NOAA Technical Memorandum NOS CS 19

VDATUM FOR EASTERN LOUISIANA AND MISSISSIPPI 

COASTAL WATERS: TIDAL DATUMS, MARINE GRIDS, 

AND SEA SURFACE TOPOGRAPHY

Silver Spring, Maryland

September 2010

noaa National Oceanic and Atmospheric Administration

U.S. DEPARTMENT OF COMMERCE

National Ocean Service

Coast Survey Development Laboratory
Office of Coast Survey

National Ocean Service

National Oceanic and Atmospheric Administration

U.S. Department of Commerce

The Office of Coast Survey (OCS) is the Nation’s only official chartmaker. As the 

oldest United States scientific organization, dating from 1807, this office has a 

long history. Today it promotes safe navigation by managing the National 

Oceanic and Atmospheric Administration’s (NOAA) nautical chart and 

oceanographic data collection and information programs.

There are four components of OCS:

The Coast Survey Development Laboratory develops new and efficient 

techniques to accomplish Coast Survey missions and to produce new and 

improved products and services for the maritime community and other 

coastal users.

The Marine Chart Division acquires marine navigational data to construct 

and maintain nautical charts, Coast Pilots, and related marine products for 

the United States.

The Hydrographic Surveys Division directs programs for ship and shorebased hydrographic survey units and conducts general hydrographic 

survey operations.

The Navigational Services Division is the focal point for Coast Survey 

customer service activities, concentrating predominately on charting 

issues, fast-response hydrographic surveys, and Coast Pilot updates.
NOAA Technical Memorandum NOS CS 19

VDATUM FOR EASTERN LOUISIANA AND MISSISSIPPI 

COASTAL WATERS: TIDAL DATUMS, MARINE GRIDS, 

AND SEA SURFACE TOPOGRAPHY

Zizang Yang and Edward P. Myers 

Office of Coast Survey, Coast Survey Development Laboratory,

Silver Spring, MD

Stephen A. White

National Geodetic Survey, Silver Spring, MD

September 2010

noaa National Oceanic and Atmospheric Administration

U. S. DEPARTMENT National Oceanic and National Ocean Service

OF COMMERCE Atmospheric Administration David Kennedy

Gary Locke, Dr. Jane Lubchenco Acting Assistant

Secretary Under Secretary Administrator

Office of Coast Survey Coast Survey Development Laboratory

Captain John Lowell, NOAA Mary Erickson
ii

NOTICE

Mention of a commercial company or product does not constitute an 

endorsement by NOAA. Use for publicity or advertising purposes of 

information from this publication concerning proprietary products or 

the tests of such products is not authorized.
iii

TABLE OF CONTENTS

LIST OF FIGURES .........................................................................................................................v

LIST OF TABLES........................................................................................................................ vii

ABSTRACT................................................................................................................................... ix

1. INTRODUCTION .......................................................................................................................1

2. COASTLINE, BATHYMETRY, AND TIDAL DATUM OBSERVATIONS...........................5

2.1. Digital Coastline ...........................................................................................................5

 2.2. Bathymetric Data ..........................................................................................................5

2.3. Tidal Datum Data..........................................................................................................7

3. TIDAL DATUM SIMILATION..................................................................................................9

3.1. Hydrodynamic Model ...................................................................................................9

 3.2. Model Grid....................................................................................................................9

3.3. Bathymetry of Model Grid..........................................................................................12

3.4. Model Parameter Setup...............................................................................................14

3.5. Tidal Datum Computation and Results.......................................................................15

3.6. Verifications and Error Corrections............................................................................18

4. CREATION AND POPULATION OF THE MARINE GRID .................................................25

4.1. Creation of VDatum Marine Grid...............................................................................25

4.2. Population of VDatum Grid with Tidal Datums.........................................................27

5. TOPOGRAPHY OF THE SEA SURFACE ..............................................................................29

5.1. Derivation of TSS .......................................................................................................30

5.2. Quality Control ...........................................................................................................31

6. SUMMARY...............................................................................................................................35

ACKNOWLEDGMENTS .............................................................................................................35

REFERENCES ..............................................................................................................................36

APPENDIX A. HORIZONTAL AND VERTICAL ACCURACY STANDARDS FOR 

NOAA BATHYMETRY SURVEY ..................................................................................39

APPENDIX B. WATER LEVEL STATION DATA....................................................................41

APPENDIX C. TIDAL DATUM FIELDS DEFINED ON VDATUM MARINE GRID.............45

APPENDIX D. TIDAL GAUGE AND BENCH MARKS DATA USED TO CREATE 

THE TSS............................................................................................................................49

APPENDIX E. DERIVED NAVD 88-TO-MSL VALUES. .........................................................51

APPENDIX F. QC DELTAS AT STATIONS FOR TSS GRIDS ................................................53
iv

APPENDIX G. COMPARISONS of DERIVED TSS WITH OBSERVATIONS AT 

TIDAL GAUGE AND TIDAL BENCH MARKS ............................................................55
v

LIST OF FIGURES

Figure 1. Map of the coastal areas of LA and MS. Black lines illustrates MHW coastal 

lines. Green line denotes a distance 25-nautical miles offshore. ......................................3

Figure 2. Locations of NOS sounding survey data ..........................................................................6

Figure 3. Locations of ENC bathymetric data .................................................................................6

Figure 4. Finite element grid for the entire model domain. Red dots denote the model 

open ocean boundary nodes............................................................................................10

Figure 5. Close-up views of the model grid, (a) mid- to eastern LA coast, (b) Mississippi 

River Delta, and (c) Mississippi coast. ...........................................................................10

Figure 6 Model grid bathymetry relative to MZ. Color bars are in meters. (a) 

bathymetries between [0, 300] m; those beyond 100 m are shown in the same 

scale as the 300-m bathymetry; (b) bathymetries between [300, 2700] m; those 

less than 300 m are shown in the same scale as the 300-m bathymetry .........................13

Figure 7. Spatially-varied bottom friction coefficient (Cf)............................................................14

Figure 8. Model-derived tidal datum fields, (a) MHHW, (b) MHW, (c) MLW, and (d) 

MLLW. Color bars are in meters....................................................................................16

Figure 9. Comparisons of the modeled (a) MHHW, (b) MHW, (c) MLW, and (d) MLLW 

datums against observations. ..........................................................................................18

Figure 10. Color-scaled averaged model-data errors (|Avg|). Color bar is in cm..........................19

Figure 11. Outlines of the present hydrodynamic model domain (blue lines) and 

bounding polygons (cyan and black lines) of two neighboring VDatum areas. 

The cyan and black lines illustrate bounding polygons of the Alabama Bays 

and Gulf of Mexico VDatum areas, respectively. Transect AA’ indicates the 

locations where tidal datum discrepancies between adjacent areas were 

examined......................................................................................................................20

Figure 12. Error-corrected tidal datum fields over the whole model domain, (a) MHHW, 

(b) MHW, (c) MLW, and (d) MLLW. Color bars are in meters .................................23

Figure 13. Definition of VDatum marine grid bounding polygon: MHW coastline (cyan 

line), bonding polygon (blue line) ...............................................................................26

Figure 14. Location of tidal bench marks and tide stations used to compute the New 

Orleans VDatum TSS grids .........................................................................................29
vi

Figure 15. The New Orleans TSS field based on NAVD88 realized through GEOID99 ............32

Figure 16. The New Orleans TSS field based on NAVD88 realized through GEOID03 ............33
vii

LIST OF TABLES

Table 1. Statistics of model-data errors ........................................................................................19

Table 2 Statistics of tidal datum differences (∆) between the present model results and 

those for the Alabama Bays and Gulf of Mexico along transect AA’(Figure 11)..........20

Table 3. Marine grid parameters ..................................................................................................25
viii
ix

ABSTRACT

A vertical datum transformation software tool, VDatum, is developed for an area 

covering the coastal waters of Mississippi and the eastern half of Louisiana. The area 

encompasses major embayments (Atchafalya, Terrebonne, and Barataria Bays, LA), the 

Mississippi River Delta, and sounds (Breton, Chandeleur, and Mississippi Sounds, MS). 

VDatum provides spatially-varying conversions between tidal, orthometric, and ellipsoidbased 3D reference frames. 

The tidal datums fields were derived from tidal simulations using ADCIRC, a finite 

element hydrodynamic model which uses unstructured triangular grids. A grid consisting 

of 167,646 nodes and 306,749 cells was created for this project. The model was forced 

with nine tidal constituents (M2, S2, N2, K2, K1, P1, O1, Q1, and M4) and integrated for 65

days. Various tidal datum fields, including mean lower low water (MLLW), mean low 

water (MLW), mean high water (MHW), and mean higher high water (MHHW), were 

derived using the water level time series from the final 55 days of the simulation. Model 

results were validated by comparing with observations at 70 water level stations 

maintained by the NOAA’s Center for Operational Oceanographic Products and Services 

(CO-OPS). Discrepancies between model results and observational datums were 

attributed to model errors and interpolated over the whole model domain using TCARI

(Tidal constituent And Residual Interpolation), a spatial interpolation tool based on 

solution of Laplace’s equation. The error fields were applied to the direct model results 

to derive corrected tidal datums on the model grid. These final tidal datum fields were 

interpolated onto a regularly structured marine grid to be used by the VDatum software.

The Topography of Sea Surface (TSS), defined as the elevation of NAVD88 relative to 

local mean sea level (LMSL), was developed based on interpolation of bench mark data 

maintained by CO-OPS and the National Geodetic Survey (NGS). The NAVD88-toLMSL values were derived either by fitting tidal model results to tidal bench marks 

leveled in NAVD88 or by calculating orthometric-to-tidal datum relationships at NOAA 

tidal gauges. Results by both methodologies were coupled to create the final TSS grids 

using spatial interpolation. 

Operationally, this particular VDatum grid will have to be updated at least every 5-years 

in order to account for rapid elevation changes in tidal datums and NAVD88 due to land 

subsidence in the region. CO-OPS has formal Modified 5-Year Tidal Epoch procedures 

for updating tidal datums and NGS is developing a Vertical Time Dependent NAVD 

system for Louisiana.

Key Words: tides, tidal datums, Louisiana and Mississippi coast waters, ADCIRC, mean 

sea level, bathymetry, coastline, spatial interpolation, marine grid, North American 

Vertical Datum of 1998
x
1

1. INTRODUCTION

NOAA’s NOS has developed software tool called VDatum to transform elevation data 

among approximately 30 vertical datums (Gill and Schultz, 2001; Hess et al., 2003; 

Milbert, 2002; Parker, 2002; Myers et al., 2005; Spargo, et al., 2006). Once VDatum has 

been established for a region, data sets referenced to different vertical datums can be 

integrated through transformations to a common vertical datum (Parker et al., 2003). 

VDatum allows all bathymetric and topographic data to be integrated in this manner 

through its inherent geoidal, ellipsoidal, and tidal datum relationships. 

To be applicable over coastal waters, VDatum requires spatially varying fields of the tidal 

datums and the Topography of Sea Surface (TSS). The former involves datums such as 

MHHW, MHW, MLW, MLLW, Mean Tide Level (MTL), and Diurnal Tide Level (DTL)

defined relative to local mean sea level (LMSL). The latter refers to the elevation of the 

North American Vertical Datum of 1988 (NAVD88) relative to LMSL. 

