A first-surface topography Digital Elevation Model (DEM) mosaic for the Canyonlands and Upper Neches River Corridor Units of Big Thicket National Preserve in Texas was produced from remotely sensed, geographically referenced elevation measurements collected on January 11, 15, 17, 18, 21, 23, 25, and 29, 2014 by the U.S. Geological Survey, in cooperation with the National Park Service - Gulf Coast Network. Elevation measurements were collected over the area using the second-generation Experimental Advanced Airborne Research Lidar (EAARL-B), a pulsed laser ranging system mounted onboard an aircraft to measure ground elevation, vegetation canopy, and coastal topography. The system uses high-frequency laser beams directed at the Earth's surface through an opening in the bottom of the aircraft's fuselage. The laser system records the time difference between emission of the laser beam and the reception of the reflected laser signal in the aircraft. The plane travels over the target area at approximately 55 meters per second at an elevation of approximately 300 meters, resulting in a laser swath of approximately 240 meters with an average point density of 1.4 points per square meter. A peak sampling rate of 15-30 kilohertz results in an extremely dense spatial elevation dataset. More than 100 kilometers of coastline can be surveyed easily within a 3- to 4-hour mission. When resultant elevation maps for an area are analyzed, they provide a useful tool to make management decisions regarding land development.

BLM Priority areas that include the following. High – These areas include BLM managed lands within the larger collaborative multi-agency LiDAR acquisition areas that are ongoing. Medium – These include PHMA – BLM administered lands identified as having the highest value to maintaining sustainable greater sage-grouse populations and Salinity project boundary – that provides a framework for improving the effectiveness of the Colorado River Basin of BLM managed lands. Low – These include GHMA – BLM administered lands identified that are occupied seasonally or year old and are outside of PHMA and all remaining BLM managed lands. Complete – Areas of BLM administered lands of where LiDAR acquisitions is complete and is available at the USGS National Map.