High erosion rate (more than 8 ft/yr) Moderate erosion rate (4-8 ft/yr) Low erosion rate (2-4 ft/yr) Slight erosion rate (0-2 ft/yr) No change Accretion Protected Unknown No DataThe data set contains recent shoreline vectors for sixteen coastal counties and Baltimore City (see Appendix 1), assigned both shoreline type and erosion rate attributes. The vectors represent shoreline positions between the years 1988 and 1995. The metadata was originally written to document the recent shoreline vectors, interpreted, directly or indirectly, from DOQQs and merged by 7.5-minute quadrangle. It was amended to include information about the erosion rate attributes later assigned to the county shorelines.
Maryland Department of Natural , Chesapeake Bay & Watershed Programs, Resou, 2003, QueenAnne.shp:Recent (1988-1995) Maryland Shorelines with Erosion Rate Attributes specifically for Queen Anne County: Maryland Department of Natural Resources, Chesapeake Bay & Watershed Programs, Resource Assessment Service, Maryland Geological Survey (MGS), Baltimore, Maryland, USA.Online Links:
This is a Vector data set. It contains the following vector data types (SDTS terminology):
Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.000000. Longitudes are given to the nearest 0.000000. Latitude and longitude values are specified in Decimal degrees.
The horizontal datum used is North American Datum of 1983.
The ellipsoid used is Geodetic Reference System 80.
The semi-major axis of the ellipsoid used is 6378137.000000.
The flattening of the ellipsoid used is 1/298.257222.
Sequential unique whole numbers that are automatically generated.
Coordinates defining the features.
| Value | Definition |
|---|---|
| beach | Any sandy beach-like area, not including mud flats. All beaches on this CD-ROM are linear features. Originally, very narrow beaches were represented as linear features; wider beaches were represented as both lines and polygons. For this exercise, the landward edge of beach polygons was erased, leaving a line that represents the land/water boundary. |
| structure | Any type of manmade object that serves as the land/water boundary. Structures include, but are not limited to, bulkheads, seawalls, and riprap. |
| vegetated | Any portion of shoreline with vegetation, such as marsh, forest, or cropland, as the dominant land cover. |
| waters edge | Any reach of shoreline that does not qualify as beach, structure, or vegetated. This may include mud flats. |
| unclassified | Used to identify the DOQQ tile boundary line. Also used to identify the large polygon(s) enclosed by the DOQQ tile boundary line. |
Partial funding for this data set was provided by the National Oceanic and Atmospheric Administration (NOAA) and made available through the Maryland Coastal Zone Management Program of the Department of Natural Resources (CZM). In particular, shorelines were extracted or photo interpreted under NOAA Award No. NA87OZ0236, CZM Grant M00-050 CZM 031; erosion rate attributes were assigned under NOAA Award No. NA17OZ1124, CZM Grant 14-03-891 CZM 046. The views expressed herein are those of the authors and do not necessarily reflect the views of NOAA or any of its sub-agencies.
(410) 554-5519 (voice)
(410) 554-5502 (FAX)
lhennessee@dnr.state.md.us
This data set complements a set of historical digital shorelines for the Maryland reaches of the Chesapeake Bay, the coastal bays, and the Atlantic coast. That data set spans the period 1841-1977. The two data sets are being used to update a series of Shoreline Changes maps and to determine coastal land loss during the last half of the 20th century. Other State agencies will be able to use this data to analyze and update land loss information, analyze historical erosion trends, and assess the extent and magnitude of shore erosion on a regional geographic basis. In particular, the availability of up-to-date shoreline change data will support the design and implementation of shore protection projects and the development of a comprehensive shore erosion control plan.
Maryland Department of Natural , Chesapeake and Coastal Watershed Service, , 1988-1995, Digital Orthophoto Quarter Quads (DOQQs): Maryland Department of Natural Resources, Chesapeake and Coastal Watershed Service, Geographic Information Services Division, Annapolis, Maryland, USA.
