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Everglades National Park sediment elevation and marker horizon data release

October 9, 2019

This data set represents the relevant study site information for the Everglades National Park LTER sediment elevation table - marker horizon study. Nine SETs study sites are located near U.S. Geological Survey (USGS) hydrological stations in Everglades National Park. The coupling of coastal sediment elevation with Hydrology data is important aid in evaluating sea level changes influences to coastal ground elevations. The basic concept of the SET is a fixed reference point either local surveyed or tied to a known vertical datum is used to evaluate sediment change over time. Sediment change can occur from physical and biological factors, which through erosion or accretion raise or lower the sediment profile. There are three modified SET designs used by the USGS in the Everglades (Original, Shallow and Deep). However, all are based on the SET design, consisting of a mechanical arm with a measurement plate at the end, which is pivoted out from the fixed reference point and leveled. The cantilevered mechanical arm radiates out from the fixed reference point in a circle to a determined bearing (typically the reference SET point is measured at four bearings) where a sediment measurement can be sampled. The measurement plate (or bar) has a series of machined holes (typically nine) through the plate, allowing fiberglass rods (also referred to as pins) to be inserted and lower through the plate to the ground surface. Each fiberglass rod is gently lowered through the plate hole until the rod tip touches the ground surface. The rod segment above plate is measured and the change in ground surface elevation is determined by subtracting the known rod length from the above rod segment length (i.e.: more rod segment above the plate is indicative of increased sediment. At each SET four fixed bearing measurements, nine measuring pins are lowered to the soil surface to obtain a relative soil elevation.