Salt marsh elevation monitoring

Asper, Jennifer; Curtis, Tony

The following Standard Operating Procedure (SOP) outlines the procedure involved using the rod surface elevation table (RSET) to monitor salt marsh elevation change. The following procedures have been adapted from the sampling method developed by Cahoon et al. (2002) and Folse and West (2004). The sampling methodology is also thoroughly explained on the USGS web site http://www.pwrc.usgs.gov/set/. The Southeast Coast Network (SECN) has implemented the use of the rod-surface elevation table (RSET) technique that has been developed by (Cahoon et al. 2002). The RSET is the preferred version of the SET and benchmarks will be established at specified locations in attached, herbaceous marsh and mangrove scrub/shrub ecosystems. The RSET method provides a non-destructive process which precisely measures the sediment elevation over a long period of time relative to a fixed subsurface datum (Figure 1). Briefly, a series of 4-ft. stainless steel rods are driven through the root zone, the organic matter, and any soft underlying materials until refusal is encountered from a driving force on the rod. Near the surface, a custom-made stainless- steel receiver is attached to the rod which is stabilized by a 6-in. diameter pipe that is cemented at the surface. This stainless steel receiver provides a constant horizontal reference plane as well as long-term repeatability as the RSET arm remains fixed for each sampling period. Detailed installation procedures are written in SOP 1.3.19 (Asper and Curtis 2012). Data collection occurs by attaching a custom-made RSET arm (Figure 2) to the receiver and nine fiberglass pins are lowered through the RSET arm to the marsh surface. The height (measured in millimeters) that each pin extends above the arm is used to calculate vertical changes of the marsh surface over time. Using previously-collected data, the rate of change can be calculated to provide status and trends with respect to changes occurring between the surface and the bottom of the stainless steel rods.

Salt marsh elevation monitoring

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