To quantify rates of change (erosion or accretion) along coastal and estuarine shorelines in Maryland, the Maryland Geological Survey (MGS), in conjunction with Towson University's Center for Geographic Information Sciences (CGIS) and the U.S. Geological Survey (USGS), installed and ran a computer program, the Digital Shoreline Analysis System (DSAS), using as input a series of digital shoreline vectors dating from 1841-1995. Shorelines were derived from three sources: (1) maps from a Historical Shorelines and Erosion Rates Atlas (Conkwright, 1975), (2) Coastal Survey maps (topographic or T-sheets) produced by the National Ocean Service (NOS), a branch of the National Oceanic and Atmospheric Administration (NOAA), and (3) a digital wetlands delineation based on photo interpretation of digital orthophoto quarter quads. DSAS constructed a "baseline" landward of and approximately parallel to the shorelines, inserted nodes every 20 m along the baseline, and cast straight-line transects from each node, perpendicular to the baseline, across the shorelines. Based on the time elapsed and the along-transect distance between shoreline pairs, DSAS calculated rates of change for each transect.Subsequently, updates began in 2015 is updating by county the DSAS process using newer Shoreline data and refined calculations to update the Rates of Change erosion values by county. Currently Anne Arundel, Baltimore, Calvert, Harford and Prince George's counties have the newest erosion rate values contained in this Data set.Funding for this data set was provided by two Projects of Special Merit (CZM # 14-14-1868 CZM 143 and CZM # 14-15-2005 CZM 143), funded by the National Oceanic and Atmospheric Administration (NOAA) and made available to MGS through the Department of Natural Resources (MD DNR) Chesapeake and Coastal Service (CCS). MGS wishes to thank the following project partners: 1) MD DNR CCS, Contact: Mr. Chris Cortina, Role: CCS Project Manager; 2) NOAA, Contact: Mr. Doug Graham, NOAA National Geodetic Survey, Role: Project partner & source of historical and recent shorelines; 3) MD DNR Critical Areas Commission (CAC), Contact: Ms. Lisa Hoerger, Role: Project partner & source of recent shorelines; 4) Eastern Shore Regional GIS Cooperative (ESRGC), Salisbury University, Contact: Ryan Mello, Role: Performing the critical area re-mapping for MD DNR CAC and supplying MGS with CAC shorelines; and 5) Ms. Lamere Hennesse, MGS Geologist, retired, Role: Project guidance & technical support.The views expressed herein are those of the authors and do not necessarily reflect the views of the National Oceanic and Atmospheric Administration (NOAA) or any of its sub-agencies. These transects were created for the sole purpose of calculating shoreline rates of change information.This is a MD iMAP hosted service layer. Find more information athttps://imap.maryland.gov.Feature Service Layer Link:https://geodata.md.gov/imap/rest/services/Hydrology/MD_ShorelineChanges/MapServer/0
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