The VDatum tool software is currently available for Tampa Bay (Hess, 2001), Long 

Island Sound and New York Bight and Harbor (Yang et al., 2008(2)), Delaware and 

Chesapeake Bays (Yang et al., 2008(1)), central California (Myers and Hess, 2006), 

southern California (Yang et al., unpublished manuscript), central/northern North 

Carolina (Hess et al., 2005), Lake Calcasieu and Charles River (Spargo and Woolard, 

2005), Port Fourchon, Puget Sound (Hess and Gill, 2003; Hess and White, 2004), and the 

Strait of Juan de Fuca (Spargo et al., 2006(1)).

This report describes the development of VDatum for an area covering the coastal waters 

of the eastern half of Louisiana and of Mississippi (Figure 1). It encompasses all major 

embayments (Atchafalya, Terrebonne, and Barataria Bays, LA), sounds (Breton, 

Chandeleur, and Mississippi Sounds, MS), and lakes (Lake Maurepas and Pontchartrain) 

in the area, as well as the Mississippi River Delta waters. In Figure 1, black lines 

represent the MHW coastline and the green line denotes the 25-nm offshore demarcation. 

Tidal datums for VDatum are generally developed for water areas between the coastline 

and the 25-nm offshore limit.

Development of VDatum begins with tidal simulations using a hydrodynamic model. 

Various tidal datum fields (MHHW, MHW, MLW, and MLLW) were derived using the

simulated water level time series. The tidal datums were verified by comparing with 

observational data, and error corrections were made based on these comparisons. 

Regularly structured VDatum marine grids were created and populated with corrected 

tidal datums. Finally, for the same marine grid, the NAVD88-to-LMSL field was derived 

by either fitting tidal model results to tidal bench marks leveled in NAVD88 or 

calculating orthometric-to-tidal datum relationships at NOAA tidal gauges. 

This technical report is organized as follows: After an introduction in Section 1, Section 2 

discusses data input needed to set up the hydrodynamic model run and the validation of 

the model results.Such data inputs include digital coastline, bathymetry, and tidal datums 

derived from observational data. Section 3 details tidal datum simulation procedures, 
2

including an introduction of the tidal hydrodynamic model, its setup, validation of results, 

and error corrections. Section 4 discusses creation of the regularly structured marine grid 

required for the VDatum software tool and its population with error-corrected model 

datums. In Section 5, creation of TSS for the area is described. Finally, a summary is 

given in Section 6.
Figure 1. Map of the coastal areas of LA and MS. Red lines illustrate the MHW shoreline. The 

green line denotes a distance 25-nautical miles offshore.

3

Atchafalaya 

Bay

Chandeleur

Island

Terrebonne

Bay

Mississippi 

River

Calcasieu 

Lake

Barataria 

Bay

Atchafalaya 

River

Gulf of Mexico

MS River

Delta

Lake 

Pontchartrain

MS Sound

Lake Borgne
4
5

2. COASTLINE, BATHYMETRIC, AND WATER LEVEL DATA

VDatum requires an accurate representation of spatially varying tidal datum fields

(Milbert and Hess, 2001). To achieve this, VDatum applications are developed using a 

combination of observational data, hydrodynamic models, and spatial interpolation 

techniques (Spargo et al., 2006(2); Yang et al., 2006, Spargo and Woolard, 2005). For 

this VDatum application for Mississippi and eastern Louisiana, a tide model was first set 

up to compute spatially varying tidal datums. The modeled tidal datums were next 

compared with those derived from CO-OPS observational data. Finally, spatial 

interpolation techniques were used to create a correction field to be applied to the model 

results to derive a corrected field of tidal datums that are consistent with the observations. 

For the tidal simulations, coastline data are required for delineating land-water 

boundaries so as to define hydrodynamic model domains. In addition, bathymetric data 

are needed to provide the model grid bathymetry. Numerical model results may not 

exactly match CO-OPS observations, and therefore observational data are needed to 

validate and correct the model results. 

2.1. Digital Coastline

For VDatum the mean high water shoreline is used as the coastline to delineate the landwater boundaries (Parker, 2002). The shoreline data used in the present study were 

mainly based on the Electronic Navigational Chart (ENC) Shoreline from the NOS Office 

of Coast Survey (OCS). However, in certain areas the ENC shoreline appears to be 

incomplete/inaccurate in terms of the existence of dangling shoreline segments or 

confusing outlines of artificial constructs with true shorelines. The erroneous MHW 

depictions were corrected using computer-aided techniques to match the MHW coastlines 

illustrated on raster nautical charts (RNCs). This was implemented via a commercial 

software package called Surface-Water Modeling System (SMS). Using SMS, georeferenced RNCs and the ENC shoreline data were overlaid and contrasted visually. 

Wherever the two do not match, the latter was judged to be inaccurate and replaced by 

the corresponding chart coastline. In Figure 1, the red line illustrates the final corrected 

coastline. 

2.2. Bathymetric Data

Bathymetric data used in this study were from two sources: NOS soundings and the 

NOAA Electronic Navigational Charts (ENCs) bathymetry. The former were from the 

NOS/OCS hydrographic database maintained at the National Geophysical Data Center 

(NGDC), and the latter were based on the NOAA ENCs. Figures 2 and 3 illustrate the 

spatial coverage of the soundings and ENC data, respectively.
6

Figure 2. Locations of NOS sounding survey data.

Figure 3. Locations of ENC bathymetric data

The NOS sounding data include surveys conducted between 1885 and 2000. In the areas 

where data from multiple years were available, those from more recent years were used. 

The datums were referenced to either MLW or MLLW, depending on the years of data 

collection. The ENC data were referenced to MLLW. The horizontal and vertical 

accuracy standards for NOAA surveys are listed in Table A.1 of Appendix A . 
7

The NOS soundings possess a higher spatial distribution density than the ENC data. 

However, neither of them provides complete coverage for the whole study area. Hence, 

they were blended for a better regional coverage.

2.3. Tidal Datum Elevations 

Tidal datums from CO-OPS water level stations were used for validating model results.

These observational data are available online (Hess and Spargo, 2005) and correspond to 

the 1983-2001 National Tidal Datum Epoch (NTDE). Many of the tide stations in 

Louisiana are now part of a Modified 5-year Tidal Epoch process in which tidal datums 

are frequently updated using the most recent 5-years of monthly mean sea level (still 

using a Diurnal Range based on the 1983-2002 NTDE). These stations are asterisked in 

the Appendix B.

Many stations are located within either embayments or near obstructions not mapped by

the present model grid (Section 3.2), or at upper-reaches of riverine areas where datums 

exhibit strong seasonal variability. These observations were determined to be unsuitable 

for validating model results and were therefore discarded. Data from 70 stations were 

selected for use in the model validations. This area is subject to rapid rates of land 

subsidence, and listings of stations will frequently change as new tidal and geodetic 

observations are made. Tables B.1 and B.2 in Appendix B list the station and tidal datum 

information used for this particular model.
8
9

3. TIDAL DATUM SIMULATION

3.1. Hydrodynamic Model

The ADvanced CIRCulation (ADCIRC) model (Westerink, et al., 1993) was used to 

simulate water level time histories. The ADCIRC model is an unstructured grid 

hydrodynamic circulation model. It solves the shallow water equations and has been used 

in modeling tides in various ocean, coastal and estuarine environments (Luettich et al., 

1999; Mukai et al., 2002). The ADCIRC model provides a variety of options for users to 

specify input parameters and execution modes. For instance, the model may be run in 

either 2- or 3-dimensonal modes, serial or parallel execution, linear or quadratic bottom 

friction formulation with constant or variable friction coefficients, etc. More details on 

the model setup such as model grid generation, bathymetry definitions, and parameter 

specifications are addressed in following sections. 

3.2. Model Grid

The model domain for this VDatum application is shown in Figure 4. A high-resolution, 

unstructured grid of 167,646 nodes and 306,562 triangular elements was created to map

the domain up to the MHW shoreline. The spacing between grid nodes ranges from 

around 17 m to 5.5 km. In general, finer elements were created for nearshore areas

compared to those in deep waters, so as to accurately resolve fine coastline features and 

the bathymetric-dependent variability of the tidal wavelengths.

Figures 5(a) and (c) show close-up views of three sections (from west to east) of the 

model grid. They correspond to the water areas of the mid- to eastern Louisiana coast 

(Figure 5(a)), Mississippi River Delta (Figure 5(b), and Mississippi coast (Figure 5(c)). 

Note that the present model domain goes far beyond the area in which the present 

VDatum development is concerned. This is for the sake of ensuring model computational 

stability and pursuing accurate tidal simulations. In areas far away from the shoreline, 

tidal currents are relatively weak and tidal fields exhibit rather gradual variability. The 

former helps maintain model computational stability, while the latter helps choose 

accurate tidal harmonic constants used as the model forcing on its open boundary. 
10

Figure 4. Finite element grid for the entire model domain. Red dots denote the model 

open ocean boundary nodes.

Figure 5. Close-up views of the model grid, (a) mid- to eastern Louisiana coast, 

(b) Mississippi River Delta, and (c) Mississippi coast.

(a)
11

Figure 5. (Continued)

(b)

(c)
12

3.3. Bathymetry of Model Grid

The bathymetry datasets described in Section 2.2 were used to specify the model grid 

bathymetry. Note that NOS soundings and ENC data were of different spatial resolution 

and coverage. As for the soundings alone, bathymetry may be referenced to either MLW 

or MLLW. Hence, they were categorized into two groups and applied to the grid 

separately. In short, the bathymetry data were classified into three groups: (1) MLLW 

NOS soundings (2) MLW NOS soundings, and (3) MLLW ENC data. The three groups 

were interpolated onto the model grid separately, resulting in three meshes corresponding 

to the three bathymetric datasets. 

The algorithm used for interpolating bathymetry onto the three meshes was the same. 

Bathymetry at each model node represents an average of data points within the node’s 

surrounding elements. Since element size changes throughout the model domain, the 

searching range for bathymetric data points varies from node to node. As the element size 

is smaller in coastal waters, bathymetry for nodes near the coastline were from more 

locally distributed data points compared to those in deep waters.

As none of the three data sets provided complete coverage of the model domain, each of 

the three meshes left numerous unpopulated nodes. Hence, the three meshes were 

combined to obtain a more complete coverage. At nodes where bathymetric data were 

available in more than one mesh, an arithmetic average was taken; otherwise, the value 

from the solely available mesh was taken. After merging the three meshes, there still 

remained some nodes without valid bathymetry. These nodes were populated by 

averaging bathymetry from adjacent nodes.

It is worthwhile to note that the bathymetry of the three meshes had two different 

reference datums: MLW and MLLW. Setup of the tidal model requires the grid 

bathymetry to be referenced to the model zero (MZ), a geopotential surface. It is 

therefore necessary to adjust the reference datum from MLLW/MLW to MZ prior to any 

data blending. However, the (MZ – MLLW/MLW) values are unknown prior to the model 

runs. The adjustment was accomplished by iteratively updating the ∆MLLW = (MZ-MLLW)

and ∆MLW= (MZ-MLW) fields based on model results from a series of simulations: initial 

constant values of ∆MLLW = 0.3 m and ∆MLW = 0.2 m were assumed for the whole grid. 

Following each model run, new sets of tidal datum fields were derived and were used to 

update the ∆MLLW and ∆MLW fields. Multiple runs were conducted until invariant ∆MLLW

and ∆MLW values were achieved. Multiple iterations were made to meet a convergence 

criteria of both |∆MLLW| and |∆MLW| less than 5x10-3 m. Figure 6 shows the bathymetry 

used in the final model run.
13

Figure 6. Model grid bathymetry relative to MZ. Color bars are meters. (a) bathymetry

between [0, 300] m; those beyond 300 m are shown with the same color as the 

300-m bathymetry; (b) bathymetry between [300, 2700] m; values less than 

300 m are shown in the same color as the 300-m bathymetry. 

