, 2009

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B00019 50,000 1985 NAD 83 MLLW NAD 83

B00020 50,000 1985 NAD 83 MLLW NAD 83

B00048 50,000 1986 NAD 83 MLLW NAD 83

B00051 50,000 1986 NAD 83 MLLW NAD 83

B00095 20,000 1987 NAD 83 MLLW NAD 83

Figure 6. Digital NOS hydrographic survey coverage in the Central Oregon Coast DEM region. Some older surveys were not used as 

they have been superseded by more recent surveys. DEM boundary in red.
Digital Elevation Model of Central Oregon Coast

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2) USACE hydrographic channel line surveys

Twenty-four hydrographic channel line surveys (survey lines that run parallel to the channel) and 

offshore or basin surveys were available for use in the Central Oregon Coast DEM (Table 6, Figs. 7, 8, and 

9). The surveys were downloaded in xyz format from the USACE Portland District website (https://www.

nwp.usace.army.mil/op/nwh/xyzcoastal.asp). The data were transformed from NAD 83 State Plane Oregon 

North to NAD 83 geographic and MLLW to MHW, converted to shape files using FME and quality checked

in ArcMap against other bathymetric datasets.

Table 6: USACE hydrographic surveys used in compiling the Central Oregon Coast DEM.

Region Survey ID Year Original 

Vertical Datum Original Horizontal Datum Survey Format

Depoe Bay - Boat 

basin deb 2005 MLLW NAD 83 State Plane Oregon North (feet)

Basin survey with <5 meter 

point spacing

Yaquina River - 

Depot Slough dsl 2008 MLLW NAD 83 State Plane Oregon North (feet)

Channel line survey spacing 

~6 meters apart with <2 meter 

point spacing

- Bay & Harbor yb2 2008 MLLW NAD 83 State Plane Oregon 

North (feet)

Channel line survey spacing 

~20 meters apart with ~10 

meter point spacing

- South Beach Marina yb3 2008 MLLW NAD 83 State Plane Oregon 

North (feet)

Channel line survey spacing 

~20 meters apart with ~10 

meter point spacing

- Entrance YB1110607 2008 MLLW NAD 83 State Plane Oregon 

North (feet)

Channel line survey spacing 

~15 meters apart with ~15 

meter point spacing

- Section 103 interim ybd 2006 MLLW NAD 83 State Plane Oregon 

North (feet)

Offshore survey spacing ~80 

meters apart with ~20 meter 

point spacing

- North site YDN071707 2007 MLLW NAD 83 State Plane Oregon 

North (feet)

Offshore survey spacing ~80 

meters apart with ~20 meter 

point spacing

- South site yds 2007 MLLW NAD 83 State Plane Oregon 

North (feet)

Channel line survey spacing 

~20 meters apart with ~10 

meter point spacing

- Approaches yqa 2006 MLLW NAD 83 State Plane Oregon 

North (feet)

Offshore survey spacing ~300 

meters apart with ~30 meter 

point spacing

Siuslaw River - 

Cannery Hill Reach ss2 2008 MLLW NAD 83 State Plane Oregon 

North (feet)

Channel line survey spacing 

~20 meters apart with ~10 

meter point spacing

- Spruce Point Bend ss3 2008 MLLW NAD 83 State Plane Oregon 

North (feet)

Channel line survey spacing 

~20 meters apart with ~10 

meter point spacing

- Florence ss4 2008 MLLW NAD 83 State Plane Oregon 

North (feet)

Channel line survey spacing 

~20 meters apart with ~10 

meter point spacing

- Entrance SS1012308 2008 MLLW NAD 83 State Plane Oregon 

North (feet)

Channel line survey spacing 

~20 meters apart with ~10 

meter point spacing

- Approaches ssa 2006 MLLW NAD 83 State Plane Oregon 

North (feet)

Offshore survey spacing ~300 

meters apart with ~30 meter 

point spacing

- Site B SSB071707 2007 MLLW NAD 83 State Plane Oregon 

North (feet)

Offshore survey spacing ~80 

meters apart with ~20 meter 

point spacing
Carignan et. al, 2009

12

Umpqua River - 

Entrance UP1012308 2007 MLLW NAD 83 State Plane Oregon North (feet)

Channel line survey spacing 

~20 meters apart with ~10 

meter point spacing

- Salmon Harbor 

Reach UP2022508 2008 MLLW NAD 83 State Plane Oregon North (feet)

