Metadata: Identification_Information: Citation: Citation_Information: Originator: Kate V. Ackerman Originator: Zafer Defne Originator: Neil K. Ganju Publication_Date: 20230328 Title: Elevation of marsh units in Eastern Shore of Virginia salt marshes Edition: 1.0 Geospatial_Data_Presentation_Form: vector digital dataset (polygon) Series_Information: Series_Name: data release Issue_Identification: DOI:10.5066/P9E6V0QK 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 Online_Linkage: https://doi.org/10.5066/P9E6V0QK Online_Linkage: https://www.sciencebase.gov/catalog/item/63e53993d34efa0476ade042 Larger_Work_Citation: Citation_Information: Originator: Kate V. Ackerman Originator: Zafer Defne Originator: Neil K. Ganju Publication_Date: 2023 Title: Geospatial characterization of salt marshes on the Eastern Shore of Virginia Edition: 1.0 Geospatial_Data_Presentation_Form: vector digital data Series_Information: Series_Name: data release Issue_Identification: DOI:10.5066/P9E6V0QK Publication_Information: Publication_Place: Reston, VA Publisher: U.S. Geological Survey Other_Citation_Details: Suggested citation: Ackerman, K.V., Defne, Z., and Ganju, N.K., 2023, Geospatial characterization of salt marshes on the Eastern Shore of Virginia: U.S. Geological Survey data release, https://doi.org/10.5066/P9E6V0QK. Online_Linkage: https://doi.org/10.5066/P9E6V0QK Online_Linkage: https://www.sciencebase.gov/catalog/item/63dd3cecd34e9fa19a9ad055 Description: Abstract: This data release contains coastal wetland synthesis products for the Atlantic-facing Eastern Shore of Virginia (the data release for the Chesapeake Bay-facing portion of the Eastern Shore of Virginia is found here: https://doi.org/10.5066/P997EJYB). Metrics for resiliency, including unvegetated to vegetated ratio (UVVR), marsh elevation, and tidal range are calculated for smaller units delineated from a digital elevation model, providing the spatial variability of physical factors that influence wetland health. The U.S. Geological Survey has been expanding national assessment of coastal change hazards and forecast products to coastal wetlands 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. Purpose: The purpose of this shapefile is to calculate the mean elevation for each marsh unit and its vegetated component. Analysis of marsh elevation is part of a comprehensive assessment to identify the factors and their weights in determining the vulnerability and resiliency of salt marshes. Elevation distribution in the Eastern Shore of Virginia salt marshes is given in terms of mean elevation of conceptual marsh units, as well as the vegetated portion of the marsh unit. The elevation data is based on the 1-meter 2015 USGS Lidar DEM. Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 2023 Currentness_Reference: publication date Status: Progress: Complete Maintenance_and_Update_Frequency: None Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -75.977747 East_Bounding_Coordinate: -75.474028 North_Bounding_Coordinate: 37.881830 South_Bounding_Coordinate: 37.085411 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: vegetation Theme: Theme_Keyword_Thesaurus: None Theme_Keyword: salt marsh Theme_Keyword: marsh health Theme_Keyword: estuary Theme_Keyword: elevation Theme: Theme_Keyword_Thesaurus: USGS Metadata Identifier Theme_Keyword: USGS:63e53993d34efa0476ade042 Place: Place_Keyword_Thesaurus: None Place_Keyword: United States Place_Keyword: Atlantic Ocean Place_Keyword: Virginia Place_Keyword: Wallops Island Place_Keyword: Chincoteague National Wildlife Refuge Place_Keyword: Metompkin Island Place_Keyword: Cedar Island Place_Keyword: Parramore Island Place_Keyword: Hog Island Place_Keyword: Mockhorn Island Place_Keyword: Smith Island Place_Keyword: Fisherman Island National Wildlife Refuge Place_Keyword: Eastern Shore National Wildlife Refuge Place_Keyword: Virginia Coast Reserve Access_Constraints: None Use_Constraints: The mean elevation for each marsh unit is 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: Kate Ackerman Contact_Organization: U.S. Geological Survey Contact_Position: Geologist 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 x2331 Contact_Facsimile_Telephone: 508-457-2310 Contact_Electronic_Mail_Address: kackerman@usgs.gov Browse_Graphic: Browse_Graphic_File_Name: https://www.sciencebase.gov/catalog/file/get/63e53993d34efa0476ade042/?name=Elev_ESV_Browse.png&allowOpen=true Browse_Graphic_File_Description: Graphic that shows elevation of conceptual marsh units in Eastern Shore of Virginia salt marshes. Browse_Graphic_File_Type: PNG Native_Data_Set_Environment: Environment as of Metadata Creation: Microsoft Windows 10; Esri ArcGIS Pro (version 2.8.8) Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: Marsh units and water and land boundaries inherit their horizontal accuracy from the accuracy of the source data, the conceptual marsh units, and their vertical accuracy from the elevation dataset (1-meter 2015 USGS Lidar DEM). Logical_Consistency_Report: Positive elevation indicates above sea level. Marsh units with extremely low elevation (smaller than the 0.2 percentile value), extremely high elevation (larger than the 99.8 percentile value) or areas less than 900 square meters were flagged. Completeness_Report: The marsh polygons are bound to the borders of the Eastern Shore of Virginia's estuarine intertidal areas that include: 1) emergent wetlands, 2) scrub-shrub areas, 3) rooted vascular aquatic beds, 4) organic unconsolidated shores, and 5) channels of open water that are narrower than 10 meters. Occasionally, marsh units are retained in this dataset even though the imagery displayed extreme change (e.g., partially or completely converted to water) from the NWI wetland delineation (e.g., marsh units 638, 796, 1366). In a few areas, there are no marsh units where there is visible marsh plain (e.g., west of marsh units 4583 and 4566; west of 5878; south of 5910; west of 5855), because the areas are classified in the NWI as estuarine intertidal unconsolidated shore, which is not included in our salt marsh boundaries. In a few locations, there may be areas that that are classified as unvegetated but are in fact very sparsely vegetated. A detailed on-the-ground analysis of a single site may result in a different interpretation of the wetland and marsh unit boundaries than those established through this analysis. Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: Horizontal accuracy for the polygon boundaries is inherited from the source layer, the conceptual marsh units, and is considered to be +/- 6 meters. Vertical_Positional_Accuracy: Vertical_Positional_Accuracy_Report: Because the elevation values are averaged over delineated polygons, vertical accuracy depends on both the horizontal accuracy of the NWI dataset and the vertical accuracy of the source elevation dataset (1-meter 2015 USGS Lidar DEM). The vertical accuracy is inherited from the source elevation dataset; it is reported to be 0.06 meters. No additional accuracy assessment of the vertical accuracy has been conducted. Lineage: Source_Information: Source_Citation: Citation_Information: Originator: U.S. Geological Survey Publication_Date: 2018 Title: 2015 USGS Lidar DEM: Eastern Shore VA Edition: First Geospatial_Data_Presentation_Form: raster digital dataset Publication_Information: Publication_Place: Reston, VA Publisher: U.S. Geological Survey Other_Citation_Details: Downloaded 1-meter 2015 USGS Lidar DEM. Projection was NAD 1983 UTM Zone 18N with the North American Vertical Datum of 1988 (NAVD 88). Download date was 04/13/2021. Online_Linkage: https://www.fisheries.noaa.gov/inport/item/51444 Type_of_Source_Media: Digital Source_Time_Period_of_Content: Time_Period_Information: Range_of_Dates/Times: Beginning_Date: 20150411 Ending_Date: 20150424 Source_Currentness_Reference: ground condition Source_Citation_Abbreviation: USGS DEM Source_Contribution: Elevation dataset Source_Information: Source_Citation: Citation_Information: Originator: Ackerman, K.V., Defne, Z., and Ganju, N.K. Publication_Date: 2023 Title: Conceptual marsh units of salt marshes on the Eastern Shore of Virginia Geospatial_Data_Presentation_Form: vector digital dataset (polygon) Publication_Information: Publication_Place: Reston, VA Publisher: U.S. Geological Survey Online_Linkage: https://www.sciencebase.gov/catalog/item/63e53a36d34efa0476ade047 Type_of_Source_Media: Digital Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 2023 Source_Currentness_Reference: publication date Source_Citation_Abbreviation: CMU_ESV Source_Contribution: Used conceptual marsh units, generated as part