(a)

(b)
14

3.4. Model Parameters Setup 

In the present study, model parameters were set up to solve the shallow water equations 

in Two-Dimensional Depth-Integrated (2DDI) mode with finite amplitude and 

convection terms and the wetting and drying option activated. Lateral viscosity was set as 

a constant, 5.0 m s-2

, throughout the model domain. A quadratic friction scheme with a 

spatially-varying coefficient (Cf) was specified to calculate bottom friction. Multiple runs 

were conducted to test various Cf values in an attempt to mitigate model-data discrepancy 

in terms of tidal datums. Figure 7 shows the Cf values derived for the final tidal 

simulations. 

Figure 7. Spatially variable bottom friction coefficients used for model simulations. 

The nine most significant astronomical tidal constituents (M2, S2, N2, K2, K1, P1, O1, Q1, 

and M4) in the area were chosen to drive the model on its open boundary. Corresponding 

harmonic constants were interpolated based on a tidal database derived from the Western 

North Atlantic Ocean tidal model (WANTM) (Meyers, 2003). A time step equal to 1.0

Figure 7. Spatially-varied bottom friction coefficient (Cf).

Nine astronomical tidal constituents (M2, S2, N2, K2, K1, P1, O1, Q1, and M4) were input 

as tidal forcings along the model’s open boundary. Corresponding harmonic constants 

were interpolated based on a tidal database derived from the West North Atlantic Ocean 

Tidal Model (Myers, unpublished manuscript). A time step equal to 3 seconds was used 

to ensure computational stability. The simulation covered a period of over 65 days. First, 

the model was ramped up for 5 days with a hyperbolic tangent function. It was then 

integrated for another 5 days to allow for the tidal field to reach an equilibrium state. 

Afterwards, 6-minute interval water level time series were recorded for 55 days to derive 

the tidal datums. It is noted that water level records of various lengths were tested to gain 

insight into the sensitivity of record lengths to the stability of the resultant tidal datum 

values. The test proved that a 55-day period is an appropriate choice to obtain statistically 

stable results. 

Cf (×103)
15

The present setup did not apply the Mississippi River inflow at the River’s upstream end. 

However, it is noted that some pre-final model testing runs were conducted with monthly 

mean river inflows. The results did indicate significant improvement on the tidal datum 

results compared with the case without the river forcing. 

The parallel version of ADCIRC model was adopted and the model run was conducted on 

50-processors on the JET computer at NOAA’s Earth System Research Laboratory. It 

took approximately 7.5 hours to complete the 65-day simulation. 

3.5. Tidal Datum Computation and Results

From the modeled water time series, tidal datums including MSL, MHHW, MHW, 

MLW, and MLLW at each model node were derived by selecting the tides over a 19-year 

time period on a predicted tide curve derived from the modeled-output harmonic 

constants, averaging them over the period and then referencing each to the modeled 

MSL. Henceforth, references to each of the tidal datums shall imply this adjusted value 

relative to MSL. Note that MTL is defined as the algebraic average of MHW and MLW, 

and DTL is the algebraic average of MHHW and MLLW. The two fields were not 

computed until error-corrected MHHW, MHW, MLW, and MLLW fields were obtained 

(Section 4.2). 

Figures 8(a)-(d) display the model derived tidal datum fields for MHHW, MHW, MLW, 

and MLLW, respectively. As expected, the four fields exhibit a similar spatial pattern. In 

general the LA coast demonstrates a higher tidal range (around 0.6 m) than that around 

the Mississippi River Delta (about 0.3 m) or Mississippi Sound (about 0.4 m). The tidal 

range in Lake Pontchartrain appears to be ~0.12 m. 
16

Figure 8. Model-derived tidal datum fields, (a) MHHW, (b) MHW, (c) MLW, and 

(d) MLLW. Color bars are in meters.

(b)

MHW

(a)

MHHW
17

Figure 8. (Continued)

(d)

MLLW

(c)

MLW
18

3.6. Validation and Error Corrections

3.6.1. Comparisons with Observations

To validate model results, modeled tidal datums were compared with those from 70 COOPS water level gauges in the region (Appendix B). Figures 9(a)-(d) display model-data 

contrasts for MHHW, MHW, MLW, and MLLW, respectively. In general, there exhibits

good model-data agreement. Over the 70 stations, magnitudes of the model-data 

differences are averaged to be 1.8 cm, 2.0 cm, 1.6 cm, and 1.8 cm for MHHW, MHW, 

MLW, and MLLW, respectively. The model-data correlation coefficients are between 

0.98-0.99 for all four tidal datums. 

Figure 9. Comparisons of the modeled (a) MHHW, (b) MHW, (c) MLW, and (d) MLLW 

datums against observations.

(a) (b)

(c) (d)
19

For each individual station, averaged magnitudes (|Avg|) of model-data differences over 

the four datums are examined. Figure 10 illustrates |Avg|’s scaled in color-coded 

symbols. Table 1 lists the mean and standard deviation (std) of the |Avg|’s for MHHW, 

MHW, MLW, and MLLW over the 70 stations. 

Figure 10. Color-scaled average model-data errors (|Avg|). Color bar is in cm.

 Table 1. Statistics of model-data errors 

MHHW 

(cm)

MHW

(cm)

MLW

(cm)

MLLW 

(cm)

mean(|Avg|) 1.8 2.0 1.6 1.8

std(|Avg|)) 1.6 1.7 1.7 1.8

3.6.2. Match with Tidal Datums in Adjacent areas

The present model domain overlaps with the Gulf of Mexico and Alabama Bays VDatum 

applications (Spargo et al., 2008) (Figure 12). In reality, tidal datum fields should be 

matched seamlessly across domain boundaries. However, this is not necessarily 

engendered when the two tidal datum fields datasets were developed separately with

slightly different model setups in terms of tidal boundary forcings, magnitudes of the 

bottom friction coefficients, etc. It is therefore worthwhile to examine discrepancies and 

work out ways to reach seamless matches if needed. 
20

 

Comparisons between the present model results and those of the Gulf of Mexico and

Alabama Bays VDatum applications were made along transect AA’, shown in Figure 11. 

The two exhibit similar magnitude of the differences and hence were combined to 

examine the statistics. Table 2 lists the statistics of the tidal datum differences. 

Figure 11. Outlines of the present hydrodynamic model domain (blue lines) and bounding 

polygons (cyan and black lines) of two neighboring VDatum areas. The cyan 

and black lines illustrate bounding polygons of the Alabama Bays and Gulf of 

Mexico VDatum areas, respectively. Transect AA’ indicates the locations 

where tidal datum discrepancies between adjacent areas were examined. The 

green line illustrates locations 25-nm offshore.

Table 2. Statistics of tidal datum differences (∆) between the present model results and 

those for the Alabama Bays and Gulf of Mexico along transect AA’ (Figure 11).

MHHW 

(cm)

MHW

(cm)

MLW

(cm)

MLLW 

(cm)

mean(|∆|) 2.6 0.7 0.7 1.5

Standard 

deviation (∆) 1.2 0.3 0.6 1.2

A

A’
21

The mean |∆| for MHHW and MLLW are greater than 1.5 cm. The standard deviation of 

the differences ranges from 0.3 to 1.2 cm. It was therefore necessary to make adjustments 

to the present model results so as to reach a seamless match of tidal datums between 

different adjacent regions. This was accomplished by using TCARI, the details of which 

are described in the next section. 
22

3.6.3. Corrections 

Tidal datum corrections were developed to eliminate model-data differences at 

observational stations (Section 3.6.1) as well as to minimize datum discrepancies across 

boundaries of different VDatum domains (Section 3.6.2). This was achieved using the 

TCARI (Tidal Constituent And Residual Interpolation spatial interpolation tool (Hess, 

2002; Hess, 2003). TCARI was used to spatially interpolate the error fields defined at a 

number of individual control stations onto the whole domain by solving Laplace’s 

equation. TCARI has been developed for use with both structured and unstructured 

model grids, and a version of the latter was employed in this study.

To run TCARI, both the observational stations and the domain boundary stations were

treated as control stations. For each tidal datum, both model-data differences (at 70 tidal 

stations) and across-boundary discrepancies were computed and merged into one dataset

for input to TCARI. 

After applying TCARI, error fields for MHHW, MHW, MLW, and MLLW were derived 

that matched the tidal datum differences at the 70 control stations. The initial model

results (Section 3.5) were then corrected by subtracting the error fields over the entire 

model grid. Figures 12(a)-(d) display the final corrected tidal datum fields. 
23

Figure 12. Error-corrected tidal datum fields over the whole model domain, (a) MHHW, 

(b) MHW, (c) MLW, and (d) MLLW. Color bars are in meters.

(b)

MHW

(a)

MHHW

(d)

MLLW

(c)

MLW
24
25

4. CREATION AND POPULATION OF THE MARINE GRID

4.1. Creation of VDatum Marine Grid

Tidal datums in the VDatum software are defined on a regularly structured grid, referred 

to as the marine grid (Hess and White, 2004). Hence, it is necessary to convert the tidal 

datum fields from the unstructured grid onto the equally-spaced raster VDatum marine 

grid. 

Nodes in the marine grid were specified as either water points or land points. The water 

nodes are to be populated with valid tidal datum values and the land nodes are assigned 

with null values. To create the marine grid, the high-resolution MHW coastline (Section 

2.1) and a bounding polygon (Figure 13) were used. The bounding polygon was set up to 

guide the delineation of water/land nodes. Only nodes within the bounding polygons or 

within up to one half of a cell size outside the coastline are delineated as water nodes; 

those outside of the bounding polygons or those more than one half of a cell size away 

from the coastline are marked as land nodes. 

Marine grid points are equally spaced. For a point at the i-th row and j-th column relative 

to the point (longitude0, latitude0) at the region’s southwest corner, its location 

(longitude_i, latitude_j) is defined as,

Longitude_i = longitude0 + (i-1)×del_lon, i=1, ..., N_lon,

Latitude_j = latitude0 + (j-1) ×del_lat, j=1, ..., N_lat,

where del_lon, and del_lat denote separation between neighboring points along the 

meridional and zonal directions, respectively; N_lon and N_lat represent, respectively, 

the longitude and latitude dimensions of the raster data set. It is noted that the del_lon and 

del_lat are prescribed parameters representing the expected grid resolutions, while N_lon

and N_lat are derived parameters according to

N_lon = 1 + (longitude1 - longitude0)/del_lon

N_lat = 1 + (latitude1 - latitude0)/del_lat

where (longitude1, latitude1) are the coordinate at the raster region’s northeast corner. 

Table 3 lists parameters used to define the marine grid. 

 Table 3. Marine grid parameters

Region

Name

Longitude0

(degree)

Latitude0

(degree)

del_lon

(degree)

del_lat

(degree) N_lon N_lat

RA Eastern LA 

and MS -93.0 28.0 0.001 0.001 5001 2501

The water-land node specifications in the grid were then further quality controlled by 

comparing with coastline imagery acquired by NGS. Compared with the aforementioned 

MHW coastline (Section 2.1), the imagery coastline is more recently updated and gives a
26

more realistic coastline representation. By comparing with the NGS coastline, the 

nearshore water-land node specifications in the original marine grid were adjusted, while 

the definition of the marine grid parameters (Table 3) was retained. This NGS marine 

grid was then used to populate the tidal datums. 

