MD iMAP: Maryland Shoreline Changes - Baseline

This is a MD iMAP hosted service layer. Find more information at http://imap.maryland.gov. In 2000 -  the Maryland Geological Survey (MGS) was awarded a Coastal Zone Management grant to complete the acquisition of a recent (ca. 1990) digital shoreline for the coastal regions of Maryland -- the Chesapeake Bay -  its tributaries -  the coastal bays -  and the Atlantic coast. MGS contracted the services of EarthData International -  Inc. (EDI) -  currently of Frederick -  Md. -  to extract shorelines from an existing wetlands delineation -  which was based on photo interpretation of 3.75-minute digital orthophoto quarter quads (DOQQs). In areas where a wetlands coverage was not yet available -  EDI interpreted shorelines directly from the orthophotography. DOQQ registration (Maryland State Plane Coordinate System -  NAD 83 -  meters) was transferred automatically to the shoreline vectors. Following shoreline extraction or interpretation -  EDI assigned attributes to the vectors based on shoreline type: beach -  vegetated -  structure -  or water's edge. All four categories are linear features -  except 'beach - ' which -  if sufficiently wide -  can be both linear and polygonal. Shorelines were merged into 7.5-minute quadrangles -  provided that the aerial photography on which the DOQQs were based was flown in the same year. MGS used the shorelines to create a series of Shoreline Changes maps. In doing so -  MGS erased the landward edge of beach polygons -  leaving the seaward edge intact as a linear feature. The Geographic Information Services Division of the Maryland Department of Natural Resources (DNR) merged the shorelines for all of the 7.5-minute quadrangles into a single -  statewide coverage. MGS -  working collaboratively with Towson University's Center for Geographic Sciences (CGIS) -  subsequently used the recent shorelines -  along with historical ones -  as input into a U.S. Geological Survey (USGS) program -  the Digital Shoreline Analysis System (DSAS) (Danforth and Thieler -  1992; Thieler and others -  2001). DSAS determines linear rates of shoreline change (erosion or accretion) along closely spaced -  shore-normal transects. Based on DSAS output -  the collaborators assigned the following erosion rate categories as attributes to the recent shoreline -  clipped by county from the statewide coverage: a) High erosion rate (more than 8 ft/yr) -  b) Moderate erosion rate (4-8 ft/yr) -  c) Low erosion rate (2-4 ft/yr) -  d) Slight erosion rate (0-2 ft/yr) -  e) No change -  f) Accretion -  g) Protected -  h) Unknown and i) No Data 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. See Horizontal Positional Accuracy Report for positional inaccuracies in the data set. The aerial photography from which the DOQQs were developed was not tide-coordinated. Therefore -  shoreline in this data set do not reprsent a consistent vertical datum. Last Updated:  Feature Service Layer Link: https://mdgeodata.md.gov/imap/rest/services/Hydrology/MD_ShorelineChanges/MapServer ADDITIONAL LICENSE TERMS: The Spatial Data and the information therein (collectively "the Data") is provided "as is" without warranty of any kind either expressed implied or statutory. The user assumes the entire risk as to quality and performance of the Data. No guarantee of accuracy is granted nor is any responsibility for reliance thereon assumed. In no event shall the State of Maryland be liable for direct indirect incidental consequential or special damages of any kind. The State of Maryland does not accept liability for any damages or misrepresentation caused by inaccuracies in the Data or as a result to changes to the Data nor is there responsib

Tags: baseline, department-of-natural-resources, dnr, dynamic, historic, hydr, hydrology, kml, maryland, maryland-geological-survey, md, md-imap, mgs, shoreline-changes, shorelines, transects, vector, wfs, wms
Organization: State of Maryland