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.
Elevation contours at 2 foot intervals for the State of Delaware were produced for New Castle and Kent Counties based on the 2007 LIDAR) and for Sussex County (based on the 2005 LIDAR.) Data are in line shapefile format.
To conduct an elevation survey, a surveyor needs a starting point for which the exact elevation above mean sea level is known. These starting points are called benchmarks. State and federal agencies install benchmarks throughout every State, creating a network of elevation points which covers the entire continental United States. These benchmarks are considered to be permanent, and usually consist of a brass, bronze, or aluminum disc about 4 inches in diameter mounted in a cement post or in a drill hole in a permanent foundation. Each benchmark also has the installing agency's name and an identification number stamped into it. In December of 1980 the Federal Emergency Management Agency (FEMA) allotted the State of Delaware funds to determine the number and condition of federal benchmarks and other elevation reference control points. The National Flood Insurance Program (NFIP), contained within FEMA, requires accurate flood surveys of property in flood-prone areas. An extensive and accurate benchmark network throughout the State is needed to help meet these needs.