Maryland Department of Natural , Chesapeake and Coastal Watershed Service, , 1988-1995, Maryland DNR Wetlands Inventory: Maryland Department of Natural Resources, Chesapeake and Coastal Watershed Service, Geographic Information Services Division, Annapolis, Maryland, USA.
Maryland Department of Natural , Chesapeake Bay & Watershed Programs, Resou, Determining Shoreline Erosion Rates for the Coastal Regions of Maryland (Part 2): Maryland Department of Natural Resources, Chesapeake Bay & Watershed Programs, Resource Assessment Service, Maryland Geological Survey (MGS), Baltimore, Maryland, USA.
Person who carried out this activity:
(301) 948-8550 (voice)
(301) 963-2064 (FAX)
<http://www.earthdata.com>
1. Color-coding transects according to previously established rate-of-change categories: High - High erosion rate (more than 8 ft/yr) Moderate - Moderate erosion rate (4-8 ft/yr) Low - Low erosion rate (2-4 ft/yr) Slight - Slight erosion rate (0-2 ft/yr) Accretion 2. Visually grouping similarly colored transects, 3. Inserting nodes between transects that differed in color, and 4. Assigning the appropriate classification code to the shoreline reach.The rules that CGIS followed in the process are described in Completeness Report.
Person who carried out this activity:
(410) 704-3887 (voice)
(410) 704-3888 (FAX)
Person who carried out this activity:
(508) 548-8700 x2251 (voice)
(508) 457-2310 (FAX)
vatnipp@usgs.gov
Person who carried out this activity:
(508) 548-8700 x2251 (voice)
(508) 457-2310 (FAX)
vatnipp@usgs.gov
Data sources produced in this process:
Person who carried out this activity:
(508) 548-8700 x2251 (voice)
(508) 457-2310 (FAX)
vatnipp@usgs.gov
Data sources produced in this process:
Survey, Maryland Geological , 2003, Determining Shoreline Erosion Rates for the Coastal Regions of Maryland (Part 2): Maryland Geological Survey, Baltimore, Maryland, USA.
Survey, Maryland Geological , 2000, Historical Shorelines, 1841-1976: Chesapeake Bay Region of Maryland: Maryland Geological Survey, Baltimore, Maryland, USA.
Survey, Maryland Geological , 2001, Shoreline Changes maps: Maryland Geological Survey, Baltimore, Maryland, USA.
Accuracy of the shoreline type attributes was not assessed. CGIS checked the accuracy of the erosion rate classification by displaying both the shore-normal transects and the shoreline, color-coded, respectively, by erosion rate (ft/yr) and erosion rate category (high, moderate, low, etc.). If the color of the transects matched the color of the associated shoreline segment, CGIS accepted the erosion rate classification. Otherwise, CGIS changed the classification.
The DOQQs meet National Map Accuracy Standards at the production scale of 1:12,000, using the American Society for Photogrammetry and Remote Sensing (ASPRS) method. The contractor who produced the DOQQs provided a detailed aerotriangulation report for each production area. The production of accurately georeferenced DOQQs depends on sufficient ground control. In open water, ground control is necessarily lacking, because land areas, if they exist at all, are small and/or inaccessible. Two quarter quads in the data set, Deal Island NW and Barren Island NE, contain so much open water that they are not properly tied to the adjoining tiles, Nanticoke SW and Honga NW, respectively. Consequently, the corresponding linework (shoreline) is not properly georeferenced. The shorelines derived from those two DOQQs are included in the data set solely for the associated attribute (shoreline type) information. Their positions are inaccurate.
