Measurements of water table height in the Nelson Island marsh located near Nelson Island eddy flux tower. Measurements were taken every 5 minutes at each logger along a transect of water level loggers running perpendicular to the Nelson stream bank at Nelson Island, Rowley, MA, MAR-RO-Wtable-Nel for May-October 2017.
A transect of wells is established on the marsh platform, perpendicular to the marsh edge. A total of 5 wells are dug to the depth of the water table under the marsh platform. Wells N201 to N204 are spaced approximately evenly within the first 6m of marsh edge with well N205 approximately 10m upland from the marsh edge. A water level logger, referred to as the tide gauge, (Onset HOBO U20 series) is placed at the river bottom directly in front of the transect . Individual water level loggers (Onset HOBO U20 series) are used in each well and they measure water height in terms of absolute pressure. Barometric pressure is measured above ground with an additional Onset HOBO U20 series water level logger to tease out the atmospheric pressure from water column pressure. Prior to deployment, each water level logger is sealed in protective plastic whirl-pak bags filled with freshwater, and calibrated to known water depths. Once in the field, water height measurements, in terms of absolute pressure, are recorded every 5 minutes. Pressure readings are uploaded from the HOBO water level loggers using HOBOware software which compensates for temperature, fluid density, and barometric pressure, then are converted to absolute water height above the river bottom. Data is QA/QC'd to ensure that the loggers report the same flood water elevation on the marsh surface. The surface elevation of the marsh as measured by the marsh water level loggers must match that of the gps'd surface elevation. Any corrections made to a particular logger data field (logger # Dc (m)) are reported in the Offset corr field (Offset corr logger # (m)).
Well Location Information:
Logger Well Height of Marsh Surface Above Creek Bottom (m) Horizontal Distance Upland of Creek Edge (m)
Nref tide gauge 0 -1.62
N201 N201 1.57 -0.43
N202 N202 1.66 0.00
N203 N203 1.76 0.80
N204 N204 1.98 2.80
N205 N205 2.10 7.64
Tide gauge logger located near river bottom.
Marsh wells N201, N202, N203, N204 and N205, move from water edge into the marsh platform.
NOTES AND COMMENTS:
Due to occasional equipment malfunction, readings are not continuous throughout the field season. Times in EST.
The core heights are uncertain for 2017 so 2018 data were used. They should be very similar because the same cores are used in the same core holes.
Version 01: August 14, 2019, data and metadata updates to comply with importation to DEIMS7 and LTER Data Portal. Used MarcrosExportEML_HTML (working)pie_excel2007_Jun2019.xlsm 6/7/19 12:58 PM for QA/QC to EML 2.1.0