Figure 13. Definition of VDatum marine grid bounding polygon: MHW coastline 

(cyan line), bonding polygon (blue line).

 
27

4.2. Population of VDatum Grid with Tidal Datums

Tidal datums on the VDatum marine grid were populated by interpolating the TCARIcorrected tidal datums (Section 3.6) following the algorithm of Hess and White (2004). 

Datums at each grid point were computed by averaging or linearly interpolating those 

values within a user-specified searching radius or the closest user-specified number of 

points. Marine points were populated differently depending on whether a point was

inside/outside of the ADCIRC model grid elements. If it was inside an element, datums 

were calculated using an interpolation of the 3 nodes of the element; otherwise, datums 

were computed using the inverse distance weighting of the closest two node values.

Figures C.1(a)-(e) in Appendix C display the populated tidal datums, MHHW, MHW, 

MLW, MLLW, MTL, and DTL, respectively. 

As a quality control procedure, the tidal datum fields were further verified against those 

from the water level stations (Section 3.6.1). The test gave a maximum absolute modeldata error less than 0.2 cm and an rms error less than 0.1 cm for all four datums (MHHW, 

MHW, MLW, and MLLW).

In addition, the datum consistency along a border transect (AA’ in Figure 11) between 

the present VDatum domain and those of the Gulf of Mexico and Alabama Bays VDatum 

applications (Section 3.6.2) were tested. A good agreement was achieved: For each of 

MHHW, MHW, MLW, and MLLW, the maximum absolute differences were less than 

0.1 cm.
28
29

5. GENERATION OF THE SEA SURFACE

The TSS is defined as the elevation of NAVD 88 relative to local MSL. It is created by 

combining observed datums at NGS bench marks and CO-OPS water level stations with 

the tidal model results. Figure 14 illustrates the station locations used in this application 

(see details of the station information in Table D.1 of Appendix D). To create the TSS 

over the VDatum domain, the TSS values at the observation stations were first derived. 

These values were then interpolated over the whole domain. Afterwards, a quality control 

procedure was followed and appropriate changes were made to meet certain criteria. The 

NAVD 88 heights are realized utilizing either GEOID99 or GEOID03. Hence two sets of 

NAVD88 data were created. It is noted that the generation of both data sets shared the 

same algorithms and procedures.

Figure 14. Locations of tidal bench marks and tide stations used to compute the New 

Orleans VDatum TSS grids.
30

5.1. Derivation of TSS

Two methodologies were used to compute the TSS at the observational stations: an 

indirect method using data from the NGS database (see Appendix E) and a direct method 

using data from the CO-OPS database (see Appendix F). To derive the TSS at the NGS 

stations using the indirect method, residuals (Rdatum) at every NGS bench mark location 

were computed as:

Rdatum = TBMnavd88 – TBMdatum + VDdatum

where TBMnavd88 and TBMdatum are the observed (NAVD88–MLLW) and (DatumMLLW) differences, respectively, and VDdatum denotes modeled (Datum–MSL) 

differences. The residual, Rdatum, represents an estimation of the (MSL-NAVD88) 

difference.

There are four sets of Rdatum, corresponding to MHHW, MHW, MLW, and MLLW. Each 

represents an independent estimation of the quantity MSL–NAVD88 associated with a 

tidal datum. Tables E.1 lists Rdatum’s at stations located within the present VDatum 

bounding polygons (Figure 13). At each station, the four Rdatum’

s were then averaged to 

produce a mean residual ( Rdatum ). Rdatum represents an overall estimation of MSL–

NAVD88 and is used for further development of the TSS grid. 

The TSS values at CO-OPS stations were simply derived by calculating orthometric-totidal datum relationships. Table F.1 shows the station location inventories and 

observations of elevation information. 

Next, the Rdatum values are merged with TSS values from CO-OPS stations to form a data 

set for creating a TSS mesh using the gridding software, Surfer©. A grid covering the 

entire area of bench marks and water level stations with a spatial resolution similar to that 

of the VDatum marine grid was created. Breaklines were inserted to represent the 

influence of land. The Surfer© software’s minimum curvature algorithm was employed 

to create a primary TSS field (TSSgrid) that honors the data as closely as possible. The 

maximum allowed departure value used was 0.0001 meters. To control the amount of 

bowing on the interior and at the edges of the grid, an internal and boundary tension of 

0.3 was utilized. Once the gridded topography field had been generated, null values were 

obtained from the marine tidal grids and are inserted to denote the presence of land.

It is noted that the TSSgrid represents an estimation of the quantity MSL- NAVD88 and 

still requires further quality control and correction procedures (Section 5.2). Figures 15

and 16 show the final TSS fields based on NAVD88 realized through GEOID99 and 

GEOID03, respectively. In each figure, a positive value specifies that the NAVD 88 

reference value is further from the center of the Earth than the MSL surface. Data derived 

from both the indirect and direct methodology are initially relative to NAVD88 realized 

through GEOID03. This data derived for both methods is transformed back through 

GEOID03 to an ellipsoidal reference and then transformed back utilizing GEOID99.

Therefore, we now have two datasets for both methods, one relative to GEOID03 and the 
31

other relative to GEOID99. This particular area is lacking in sufficient observation points 

for tidal datums, NAVD88 elevations, and GPS ellipsoidal connections. NOAA is 

actively working to fill these observational gaps. Full evaluation and calibration of the 

transformations awaits more observational points.

5.2. Quality Control 

Quality control is necessary for obtaining a final TSS field. This is facilitated through 

examining the differences (∆R-TSS) between Rdatum and TSSgrid observational stations:

∆R-TSS = -(Rdatum - TSSgrid)

The ∆R-TSS approximately represents the difference between the observed tidal datum and 

the datum as computed by the gridded fields. The average ∆R-TSS at each bench mark

should be less than 0.01 m. If it is not, the input data and grids are checked, appropriate 

changes are made, and the values are recomputed until the criterion is met. This results in 

a final TSS field. Tables F.1 and F.2 in Appendix F list the average ∆R-TSS at 

observational stations for the GEOID 99 and GEOID 03 grids, respectively. They are 

consistent and small. This provides confidence that grids are in agreement. Finally, a land 

mask is applied to denote the presence of land.

In response to the limited amount of data available, the data used to compile the TSSgrid

for both methods described in Section 5.1 were utilized in comparing against the TSSgrid

to generalize internal consistency. Tables G.1 and G.2 in Appendix G tabulate the modeldata differences for the TSS realized through GEOID99 and GEOID03, respectively. For 

the GEOID99 case, the mean and standard deviation were 2.3×10-4 meters and 2.7×10-3

meters, respectively. In the GEOID03 case, they were 1.2×10-4 meters and 2.6×10-3

 

meters, respectively. Note that this qulaity control is performed using available 

observation points. These points are not uniformly distributed over the model domain, 

this adding some uncertainty to the process. The rapid rate of subsidence adds 

complexity to understanding and deriving the TSS grids (Shinkle and Dokka, 2004).
32

Figure 15. The New Orleans TSS field based on NAVD88 realized through GEOID99.
33

Figure 16. The New Orleans TSS field based on NAVD88 realized through GEOID03.
34
35

6. SUMMARY

VDatum tidal datum and TSS fields for the coastal waters of eastern Louisiana and 

Mississippi were developed in this study. Creation of VDatum begins with creating tidal 

datums with numerical tidal simulations using the ADCIRC model. A triangular finiteelement grid consisting of 167,646 nodes and 306,749 cells was created. The model was 

forced with nine tidal constituents (M2, S2, N2, K2, K1, P1, O1, Q1, and M4) and run for 65

days. Various tidal datum fields, including mean lower low water (MLLW), mean low 

water (MLW), mean high water (MHW), and mean higher high water (MHHW), were 

derived using the modeled water level time series from the final 55 days of the 

simulation. Model results were validated by comparing with observations at 70 water 

level stations maintained by NOAA’s Center for Operational Oceanographic Products 

and Services (CO-OPS). Discrepancies between model results and observational datums 

were attributed to model errors and interpolated over the whole model domain using the 

tidal constituent and residual interpolation (TCARI) technique. The error fields were 

applied to the direct model results to achieve error-corrected tidal datums on the model

grid. Finally, tidal datum fields were interpolated onto a regular VDatum marine grid.

A regular VDatum marine grid was created to be used as input to the VDatum software 

tool. Tidal datums defined on the unstructured grid were interpolated onto the regular 

grid to form the final datums as input to the VDatum tool. 

The TSS fields were derived using two methodologies: by fitting tidal model results to 

tidal bench marks leveled in NAVD88 or by calculating orthometric-to-tidal datum 

relationships at NOAA tidal gauges. Results from the two methods were coupled to 

create the final TSS grids and incorporated into the VDatum tool.

The Louisiana portion of the VDatum grid has significantly more uncertainty due to the 

lack of observational tidal data and geodetic data. In addition, the significant vertical 

land subsidence in the region created the need for frequent tidal datum updates and 

updated in geodetic datum elevations. This will require frequent updates to the 

operational VDatum products for this particular model domain.

ACKNOWLEDEGEMENTS

Digital coastline and bathymetric data sets were provided by Julia Skory and Cuong 

Hoang, respectively. Dr. Kurt Hess developed the software for the VDatum grid 

generation, tidal datum population, and final product quality control tests. Drs. Richard 

A. Schmalz, Jr. at CSDL and Stephen Gill at CO-OPS reviewed the entire manuscript. 

The authors would like to express genuine gratitude for their time and effort.
36

REFERENCES

Dhingra, E. A., K. W. Hess, and S. A. White, 2008: VDatum for the Northeast Gulf of 

Mexico from Mobile Bay, Alabama, to Cap San Blas, Florida: Tidal Datum Modeling 

and Population of the marine Grids. U.S. Department of Commerce, National Oceanic 

and Atmospheric Administration, Silver Spring, Maryland, NOAA Technical 

Memorandum NOS CS 14, 64 pp.

Gill, S. K., and J. R. Schultz, 2001: Tidal Datums and Their Applications. Silver Spring, 

Maryland: U.S. Department of Commerce, National Oceanic and Atmospheric 

Administration, Silver Spring, MD. NOAA Special Publication NOS CO-OPS 1, 111 pp 

+ appendix.

Hess, K. W, 2001: Generation of Tidal Datum Fields for Tampa Bay and the New York 

Bight. U.S. Department of Commerce, National Oceanic and Atmospheric 

Administration, Silver Spring, Maryland, NOAA Technical Report NOS CS 11, 43 pp.

___, 2002: Spatial interpolation of tidal data in irregularly-shaped coastal regions by 

numerical solution of Laplace’s equation. Estuarine, Coastal and Shelf Science, 54(2), 

175-192.

___, 2003: Water level simulation in bays by spatial interpolation of tidal constituents, 

residual water levels, and datums. Continental Shelf Research, 23(5), 395-414.

___, D. G. Milbert, S.K. Gill, and D.R. Roman, 2003: Vertical Datum Transformations 

for Kinematic GPS Hydrographic Surveys. Proceedings, U.S. Hydrographic 

Conference, March 24 – 27, 2003. Biloxi, MS. 8 pp.

___, and S. K. Gill, 2003: Puget Sound Tidal Datums by Spatial Interpolation. 

Proceedings, Fifth Conference on Coastal Atmospheric and Oceanic Prediction and 

Processes. Am. Meteorological Soc., Seattle, August 6-8, 2003. Paper 6.1, 108 - 112.