Channel line survey spacing 

~20 meters apart with ~10 

meter point spacing

- Barretts Range UP3031808 2008 MLLW NAD 83 State Plane Oregon 

North (feet)

Channel line survey spacing 

~20 meters apart with ~10 

meter point spacing

- Mile 6 Bar UP4031908 2008 MLLW NAD 83 State Plane Oregon 

North (feet)

Channel line survey spacing 

~20 meters apart with ~10 

meter point spacing

- Cannery Sands UP5032008 2007 MLLW NAD 83 State Plane Oregon 

North (feet)

Channel line survey spacing 

~20 meters apart with ~10 

meter point spacing

- Reedsport Reach UP6032408 2008 MLLW NAD 83 State Plane Oregon 

North (feet)

Channel line survey spacing 

~20 meters apart with ~10 

meter point spacing

- Approaches upa 2007 MLLW NAD 83 State Plane Oregon 

North (feet)

Offshore survey spacing ~300 

meters apart with ~30 meter 

point spacing

- Section 103 site UPD050107 2008 MLLW NAD 83 State Plane Oregon 

North (feet)

Offshore survey spacing ~60 

meters apart with ~20 meter 

point spacing

- Winchester Bay WIN042908 2008 MLLW NAD 83 State Plane Oregon 

North (feet)

Channel line survey spacing 

~7 meters apart with ~10 meter 

point spacing

Figure 7. Spatial coverage of USACE hydrographic channel line and offshore surveys for Depoe Bay and the Yaquina River.
Digital Elevation Model of Central Oregon Coast

13

 Figure 8. Spatial coverage of USACE hydrographic channel line and offshore surveys for the Siuslaw River.

Figure 9. Spatial coverage of USACE hydrographic channel line and offshore surveys for the Umpqua River.
Carignan et. al, 2009

14

3) Multibeam swath sonar files

Eleven multibeam swath sonar surveys were available from the NGDC multibeam database (http://www.

ngdc.noaa.gov/mgg/bathymetry/multibeam.html) for use in the Central Oregon Coast DEM (Table 7, Fig. 

10). This database is comprised of the original swath sonar files of surveys conducted mostly by the U.S.

academic fleet. Most of the multibeam swath surveys offshore were transits rather than dedicated sea-floor

surveys. All have a horizontal datum of WGS 84/NAD 83 geographic and undefined vertical datum, assumed

to be equivalent to mean sea level (MSL).

The downloaded data were gridded to 1/3 arc-second resolution using MB-System. MB-System is 

an NSF-funded free software application specifically designed to manipulate multibeam swath sonar data

(http://www.ldeo.columbia.edu/res/pi/MB-System/). The gridded data were converted to shapefiles and

transformed to MHW using FME. Individual surveys were evaluated for errors and compared to neighboring 

high resolution NOS survey data and the RNCs. Techniques used to remove errors included filtering data

by elevation using FME, clipping large regions of points using QT Modeler, and editing single points using 

ArcMap editing tools. Figure 11 shows numerous anomalous elevation values deeper than -10,000 meters in 

the northern section of the CNTL04RR survey. These values were removed from the survey by filtering out

elevations below -500 meters using FME and edited in ArcMap by comparing to neighboring surveys and 

nautical chart soundings.

Table 7: Multibeam swath sonar surveys used in compiling the Central Oregon Coast DEM.

Cruise ID Ship Year Original Vertical 

Datum

Original Horizontal 

Datum Institution

AII8L20 Atlantis II 1987 assumed Mean Sea 

Level WGS 84 geographic University of Rhode Island (URI)

AII8L21 Atlantis II 1987 assumed Mean Sea 

Level WGS 84 geographic University of Rhode Island (URI)

AII8L22 Atlantis II 1987 assumed Mean Sea 

Level WGS 84 geographic University of Rhode Island (URI)

RNDB05WT Washington 1988 assumed Mean Sea 

Level WGS 84 geographic University of California, Scripps Institution of Oceanography (UC/SIO)

SO108 Sonne 1996 assumed Mean Sea 

Level WGS 84 geographic University of Kiel, Germany, GEOMAR Forshungszentrum

Tecfluc Ocean Alert 

(1) 1998 assumed Mean Sea Level WGS 84 geographic Monterey Bay Aquarium Research Institute (MBARI)

Tran2new Ocean Alert 

(2) 1999 assumed Mean Sea Level WGS 84 geographic Monterey Bay Aquarium Research Institute (MBARI)

