Projections of vegetated area and vegetated plain elevation in Chesapeake Bay salt marsh units

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Metadata:

Identification_Information
Data_Quality_Information
Spatial_Reference_Information
Entity_and_Attribute_Information
Distribution_Information
Metadata_Reference_Information

Identification_Information:

Citation:

Citation_Information:

Originator: Neil K. Ganju
Originator: Kate V. Ackerman
Originator: Zafer Defne
Publication_Date: 20250924
Title:

Projections of vegetated area and vegetated plain elevation in Chesapeake Bay salt marsh units

Edition: 1.0
Geospatial_Data_Presentation_Form: comma separated text files (.csv)
Series_Information:

Series_Name: data release
Issue_Identification: DOI:10.5066/P1ASOF7N

Publication_Information:

Publication_Place: Woods Hole Coastal and Marine Science Center, Woods Hole, MA
Publisher:

U.S. Geological Survey, Coastal and Marine Hazards and Resources Program

Other_Citation_Details:

Suggested citation: Ganju, N.K., Ackerman, K.V., and Defne, Z., 2025, Projections of vegetated area and vegetated plain elevation in Chesapeake Bay salt marsh units: U.S. Geological Survey data release, https://doi.org/10.5066/P1ASOF7N.

Online_Linkage: https://doi.org/10.5066/P1ASOF7N
Online_Linkage:

https://www.sciencebase.gov/catalog/item/67ea9dc8d34ed02007f8335b

Description:

Abstract:

Projections of vegetated area and vegetated plain elevation for salt marsh units within the Chesapeake Bay (CB) salt marsh complex are calculated using geospatial information for conceptual marsh units defined by Ackerman and others (2022) and Defne and others (2023). The projections are based on the UBMorph model, described in Ganju and others (2025), which estimates changes in areal cover and elevation due to open-water expansion and sea-level rise (SLR). Sea-level rise rate predictions are implemented at constant rates of 3, 5, 7, and 10 mm/y, beginning in 2010, along with two time-varying cases corresponding to a linear decadal increase in rate from 3 to 12 mm/y and an “upper end of likely range limit” scenario described by Ganju and others (2025). Through scientific efforts initiated with the Hurricane Sandy Science Plan, the U.S. Geological Survey has been expanding national assessment of coastal change hazards and forecast products to coastal wetlands, including the Chesapeake Bay salt marshes, with the intent of providing Federal, State, and local managers with tools to estimate the vulnerability and ecosystem service potential of these wetlands. For this purpose, the response and resilience of coastal wetlands to physical factors need to be assessed in terms of the ensuing change to their vulnerability and ecosystem services.
References: Ackerman, K.V., Defne, Z., and Ganju, N.K., 2022, Geospatial characterization of salt marshes in Chesapeake Bay: U.S. Geological Survey data release, https://doi.org/10.5066/P997EJYB.
Defne, Z., Ganju, N.K., and Ackerman, K.V., 2023, Lifespan of Chesapeake Bay salt marsh units: U.S. Geological Survey data release, https://doi.org/10.5066/P9FSPWSF.
Ganju, N.K., Ackerman, K.V., Defne, Z., Mariotti, G., Curson, D., Posnik, Z., Carr, J.A., and Grand, J., 2025, A Simple Predictive Model for Salt Marsh Internal Deterioration Under Sea-Level Rise and Sediment Deficits: Application to Chesapeake Bay: Estuaries and Coasts 48, 178, https://doi.org/10.1007/s12237-025-01618-w.

Purpose:

The purpose of this set of tables is to present projections of vegetated area and vegetated plain elevation for each marsh unit in the Chesapeake Bay.