___, and S. A. White, 2004: VDatum for Puget Sound: Generation of the Grid and 

Population with Tidal Datums and Sea Surface Topography. U.S. Department of 

Commerce, National Oceanic and Atmospheric Administration, Silver Spring, Maryland, 

NOAA Technical Memorandum NOS CS 4, 27 pp.

Hess, K.W., E. A. Spargo, A. Wong, S. A. White, and S. K. Gill, 2005 : VDatum for 

Central Coastal North Carolina: Tidal Datums, Marine Grids, and Sea Surface 

Topography. U.S. Department of Commerce, National Oceanic and Atmospheric 

Administration, Silver Spring, Maryland, NOAA Technical Report NOS CS 21, 46 pp.

Leuttich, Jr., R. A., J. L. Hench, C. W. Fulcher, F. E. Werner, B. O. Blanton, and J. H. 

Churchill, 1999: Barotropic tidal and wind driven larval transport in the vicinity of a 

barrier island inlet. Fisheries Oceanography, 33 (April), 913 – 932.
37

Milbert, D. G. and K. W. Hess, 2001: Combination of Topography and Bathymetry 

Through Application of Calibrated Vertical Datum Transformations in the Tampa Bay 

Region. Preceedings of the 2nd Biennial Coastal GeoTools Conferences, Charleston, 

SC.

Milbert, D.G., 2002: Documentation for VDatum (and VDatum Tutorial): Vertical datum 

transformation software. Ver. 1.06 (nauticalcharts.noaa.gov/bathytopo/vdatum.htm).

Mukai, A. Y., J. J. Westerink, R. A. Luettich Jr., and D. Mark, 2002, Eastcoast 2001: A 

tidal constituent database for the western North Atlantic, Gulf of Mexico and Caribbean 

Sea, US Army Engineer Research and Development Center, Coastal and Hydraulics 

Laboratory, Technical Report, ERDC/CHL TR-02-24, September 2002, 201p.

Myers, E. P., Wong, A., Hess, K., White. S., Spargo, E., Feyen, J., Yang, Z., Richardson, 

P., Auer, C., Sellars, J., Woolard, J., Roman, D., Gill, S., Zervas, C. and K. Tronvig, 

2005: Development of a National VDatum, and its Application to Sea Level Rise in 

North Carolina. Proceedings of the 2005 Hydro Conference, San Diego, CA.

Myers, E. P. and Hess, K., 2006: Modeling of Tidal Datum Fields in Support of VDatum 

for the North and Central Coasts of California. U.S. Department of Commerce, National 

Oceanic and Atmospheric Administration, Silver Spring, Maryland, NOAA Technical 

Memorandum NOS CS 6, 15 pp.

Myers, E. P., unpublished manuscript: Tidal Datum Inversion Model of the Eastcoast of 

the United States.

Parker, B. P., 2002: The integration of bathymetry, topography, and shoreline, and the 

vertical datum transformations behind it. International Hydrographic Review (3) 3 

(November 2002).

Parker, B., K. W. Hess, D. Milbert, and S. K. Gill, 2003: A national vertical datum 

transformation tool. Sea Technology, v. 44. no. 9 (Sept. 2003), 10 - 15.

Shinkle, K.D., and R.K. Dokka, 2004: Rates of Vertical Displacement at Benchmarks in 

the Lower Mississippi Valley and the Northern Gulf Coast, U.S. Department of 

Commerce, National Oceanic and Atmospheric Administration, Silver Spring, Maryland, 

NOAA Technical Report 50, 135pp.

Spargo, E. A., and J. W. Woolard, 2005. VDatum for the Calcasieu River from Lake 

Charles to the Gulf of Mexico, Louisiana: Tidal Datum Modeling and Population of the 

Grid. NOS Technical Report NOS CS 19, 26 pp.

Spargo, E.A., K.H. Hess, and S.A. White, 2006: VDatum for the San Juan Islands and 

Juan de Fuca Strait with Updates for Southern Puget Sound: Tidal Datum Modeling and 

Population of the VDatum Marine Grids. U.S. Department of Commerce, National 
38

Oceanic and Atmospheric Administration, Silver Spring, Maryland, NOAA Technical 

Report NOS CS 25, 50 pp.

Spargo, E.A., Hess, K.H., Myers, E.P., Yang, Z., and A.Wong, 2006: Tidal Datum 

Modeling in support of NOAA’s Vertical Datum Transformation Tool. Proceedings of 

the 9th International Conference on Estuarine and Coastal Modeling, October 31-

November 2, 2005, Charleston, SC. p. 523-536.

Westerink, J.J., R. A. Luettich, and J. C. Muccino, 1993: An Advanced ThreeDimensional Circulation Model for Shelves, Coasts, and Estuaries, Report 3: 

Development of a Tidal Constituent Database for the Western North Atlantic and Gulf of 

Mexico, Technical Report DRP-92-6, U.S. ACE Waterways Experiment Station, 

Vicksburg, MS.

Yang, Z., Hess, K.H., Myers, E.P., Spargo, E.A., Wong, A., and J. Feyen, 2006:

Numerical Simulation of Tidal Datum Fields for the Long Island Sound, New York 

Bight, and Narragansett Bay Area. Proceedings of the 9th International Conference on 

Estuarine and Coastal Modeling, October 31-November 2, 2005, Charleston, SC. p. 

548-567.

Yang, Z., E. Myers, A. Wong, and S. White, 2008: Vdatum for Chesapeake Bay, 

Delaware Bay, and Adjacent Coastal Water Areas: Tidal Datums and Sea surface 

Topography. U.S. Department of Commerce, National Oceanic and Atmospheric 

Administration, Silver Spring, Maryland, NOAA Technical Memorandum NOS CS 15, 

110 pp.

Yang, Z., K. Hess, E. Spargo, A. Wong, S. White, and E. Myers, 2008: VDatum for the 

Long Island Sound, Narragansett Bay, and New York Bight and New York Harbor: Tidal 

Datums, Marine Grids, and Sea Surface Topography. U.S. Department of Commerce, 

National Oceanic and Atmospheric Administration, Silver Spring, Maryland, NOAA 

Technical Memorandum NOS CS 16, 62 pp.

Yang, Z., E. Myers, A. Spargo, A. Wong, and S. White, unpublished manuscript: 

“Vdatum for Coastal Waters of Southern California: Tidal Datums and Sea Surface 

Topography.” 
39

APPENDIX A. HORIZONTAL AND VERTICAL ACCURACY STANDARDS 

FOR NOAA BATHYMETRY SURVEY

Table A.1. The required horizontal and vertical accuracy standards for NOAA surveys. 

Accuracy requirements before 1957 were prescribed for survey projects.

Survey Year* Horizontal 

Accuracy

Vertical 

Accuracy Standard 

1998 –

present

Order 1

1 – 100 m depth: 

5.0 m + 5% of depth

Order 2 

100 – 200 m depth: 

20 m + 5% of depth

Order 3 

100 – 200 m depth: 

150 m + 5% of depth

Order 1

1 – 100 m depth: 

0.5 – 1.4 m 

Order 2 

100 – 200 m depth: 

2.5 – 4.7 m

Order 3 

> 100 m depth: 

same as Order 2

IHO S-44 1

and NOAA 2

1988 – 1998

95% probability that the 

true position lies within a 

circle of radius 1.5 mm, at 

the scale of the survey

0 – 30 m depth: 0.3 m 

> 30 m depth: 1% of 

depth 

IHO S-44 1

and NOAA 2

1982 – 1988

probable error shall 

seldom exceed twice the 

plottable error (1.0 mm) at 

the scale of the survey 

0 – 20 m depth: 0.3 m 

20 – 100 m depth: 1.0 m

> 100 m depth: 1% of 

depth 

IHO S-44 1

and NOAA 2

1957 – 1982

maximum error of 

plotted positions shall 

seldom exceed 1.5 mm at 

the scale of the survey

0 – 20 m depth: 0.3 m 

20 – 100 m depth: 1.0 m

> 100 m depth: 1% of 

depth 

IHC 3

NOAA 2

and

IHO S-44 1

before 1957 undetermined undetermined undocume

nted

* end of field collection 1

 International Hydrographic Organization (IHO) Standards for Hydrographic Surveys, Special Publication 44, 

(First Edition, 1968; Second Edition, 1982; Third Edition, 1987; Fourth Edition, 1998). 2

 U.S. Department of Commerce Coast and Geodetic Survey Hydrographic Manual (1931, 1942, 1960, 1976) 

 NOAA NOS Office of Coast Survey Specifications and Deliverables, 1999 – 2006. 

 NOAA was established in 1970. 3

 International Hydrographic Conference, 1957. 
40
41

APPENDIX B. WATER LEVEL STATION DATA

Table B.1. NOS Water Level Station Names

1 8729678 NAVARRE BEACH

2 8731952 BON SECOUR

3 8735180 DAUPHIN ISLAND, MOBILE BA

4 8735587 NORTH POINT DAUPHIN ISLAN

5 8741196 PASCAGOULA POINT, MISS. S

6 8742221 HORN ISLAND, MISSISSIPPI 

7 8743281 OCEAN SPRINGS 

8 8743735 BILOXI (CADET POINT), BIL

9 8744117 BILOXI, BAY OF BILOXI 

10 8744756 SHIP ISLAND, MISSISSIPPI 

11 8745557 GULFPORT HARBOR, MISSISSI

12 8745799 CAT ISLAND, MISSISSIPPI S

13 8746819 PASS CHRISTIAN YACHT CLUB

14 8746943 HENDERSON AVENUE BRIDGE

15 8747131 MALLINI BAYOU NORTH 

16 8747145 MALLINI BAYOU SOUTH 

17 8747398 NORTH SHORE, BAY OF ST. L

18 8747437 BAY WAVELAND YC BAY ST. 

19 8747739 JOURDAN RIVER ENTRANCE 

20 8747766 WAVELAND, MISSISSIPPI SOU

21 8748525 LOWER POINT CLEAR MISS SO

22 8748842 WESTERN CAMPBELL OUTSIDE 

23 8760412 NORTH PASS 

24 8760551 SOUTH PASS 

25 8760595 BRETON ISLAND 

26 8760668 GRAND PASS 

27 8760742 COMFORT ISLAND 

28 8760781 SHELL OIL, EAST BAY

29 8760849 VENICE, GRAND PASS 

30 8760889 OLGA COMPRESSOR STATION, 

31 8760922 PILOTS STATION EAST, SOUT

32 8760943 PILOT STATION, SW PASS 

33 8761108 BAY GARDENE 

34 8761207 EMPIRE DOULLUT CANAL LA 

35 8761305 SHELL BEACH, LAKE BORGNE 

36 8761402 U.S. HIGHWAY 90, THE RIGO

37 8761426 GREENS DITCH, LAKE ST. CA

38 8761487 CHEF MENTEUR, CHEF MENTEU

39 8761529 MARTELLO CASTLE, LAKE BOR

40 8761534 BIG POINT, LAKE PONTCHART

41 8761623 HUMBLE OIL PLATFORM GRAND

42 8761677 INDEPENDENCE IS BARATARIA

43 8761678 MICHOUD SUBSTATION, ICWW 

44 8761679 ST. MARYS POINT, BARATARI

45 8761722 GRAND ISLE EAST POINT LA 
42

46 8761724 GRAND ISLE, EAST POINT 

47 8761732 MANILLA VILLAGE BARATARIA

48 8761742 MENDICANT ISLAND, BARATAR

49 8761799 M.V. PETROLEUM DOCK, BAYO

50 8761819 TEXACO DOCK, HACKBERRY BA

51 8761826 CHENIERE CAMINADA, CAMINA

52 8761927 USCG NEW CANAL STA., LAKE

53 8761993 TCHEFUNCTA RIVER, LAKE PO

54 8762223 EAST TIMBALIER ISLAND, TI

55 8762273 EAST END, PASS MANCHAC 

56 8762372 EAST BANK 1, NORCO, BAYOU

57 8762419 U.S. HIGHWAY 51 PASS MAN

58 8762481 PELICAN ISLAND TIMBALIER 

59 8762582 TIMBALIER ISLAND TIMBALIE

60 8762888 E ISLE DERNIERES LAKE PEL

61 8762938 TEXACO TB#3 BAYOU PETIT C

62 8764025 STOUTS PASS AT SIX MILE L

63 8764044 TESORO MARINE TERM, ATCH 

64 8764227 LAWMA, AMERADA PASS

65 8764311 EUGENE ISLAND 

66 8765148 WEEKS BAY 

67 8765251 CYPREMORT POINT 

68 8766072 FRESHWATER CANAL LOCKS 

69 8771416 GALVESTON BAY ENTRANCE, S

70 8771510 GALVESTON LEASURE PIER
43

Table B.2. Tidal datums (meters) relative to mean seal level. The ‘N/A’s in the table 

denote missing values.

