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 intervals. 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. In order to set the second Y Axis relative to the elevation change data, site elevation is plotted against date and the 2nd Y Axis is shifted so that the survey point fits on the elevation change line.

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 are represented in this figure. When more than one vertical accretion estimate is made, the vertical accretion rate reported here is the mean of all vertical accretion estimates.