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- Title
Measuring sediment accretion in early tidal marsh restoration.
- Authors
Takekawa, John; Woo, Isa; Athearn, Nicole; Demers, Scott; Gardiner, Rachel; Perry, William; Ganju, Neil; Shellenbarger, Gregory; Schoellhamer, David
- Abstract
Sediment accretion is a critical indicator of initial progress in tidal marsh restoration. However, it is often difficult to measure early deposition rates, because the bottom surface is usually obscured under turbid, tidally-influenced waters. To accurately measure early sediment deposition in marshes, we developed an echosounder system consisting of a specialized acoustic profiler, differential global positioning system unit, and laptop computer mounted on a shallow-draft boat. We conducted a bathymetry survey at the Tubbs Setback tidal restoration site on San Pablo Bay, California, along north–south transects at 25-m intervals. Horizontal position was recorded within 1 m each second and water depth to 1 cm every 0.05 s. Bottom elevations were adjusted for tidal height with surveyed tide gages. We created detailed bathymetric maps (grid cell size: 12.5 m × 12.5 m) by interpolation with inverse distance weighting. During the third year after restoration, sediment accretion averaged 57.1 ± 1.1 cm and the estimated sediment gain was 132,900 m3. The mean difference between the elevations from the bathymetry system and the 9 sediment pins was 2.0 ± 1.0 cm. The mean difference of the intersection points of east–west and north–south survey transects was 2.1 ± 0.2 cm, which provided a measure of repeatability with changing water levels. Our echosounder system provided accurate and repeatable measurements of sediment accretion of a recently restored tidal wetland, and this system proved to be a viable tool for determining sediment deposition in marshes and assessing early restoration progress.
- Subjects
SAN Pablo Bay (Calif.); CALIFORNIA; SEDIMENTATION &; deposition research; SALT marsh restoration; INTERPOLATION; WATER depth
- Publication
Wetlands Ecology & Management, 2010, Vol 18, Issue 3, p297
- ISSN
0923-4861
- Publication type
Article
- DOI
10.1007/s11273-009-9170-6