Heceta Ocean Alert 1998 assumed Mean Sea 

Level WGS 84 geographic Monterey Bay Aquarium Research Institute (MBARI)

LWAD99MV Melville 1999 assumed Mean Sea 

Level WGS 84 geographic University of California, Scripps Institution of Oceanography (UC/SIO)

AT07L20 Atlantis I 2002 assumed Mean Sea 

Level WGS 84 geographic Woods Hole Oceanographic Institution (WHOI)

AT07L14 Atlantis I 2002 assumed Mean Sea 

Level WGS 84 geographic Woods Hole Oceanographic Institution (WHOI)

CNTL04RR Revelle 2003 assumed Mean Sea 

Level WGS 84 geographic University of California, Scripps Institution of 

Oceanography (UC/SIO)
Digital Elevation Model of Central Oregon Coast

15

Figure 10. Spatial coverage of multibeam swath sonar surveys in the NGDC multibeam database that were used in the 

Central Oregon Coast DEM.
Carignan et. al, 2009

16

Figure 11. The CNTL04RR multibeam survey located offshore of Cascade Head and Siletz Bay colored by elevation. The arrows point 

to areas where elevations were incorrect by hundreds of meters. These values were deleted.
Digital Elevation Model of Central Oregon Coast

17

4) PMEL/OSU Alsea Bay extracted hydrographic survey 

PMEL provided NGDC with bathymetric and topographic data of the Alsea Bay area, collected by 

Oregon State University. Only the bathymetry from this dataset was used for the DEM, as the topographic 

data were derived from USGS NED DEMs where higher resolution CSC LiDAR data are now available. The 

bathymetric elevations were extracted from the dataset in xyz format and converted to MHW using FME. 

Figure 12 shows the extracted points with RNC #18561 for Alsea Bay area in the background.

Figure 12. Spatial coverage of PMEL/OSU bathymetric data for Alsea Bay with RNC #18561 in the background.
Carignan et. al, 2009

18

5) Oregon Department of Fish and Wildlife multibeam survey of Siletz Reef and DEM of Seal Rock

The Oregon Department of Fish and Wildlife (ORDFW) provided NGDC with a 1 meter resolution 

multibeam survey of Siletz Reef and a 2 meter DEM of Seal Rock (Fig. 13). The multibeam survey data 

were converted from WGS 84 UTM Zone 10 North horizontal datum and MLLW to NAD 83 geographic and 

MHW using FME and reviewed in ArcMap. The Seal Rock DEM was converted to MHW using ArcCatalog, 

converted to points using FME, and reviewed in ArcMap. 

Figure 13. Spatial coverage of ORDFW multibeam dataset.
Digital Elevation Model of Central Oregon Coast

19

3.1.3 Topography

Five topographic datasets in the Central Oregon coastal region were obtained and used to build the Central Oregon 

Coast DEM (Table 8; Fig. 14). The USGS NED 1/3 arc-second data provided full coverage for the DEM area and the 

CSC LiDAR Assessment of Coastal Erosion (ALACE) Project high-resolution data covered the entire coastline. An 

approximate 1 km2 section of the Shuttle Radar Topography Mission (SRTM) Elevation 1 arc-second DEM was used, 

as was a selection of land elevation points extracted from the two ENCs available within the DEM area. NGDC also 

digitized some coastal features not fully resolved in the NED, CSC, and SRTM datasets.

Table 8: Topographic datasets used in compiling the Central Oregon Coast DEM.

Source Year Data Type Spatial

Resolution

Original 

Horizontal Datum/

Coordinate System

Original 

Vertical 

Datum

URL

USGS 

NED 1999 topographic DEM

1/3 arcsecondNAD 83 

geographic

NAVD88

(meters) http://ned.usgs.gov/

CSC 

ALACE

1997 

- 

2002

LiDAR 

points ~2 meters NAD 83 geographic

NAVD88

(meters) http://maps.csc.noaa.gov/TCM/

NASA 

SRTM 2000 topographic DEM

1 arcsecondWGS 84 

geographic

NAVD88 

(meters) http://seamless.usgs.gov/

ENC land 

elevations 2008

S-57 

extracted 

points

WGS 84 

geographic MHW http://chartmaker.ncd.noaa.gov/MCD/enc/index.htm

NGDC 

digitized 

jetties

digitized 

points

WGS 84 

geographic MHW
Carignan et. al, 2009

20

Figure 14. Spatial coverage of topographic datasets used in compiling the Central Oregon Coast DEM.
Digital Elevation Model of Central Oregon Coast

