Comparing Wetland Elevation Change Using a Surface Elevation Table, Digital Level, and Total Station

Abstract

The surface elevation table (SET) approach and two survey instruments, a digital level (DL) and a total station (TS), were used to evaluate elevation change at a 1-ha, micro-tidal, back-barrier salt marsh at Assateague Island National Seashore (Berlin, MD, USA) from 2016 to 2022. SET data were collected at 3 sampling stations along the perimeter of the plot, 36 pins per station, and the DL and TS data were collected adjacent to 36 stakes, four readings per stake, throughout the plot. The average elevation range of the marsh surface measurements at the SET stations was 2 cm, while the range was considerably greater within the larger 1-ha DL and TS sampling area (24 cm). The average elevation of the marsh surface only varied by 2 cm among the three methods. Elevation change trends of the three methods ranged from 2.8 to 3.5 mm year−1 and were not significantly different from each other. Despite differences in sample size and spatial distribution of measurements, these methods provided comparable measures of long-term trends in marsh surface elevation probably because the marsh at this site was structurally homogeneous with low topographic relief.