The area covered includes 125 7.5-minute quadrangles lying at least partially within Baltimore City or one of the 16 coastal counties of Maryland. Shorelines located in out-of-state areas, such as the Virginia side of the Potomac River, were excluded. In digitizing historical shorelines from hard copy maps, MGS had adopted an operational definition of the headward extent of a stream - the point at which the stream was represented on the map by a single line rather than a double line delineating opposite stream banks. That point, dependent as it is on the scale of the map, does not necessarily represent the head of tide. A similar criterion was used in extracting the 1990 shoreline. To the extent that the contractor could fit a double line on photography displayed at a scale of 1:24,000, the shoreline was extracted. Reaches upstream of that point were excluded. Again, the headward extent of a digitized stream does not necessarily correspond with head of tide. Shorelines in the 1990 data set bounded several different wetlands classifications (Cowardin et al., 1979):
1. E 1 UB L (Estuarine -- Subtidal -- Unconsolidated bottom -- Subtidal) 2. E 2 US M (Estuarine -- Intertidal -- Unconsolidated shore -- Irregularly exposed) 3. E 2 US N (Estuarine -- Intertidal -- Unconsolidated shore -- Regularly flooded) 4. E 2 US P (Estuarine -- Intertidal -- Unconsolidated shore -- Irregularly flooded) 5. M 2 US M (Marine -- Intertidal -- Unconsolidated shore -- Irregularly exposed) 6. M 2 US N (Marine -- Intertidal -- Unconsolidated shore -- Regularly flooded) 7. R 1 UB V (Riverine -- Tidal -- Unconsolidated bottom -- Permanent tidal (tidally influenced, freshwater system) 8. R 2 UB 8 -- (Riverine -- Lower perennial -- Unconsolidated bottom -- Eusaline)In addition to designating UB L and UB V as water, M 2 or E 2 US (Unconsolidated shore) M (Irregularly flooded) or N (Regularly flooded) classifications were considered water, given that those areas were more likely to be under water than above. E 2 US P (Irregularly flooded) was considered upland, given that those areas were more likely to be above water than under. In assigning rate-of-change attributes, MGS and CGIS devised and applied a number of rules, which are summarized below:
Classify shoreline segments of the shoreline type "structure" as "protected." When adding nodes to distinguish between shoreline reaches with different rates of change, insert nodes only after the occurrence of a series of four or more similarly colored transects. For example, along an extensive reach that has experienced moderate rates of erosion, interrupted by two adjacent transects characterized by high erosion rates, classify the entire stretch of shoreline as "moderate." If, instead of two high-rate transects, six high-rate transects occur in a row, insert nodes on either side of the six transects, and classify that shoreline reach as "high." If shorelines are so complex that it is difficult to distinguish between the two shoreline years or to see that they are properly positioned, assign the erosion rate category "Unknown." This problem is particularly common in marshy areas and/or along minor tributaries of dubious positional accuracy. A common manifestation of the latter is that one bank of the tributary is erosional along its entire length, while the opposite bank is accretional. For reaches lacking transects, estimate rates based on the relative positions of the two shorelines. This situation is common along points of land projecting into the water. Classify stretches represented by a single shoreline as "No Data." If the two shorelines interweave over an extended reach, with little lateral displacement, classify the stretch as "No Change."
EDI checked logical consistency through a series of quality assurance/quality control (QA/QC) procedures, reported in Section 2.5.2 Process Step (interpretation/extraction of shorelines).
Are there legal restrictions on access or use of the data?
- Access_Constraints: None.
- Use_Constraints:
- The DOQQs from which the shorelines were interpreted meet National Map Accuracy Standards at the production scale of 1:12,000 using the American Society for Photogrammetry and Remote Sensing (ASPRS) method. Consider the scale in displaying and using the vectors. Displaying the vectors at scales larger than those of the source documents is considered bad practice. The aerial photography from which the DOQQs were developed was not tide-coordinated. Therefore, shorelines in this data set do not represent a consistent vertical datum.
Downloadable Data
| Data format: | Size: 1.533 |
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(410) 554-5519 (voice)
(410) 554-5502 (FAX)
lhennessee@dnr.state.md.us