21

1) USGS NED topographic 1/3 arc-second DEMs

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

complete 1/3 arc-second coverage of the Central Oregon Coast coastal region4. Data are in NAD 83 geographic 

coordinates and NAVD88 vertical datum (meters), and are available for download as raster DEMs. The bareearth 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 1999. The NED DEMs were transformed to NAD 83 and MHW using Arc Catalog 

tools. The gridded data were evaluated in ArcMap and positive elevations over open water were removed 

by clipping data to the ‘combined’ coastline using Arc Catalog tools. The resulting data were converted to 

points with FME. Some land features were not resolved in the NED data. Figure 15A shows the NED data at 

Yaquina Harbor without the jetties and smaller harbor features visible in Figure 15B.

Figure 15. Comparison of the NED 1/3 arc-second DEM shown in QT Modeler (A) and USACE aerial photograph 

(B) of Yaquina Harbor. Note absence of jetties in the NED DEM at mouth of river. Photo from U.S. Army Corps of 

Engineers Digital Visual Library (https://eportal.usace.army.mil/sites/DVL/default.aspx).

4. 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 NAD 83, except for AK, which is NAD 27. 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]
Carignan et. al, 2009

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2) CSC ALACE LiDAR Project topography

The NASA/USGS Airborne LiDAR Assessment of Coastal Erosion (ALACE) Project topographic 

LiDAR data from 1997, 1998, and 2002 were downloaded from the NOAA CSC website (http://maps.csc.

noaa.gov/TCM/) and transformed to NAD 83 and MHW using FME. As these data were not processed 

to bare earth and contained elevation values over open water as well as vegetation and buildings, NGDC 

processed the data using FME to simulate bare earth. The data were compared to the USGS NED topographic 

DEM and points were retained where the difference in elevation between the NED and the LiDAR data 

points was less than 12 meters. Most tall buildings and vegetation were eliminated while the high sand dunes 

and berms along the beaches remain. Figure 16 shows a comparison of a section of the LiDAR data before 

processing (image A) and after processing (image B). This technique also created a smoother seam between 

the topographic datasets in most areas. The data were clipped to the Central Oregon Coastline and filtered to

remove elevation points located over ocean.

Figure 16. Comparison of CSC 2002 ALACE LiDAR data before NGDC processing (image A) and post-processing (image B).
Digital Elevation Model of Central Oregon Coast

23

3) NASA SRTM 1 arc-second DEM

 The SRTM 1 arc-second DEM data5

 was used in lieu of the NED data near Placer Lake ~7 km south of 

Waldport where the transition from LiDAR to NED created a step of up to 8 meters in a preliminary DEM 

(Fig. 17). The SRTM DEM more accurately captured the topography of the area when compared to the 

CSC LiDAR data. The SRTM DEM was downloaded from the USGS seamless website and transformed 

from NAVD88 to MHW using ArcCatalog tools. A mask was created by converting a polygon of the area 

to a raster using ArcCatalog tools and clipping out the selection from the SRTM DEM. The selection was 

converted to points and transformed to MHW using FME for use in the final gridding process.

Figure 18 shows Google Earth imagery (perspective view from the west) of the same area near Placer 

Lake as depicted in Figure 17. The area circled in yellow shows where SRTM data points were substituted 

for the NED data. Figure 19 shows the final Central Oregon Coast DEM at approximately the same location

and perspective.

Figure 17. Detail image of a preliminary DEM showing ‘step’ in elevation in the Placer Lake area. SRTM data were substituted for NED data to 

minimize dataset transition errors.

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]
Carignan et. al, 2009

24

Figure 18. Aerial photo of Placer Lake from Google Earth imagery. Yellow line indicates where SRTM data replaced NED data in building the 

Central Oregon Coast DEM.

Figure 19. Quick Terrain Modeler image of final Central Oregon Coast DEM at Placer Lake with similar perspective as Figure 18. Edge effects 

remain at this location but are significantly reduced.
Digital Elevation Model of Central Oregon Coast

25

4) Extracted ENC S-57 land elevations

Land elevation points located on offshore rocks and islets were extracted from ENCs #18520 and #18580 

(Fig. 20) as no elevation data were available in the other topographic datasets for these features. For rocks 

present in the ‘combined’ coastline with no associated digital elevations, NGDC digitized elevation values 

based on USGS topographic quads and NOAA RNCs.

