This coastal wetlands data set reclassifies wetlands data from the Maryland Department of Natural Resources (DNR) and the National Wetlands Inventory (NWI) within the coastal zone of Maryland. We used the DNR data wherever it was available, and the NWI data elsewhere. Within the attribute table under the field titled "CODE", 1. TO represents tidal open water (includes mudflats) 2. TW represents tidal wetlands 3. NO represents non-tidal open water 4. NW represents non-tidal wetlands 5. UP represents dry land The dataset covers coastal Maryland. Files associated with this data set should include: 1. README_MD_Elevation.doc, which provides a brief overview of the relationship between this dataset and related data 2. Classification_of_Coastal_Wetlands.doc 3. Maryland_DNR_Wetland_Data_Coverage.jpg
1. To be used along with the outside-of-study-area (md_out_of_study_area.shp) as an overlay to the Maryland sea level rise planning study's shore protection scenario data set, either for creating for maps or calculating statistics. The sea level rise planning study examined only land that is either below the 20-ft contour or within 1,000 feet of the shore. Any shore protection attribute values for lands that are either wetlands, open water, or land above the 20 ft NGVD contour may be misleading or wrong, and have not been reviewed. Therefore, some sort of "wetland mask" and "out of study area mask" must always be used with the Maryland shore protection data set. 2. To be used along with the Maryland Elevation Data to display wetlands and water in elevation maps of lands close to sea level. The DEM provides "no data" (-9999) for all cells that are either open water or tidal wetlands.
ground condition
1310 L Street, NW
US Environmental Protection Agency
The underlying data used in the creation of this layer may contain errors or omissions. Attribute errors may have resulted from errors in the creation of the underlying (NWI) data, or from how we classified the various types of wetlands. Errors in Underlying Data. Common errors in the underlying DNR and NWI data include changes since the imagery was collected, including: a. Rising sea level may have converted dry land to tidal wetlands b. Rising sea level and other processes may have eroded dry land or tidal wetlands, converting it to open water c. Nontidal wetlands may have been drained or filled for development. In addition, the NWI assessments often miss relatively small areas, such as the heads of creeks. Errors in how we classified wetlands. There is little doubt that we were correct in treating some NWI categories (such as marine intertidal and estuarine intertidal wetlands) as tidal wetlands. However, other categories that we identified as subtidal (e.g. mudflats) might be properly considered intertidal for some purposes. Some of the lacustrine and palustrine wetlands in relatively obscure tidal regimes (e.g. tidal, irregularly flooded) may provide an upper tidal wetland boundary that diverges from the "spring high water" elevation we sought. Some classifications of open water may be partly tidal and partly subtidal. In cases where a particular vegetation type may be found in both tidal and nontidal wetlands, our site-specific procedure of classifying wetlands along a tidal river as tidal wetlands may overlook the presence of a dike.
Commensurate with source data sets
Commensurate with source data sets
Commensurate with source data sets
Spatial and attribute data
Spatial and attribute data
We imported the DNR and NWI data into an ArcInfo coverage format
We projected the datasets into Albers projection.
Both DNR and NWI dataset adopted NWI Wetland and Deepwater Habitat Classification. We reclassified the dataset into tidal open water, tidal wetland, non-tidal open water, non-tidal wetland, and dry land according to system, subsystem, class, and water regime modifiers in the classification. For a table that shows the relationship between the DNR and NWI classes and our five classes, please see Classification_of Coastal_Wetlands.doc, which is included in the zip file in which this data is distributed. The following explanation uses prose to convey the same information. 1. Tidal Open water consists of marine, estuarine, riverine, palustrine, and lacustrine open water influenced by tide. In our reclassification, open water consists of (A) subtidal subsystems in marine and estuarine systems; (B) aquatic bed, reef, and streambed in the intertidal subsystem of the Marine and Estuarine system; (C) tidal rivers in riverine systems; and (D) the rocky bottom, unsolicited bottom, aquatic bed, and open water classes with tidal water regimes in palustrine and lacustrine systems. 2. Tidal wetlands consist of both salt tolerant wetlands and tidal freshwater wetlands. In our reclassification, tidal wetlands are (A) rocky shore, unconsolidated shore, emergent, scrub-shrub, and forested in the intertidal subsystems in marine and estuarine systems; (B the rocky shore, unconsolidated shore, Moss-Lichen, emergent, scrub-shrub, and forested classes with tidal water regimes in palustrine and lacustrine systems. 3. Non-tidal Open Water consists of riverine, lacustrine, and palustrine open water that are not influenced by the tides. In our reclassification, non-tidal open water is (A) the rock bottom, unconsolidated bottom, aquatic bed, and open water classes in riverine systems (except tidal rivers); and (B) the rock bottom, unconsolidated bottom, aquatic bed, and open water classes with non-tidal water regimes in lacustrine and palustrine systems. 4. Non-tidal Wetlands consist of riverine, lacustrine, and palustrine wetlands that are not influenced by tides. In our reclassification, non-tidal wetlands are (A) the rocky shore, unconsolidated shore, and emergent classes in riverine systems (except tidal rivers); and (B) the rocky shore, unconsolidated shore, emergent, scrub-shrub, and forested classes with non-tidal water regimes in palustrine and lacustrine systems. 5. We treated all other attributes as dry land. A few types of attributes required site-specific inspection. Please see Classification_of_Coastal_Wetlands.doc for details. This dataset covers eastern Maryland.
We combined both DNR and NWI wetland datasets together, where the DNR data take precedence where available. See Maryland_DNR_Wetland_Data_Coverage.jpg, which is included in the zip file in which this data is distributed
We converted the wetland polygons into raster format (30 meters) and aligned to the elevation dataset.
Integer value of wetland type
ICF
Tidal Open Water, including saline and fresh water
ICF
Tidal Wetlands, including salt marsh and tidal freshwater wetlands
ICF
Non-tidal Open Water, including lakes, ponds, reservoirs, and other non-tidal bodies of water
ICF
Non-tidal Wetlands, including all wetlands other than tidal wetlands
ICF
Dry Lands
ICF
Internal feature number.
ESRI
Number of cells of Value field
ESRI
Wetland code
ICF
Tidal Open Water, including saline and fresh water
ICF
Tidal Wetlands, including salt marsh and tidal freshwater wetlands
ICF
Non-tidal Open Water, including lakes, ponds, reservoirs, and other non-tidal bodies of water
ICF
Non-tidal Wetlands, including all wetlands other than tidal wetlands
ICF
Dry Lands
ICF
Includes: TO - Tidal Open Water TW - Tidal Wetlands NO - Non-tidal Open Water NW - Non-tidal Wetlands UP - Uplands
USEPA (6207-J)
1200 Pennsylvania Ave. NW
Although this data was created under the direction of the EPA, no warranty expressed or implied is made regarding the accuracy or utility of the data. Neither EPA nor the data developers shall be held liable for any use of the data and information described and/or contained herein.
Data available Alan Cohn at 202-343-9814.
1881 9th St. Suite 201 (Jones)