Time_Period_of_Content:

Time_Period_Information:

Single_Date/Time:

Calendar_Date: 2025

Currentness_Reference: publication date

Status:

Progress: Complete
Maintenance_and_Update_Frequency: None

Spatial_Domain:

Bounding_Coordinates:

West_Bounding_Coordinate: -77.3747
East_Bounding_Coordinate: -75.5934
North_Bounding_Coordinate: 39.5898
South_Bounding_Coordinate: 36.3744

Keywords:

Theme:

Theme_Keyword_Thesaurus: ISO 19115 Topic Category
Theme_Keyword: oceans
Theme_Keyword: inlandWaters
Theme_Keyword: environment
Theme_Keyword: elevation

Theme:

Theme_Keyword_Thesaurus: USGS Thesaurus
Theme_Keyword: geospatial datasets
Theme_Keyword: wetland ecosystems
Theme_Keyword: wetland functions
Theme_Keyword: coastal ecosystems
Theme_Keyword: coastal processes
Theme_Keyword: sea-level change
Theme_Keyword: sediment transport
Theme_Keyword: estuarine processes
Theme_Keyword: vegetation

Theme:

Theme_Keyword_Thesaurus: None
Theme_Keyword: salt marsh
Theme_Keyword: marsh health
Theme_Keyword: lifespan
Theme_Keyword: estuary
Theme_Keyword: Long-Term Ecological Research
Theme_Keyword: LTER

Theme:

Theme_Keyword_Thesaurus: USGS Metadata Identifier
Theme_Keyword: USGS:67ea9dc8d34ed02007f8335b

Place:

Place_Keyword_Thesaurus: Common geographic areas
Place_Keyword: Atlantic
Place_Keyword: United States
Place_Keyword: Maryland
Place_Keyword: Virginia
Place_Keyword: Chesapeake

Access_Constraints:

No access constraints. Please see 'Distribution Information' for details.

Use_Constraints:

These data are marked with a Creative Commons CC0 1.0 Universal License. These data are in the public domain and do not have any use constraints. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations. The area and elevation projections for each marsh unit are defined for scientific research purposes and should not be used as a sole source of reference for any regulations and policy making. Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey as the source of this information.

Point_of_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: Neil Ganju
Contact_Organization: U.S. Geological Survey

Contact_Position: Research Oceanographer
Contact_Address:

Address_Type: mailing address
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543
Country: US

Contact_Voice_Telephone: 508-548-8700 x2252
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: nganju@usgs.gov

Browse_Graphic:

Browse_Graphic_File_Name:

https://www.sciencebase.gov/catalog/file/get/67ea9dc8d34ed02007f8335b/?name=CB_SaltMarsh_Browse.png&allowOpen=true

Browse_Graphic_File_Description: Graphic that shows salt marshes of Chesapeake Bay.
Browse_Graphic_File_Type: PNG

Native_Data_Set_Environment:

Environment of Metadata Creation: Microsoft Windows 10 Version 22H2 (Build 19045); Matlab 2018b

Cross_Reference:

Citation_Information:

Originator: Kate V. Ackerman
Originator: Zafer Defne
Originator: Neil K. Ganju
Publication_Date: 2023
Title: Geospatial characterization of salt marshes in Chesapeake Bay
Edition: 1.0
Geospatial_Data_Presentation_Form: Vector Digital Data Set (Polygon)
Series_Information:

Series_Name: data release
Issue_Identification: DOI:10.5066/P997EJYB

Publication_Information:

Publication_Place: Reston, VA
Publisher: U.S. Geological Survey

Online_Linkage: https://doi.org/10.5066/P997EJYB
Online_Linkage:

https://www.sciencebase.gov/catalog/item/630f73acd34e36012efa0842

Cross_Reference:

Citation_Information:

Originator: Zafer Defne
Originator: Neil K. Ganju
Originator: Kate V. Ackerman
Publication_Date: 2023
Title: Lifespan of Chesapeake Bay salt marsh units
Edition: 1.0
Geospatial_Data_Presentation_Form: Vector Digital Data Set (Polygon)
Series_Information:

Series_Name: data release
Issue_Identification: DOI:10.5066/P9FSPWSF

Publication_Information:

Publication_Place: Reston, VA
Publisher: U.S. Geological Survey

Online_Linkage: https://doi.org/10.5066/P9FSPWSF
Online_Linkage:

https://www.sciencebase.gov/catalog/item/63a32f2bd34e176674f520ee

Cross_Reference:

Citation_Information:

Originator: Neil K. Ganju
Originator: Kate V. Ackerman
Originator: Zafer Defne
Originator: Giulio Mariotti
Originator: David Curson
Originator: Zachary Posnik
Originator: Joel A. Carr
Originator: Joanna Grand
Publication_Date: 2025
Title:

A simple predictive model for salt marsh internal deterioration under sea-level rise and sediment deficits: application to Chesapeake Bay

Edition: 1.0
Series_Information:

Series_Name: Estuaries and Coasts
Issue_Identification: 48

Online_Linkage: https://doi.org/10.1007/s12237-025-01618-w

Cross_Reference:

Citation_Information:

Originator: Neil K. Ganju
Originator: Zafer Defne
Originator: Matthew L. Kirwan
Originator: Sergio Fagherazzi
Originator: Andrea D'Alpaos
Originator: Luca Carniello
Publication_Date: 2017
Title:

Spatially integrative metrics reveal hidden vulnerability of microtidal salt marshes

Edition: 1.0
Series_Information:

Series_Name: Nature Communications
Issue_Identification: 8:14156

Online_Linkage: https://doi.org/10.1038/ncomms14156

Data_Quality_Information:

Attribute_Accuracy:

Attribute_Accuracy_Report:

Marsh units, and water and land boundaries inherit their accuracy from accuracy of the source data, Chesapeake Bay marsh units. The vertical accuracy of the marsh unit elevation is inherited from the 1-meter resolution U.S. Geological Survey Coastal National Elevation Database (USGS CoNED) data from 1859 to 2015 and the NOAA North Carolina DEM dataset. The uncertainty in the area and elevation projections is large because of the nature of the empirical equations used and the uncertainty in the source data. For example, a 20% variation in each of the unvegetated to vegetated marsh ratio (UVVR), elevation, bulk density and sea-level rise variables, when all in favor of increasing sediment export and decreasing lifespan, may result in accelerated marsh loss by 50%.

Logical_Consistency_Report:

For area and elevation calculations, no calculations were performed if the marsh unit had a flagged UVVR value of -1 or elevation value of -9999 in the original datasets.

Completeness_Report:

The results are specific to the marsh polygons definition within the boundaries of the Chesapeake Bay salt marsh complex. A detailed on-the-ground analysis of a single site may result in a different interpretation of the wetland and marsh unit boundaries.

Positional_Accuracy:

Horizontal_Positional_Accuracy:

Horizontal_Positional_Accuracy_Report:

Horizontal accuracy is inherited from the source dataset that delineates the marsh units and can be considered to be +/-6 meters.

Vertical_Positional_Accuracy:

Vertical_Positional_Accuracy_Report:

Because the elevation values are averaged over delineated polygons, vertical accuracy of marsh unit elevation depends on both the horizontal accuracy of NWI dataset and the vertical accuracy of source elevation data. CoNED vertical elevation accuracy is 0.2 meters. NOAA North Carolina DEM dataset resolution is 0.06 meters. Additionally, the transformation between the vertical datums is based on the VDatum model which had a vertical uncertainty of 0.1 meters for the transformation points with the domain. Therefore, when all combined the maximum uncertainty could be in excess of 0.36 meters.

Lineage:

Source_Information:

Source_Citation:

Citation_Information:

Originator: Zafer Defne
Originator: Neil K. Ganju
Originator: Kate V. Ackerman
Publication_Date: 2023
Title: Lifespan of Chesapeake Bay salt marsh units
Geospatial_Data_Presentation_Form: Vector Digital Data Set (Polygon)
Series_Information:

Series_Name: data release
Issue_Identification: DOI:10.5066/P9FSPWSF

Publication_Information:

Publication_Place: Reston, VA
Publisher: U.S. Geological Survey

Online_Linkage:

https://www.sciencebase.gov/catalog/item/63a32f2bd34e176674f520ee

Online_Linkage: https://doi.org/10.5066/P9FSPWSF

Type_of_Source_Media: online
Source_Time_Period_of_Content:

Time_Period_Information:

Single_Date/Time:

Calendar_Date: 2023

Source_Currentness_Reference: publication date

Source_Citation_Abbreviation: mu_lifespan_CB.shp
Source_Contribution:

Used the vegetated fraction elevation relative to mean tidal level (VG_ELEVMTL), total marsh unit area (ATOT_M2), and UnVegetated-Vegetated Ratio (UVVR) as inputs.

Process_Step:

Process_Description:

The process step uses the initial conditions for vegetated area and elevation, along with the empirical equations presented by Ganju and others (2025), to project future changes in response to sea-level rise scenarios.
1) Import the following variables from mu_lifespan_CB.shp into Matlab (v. 2018b): marsh unit ID (FID_CMU), total marsh unit area in square meters (m2) (ATOT_M2), vegetated plain elevation relative to mean tidal level in meters (m) (VG_ELEVMTL), and the dimensionless UnVegetated-Vegetated Ratio (UVVR).
2) To eliminate spurious calculations in marsh units with flags for the UVVR, replace UVVR values less than 0 (fill values) with NaNs.
3) For each marsh unit (FID_CMU), extract the UVVR and VG_ELEVMTL, and set the two main parameters (surface accretion rate, loss partition coefficient) to surface accretion rate (sar)=0.9, and loss partition coefficient (w)=0.8. These two parameters and their selection are described by Ganju and others (2025). Set substrate density (rho_sub)=373 kg/m3 and depositional density (rho_dep)=159 kg/m3.
4) Specify time-varying sea-level rise rate (slr, meters/year (m/y)) at annual interval. Rates are either constant values of 3, 5, 7, or 10 millimeters/year (mm/y), variable rates corresponding to a linear decadal increase from 3 to 12 mm/y, or variable rates corresponding to the “upper limit of likely range” from Ganju and others (2025). Specify background sea-level rise rate (slr_bgrnd (m/y)) as 0.003 m/y. Specify maximum time step, t, as 100 years.
5) This step initializes model variables. Calculate the initial vegetated area as area_veg(t=0) = ATOT_M2/(1+UVVR).
Calculate the initial unvegetated area as area_unveg(t=0) = ATOT_M2 - area_veg (t=0)
Calculate the initial sediment mass as sed_mass(t=0)=area_veg(t=0) x VG_ELEVMTL x rho_sub
Calculate the initial sediment budget as sed_bud(t=0)=(-0.416 x log(UVVR)-1.0749) x ATOT_M2-(slr(t=0)-slr_bgrnd) x rho_dep x ATOT_M2, following Ganju and others (2017). If more than zero, indicating sediment import, set to zero.
Calculate initial elevation loss as elev_loss(t=0)=(sed_bud(t=0) x w)/(rho_sub x area_veg(t=0))
Calculate initial areal loss as area_veg_loss(t=0)=((1-w) x sed_bud(t=0))/(rho_sub x VG_ELEVMTL)
If VG_ELEVMTL is equal to zero the calculation is terminated.
6) This step begins forward time-stepping, t=t+1, and updates UVVR and VG_ELEVMTL at each time step. If area or elevation drop below 0, stop computation. Calculate vegetated elevation at next time step, VG_ELEVMTL(t+1)=VG_ELEVMTL(t)+elev_loss(t)-slr(t+1)+[slr(t+1) x sar]
Calculate vegetated area at next time step, area_veg(t+1)=area_veg(t)+area_veg_loss(t)
Calculate sediment mass at next time step, sed_mass(t+1)=area_veg(t+1) x VG_ELEVMTL(t+1) x rho_sub
Calculate unvegetated area at next time step, area_unveg(t+1)=ATOT_M2-area_veg(t+1)
Calculate UVVR at next time step, UVVR(t+1)=area_unveg(t+1)/area_veg(t+1)
Calculate sediment budget at next time step, sed_bud(t+1)=(-0.416 x log(UVVR(t+1))-1.0749) x ATOT_M2-(slr(t+1)-slr_bgrnd) x rho_dep x ATOT_M2. If more than zero, indicating sediment import, set to zero.
Calculate elevation loss at next time step, elev_loss(t+1)=(sed_bud(t+1) x w)/(rho_sub x area_veg(t+1))
Calculate areal loss at next time step area_veg_loss(t+1)=((1-w) x sed_bud(t+1))/(rho_sub x VG_ELEVMTL(t+1))
Repeat process step 6 until area or elevation drop below 0, or maximum time step is reached.
If maximum time step is reached for all units, stop computation.
7) This step exports the projections for vegetated plain elevation and vegetated area (VG_ELEVMTL and AREA_VEG) for all timesteps and marsh units to CSV using Matlab csvwrite command. For each sea-level rise case, export the AREA_VEG and VG_ELEVMTL matrices to separate CSV files. Append FID_CMU to the first column, and the year, truncated variable name, and truncated sea-level rise scenario identifier (e.g., “2010_e3” for the year 2010, elevation variable, and 3 mm/y scenario) to the first row.
These CSV files can be joined to shapefile mu_lifespan_CB.shp (Join Field= FID_CMU) to be examined spatially.