Figure 20. The spatial coverage of the extracted ENC land elevation data.
Carignan et. al, 2009

26

5) NGDC digitized jetties

The jetties at Yaquina River and Siuslaw River were not fully resolved in either the NED DEM or the 

CSC coastal LiDAR datasets. To ensure these features were represented in the final Central Oregon Coast

DEM, NGDC digitized the jetties and assigned them elevations listed on the USACE Coastal Inlets Research 

Program website (http://cirp.wes.army.mil/cirp/). The features are shown in USACE aerial photos in figures

21 and 22 (https://eportal.usace.army.mil/sites/DVL/default.aspx). 

Figure 21. Aerial photo of Yaquina River jetties. Photo from U.S. Army Corps of Engineers Digital Visual Library (https://eportal.usace.army.

mil/sites/DVL/default.aspx).

Figure 22. Aerial photo of Siuslaw River Jetties. Photo from U.S. Army Corps of Engineers Digital Visual Library (https://eportal.usace.army.

mil/sites/DVL/default.aspx).
Digital Elevation Model of Central Oregon Coast

27

ESRI shapefiles were created in ArcCatalog with point spacing of 5 meters and elevation values at MHW of 3.53

and 3.84 meters for Siuslaw jetty and 3.77 meters for Yaquina jetty. The breakwater in Yaquina Bay was added to the 

coastline and assigned a MHW elevation of 1 meter. Submerged groins located at the Yaquina inlet on the south side 

and at the end of the north jetty were not added to the coastline but were digitized and set to zero meters (Fig. 23). The 

north and south jetties of Siuslaw River were set to MHW elevations of 3.84 and 3.53 meters respectively (Fig. 24). 

After the topographic data were viewed in ArcMap to ensure the transitions between datasets were smooth, the data 

were converted to xyz format using FME for the final gridding process.

Figure 23. NGDC digitized features at Yaquina River.

Figure 24. NGDC digitized features at Siuslaw River.
Carignan et. al, 2009

28

3.2 Establishing Common Datums

3.2.1 Vertical datum transformations

Datasets used in the compilation and evaluation of the Central Oregon Coast DEM were originally referenced to 

a number of vertical datums including Mean Lower Low Water (MLLW), Mean Sea Level (MSL), and NAVD88. All 

datasets were transformed to MHW to provide the maximum flooding for inundation modeling. Units were converted

from feet to meters as appropriate.

1) Bathymetric data

NGDC created two offset grids approximating the relationship between MLLW and MHW, and MSL 

and MHW for the west coast of Oregon and Washington. The grids were built in ArcGIS using the Inverse 

Distance Weighting (IDW) tool and the differences between the vertical datums as measured at 25 NOAA 

tide stations in the area (http://tidesandcurrents.noaa.gov/). The grids spanned from 40.7167° to 48.4167° N, 

and 124.6867° to 122.8868° W with a grid cell size of 0.1 degrees. The NOS hydrographic surveys, USGS 

and NGDC multibeam surveys, and USACE surveys were transformed from MLLW and MSL to MHW, 

using FME software, by adding the appropriate offset grid.

2) Topographic data

NGDC created an offset grid approximating the relationship between NAVD88 and MHW along the 

Pacific Northwest coast. The grid was built in ArcGIS using the Inverse Distance Weighting (IDW) tool

and the difference between the vertical datums as measured at 16 NOAA tide stations in the region (http://

tidesandcurrents.noaa.gov/). The grids spanned from 40.7167° to 48.4167° N, and 124.6867° to 122.8868° W 

with a grid cell size of 0.1 degrees. The USGS NED 1/3 arc-second DEMs and the CSC topographic LiDAR 

data were originally referenced to NAVD88. The datasets were converted to MHW by adding the offset grid 

using FME.

Table 9. Relationship between Mean High Water and other vertical datums at the South Beach tide station #9435380 (Fig. 32).

Vertical datum Difference to MHW in meters

MSL -0.972

NAVD88 -2.105

MLLW -2.330

3.2.2 Horizontal datum transformations

Datasets used to compile the Central Oregon Coast DEM were originally referenced to WGS 84 geographic, NAD 

83 geographic, NAD 27 geographic, NAD 83 Oregon State Plane North, and NAD 83 UTM Zone 10 North datums. 

