In early 2014, topographic LiDAR was collected for the entire state of Delaware through a collaboration between the USGS, Delaware Geological Survey (DGS), Department of Natural Resources and Environmental Control (DNREC), and Delaware Department of Transportation (DelDOT), funded through the Hurricane Sandy Supplemental Fund. The state-wide LiDAR data has a RMSEz of 6.3 cm in open terrain. From these data, a seamless, statewide 1-meter, hydro-flattened, bare earth digital elevation model (DEM) was produced. This topographic DEM was used to develop new bathtub-model coastal inundation maps for the state of Delaware. Inundation maps correspond to inundatation scenarios and include surfaces from Mean Higher-High Water (MHHW) to 7 feet above MHHW, in 1-foot increments. These maps will help assess the potential impacts of sea-level rise and advise long-range planning of infrastructure, facilities, land management, land use, and capital spending.
Improving geospatial knowledge - Professors launch DelawareView to improve public access to remote sensing and geospatial data
The Delaware Geological Survey Cartographic Information Center has made the DGS a focal point for questions concerning the availability of all types of aerial photography, thematic maps, planimetric maps, topographic maps, historic maps, LANDSAT imagery, space imagery, side looking aerial radar imagery (SLAR), and geodetic control. Sources of maps, charts, aerial photography, boundary mark information, and vertical geodetic control can be obtained for your area of interest within the State through the Center's computer-searchable data bases. In addition, through the Center's affiliation with the U. S. Geological Survey's National Cartographic Information Center (NCIC) in Reston, Virginia, we can locate all cartographic materials covering the United States produced by federal agencies.
One hundred seventy-nine monuments help to mark Delaware's boundaries with Maryland, Pennsylvania, and New Jersey. Although there are only four major boundaries, there are seven boundary lines that make up the confines of the State. They are the east-west boundary, or Transpeninsular Line; the north-south boundary, or the Tangent Line, Arc, and North lines;; the Delaware-Pennsylvania boundary, including the Top of the Wedge Line and the 12-mile Circle; and the Delaware-New Jersey boundary including the 1934 Mean Low Water Line and the Delaware Bay Line. Only the Transpeninsular, Tangent, Arc, North, 12-mile Circle, and 1934 Mean Low Water lines are monumented. The Delaware Bay Line is defined by the navigational
channel. The boundaries described here evolved through long, complex histories (see references). They are based largely on adjudication in England of conflicting claims by the Penns and the Calverts for the Pennsylvania and Maryland colonies.
In the same ways as our printed publications, digital data released by the DGS represent the results of original professional research and as such are used by professionals and the public.
RI74 Locating Ground-Water Discharge Areas in Rehoboth and Indian River Bays and Indian River, Delaware Using Landsat 7 Imagery
Delaware’s Inland Bays in southeastern Sussex County are valuable natural resources that have been experiencing environmental degradation since the late 1960s. Stresses on the water resource include land use practices, modifications of surface drainage, ground-water pumping, and wastewater disposal. One of the primary environmental problems in the Inland Bays is nutrient over-enrichment. Nitrogen and phosphorous loads are delivered to the bays by ground water, surface water, and air. Nitrogen loading from ground-water discharge is one of the most difficult to quantify; therefore, locating these discharge areas is a critical step toward mitigating this load to the bays. Landsat 7 imagery was used to identify ground-water discharge areas in Indian River and Rehoboth and Indian River bays in Sussex County, Delaware. Panchromatic, near-infrared, and thermal bands were used to identify ice patterns and temperature differences in the surface water, which are indicative of ground-water discharge. Defining a shoreline specific to each image was critical in order to eliminate areas of the bays that were not representative of open water. Atmospheric correction was not necessary due to low humidity conditions during image acquisition. Ground-water discharge locations were identified on the north shore of Rehoboth Bay (west of the Lewes and Rehoboth Canal), Herring and Guinea creeks, the north shore of Indian River, and the north shore of Indian River Bay near Oak Orchard.
Digital watershed and bay polygons for use in geographic information systems were created for Rehoboth Bay, Indian River, and Indian River Bay in southeastern Delaware. Polygons were created using a hierarchical classification scheme and a consistent, documented methodology that enables unambiguous calculations of watershed and bay surface areas within a geographic information system. The watershed boundaries were delineated on 1:24,000-scale topographic maps. The resultant polygons represent the entire watersheds for these water bodies, with four hierarchical levels based on surface area. Bay boundaries were delineated by adding attributes to existing polygons representing water and marsh in U.S. Geological Survey Digital Line Graphs of 1:24,000-scale topographic maps and by dissolving the boundaries between polygons with similar attributes. The hierarchy of bays incorporates three different definitions of the coastline: the boundary between open water and land, a simplified version of that boundary, and the upland-lowland boundary. The polygon layers are supplied in a geodatabase format.
The Delaware Geological Survey (DGS) is a science-based, public-service-driven Delaware state agency at the University of Delaware (UD) that conducts geologic and hydrologic research, service, and exploration for the benefit of the citizens of the First State. The mission of the DGS is to provide objective earth science information, advice, and service to its stakeholders, the citizens, policy makers, industries, and educational institutions of Delaware.