About the Soil Elevation Change and Vertical Accretion Summary Figure:

Elevation Change is measured with the Rod Surface Elevation Table (RSET) and is calculated cumulatively relative to readings made during station establishment. Vertical Accretion is measured above feldspar marker horizons. Original marker horizons are established concurrently with initial RSET measurements. New feldspar marker horizons are regularly established providing multiple vertical accretion measurements. The lines in this figure are linear fits through the elevation change measurements for each direction (n=4 per sample date) and vertical accretion measurements (n=3 per sample date, establishment date) and their 95% confidence bands. Rates reported for elevation change and accretion are the slopes of linear fits (cm yr-1). The relative sea level rise (RSLR) rate is from either the Sabine Pass Gauge (0.566 cm yr-1, Texas to E. Cote Blanche Bay) or the Grand Isle Gauge (0.924 cm yr-1, E. Cote Blanche Bay to Mississippi) depending on the CRMS site location within coastal Louisiana. Shallow subsidence is calculated as the difference between vertical accretion (cm yr-1) and elevation change (cm yr-1). Positive shallow subsidence indicates the rate that materials are being accreted but aren't contributing to elevation. Negative shallow subsidence indicates the rate that elevation is increasing above the rate that materials are being accreted. When sites have been surveyed to a vertical datum (ft NAVD 88), a second Y Axis is populated. Both axes have the same range. The elevation in the second Y Axis is the initial site survey elevation which is plotted on the second Y Axis against the date of the first RSET reading. Subsequent data are elevation change, not pin elevation.

A note about multiple vertical accretion fits: New feldspar is regularly established in order to provide same aged plots from which to estimate vertical accretion coastwide. Older plots are regularly revisited until they no longer provide accretion data. As new feldspar stations are established, multiple accretion estimates can be made. For this figure, if the data is available, the accretion rate reported is the mean of all estimates made through the first two years of intensive sampling for each set of stations established. If only one set of stations has been established or there is less than two years of data available from subsequent plot establishments, the accretion rate is all data from the first station establishment. Accretion rate estimates through all available data for each station establishment are available under the soils data tab.