1 8729678 -86.865 30.37667 0.22 0.2 -0.185 -0.201 NAVARRE_BEACH 1983-2002

2 8731952 -87.735 30.30333 0.236 0.225 -0.221 -0.234 BON_SECOUR 1983-2002

3 8735180 -88.075 30.25 0.195 0.189 -0.169 -0.172 DAUPHIN_ISLAND,_MOBILE_BA 1983-2002

4 8735587 -88.1133 30.25833 0.247 0.226 -0.229 -0.259 NORTH_POINT_DAUPHIN_ISLAN_ 1960-1979

5 8741196 -88.5333 30.34 0.234 0.209 -0.207 -0.233 PASCAGOULA_POINT,_MISS._S_ 1983-2001

6 8742221 -88.6667 30.23833 0.243 0.211 -0.208 -0.245 HORN_ISLAND,_MISSISSIPPI__ 1983-2001

7 8743281 -88.7983 30.39167 0.262 0.237 -0.22 -0.264 OCEAN_SPRINGS_____________ 1983-2001

8 8743735 -88.8567 30.39 0.267 0.235 -0.237 -0.27 BILOXI_(CADET_POINT),_BIL_ 1983-2001

9 8744117 -88.9033 30.41167 0.266 0.24 -0.231 -0.276 BILOXI,_BAY_OF_BILOXI_____ 1983-2001

10 8744756 -88.9717 30.21333 0.256 0.219 -0.222 -0.257 SHIP_ISLAND,_MISSISSIPPI__ 1983-2001

11 8745557 -89.0817 30.36 0.25 0.223 -0.197 -0.25 GULFPORT_HARBOR,_MISSISSI_ 1983-2001

12 8745799 -89.1167 30.23167 0.243 0.214 -0.208 -0.236 CAT_ISLAND,_MISSISSIPPI_S_ 1983-2001

13 8746819 -89.245 30.31 0.259 0.232 -0.234 -0.267 PASS_CHRISTIAN_YACHT_CLUB_ 1983-2001

14 8746943 -89.265 30.34167 0.268 0.22 -0.23 -0.278 HENDERSON_AVENUE_BRIDGE 1983-2001

15 8747131 -89.2883 30.32667 0.265 0.234 -0.228 -0.271 MALLINI_BAYOU_NORTH_______ 1983-2001

16 8747145 -89.2867 30.31167 0.261 0.227 -0.222 -0.262 MALLINI_BAYOU_SOUTH_______ 1983-2001

17 8747398 -89.3217 30.37333 0.268 0.22 -0.226 -0.274 NORTH_SHORE,_BAY_OF_ST._L_ 1983-2001

18 8747437 -89.325 30.325 0.262 0.231 -0.233 -0.265 BAY_WAVELAND_YC__BAY_ST.__ 1983-2001

19 8747739 -89.3667 30.33667 0.27 0.222 -0.23 -0.278 JOURDAN_RIVER_ENTRANCE____ 1983-2001

20 8747766 -89.3667 30.28167 0.244 0.221 -0.217 -0.244 WAVELAND,_MISSISSIPPI_SOU_ 1983-2001

21 8748525 -89.4633 30.17333 0.241 0.213 -0.214 -0.244 LOWER_POINT_CLEAR_MISS_SO_ 1960-1979

22 8748842 -89.5067 30.18667 0.229 0.205 -0.201 -0.21 WESTERN_CAMPBELL_OUTSIDE__ 1960-1979

23 8760412 -89.0367 29.205 0.17 0.165 -0.163 -0.166 NORTH_PASS________________ 1983-2001

24 8760551 -89.14 28.99 0.187 0.181 -0.18 -0.185 SOUTH_PASS________________ 1983-2001*

25 8760595 -89.1733 29.49333 0.199 0.199 -0.217 -0.218 BRETON_ISLAND_____________ 1983-2001*

26 8760668 -89.2217 30.12667 0.226 0.209 -0.204 -0.221 GRAND_PASS________________ 1983-2001*

27 8760742 -89.27 29.82333 0.229 0.216 -0.227 -0.249 COMFORT_ISLAND____________ 1983-2001*

28 8760781 -89.305 29.0533 0.202 0.197 -0.192 -0.199 SHELL_OIL,_EAST_BAY 1983-2001*

29 8760849 -89.3517 29.27333 0.149 0.149 -0.149 -0.149 VENICE,_GRAND_PASS________ 1983-2001*

30 8760889 -89.38 29.385 0.198 0.183 -0.198 -0.211 OLGA_COMPRESSOR_STATION,__ 1983-2001*

31 8760922 -89.4067 28.93167 0.185 0.183 -0.185 -0.189 PILOTS_STATION_EAST,_SOUT_ 1983-2001*

32 8760943 -89.4183 28.925 0.189 0.184 -0.187 -0.194 PILOT_STATION,_SW_PASS____ 1983-2001*

33 8761108 -89.6183 29.59833 0.212 0.197 -0.21 -0.227 BAY_GARDENE_______________ 1983-2001*

34 8761207 -89.6017 29.375 0.15 0.144 -0.143 -0.146 EMPIRE_DOULLUT_CANAL_LA___ 1960-1979

35 8761305 -89.6733 29.86833 0.239 0.226 -0.194 -0.225 SHELL_BEACH,_LAKE_BORGNE__ 1983-2001

36 8761402 -89.7367 30.16667 0.116 0.11 -0.121 -0.125 U.S._HIGHWAY_90,_THE_RIGO_ 1983-2001

37 8761426 -89.76 30.11167 0.118 0.11 -0.117 -0.121 GREENS_DITCH,_LAKE_ST._CA_ 1983-2001

38 8761487 -89.8 30.065 0.153 0.141 -0.154 -0.17 CHEF_MENTEUR,_CHEF_MENTEU_ 1983-2001
44

39 8761529 -89.835 29.945 0.212 0.175 -0.192 -0.207 MARTELLO_CASTLE,_LAKE_BOR_ 1983-2001

40 8761534 -89.8533 30.22833 0.072 0.07 -0.082 -0.083 BIG_POINT,_LAKE_PONTCHART_ 1983-2001

41 8761623 -89.9 29.16667 0.219 0.208 -0.223 -0.232 HUMBLE_OIL_PLATFORM_GRAND

_ N/A

42 8761677 -89.9383 29.31 0.181 0.169 -0.176 -0.185 INDEPENDENCE_IS_BARATARIA_ N/A

43 8761678 -89.9367 30.00667 0.21 0.188 -0.188 -0.212 MICHOUD_SUBSTATION,_ICWW__ 1983-2001

44 8761679 -89.9383 29.43167 0.147 0.145 -0.149 -0.157 ST._MARYS_POINT,_BARATARI_ 1983-2001

45 8761722 -89.9583 29.275 0.167 0.161 -0.162 -0.171 GRAND_ISLE_EAST_POINT_LA__ 1960-1979

46 8761724 -89.9567 29.26333 0.159 0.157 -0.16 -0.163 GRAND_ISLE,_EAST_POINT____ 1983-2001*

47 8761732 -89.9767 29.42667 0.151 0.141 -0.146 -0.154 MANILLA_VILLAGE_BARATARIA_ N/A

48 8761742 -89.98 29.31833 0.15 0.146 -0.152 -0.155 MENDICANT_ISLAND,_BARATAR_ 1983-2001*

49 8761799 -90.025 29.49667 0.112 0.111 -0.115 -0.116 M.V._PETROLEUM_DOCK,_BAYO_ 1983-2001*

50 8761819 -90.0383 29.40167 0.134 0.131 -0.139 -0.141 TEXACO_DOCK,_HACKBERRY_BA

_ 1983-2001*

51 8761826 -90.04 29.21 0.152 0.15 -0.149 -0.15 CHENIERE_CAMINADA,_CAMINA_ 1983-2001*

52 8761927 -90.1133 30.02667 0.08 0.081 -0.075 -0.076 USCG_NEW_CANAL_STA.,_LAKE_ 1983-2001

53 8761993 -90.16 30.37833 0.083 0.082 -0.091 -0.091 TCHEFUNCTA_RIVER,_LAKE_PO_ 1983-2001

54 8762223 -90.285 29.07667 0.193 0.182 -0.198 -0.209 EAST_TIMBALIER_ISLAND,_TI_ 1983-2001*

55 8762273 -90.3117 30.29667 0.075 0.074 -0.079 -0.079 EAST_END,_PASS_MANCHAC____ 1983-2001

56 8762372 -90.3683 30.05 0.063 0.059 -0.069 -0.073 EAST_BANK_1,_NORCO,_BAYOU_ 1983-2001

57 8762419 -90.4017 30.285 0.058 0.057 -0.068 -0.068 U.S._HIGHWAY_51__PASS_MAN_ 1983-2001*

58 8762481 -90.4233 29.12833 0.181 0.169 -0.176 -0.185 PELICAN_ISLAND_TIMBALIER__ N/A

59 8762582 -90.4767 29.06667 0.208 0.192 -0.195 -0.216 TIMBALIER_ISLAND_TIMBALIE_ 1960-1979

60 8762888 -90.6417 29.07167 0.208 0.189 -0.192 -0.21 E_ISLE_DERNIERES_LAKE_PEL_ 1960-1979

61 8762938 -90.6667 29.18667 0.192 0.18 -0.18 -0.201 TEXACO_TB#3_BAYOU_PETIT_C_ 1960-1979

62 8764025 -91.23 29.7433 0.145 0.121 -0.105 -0.126 STOUTS_PASS_AT_SIX_MILE_L 1983-2001*

63 8764044 -91.2367 29.66667 0.097 0.086 -0.078 -0.099 TESORO_MARINE_TERM,_ATCH__ 1983-2001*

64 8764227 -91.34 29.45 0.246 0.202 -0.172 -0.279 LAWMA,_AMERADA_PASS 1983-2001*

65 8764311 -91.385 29.37167 0.265 0.225 -0.195 -0.33 EUGENE_ISLAND_____________ 1983-2001*

66 8765148 -91.8267 29.81167 0.219 0.192 -0.195 -0.271 WEEKS_BAY_________________ 1983-2001*

67 8765251 -91.88 29.71333 0.253 0.221 -0.204 -0.272 CYPREMORT_POINT___________ 1983-2001*

68 8766072 -92.305 29.555 0.275 0.234 -0.216 -0.363 FRESHWATER_CANAL_LOCKS___

_ 1983-2001*

69 8771416 -94.6933 29.32667 0.297 0.236 -0.23 -0.356 GALVESTON_BAY_ENTRANCE,_S 1983-2001*

70 8771510 -94.7894 29.2853 0.284 0.225 -0.219 -0.338 GALVESTON_LEASURE_PIER 1983-2001*

Note : stations with * means the control station used for datum determination used an 

accepted datum based on the 5-year Modified Tidal Epoch procedure in order to 

take into account rapid vertical land movement.
45

APPENDIX C. TIDAL DATUM FIELDS DEFINED ON VDATUM MARINE 

GRID

Figure C.1. Tidal Datums defined on VDatum marine grid, (a) MHHW, (b) MHW,

(c), MLW, (d) MLLW, (e) MTL, and (f) DTL.