The relationships and transformational equations between these horizontal datums are well established. All data were 

converted to a horizontal datum of NAD 83 geographic using FME software or ArcGIS.
Digital Elevation Model of Central Oregon Coast

29

3.3 Digital Elevation Model Development

3.3.1 Verifying consistency between datasets

After horizontal and vertical transformations were applied, the resulting ESRI shapefiles were checked in ArcMap

for consistency between datasets. 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:

•	 Suspect topographic elevations located on open-ocean in both NED and LiDAR datasets.

•	 Inconsistencies between the NED and LiDAR topographic data. 

•	 Data errors in multibeam swath sonar surveys, which were expressed as anomalous spikes and groups of 

excessively deep elevations. Manual editing of the gridded multibeam sonar data were necessary to minimize 

these artifacts. 

•	 Topographic CSC LiDAR dataset not processed to bare earth. The dataset required filtering of elevation

values on land and removal of returns from the water surface.

•	 Digital bathymetric values from NOS surveys date back over 100 years. More recent data, such as the USACE 

hydrographic survey depths, differed from older NOS data by as much as 10 meters nearshore and up to 75 

meters in deeper water compared to multibeam data. The older NOS survey data were excised where more 

recent bathymetric data exists.

•	 Topographic features not represented in any digital dataset. NGDC digitized these features for representation 

in the Central Oregon Coast DEM.

3.3.2 Smoothing of bathymetric data

The NOS hydrographic surveys are generally sparse at the resolution of the 1/3 arc-second Central Oregon Coast 

DEM: in both deep water and in some areas close to shore, the NOS survey data have point spacing up to 1900 m 

apart. In order to reduce the effect of artifacts in the form of lines of “pimples” in the DEM due to these low-resolution 

datasets, and to provide effective interpolation into the coastal zone, a 1 arc-second-spacing ‘pre-surface’ bathymetric 

grid was generated using GMT, an NSF-funded share-ware software application designed to manipulate data for 

mapping purposes (http://gmt.soest.hawaii.edu/). Figure 24 shows a preliminary gridded bathymetric surface, with 

low-resolution NOS hydrographic survey H04753 points and the corresponding smooth sheet overlay. Anomalous 

features in preliminary surfaces were examined for digitizing errors against the smooth sheets and RNCs.

Figure 25. A preliminary bathymetric surface 

showing local highs derived from low resolution 

older NOS hydrographic surveys. These points were 

not removed from the survey data as they reflect 

local relief and not digitizing errors.
Carignan et. al, 2009

30

The NOS hydrographic point data, in xyz format, were clipped to remove overlap with the USACE soundings, 

NGDC multibeam data, ORDFW multibeam survey data, and nautical chart sounding data. The data were then 

combined into a single file, along with points extracted from the combined coastline to provide a buffer along the

entire coastline. The coastline elevation value was set to -1.0 m to ensure a bathymetric surface below zero in areas 

where data are sparse or non-existent.

The point data were median-averaged using the GMT tool ‘blockmedian’ to create a 1 arc-second grid 0.05 

degrees (~5%) larger than the Central Oregon Coast DEM gridding region. The GMT tool ‘surface’ was then used to 

apply a tight spline tension to interpolate elevations for 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 original soundings to ensure grid accuracy (e.g., Fig. 25) 

and exported as an xyz file for use in the final gridding process (see Table 10).

Figure 26. Histogram of the differences between NOS hydrographic survey H08040 and the 1 arc-second pre-surfaced 

bathymetric grid.
Digital Elevation Model of Central Oregon Coast

31

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 Central 

Oregon Coast DEM. MB-System is an NSF-funded free software application specifically designed to manipulate

multibeam swath sonar data, though it can utilize a wide variety of data types, including generic xyz data. The MBSystem tool ‘mbgrid’ was used to apply a tight spline tension to the xyz data, and interpolate values for cells without 

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

Greatest weights were given to the USACE surveys, PMEL/OSU bathymetry, ORDFW Multibeam surveys, 2002 CSC 

LiDAR data, NGDC digitized jetty and ENC extracted land elevations. Least weight was given to the pre-surfaced 

1 arc-second bathymetric grid. Gridding was performed in quadrants, with the resulting Arc ASCII grids seamlessly 

merged in ArcCatalog to create the final 1/3 arc-second Central Oregon Coast DEM.

