- Copyright © 2004 Society of Exploration Geophysicists
We explore whether lidar (light detection and ranging) and EM (electromagnetic induction) can improve the accuracy and resolution of wetland mapping that has historically been based chiefly on analysis of aerial photographs. Using Mustang Island on the central Texas coast as an example, we exploit (1) the known strong relationship between elevation and coastal habitat by comparing a lidar-derived digital elevation model (DEM) with existing wetland maps and detailed vegetation transects, and (2) another known strong relationship between soil and water salinity and coastal habitat by collecting and comparing EM-derived conductivity data with elevation and vegetation type across the island.
We selected two representative transects across Mustang Island (Figure 1) where we surveyed vegetation type and measured the electrical conductivity of the ground. Electrical conductivity, which is closely correlated to salinity, was measured noninvasively along the transects using a ground conductivity meter.
We employ two classification systems to examine the relationship between elevation, conductivity, and coastal vegetation assemblages: that used by the U.S. Fish and Wildlife Service in the National Wetlands Inventory (NWI) program, and that used in our ground-based mapping that includes wetlands and other associated coastal environments. Environments include beach, dune, vegetated-barrier flat (VBF), fresh and saltwater marsh, and wind-tidal flat (Figure 2) that each have correlative categories within the NWI system (Table 1).
We combined elevations mapped using airborne lidar with ground conductivity measurements and a vegetation survey acquired along the Mustang Island State Park and Port Aransas transects (Figure 1) across the island. We compared elevation and ground conductivity data with vegetation assemblages and coastal barrier environments as determined from the vegetation survey and as depicted …