(a)

MHHW

(b)

MHW
46

Figure C.1. (Continued)

(c)

MLW

(d)

MLLW
47

Figure C.1. (Continued)

(e)

MTL

(f)

DTL
48
49

APPENDIX D. Tidal gauge and bench marks data used to create the TSS

Table D.1. Location and elevation information for NOAA water level gauges used 

to create the New Orleans TSS grid. Tidal datums are relative to MLLW. MSL data 

are from CO-OPS, and NAVD88 heights were calculated by NGS.

Station ID Latitude

(deg)

Longitude

(deg)

MSL 

(m)

NAVD88 

[GEOID03]

(m)

NAVD88 

[GEOID99]

(m)

TSS

[GEOID03]

(m)

TSS

[GEOID99]

(m)

8729678 30.37670 -86.86500 8.057 8.000 7.807 -0.057 -0.250

8735180 30.25000 -88.07500 1.049 0.947 0.822 -0.102 -0.227

8735523 30.44330 -88.11330 1.074 0.941 0.822 -0.133 -0.252

8743735 30.39000 -88.85670 1.097 0.942 0.792 -0.155 -0.305

8744756 30.21330 -88.97170 1.326 0.759 0.629 -0.567 -0.697

8745557 30.36000 -89.08170 0.996 0.823 0.723 -0.173 -0.273

8745799 30.23170 -89.11670 1.239 1.168 1.085 -0.071 -0.154

8746819 30.31000 -89.24500 0.854 0.700 0.643 -0.154 -0.211

8747437 30.32500 -89.32500 0.990 0.825 0.782 -0.165 -0.208

8747766 30.28170 -89.36670 8.696 8.518 8.492 -0.178 -0.204

8760849 29.27330 -89.35170 0.844 0.414 0.406 -0.430 -0.439

8761402 30.16670 -89.73670 1.052 0.842 0.902 -0.210 -0.150

8761426 30.11170 -89.76000 0.905 0.685 0.766 -0.220 -0.139

8761473 30.27170 -89.79330 0.920 0.688 0.711 -0.232 -0.209

8761487 30.06500 -89.80000 1.041 0.829 0.925 -0.212 -0.116

8761678 30.00670 -89.93670 1.110 0.992 1.095 -0.118 -0.015

8762184 29.37330 -90.26500 1.001 0.694 0.842 -0.307 -0.159

8762928 29.24500 -90.66170 1.082 0.821 0.915 -0.261 -0.167

8770590 29.70500 -93.85330 1.810 1.379 1.302 -0.431 -0.509
50
51

APPENDIX E. DERIVED NAVD 88-TO-MSL VALUES

Table E.1. Derived NAVD 88-to-MSL values for each tidal datum at NGS bench 

marks from the New Orleans Vicinity Tidal Grid. NAVD88 values were realized 

through GEOID99.

Benchmark Latitude Longitude

From 

MLLW 

(m)

From 

MLW 

(m)

From

MHW 

(m)

From

MHHW 

(m)

Average

(m)

Std.

Dev.

(m)

BH3007 30.00666 -89.93861 -0.008 -0.008 -0.007 -0.007 -0.007 0.001

BH1083 30.01138 -89.93916 -0.022 -0.022 -0.022 -0.021 -0.022 0.000

BJ3686 30.02611 -90.11250 -0.139 -0.138 -0.140 -0.141 -0.140 0.001

BJ1342 30.02638 -90.11250 -0.136 -0.135 -0.137 -0.138 -0.137 0.001

BJ1344 30.02666 -90.11277 -0.130 -0.129 -0.131 -0.132 -0.131 0.001

BH1133 30.06805 -89.80361 -0.116 -0.117 -0.118 -0.118 -0.117 0.001

BH1145 30.11333 -89.76138 -0.142 -0.141 -0.143 -0.141 -0.142 0.001

BH1147 30.11888 -89.76277 -0.140 -0.139 -0.143 -0.141 -0.141 0.002

BH1539 30.16500 -89.73833 -0.148 -0.147 -0.150 -0.150 -0.149 0.002

BH1160 30.16611 -89.73750 -0.146 -0.145 -0.146 -0.146 -0.146 0.001

BH1164 30.16611 -89.73722 -0.135 -0.134 -0.135 -0.135 -0.134 0.001

BH1163 30.16638 -89.73750 -0.150 -0.149 -0.150 -0.150 -0.149 0.001

BH1537 30.16666 -89.73694 -0.150 -0.149 -0.150 -0.150 -0.149 0.001

BH1538 30.16666 -89.73777 -0.150 -0.149 -0.150 -0.150 -0.149 0.001

BH1754 30.24888 -88.07666 -0.227 -0.227 -0.238 -0.238 -0.233 0.006

BH1752 30.24916 -88.07666 -0.227 -0.227 -0.238 -0.238 -0.233 0.006

BH1755 30.24916 -88.07583 -0.230 -0.230 -0.241 -0.241 -0.236 0.006

BH1756 30.24944 -88.07555 -0.227 -0.227 -0.238 -0.238 -0.233 0.006

BH0946 30.30861 -89.32666 -0.234 -0.228 -0.211 -0.200 -0.218 0.016

BH0945 30.30888 -89.32555 -0.238 -0.232 -0.214 -0.202 -0.221 0.016

BH0934 30.31888 -89.32083 -0.207 -0.205 -0.208 -0.207 -0.207 0.001

BH0935 30.31972 -89.32361 -0.206 -0.204 -0.207 -0.206 -0.206 0.001

BH0936 30.32305 -89.32638 -0.210 -0.208 -0.211 -0.210 -0.209 0.001

BH0937 30.32361 -89.32722 -0.210 -0.208 -0.211 -0.210 -0.209 0.001

BH0392 30.39000 -88.85666 -0.304 -0.305 -0.305 -0.303 -0.305 0.001

BH0390 30.39277 -88.85777 -0.307 -0.308 -0.308 -0.306 -0.307 0.001
52

Table E.2. Derived NAVD 88-to-LMSL values for each tidal datum at NGS bench 

marks from the New Orleans Vicinity Tidal Grid. NAVD88 values realized through 

GEOID03.

Benchmark Latitude Longitude

From 

MLLW 

(m)

From 

MLW 

(m)

From

MHW 

(m)

From

MHHW 

(m)

Average

(m)

Std.

Dev.

(m)

BH3007 30.00666 -89.93861 -0.111 -0.111 -0.110 -0.110 -0.110 0.001

BH1083 30.01138 -89.93916 -0.124 -0.124 -0.123 -0.123 -0.123 0.000

BJ3686 30.02611 -90.11250 -0.216 -0.215 -0.217 -0.218 -0.217 0.001

BJ1342 30.02638 -90.11250 -0.213 -0.212 -0.214 -0.215 -0.214 0.001

BJ1344 30.02666 -90.11277 -0.207 -0.206 -0.208 -0.209 -0.208 0.001

BH1133 30.06805 -89.80361 -0.211 -0.212 -0.213 -0.213 -0.212 0.001

BH1145 30.11333 -89.76138 -0.222 -0.221 -0.223 -0.221 -0.222 0.001

BH1147 30.11888 -89.76277 -0.218 -0.217 -0.221 -0.219 -0.219 0.002

BH1539 30.16500 -89.73833 -0.209 -0.208 -0.211 -0.211 -0.210 0.002

BH1160 30.16611 -89.73750 -0.207 -0.206 -0.207 -0.207 -0.207 0.001

BH1164 30.16611 -89.73722 -0.195 -0.194 -0.195 -0.195 -0.195 0.001

BH1163 30.16638 -89.73750 -0.210 -0.209 -0.210 -0.210 -0.210 0.001

BH1537 30.16666 -89.73694 -0.210 -0.209 -0.210 -0.210 -0.210 0.001

BH1538 30.16666 -89.73777 -0.210 -0.209 -0.210 -0.210 -0.210 0.001

BH1754 30.24888 -88.07666 -0.102 -0.102 -0.113 -0.113 -0.108 0.006

BH1752 30.24916 -88.07666 -0.102 -0.102 -0.113 -0.113 -0.108 0.006

BH1755 30.24916 -88.07583 -0.105 -0.105 -0.116 -0.116 -0.111 0.006

BH1756 30.24944 -88.07555 -0.102 -0.102 -0.113 -0.113 -0.108 0.006

BH0946 30.30861 -89.32666 -0.194 -0.189 -0.171 -0.160 -0.179 0.016

BH0945 30.30888 -89.32555 -0.198 -0.192 -0.174 -0.163 -0.182 0.016

BH0934 30.31888 -89.32083 -0.164 -0.162 -0.165 -0.164 -0.164 0.001

BH0935 30.31972 -89.32361 -0.164 -0.162 -0.165 -0.164 -0.164 0.001

BH0936 30.32305 -89.32638 -0.167 -0.165 -0.168 -0.167 -0.167 0.001

BH0937 30.32361 -89.32722 -0.167 -0.165 -0.168 -0.167 -0.167 0.001

BH0392 30.39000 -88.85666 -0.154 -0.155 -0.155 -0.153 -0.154 0.001

BH0390 30.39277 -88.85777 -0.157 -0.158 -0.158 -0.156 -0.157 0.001
53

APPENDIX F. QC Deltas at Stations for TSS Grids

Table F.1. QC Deltas from the New Orleans TSS Grid, based on NAVD88 heights 

realized through GEOID 99.

PID Latitude

(deg)

Longitude

(deg)

MHHW

Deltas

(m)

MHW 

Deltas

(m)

MLW

Deltas

(m)

MLLW

Deltas

(m)

Avg.

(m)

Std. 

Dev.