of this data release, to delineate marsh unit boundaries and areas of vegetation. Process_Step: Process_Description: This process step and all subsequent process steps were performed by the same person, Kate Ackerman, in ArcGIS Pro (ver. 2.8.8), unless otherwise stated. For simple operations the name of the geoprocessing tool used is given in capital letters; for complex operations, the name of geoprocessing tool used is given in capital letters and any critical parameters used are given in parentheses, separated by a semicolon, immediately after the tool name. The input and output file names are provided in [square brackets] when necessary. Units for length and area calculations are meters (m) and square meters (m^2) unless otherwise stated. a) Set the data frame coordinate system and projection to NAD 1983 UTM Zone 18N. b) Establish marsh unit boundaries. Dissolve the vegetated and unvegetated classes in each marsh unit to have only one class for each marsh unit. DISSOLVE(Input features=[CMU_ESV.shp]; Dissolve field=FID_CMU; Statistics field=ATOT_M2 and FLG with Statistics type= First). PROJECT(Input coordinate system=WGS 1984 Web Mercator Auxiliary Sphere; Output coordinate system=NAD 1983 UTM Zone 18N) the feature dataset to obtain dissolved marsh units [mu_diss.shp]. c) Prepare elevation dataset. Combine all downloaded tiles into one raster, using MOSAIC TO NEW RASTER, and PROJECT RASTER to NAD 1983 UTM Zone 18N. d) Create a polygon that covers the area of interest [extent.shp]. CLIP the mosaicked elevation dataset created in step (c) by [extent.shp] to create [elev_mosaic.tif]. Source_Used_Citation_Abbreviation: USGS DEM Source_Used_Citation_Abbreviation: CMU_ESV Process_Date: 2022 Source_Produced_Citation_Abbreviation: elev_mosaic.tif Source_Produced_Citation_Abbreviation: mu_diss.shp Process_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Kate Ackerman Contact_Organization: U.S. Geological Survey Contact_Position: Geologist 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 x2331 Contact_Facsimile_Telephone: 508-457-2310 Contact_Electronic_Mail_Address: kackerman@usgs.gov Process_Step: Process_Description: a) Remove pixels from elevation raster that are hydro-flattened. Use FOCAL STATISTICS(Input raster=[elev_mosaic.tif], Output raster=[FocalStats_3x3_range.tif], Neighborhood settings=3x3 cell, Statistics type=range) and RASTER CALCULATOR to identify (Map algebra expression: Con("%FocalStats_3x3_range.tif%" == 0,-1,1); Output raster=[elev_mosaic_One_NegOne.tif]) and remove (Map algebra expression: SetNull("%elev_mosaic_One_NegOne.tif%", "%elev_mosaic.tif%", "value = -1"); Output raster=[elev_mosaic_noHF.tif]) all hydro-flattened areas from [elev_mosaic.tif] to create [elev_mosaic_noHF.tif]. b) Calculate the mean elevation for each marsh unit with ZONAL STATISTICS AS TABLE(Feature zone data=[mu_diss.shp], Zone field=FID_CMU; Input value raster=[elev_mosaic_noHF.tif]; Statistics type=Mean; Output table=[mu]; Ignore Nodata=True). JOIN mean elevation from [mu] table to marsh units layer [mu_diss.shp] based on the "FID_CMU" field. Export dataset as a shapefile [mu_elev.shp]. Rename "mu_MEAN" to "MU_ELEV." c) Calculate the percent of the marsh unit that has hydro-flattened area. ZONAL STATISTICS AS TABLE (Feature zone data=[mu_elev.shp], Zone field=FID_CMU; Input value raster=[elev_mosaic_One_NegOne.tif]; Statistics type=Mean; Output table=[zs_muelev_HF]; Ignore Nodata=True). ADD FIELD to the output table to calculate hydro-flattened area of each marsh unit (MU_HFAR), CALCULATE FIELD (MU_HFAR= (1-MEAN)/2). JOIN MU_HFAR field to [mu_elev.shp]. If the percent hydro-flattened area is greater than 25 percent, set the marsh unit elevation to -9999. d) Calculate the elevation of the vegetated area of the marsh unit. SELECT BY ATTRIBUTES from [CMU_ESV.shp] where "TYP"= 'vegetated', output: [CMU_ESV_VEG.shp]. ZONAL STATISTICS AS TABLE(Feature zone data=[CMU_ESV_VEG.shp], Zone field=FID_CMU; Input value raster=[elev_mosaic_noHF.tif]; Statistics type=Mean; Output table=[vg]; Ignore Nodata=True). Join the mean elevation of the vegetated portion to [mu_elev.shp] and rename the field to "VG_ELEV." e) Calculate the percent of the vegetated portion of the marsh unit that has hydro-flattened area. ZONAL STATISTICS AS TABLE (Feature zone data=[CMU_ESV_VEG.shp], Zone