USGS 3D Elevation Program Supports Science Activities in the Chesapeake Watershed

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Increased acquisition of lidar in the Chesapeake Watershed

The Chesapeake Bay Program has a critical need for enhanced land cover and land-use information to better inform restoration and conservation efforts throughout the watershed. An important component of land information is more detailed land elevation data, which are collected using lidar (light detection and ranging), a remote sensing method that uses light in the form of a pulsed laser to measure ranges (variable distances) to the Earth.

The U.S. Geological Survey (USGS), through the 3D Elevation Program (3DEP), has partnered with other agencies to increase lidar acquisition in the Chesapeake watershed during 2017.

  • The USGS partnered with the National Resources Conservation Service (NRCS) to collect new information for the central portion of PA (counties identified on map), where there is a concentrated amount of agricultural lands. The lidar will help NRCS and Pennsylvania manage efforts to implement conservation practices to improve water quality in local streams and the Chesapeake Bay. The USGS works closely with the Pennsylvania lidar work group, which is led by the Topographic and Geologic Survey, a Bureau of the Department of Conservation and Natural Resources, to gather requirements and coordinate efforts for the Susquehanna Basin and other portions of the Commonwealth.
  • Earlier in 2017 acquisition was started in the James River watershed and upper Potomac watershed areas in Virginia and West Virginia supported by 3DEP partner Federal Emergency Management Agency and NRCS. These acquisition and data processing activities are continuing into the 2018 leaf-off season.

Applying lidar to improve restoration and conservation

USGS scientists, working with partners, are using LIDAR data in the Chesapeake watershed to:

  • Improve land cover information, needed to better understand water-quality conditions, forest and farm distributions, and protecting vital lands and healthy watersheds.
  • Characterize stream channel conditions, which is needed to understand their ability to support fish populations, and help target stream restoration practices.
  • Assess coastal wetlands and their vulnerability to sea-level rise.

USGS leads partnership to coordinate lidar acquisition

The collection of topographic lidar data is coordinated by the USGS, through the 3DEP, and is a partnership with 16 Federal Agencies, states, and other interested groups. Since 2014 there has been a national effort focused on acquiring LIDAR meeting QL2 specifications at a minimum in all areas of the U.S. other than Alaska. NOAA coordinates the collection of Topo/Bathometric lidar, which is focused on tidal waterways and is used to revise navigational charts.

Lidar has been collected in the Chesapeake Bay watershed since 2005 (see map below) and the quality has improved over time as technology has advanced. There are three quality levels available in the Bay watershed, initial lidar (shown in yellow on the map) has a Quality Level 3 (QL3), which provides vertical resolution of 18.5cm, QL2 (green color) and provides 10cm vertical resolution, and QL1 is the most detailed elevation data which collects 4 times the point density of QL2 data.

December 2017 Chesapeake Bay Watershed Lidar Data by County

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