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

Dataset Relative Gridding Weight

NOS hydrographic surveys 10

NGDC Multibeam surveys 10

USACE surveys 1,000

PMEL/OSU bathymetry 1,000

ORDFW Multibeam surveys 1,000

Pre-surfaced bathymetric grid 1

Central Oregon Coast coastline 1

CSC 2002 ALACE topographic LiDAR 1,000

CSC 1998 ALACE topographic LiDAR 10

CSC 1997 ALACE topographic LiDAR 10

USGS NED topographic DEM 10

NGDC digitized jetty 1,000

ENC extracted land elevations 1,000

NASA SRTM topographic DEM 100
Carignan et. al, 2009

32

3.4 Quality Assessment of the DEM

3.4.1. Horizontal accuracy

The horizontal accuracy of topographic and bathymetric features in the Central Oregon Coast DEM is dependent 

upon the datasets used to determine corresponding DEM cell values. Topographic features have an estimated accuracy 

of 10 meters along the coast and greater inland: CSC topographic LiDAR data have accuracy between 1 and 3 meters; 

NED topography is documented to be accurate to within about 10 meters and the SRTM topography between 10 and 20 

meters. Figure 27 illustrates the significant difference between the NED and SRTM data. Contour lines were generated

for both of the topographic DEM datasets using ArcCatalog tools. The figure shows the 25 and 75 meter contours

depicting geologic features that are similar in shape but offset by as much as 500 meters in low lying areas. At higher 

elevations, the offset decreases. Bathymetric features are resolved only to within a few tens of meters in deep-water 

areas. Shallow, near-coastal regions, rivers, and harbor surveys have an accuracy approaching that of sub-aerial coastal 

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 manmade morphologic 

change (e.g., channel dredging and building of jetties).

Figure 27. Comparison of NED and SRTM contour lines.

3.4.2 Vertical accuracy

Vertical accuracy of elevation values for the Central Oregon Coast DEM is also highly dependent upon the 

source datasets contributing to DEM cell values. Topographic areas have an estimated vertical accuracy between 

0.1 to 0.3 meters for CSC 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. Those values were derived from the wide range 

of input sounding data 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.
Digital Elevation Model of Central Oregon Coast

33

3.4.3 Slope maps and 3-D perspectives

ESRI ArcCatalog was used to generate a slope grid from the Central Oregon Coast DEM to allow for visual 

inspection and identification of artificial slopes along boundaries between datasets (e.g., Fig. 28). The DEM was

transformed to UTM Zone 10 coordinates (horizontal units in meters) in ArcCatalog for derivation of the slope grid; 

equivalent horizontal and vertical units are required for effective slope analysis. Analysis of preliminary grids revealed 

suspect data points, which were corrected before recompiling the DEM. Three-dimensional viewing of the UTMtransformed DEM was accomplished using ESRI ArcScene. Figure 29 shows a color perspective view of the 1/3 arcsecond Central Oregon Coast DEM in its final version.

Figure 28. Slope map of the Central Oregon Coast 

DEM. Flat-lying slopes are white; dark shading 

denotes steep slopes; Central Oregon Coast 

coastline in red.
Carignan et. al, 2009

34

Figure 29. Perspective view from the southwest of the Central Oregon Coast DEM. 2x vertical exaggeration.

3.4.4	 Comparison with source data files

To ensure grid accuracy, the Central Oregon Coast 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 differences between

the DEM and a section of CSC ALACE LiDAR survey file, located at Siletz and Depoe Bay, is shown in Figure 30.

Differences range from -88.62 to 79.93 meters. Negative values result from the elevation of the LiDAR data being 

higher than the DEM elevation. The areas with the greatest differences are on heavily vegetated, steep hillsides.

Figure 30. Histogram of the differences between a section of the CSC ALACE LiDAR survey and the Central Oregon Coast DEM.
Digital Elevation Model of Central Oregon Coast

35

3.4.5 Comparison with NGS geodetic monuments

The elevations of 814 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 NAD 83 (typically 

sub-mm accuracy) and elevations in NAVD88 (in meters). Monuments installed on lighthouses or buildings were not 

included in the assessment of the DEM.

 Elevations were shifted to MHW vertical datum (see Table 10) for comparison with the Central Oregon Coast 

DEM (see Fig. 30 for monument locations). Differences between the Central Oregon Coast DEM and the NGS 

geodetic monument elevations range from -72.94 to 95.24 meters, with the majority of them within ± 12 meters 

(Fig. 32). Negative values indicate that the DEM is less than the monument elevation. Monuments located on steep 

embankments, installed on trees, and lost monuments had the greatest negative values. The monuments with the 

greatest positive values were either lost or located on ridgelines or in areas with steep terrain. NGS lists the horizontal 

accuracy of some of these monuments as ± 6 arc-seconds (~180 meters).