field=FID_CMU; Input value raster=[elev_mosaic_One_NegOne.tif]; Statistics type=Mean; Output table=[zs_muelev_HF]; Ignore Nodata=True). ADD FIELD (VG_HFAR) to output table, CALCULATE FIELD (VG_HFAR= (1-MEAN)/2). Join VG_HFAR field to [mu_elev.shp]. If the percent hydro-flattened area is greater than 25 percent, set the vegetated elevation to -9999. f) JOIN the vegetated area (AVEG_M2) from [CMU_ESV_VEG.shp] to [mu_elev.shp]. Source_Used_Citation_Abbreviation: elev_mosaic.tif Process_Date: 2022 Source_Produced_Citation_Abbreviation: mu_elev.shp Process_Step: Process_Description: a) Run Python script (marsv5.py) in ArcGIS Pro (v.2.8.8) to calculate metrics that quantify the distribution of marsh unit elevation values. Skewness ("SKWNSS") is the measure of asymmetry of the elevation distribution in the vegetated part of a marsh unit. Positive skewness values, i.e. right-skewed distributions, indicate clustering of elevation distributions towards lower elevations. Negative skewness values indicate a left-skewed distribution and clustering towards higher elevations. Lower third ("LOW3RD") is the percent of elevation values that fall within the lowest third of the elevation range within the vegetated part of a marsh unit. SKWNSS and LOW3RD parameters are calculated by applying the formulation of Raposa et al. (2016) to the elevation raster within the vegetated part of each marsh unit. JOIN these values to [mu_elev.shp]. If VG_ELEV= -9999, set SKWNESS and LOW3RD values to -9999. Export to a new shapefile [mu_elev_ESV.shp]. Reference: Raposa, K. B., Wasson, K., Smith, E., Crooks, J. A., Delgado, P., Fernald, S. H., et al. (2016). Assessing tidal marsh resilience to sea-level rise at broad geographic scales with multi-metric indices. Biological Conservation, 204, 263–275. https://doi.org/10.1016/J.BIOCON.2016.10.015. Source_Used_Citation_Abbreviation: mu_elev.shp Process_Date: 2022 Source_Produced_Citation_Abbreviation: mu_elev_ESV.shp Process_Step: Process_Description: a) Add field "FLG" to flag anomalous marsh units based on absence of vegetation, elevation, surface area, and tidal range extrapolation. The flags are calculated in their respective shapefile (i.e., elevation flags are calculated in the elevation shapefile). Set FLG to: (-1) no vegetated area in the marsh unit; (-10) marsh unit elevation higher than the 99.8 percentile; (-100) marsh unit elevation less than the 0.2 percentile; (-200) greater than 25 percent of the marsh unit elevation is hydro-flattened; (-1000) marsh unit surface area less than 900 m^2; (-10000) mean tidal range of marsh unit is extrapolated; and (0) no flag. Combination of negative values indicates a combination of flags; for example, -1001 indicates no vegetated area and area less than 900 m^2. b) Rearrange field names and change the projection for better performance of web services with online base maps. PROJECT(Output coordinate system=WGS 1984 Web Mercator Auxiliary Sphere) the feature dataset to obtain the final elevation dataset [mu_elev_ESV.shp]. Process_Date: 2022 Source_Produced_Citation_Abbreviation: mu_elev_ESV.shp Spatial_Data_Organization_Information: Direct_Spatial_Reference_Method: Vector Point_and_Vector_Object_Information: SDTS_Terms_Description: SDTS_Point_and_Vector_Object_Type: G-polygon Point_and_Vector_Object_Count: 6358 Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Planar: Map_Projection: Map_Projection_Name: WGS 1984 Web Mercator Auxiliary Sphere (Esri full name: WGS_1984_Web_Mercator_Auxiliary_Sphere) Map_Projection_Parameters: False_Easting: 0.0 False_Northing: 0.0 Longitude_of_Central_Meridian: 0.0 Standard_Parallel: 0.0 Planar_Coordinate_Information: Planar_Coordinate_Encoding_Method: coordinate pair Coordinate_Representation: Abscissa_Resolution: 0.6096 Ordinate_Resolution: 0.6096 Planar_Distance_Units: meters Geodetic_Model: Horizontal_Datum_Name: D_WGS_1984 Ellipsoid_Name: WGS 84 Semi-major_Axis: 6378137.0 Denominator_of_Flattening_Ratio: 298.257223563 Entity_and_Attribute_Information: Detailed_Description: Entity_Type: Entity_Type_Label: mu_elev_ESV.shp attribute table Entity_Type_Definition: Table containing attribute information associated with the dataset. Entity_Type_Definition_Source: USGS Attribute: Attribute_Label: FID Attribute_Definition: Internal feature