Source_Used_Citation_Abbreviation: mu_lifespan_CB.shp
Process_Date: 2025
Source_Produced_Citation_Abbreviation: area_veg_3mmy.csv
Source_Produced_Citation_Abbreviation: area_veg_5mmy.csv
Source_Produced_Citation_Abbreviation: area_veg_7mmy.csv
Source_Produced_Citation_Abbreviation: area_veg_10mmy.csv
Source_Produced_Citation_Abbreviation: area_veg_3to12mmy.csv
Source_Produced_Citation_Abbreviation: area_veg_upperlimitoflikely.csv
Source_Produced_Citation_Abbreviation: elev_veg_3mmy.csv
Source_Produced_Citation_Abbreviation: elev_veg_5mmy.csv
Source_Produced_Citation_Abbreviation: elev_veg_7mmy.csv
Source_Produced_Citation_Abbreviation: elev_veg_10mmy.csv
Source_Produced_Citation_Abbreviation: elev_veg_3to12mmy.csv
Source_Produced_Citation_Abbreviation: elev_veg_upperlimitoflikely.csv
Process_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: Neil K. Ganju
Contact_Organization: U.S. Geological Survey

Contact_Position: Research Oceanographer
Contact_Address:

Address_Type: mailing and physical address
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543

Contact_Voice_Telephone: 508-548-8700 x2252
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: nganju@usgs.gov

Spatial_Reference_Information:

Vertical_Coordinate_System_Definition:

Depth_System_Definition:

Depth_Datum_Name: Mean Tidal Level
Depth_Resolution: 0.1
Depth_Distance_Units: meters
Depth_Encoding_Method: Attribute values

Entity_and_Attribute_Information:

Detailed_Description:

Entity_Type:

Entity_Type_Label: elev_veg_3mmy.csv
Entity_Type_Definition:

A CSV file that contains predictions of marsh vegetated plain elevation (in meters, relative to mean tidal level (MTL)) under a 3 mm/y of sea-level rise scenario as produced by the UBMorph model and the process steps above, for the conceptual marsh units of Chesapeake Bay salt marsh complex (identified by FID_CMU) for 100 years from 2010 to 2109. The field names are formatted to identify the year that the prediction is for, an “e” denoting the elevation dataset, and the value of the sea-level rise (SLR) scenario: 2010_e3 is the 2010 elevation prediction under a 3 mm/y SLR scenario. Elevations are relative to mean tidal level (MTL). The special value -9999 signifies no calculation was performed due to unavailable elevation data; values of 0 signify termination of the computation for either area or elevation, indicating conversion of the marsh unit to completely unvegetated.