Figure 31. Histogram of the differences between NGS geodetic monument elevations and the Central Oregon Coast DEM.
Carignan et. al, 2009

36

Figure 32. Location of NGS geodetic monuments, shown as green triangles, and the NOAA South Beach tide station, 

yellow circle. NGS monument elevations were used to evaluate the DEM.
Digital Elevation Model of Central Oregon Coast

37

4. Summary and Conclusions

An integrated bathymetric–topographic digital elevation model of the Central Oregon coastal 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, state and local 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, MB-System, and Quick Terrain 

Modeler software. 

Recommendations to improve the Central Oregon Coast DEM, based on NGDC’s research and analysis, are listed 

below:

•	 Conduct hydrographic surveys for near-shore areas, especially in bays and river inlets.

•	 Complete bathymetric–topographic LiDAR surveying of entire region, especially within coastal zones.

•	 Process CSC topographic LiDAR data to bare earth.

•	 Re-survey older, low-resolution NOS hydrographic surveys in deeper waters.

5. Acknowledgments

The creation of the Central Oregon Coast DEM was funded by the NOAA Pacific Marine Environmental

Laboratory. The authors thank Chris Chamberlin, Vasily Titov, and Nazila Merati (PMEL); Daniel Proudfit (U.S.

Army Corps of Engineers, Portland District); and Arlene Merems (Oregon Department of Fish and Wildlife/Marine 

Resources Program).

6. References

Fox, D.S.; Merems, A.; Amend, M.; Weeks, H.; Romsos, C.; Appy, M. 2004. Final Report. Comparative 

Characterization of Two Nearshore Rocky Reef Areas: A high use recreational fishing reef vs. an unfished reef.

U.S. Fish and Wildlife Service Division of Federal Aid Wildlife Conservation and Restoration Program Contract 

No. R-01-1. Oregon Department of Fish and Wildlife Marine Program, Marine Habitat Project. 32 pp.

Merems, A.; Romsos, C. 2004. Nearshore Rocky Reef Habitat Survey Using Multibeam Sonar. Coastal Services Center, 

Integration and Development Grant Program Bathymetric Data Collection Project. Contract No. NA170C2645. 

Oregon Department of Fish and Wildlife and Oregon State University. 18pp.

Nautical Chart #18520 (ENC and RNC), 10th Edition, 2008. Yaquina Head to Columbia River – Netarts Bay. Scale 

1:185,238. U.S. Department of Commerce, NOAA, National Ocean Service, Coast Survey.

Nautical Chart #18561 (RNC), 12th Edition, 2003. Approaches to Yaquina Bay. Scale 1:50,000. U.S. Department of 

Commerce, NOAA, National Ocean Service, Coast Survey.

Nautical Chart #18580 (ENC and RNC), 6th Edition, 2005. Cape Blanco to Yaquina Head. Scale 1:191.730. U.S. 

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

Nautical Chart #18581 (RNC), 17th Edition, 2002. Yaquina Bay and River. Scale 1:10,000. U.S. Department of 

Commerce, NOAA, National Ocean Service, Coast Survey.

Nautical Chart #18583 (RNC), 39th Edition, 2005. Siuslaw River. Scale 1:20,000. U.S. Department of Commerce, 

NOAA, National Ocean Service, Coast Survey.

Nautical Chart #18584 (RNC), 48th Edition, 2007. Umpqua River – Pacific Ocean to Reedsport. Scale 1:20,000. U.S.

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

Nautical Chart #18587 (RNC), 70th Edition, 2005. Coos Bay. Scale 1:20,000. U.S. Department of Commerce, NOAA, 

National Ocean Service, Coast Survey.
Carignan et. al, 2009

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U.S. Army Corps of Engineers, Portland District. 2005. Final Environmental Assessment Repair of North and South 

Jetties Mouth of the Columbia River Clatsop County, Oregon and Pacific County, Washington. https://www.nwp.

usace.army.mil/issues/jetty/documents.asp

7. Data Processing Software

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

FME 2008 GB – Feature Manipulation Engine, developed and licensed by Safe Software, Vancouver, BC, Canada, 

http://www.safe.com/

GEODAS v. 5 – Geophysical Data System, free software 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, free software 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, free software 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/

Quick Terrain Modeler v. 6.0.1, LiDAR processing software developed by John Hopkins University’s Applied Physics 

Laboratory (APL) and maintained and licensed by Applied Imagery, http://www.appliedimagery.com/