number. Attribute_Definition_Source: Esri Attribute_Domain_Values: Unrepresentable_Domain: Sequential unique whole numbers that are automatically generated. Attribute: Attribute_Label: Shape Attribute_Definition: Feature geometry. Attribute_Definition_Source: Esri Attribute_Domain_Values: Unrepresentable_Domain: Coordinates defining the features. Attribute: Attribute_Label: FID_CMU Attribute_Definition: Unique whole numbers used to identify each conceptual marsh unit. Attribute_Definition_Source: USGS Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 0 Range_Domain_Maximum: 6357 Attribute_Units_of_Measure: none Attribute: Attribute_Label: ATOT_M2 Attribute_Definition: Total surface area of a marsh unit. Attribute_Definition_Source: USGS Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 123.82663224 Range_Domain_Maximum: 1906442.13092 Attribute_Units_of_Measure: m^2 Attribute: Attribute_Label: AVEG_M2 Attribute_Definition: Surface area of the vegetated part of a marsh unit. Attribute_Definition_Source: USGS Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 0.0 Range_Domain_Maximum: 1628088.8009 Attribute_Units_of_Measure: m^2 Attribute: Attribute_Label: MU_ELEV Attribute_Definition: Mean elevation of a marsh unit. If the percent hydro-flattened area is greater than 25 percent (MU_HFAR is greater than 0.25), the marsh unit elevation is set to -9999 indicating insufficient elevation data. Attribute_Definition_Source: USGS Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: -0.89189303 Range_Domain_Maximum: 2.13515997 Attribute_Units_of_Measure: meters Attribute: Attribute_Label: VG_ELEV Attribute_Definition: Mean elevation of the vegetated area in a marsh unit. If there is no vegetated area in the marsh unit, the value is set to -9999. Also, if the percent hydro-flattened area in the vegetated portion is greater than 25 percent (VG_HFAR is greater than 0.25), the value is set to -9999 indicating insufficient elevation data. Attribute_Definition_Source: USGS Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: -0.390088689988 Range_Domain_Maximum: 2.06516431022 Attribute_Units_of_Measure: meters Attribute: Attribute_Label: MU_HFAR Attribute_Definition: Percent (in decimal form) of the marsh unit that contains hydro-flattened bathymetric/elevation values. Attribute_Definition_Source: USGS Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 0 Range_Domain_Maximum: 1 Attribute_Units_of_Measure: none Attribute: Attribute_Label: VG_HFAR Attribute_Definition: Percent (in decimal form) of the vegetated portion of the marsh unit that contains hydro-flattened bathymetric/elevation values. If there is no vegetated area in the marsh unit, the value is set to -9999. Attribute_Definition_Source: USGS Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 0 Range_Domain_Maximum: 1 Attribute_Units_of_Measure: none Attribute: Attribute_Label: SKWNSS Attribute_Definition: The measure of skewness of the elevation distribution in the vegetated part of a marsh unit. Positive skewness values (i.e., right-skewed distribution) indicate clustering of elevation distribution towards lower elevations. Negative values (left-skewed distribution) indicate clustering towards higher elevations. A value of -9999 indicates no vegetated area within the marsh unit or no elevation value for the vegetated portion. Attribute_Definition_Source: USGS Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: -13.06939983 Range_Domain_Maximum: 7.72143984 Attribute_Units_of_Measure: none Attribute: Attribute_Label: LOW3RD Attribute_Definition: LOW3RD is the percent of elevation values that fall within the lowest third of the elevation range within the vegetated part of a marsh unit. Value of -9999 indicates no vegetated area within the marsh unit or no elevation value for the vegetated portion. Attribute_Definition_Source: USGS Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 0.00121887 Range_Domain_Maximum: 99.76370239 Attribute_Units_of_Measure: none Attribute: Attribute_Label: FLG Attribute_Definition: Marsh unit flag indicating anomalous marsh units based on absence of vegetation, elevation, surface area and tidal range extrapolation. FLG values indicate: (-1) no vegetated area in the marsh unit; (-10) marsh unit elevation higher than the 99.8 percentile; (-100) marsh unit elevation less than the 0.2 