(m)

BH3007 30.00666 -89.93861 0.001 0.001 0.002 0.002 0.002 0.001

BH1083 30.01138 -89.93916 0.000 0.000 0.000 0.001 0.000 0.000

BJ3686 30.02611 -90.11250 -0.003 -0.002 -0.004 -0.005 -0.004 0.001

BJ1342 30.02638 -90.11250 -0.001 0.000 -0.002 -0.003 -0.002 0.001

BJ1344 30.02666 -90.11277 0.003 0.004 0.002 0.001 0.002 0.001

BH1133 30.06805 -89.80361 0.001 0.000 -0.001 -0.001 0.000 0.001

BH1145 30.11333 -89.76138 0.000 0.001 -0.001 0.001 0.001 0.001

BH1147 30.11888 -89.76277 0.001 0.002 -0.002 0.000 0.000 0.002

BH1539 30.16500 -89.73833 0.001 0.002 -0.001 -0.001 0.000 0.002

BH1160 30.16611 -89.73750 -0.001 0.000 -0.001 -0.001 -0.001 0.001

BH1164 30.16611 -89.73722 0.010 0.011 0.010 0.010 0.010 0.001

BH1163 30.16638 -89.73750 -0.003 -0.002 -0.003 -0.003 -0.003 0.001

BH1537 30.16666 -89.73694 -0.002 -0.001 -0.002 -0.002 -0.002 0.001

BH1538 30.16666 -89.73777 -0.002 -0.001 -0.002 -0.002 -0.001 0.001

BH1754 30.24888 -88.07666 0.007 0.007 -0.005 -0.005 0.001 0.006

BH1752 30.24916 -88.07666 0.006 0.006 -0.005 -0.005 0.001 0.006

BH1755 30.24916 -88.07583 0.003 0.003 -0.008 -0.008 -0.002 0.006

BH1756 30.24944 -88.07555 0.004 0.004 -0.007 -0.007 -0.001 0.006

BH0946 30.30861 -89.32666 -0.015 -0.009 0.008 0.020 0.001 0.016

BH0945 30.30888 -89.32555 -0.017 -0.011 0.007 0.018 -0.001 0.016

BH0934 30.31888 -89.32083 0.001 0.003 -0.001 0.001 0.001 0.001

BH0935 30.31972 -89.32361 0.000 0.002 -0.001 0.000 0.000 0.001

BH0936 30.32305 -89.32638 0.000 0.002 -0.001 0.000 0.000 0.001

BH0937 30.32361 -89.32722 0.000 0.002 -0.001 0.000 0.000 0.001

BH0392 30.39000 -88.85666 0.001 0.000 0.000 0.002 0.001 0.001

BH0390 30.39277 -88.85777 0.000 -0.001 -0.001 0.001 0.000 0.001
54

Table F.2. QC Deltas from the New Orleans TSS Grid, based on NAVD88 heights 

realized through GEOID 03.

PID Latitude

(deg)

Longitude

(deg)

MHHW

Deltas

(m)

MHW 

Deltas

(m)

MLW

Deltas

(m)

MLLW

Deltas

(m)

Avg.

(m)

Std. 

Dev.

(m)

BH3007 30.00666 -89.93861 0.001 0.001 0.002 0.002 0.001 0.001

BH1083 30.01138 -89.93916 -0.001 -0.001 0.000 0.000 -0.001 0.000

BJ3686 30.02611 -90.11250 -0.003 -0.002 -0.004 -0.005 -0.003 0.001

BJ1342 30.02638 -90.11250 -0.001 0.000 -0.002 -0.003 -0.001 0.001

BJ1344 30.02666 -90.11277 0.003 0.004 0.002 0.001 0.003 0.001

BH1133 30.06805 -89.80361 0.001 0.000 -0.001 -0.001 0.000 0.001

BH1145 30.11333 -89.76138 0.000 0.001 -0.001 0.001 0.000 0.001

BH1147 30.11888 -89.76277 0.001 0.002 -0.002 0.000 0.000 0.002

BH1539 30.16500 -89.73833 0.001 0.002 -0.001 -0.001 0.000 0.002

BH1160 30.16611 -89.73750 -0.001 0.000 -0.001 -0.001 0.000 0.001

BH1164 30.16611 -89.73722 0.010 0.011 0.010 0.010 0.011 0.001

BH1163 30.16638 -89.73750 -0.003 -0.002 -0.003 -0.003 -0.002 0.001

BH1537 30.16666 -89.73694 -0.002 -0.001 -0.002 -0.002 -0.002 0.001

BH1538 30.16666 -89.73777 -0.001 0.000 -0.001 -0.001 -0.001 0.001

BH1754 30.24888 -88.07666 0.007 0.007 -0.004 -0.004 0.001 0.006

BH1752 30.24916 -88.07666 0.006 0.006 -0.005 -0.005 0.001 0.006

BH1755 30.24916 -88.07583 0.003 0.003 -0.008 -0.008 -0.002 0.006

BH1756 30.24944 -88.07555 0.004 0.004 -0.007 -0.007 -0.001 0.006

BH0946 30.30861 -89.32666 -0.014 -0.008 0.009 0.020 0.002 0.016

BH0945 30.30888 -89.32555 -0.016 -0.010 0.008 0.019 0.000 0.016

BH0934 30.31888 -89.32083 0.000 0.002 -0.001 0.000 0.001 0.001

BH0935 30.31972 -89.32361 0.000 0.002 -0.001 0.000 0.000 0.001

BH0936 30.32305 -89.32638 0.000 0.002 -0.001 0.000 0.000 0.001

BH0937 30.32361 -89.32722 0.000 0.002 -0.001 0.000 0.001 0.001

BH0392 30.39000 -88.85666 0.001 0.000 0.000 0.002 0.001 0.001

BH0390 30.39277 -88.85777 0.000 -0.001 -0.001 0.001 -0.001 0.001
55

APPENDIX G. COMPARISONS of DERIVED TSS WITH OBSERVATIONS AT 

TIDAL GAUGE AND TIDAL BENCH MARKS

Table G.1. New Orleans TSS (NAVD88 realized through GEOID99) Comparison to 

Tide Gauges and Tidal Bench marks.

ID Latitude 

(deg)

Longitude 

(deg)

NAVD 88 

to MSL (m)

TSS

Derived 

Value

(m)

Delta (m)

8735180 30.25000 -88.07500 -0.227 -0.227 0.000

8735523 30.39000 -88.85670 -0.305 -0.305 0.000

8743735 30.21330 -88.97170 -0.697 -0.686 0.011

8744756 30.36000 -89.08170 -0.273 -0.273 0.000

8745557 30.23170 -89.11670 -0.154 -0.156 -0.002

8745799 30.31000 -89.24500 -0.211 -0.211 0.000

8746819 30.32500 -89.32500 -0.208 -0.208 0.000

8747437 30.28170 -89.36670 -0.204 -0.204 0.000

8747766 29.27330 -89.35170 -0.439 -0.438 0.001

8760849 30.16670 -89.73670 -0.150 -0.148 0.003

8761402 30.11170 -89.76000 -0.139 -0.139 0.000

8761426 30.06500 -89.80000 -0.116 -0.116 0.000

8761473 30.00670 -89.93670 -0.015 -0.016 -0.001

8761487 29.24500 -90.66170 -0.167 -0.167 0.000

BH3007 30.00666 -89.93861 -0.007 -0.009 -0.002

BH1083 30.01138 -89.93916 -0.022 -0.022 0.000

BJ3686 30.02611 -90.11250 -0.140 -0.136 0.004

BJ1342 30.02638 -90.11250 -0.137 -0.135 0.002

BJ1344 30.02666 -90.11277 -0.131 -0.133 -0.002

BH1133 30.06805 -89.80361 -0.117 -0.117 0.000

BH1145 30.11333 -89.76138 -0.142 -0.142 -0.001

BH1147 30.11888 -89.76277 -0.141 -0.141 0.000

BH1539 30.16500 -89.73833 -0.149 -0.149 0.000

BH1160 30.16611 -89.73750 -0.146 -0.145 0.001

BH1164 30.16611 -89.73722 -0.134 -0.145 -0.010

BH1163 30.16638 -89.73750 -0.149 -0.147 0.003

BH1537 30.16666 -89.73694 -0.149 -0.147 0.002

BH1538 30.16666 -89.73777 -0.149 -0.148 0.001

BH1754 30.24888 -88.07666 -0.233 -0.234 -0.001

BH1752 30.24916 -88.07666 -0.233 -0.233 -0.001

BH1755 30.24916 -88.07583 -0.236 -0.233 0.002

BH1756 30.24944 -88.07555 -0.233 -0.231 0.001

BH0946 30.30861 -89.32666 -0.218 -0.219 -0.001

BH0945 30.30888 -89.32555 -0.221 -0.221 0.001

BH0934 30.31888 -89.32083 -0.207 -0.207 -0.001

BH0935 30.31972 -89.32361 -0.206 -0.206 0.000

BH0936 30.32305 -89.32638 -0.209 -0.209 0.000

BH0937 30.32361 -89.32722 -0.209 -0.209 0.000

BH0392 30.39000 -88.85666 -0.305 -0.305 -0.001

BH0390 30.39277 -88.85777 -0.307 -0.307 0.000
56

Table G.2. New Orleans TSS (NAVD88 realized through GEOID03) Comparison to 

Tide Gauges and Tidal Bench marks.

ID Latitude 

(deg)

Longitude 

(deg)

NAVD 88 

to MSL (m)

TSS 

Derived 

Value

(m)

Delta (m)

8735180 30.25000 -88.07500 -0.102 -0.102 0.000

8735523 30.39000 -88.85670 -0.155 -0.155 0.000

8743735 30.21330 -88.97170 -0.567 -0.557 0.011

8744756 30.36000 -89.08170 -0.173 -0.173 0.000

8745557 30.23170 -89.11670 -0.071 -0.073 -0.002

8745799 30.31000 -89.24500 -0.154 -0.154 0.000

8746819 30.32500 -89.32500 -0.165 -0.165 0.000

8747437 30.28170 -89.36670 -0.178 -0.178 0.000

8747766 29.27330 -89.35170 -0.430 -0.430 0.000

8760849 30.16670 -89.73670 -0.210 -0.208 0.002

8761402 30.11170 -89.76000 -0.220 -0.220 0.000

8761426 30.06500 -89.80000 -0.212 -0.212 0.000

8761473 30.00670 -89.93670 -0.118 -0.119 -0.001

8761487 29.24500 -90.66170 -0.261 -0.261 0.000

BH3007 30.00666 -89.93861 -0.110 -0.112 -0.001

BH1083 30.01138 -89.93916 -0.123 -0.123 0.001

BJ3686 30.02611 -90.11250 -0.217 -0.213 0.003

BJ1342 30.02638 -90.11250 -0.214 -0.212 0.001

BJ1344 30.02666 -90.11277 -0.208 -0.210 -0.003

BH1133 30.06805 -89.80361 -0.212 -0.212 0.000

BH1145 30.11333 -89.76138 -0.222 -0.222 0.000

BH1147 30.11888 -89.76277 -0.219 -0.219 0.000

BH1539 30.16500 -89.73833 -0.210 -0.210 0.000

BH1160 30.16611 -89.73750 -0.207 -0.206 0.000

BH1164 30.16611 -89.73722 -0.195 -0.205 -0.011

BH1163 30.16638 -89.73750 -0.210 -0.208 0.002

BH1537 30.16666 -89.73694 -0.210 -0.208 0.002

BH1538 30.16666 -89.73777 -0.210 -0.209 0.001

BH1754 30.24888 -88.07666 -0.108 -0.109 -0.001

BH1752 30.24916 -88.07666 -0.108 -0.108 -0.001

BH1755 30.24916 -88.07583 -0.111 -0.108 0.002

BH1756 30.24944 -88.07555 -0.108 -0.106 0.001

BH0946 30.30861 -89.32666 -0.179 -0.180 -0.002

BH0945 30.30888 -89.32555 -0.182 -0.182 0.000

BH0934 30.31888 -89.32083 -0.164 -0.164 0.000

BH0935 30.31972 -89.32361 -0.164 -0.164 0.000

BH0936 30.32305 -89.32638 -0.167 -0.167 0.000

BH0937 30.32361 -89.32722 -0.167 -0.167 0.000

BH0392 30.39000 -88.85666 -0.154 -0.155 -0.001

BH0390 30.39277 -88.85777 -0.157 -0.157 0.001