percentile; (-200) greater than 25 percent of the marsh unit elevation is hydro-flattened; (-1000) marsh unit surface area less than 900 m^2; (-10000) mean tidal range of marsh unit is extrapolated; and (0) no flag. Combination of negative values indicates a combination of flags. For example, -1001 indicates no vegetated area and area less than 900 m^2. Attribute_Definition_Source: USGS Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: -11100 Range_Domain_Maximum: 0 Attribute_Units_of_Measure: none Overview_Description: Entity_and_Attribute_Overview: In this dataset, mean elevation for each conceptual salt marsh unit in the Eastern Shore of Virginia salt marshes has been calculated based primarily on the 1-meter 2015 USGS Lidar DEM source dataset. Decimal values in the attribute table are a result of double precision calculations while significant digits are considered in defining the attribute measurement resolutions. Therefore, the smallest unit increment for area and elevation values is assumed to be 1 meter and 0.01 meter, respectively. Entity_and_Attribute_Detail_Citation: USGS Distribution_Information: Distributor: Contact_Information: Contact_Organization_Primary: Contact_Organization: U.S. Geological Survey - ScienceBase Contact_Address: Address_Type: mailing and physical address Address: Denver Federal Center, Building 810, Mail Stop 302 City: Denver State_or_Province: CO Postal_Code: 80225 Contact_Voice_Telephone: 1-888-275-8747 Contact_Electronic_Mail_Address: sciencebase@usgs.gov Resource_Description: mu_elev_ESV.zip (ZIP file contains the shapefile mu_elev_ESV.shp and the additional shapefile components), browse graphic (Elev_ESV_Browse.png), and FGDC CSDGM metadata in xml format. Distribution_Liability: Although these data have been processed successfully on a computer system at the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. The USGS or the U.S. Government shall not be held liable for improper or incorrect use of the data described and/or contained herein. Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Not for navigational use. Standard_Order_Process: Digital_Form: Digital_Transfer_Information: Format_Name: shapefile Format_Version_Number: ArcGIS Pro 2.8.8 Format_Information_Content: This dataset contains a polygon shapefile and its components and metadata in xml format. Transfer_Size: 27 Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: https://www.sciencebase.gov/catalog/file/get/63e53993d34efa0476ade042 Network_Resource_Name: https://www.sciencebase.gov/catalog/item/63e53993d34efa0476ade042 Network_Resource_Name: https://doi.org/10.5066/P9E6V0QK Access_Instructions: The first link in network resources is to download data directly. The second link points to a landing page with metadata and data. The third link is to the main page of the data release. Digital_Form: Digital_Transfer_Information: Format_Name: WMS Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: https://www.sciencebase.gov/catalogMaps/mapping/ows/63e53993d34efa0476ade042?service=wms&request=getcapabilities&version=1.3.0 Access_Instructions: The link in network resources points to the Web Mapping Services (WMS) end point. Digital_Form: Digital_Transfer_Information: Format_Name: WFS Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: https://www.sciencebase.gov/catalogMaps/mapping/ows/63e53993d34efa0476ade042?service=wfs&request=getcapabilities&version=1.0.0 Access_Instructions: The link in network resources points to the Web Feature Service (WFS) end point. Fees: None. No fees are applicable for obtaining the dataset. Metadata_Reference_Information: Metadata_Date: 20230329 Metadata_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Kate V. Ackerman Contact_Organization: U.S. Geological Survey Contact_Position: Geologist Contact_Address: Address_Type: mailing address Address: 384 Woods Hole Rd City: Woods Hole State_or_Province: MA Postal_Code: 02543 Country: US Contact_Voice_Telephone: 508-548-8700 x2331 Contact_Facsimile_Telephone: 508-457-2310 Contact_Electronic_Mail_Address: whsc_data_contact@usgs.gov Contact_Instructions: The metadata contact email address is a generic address in the event the person is no longer with USGS. Metadata_Standard_Name: Content Standard for Digital Geospatial Metadata Metadata_Standard_Version: FGDC-STD-001-1998