Climate and vegetation change in a coastal marsh: two snapshots of groundwater dynamics and tidal flooding at Piermont Marsh, NY spanning 20 years

https://doi.org/10.5061/dryad.cjsxksncr

We include water levels measured along a transect of groundwater wells in 1999 and 2019, statistical analyses of ground water data, tidal efficiency estimates, vegetation data from 1997, 2005, 2014, and 2018, measures of tide gauge data and sea level rise from the Battery, New York Harbor. We attach the following three groups of files:
(1) Files related to data from Piermont Marsh, which includes water levels in wells, tide gauge data collected from the tidal channel, and vegetation data;
(2) Files related to analysis of water levels at Piermont Marsh;
(3) Files related to analysis of Battery tide gauge data, Battery tide predictions, and precipitation data

Description of the data and file structure

(1) Files related to data from Piermont Marsh, which includes water levels in wells, tide gauge data collected from the tidal channel, and vegetation data
1999PiermontWaterlevels.csv
2019PiermontWaterLevels.csv
channel_1999.xls
channel_2019.xls
water_level_elevations.csv
Vegetation.xls

1999PiermontWaterlevels.csv and 2019PiermontWaterLevels.csv - Water levels collected at Piermont marsh in groundwater wells, at 0-m, 6-m, 12-m, 18-m, 24-m, 36-m, and 48-m from a tidal channel. The files contain three fields: daytime, well, and elevation. The daytime is the date and time the water level was collected, hours in Eastern Daylight Time -4GMT. The well number refers to its location relative to the tidal channel, with #1 referring to 0-m, #2 referring to 6-m, #3 referring to 12-m, #4 referring to 18-m, #5 referring to 24-m, #6 referring to 36-m, and #7 referring to 48-m. The elevation field refers to the water level in meters relative to the NAVD88 datum. In 1999 water levels were collected 14 April 2019 - 26 May 2019. In 2019, water levels were collected 5 May 2019 - 30 June 2019.

channel_1999.xls - This file shows the elevation of water level in the channel. There is a field for date and time, in GMT -4, and water level in meters relative to NGVD29.

channel_2019.xls - This file shows the elevation of water level in the channel. There is a field for Date, Time, in GMT -4, absolute pressure in in mbar, temperature in degrees C, and water level in meters relative to NAVD88.

water_level_elevations.csv - This csv file includes five fields. The first is “year” or the year collected (1999 or 2019). The second is “well” numbered 1-7. Well 1 is closest to the channel while 7 is the furthest from the channel. #1 referrs to 0-m from the channel, #2 referring to 6-m from the channel, #3 referring to 12-m from the channel, #4 referring to 18-m from the channel, #5 referring to 24-m from the channel, #6 referring to 36-m from the channel, and #7 referring to 48-m from the channel. The datetime field refers to the day and time the measure was made in day/month/year HH:MM AM/PM format. The next field is lunarcyle which refers to whether the measure was made during “spring” or “neap” tidal cycles. Spring was assigned to the tides the week of full or new moons, Neap was assigned to tides the week of the first and last quarter. The last is “elevation” and is the measure of water levels in meters relative to the NAVD88 datum.

Vegetation.xls - This Excel file includes four sheets that each refer to a year of vegetation date - 1997, 2005, 2014, and 2017. The first field is “well” which has a number 1 through 7. The well number refers to its location relative to the tidal channel, with #1 referring to 0-m, #2 referring to 6-m, #3 referring to 12-m, #4 referring to 18-m, #5 referring to 24-m, #6 referring to 36-m, and #7 referring to 48-m. There is a field for latitude (lat) and longitude (long), which refers to the location of the shape in UTM, in meters, in the 18N. Cover refers to the plant cover type, area is the area of the polygon in square meters.

(2) Files related to analysis of water levels at Piermont Marsh
Distancefromsurface.R
MinNeap_MarshSurface.csv
MaxNeap_MarshSurface.csv
MinSpring_MarshSurface.csv
MaxSpring_MarshSurface.csv
PiermontEfficiencyRggplot.csv
Tidalefficiency.R

The R file Distancefromsurface.R includes calculations of mean and variance of water levels, and as well as production of relevant figures.

MinNeap_MarshSurface.csv file has low tide minimum water levels during neap tides (weeks centered on the moons first and third quarter). It includes the following fields: distance, year, water_elevation, marsh_elevation, and distance_surface. The field distance, is distance from the tidal channel, in meters. The field year, refers to is the year collected (1999 or 2019). The field water_elevation, is the elevation of the water level at low tide, in meters relative to the NGVD88 datum. The field marsh_elevation refers to the height of the marsh at that location, in meters relative to the NGVD88 datum. The field distance_surface is the difference between the marsh elevation and the water elevation. Positive values are values below the marsh surface, while negative values are values above the marsh surface.

MaxNeap_MarshSurface.csv file has high tide maximum water levels during neap tides (weeks centered on the moons first and third quarter). It includes the following fields: distance, year, water_elevation, marsh_elevation, and distance_surface. The field distance, is distance from the tidal channel, in meters. The field year, refers to is the year collected (1999 or 2019). The field water_elevation, is the elevation of the water level at high tide, in meters relative to the NGVD88 datum. The field marsh_elevation refers to the height of the marsh at that location, in meters relative to the NGVD88 datum. The field distance_surface is the difference between the marsh elevation and the water elevation. Positive values are values below the marsh surface, while negative values are values above the marsh surface.

MinSpring_MarshSurface.csv file has low tide minimum water levels during spring tides (weeks centered on the new and full moon). It includes the following fields: distance, year, water_elevation, marsh_elevation, and distance_surface. The field distance, is distance from the tidal channel, in meters. The field year, refers to is the year collected (1999 or 2019). The field water_elevation, is the elevation of the water level at low tide, in meters relative to the NGVD88 datum. The field marsh_elevation refers to the height of the marsh at that location, in meters relative to the NGVD88 datum. The field distance_surface is the difference between the marsh elevation and the water elevation. Positive values are values below the marsh surface, while negative values are values above the marsh surface.

MaxSpring_MarshSurface.csv file has high tide maximum water levels during spring tides (weeks centered on the new and full moon). It includes the following fields: distance, year, water_elevation, marsh_elevation, and distance_surface. The field distance, is distance from the tidal channel, in meters. The field year, refers to is the year collected (1999 or 2019). The field water_elevation, is the elevation of the water level at high tide, in meters relative to the NGVD88 datum. The field marsh_elevation refers to the height of the marsh at that location, in meters relative to the NGVD88 datum. The field distance_surface is the difference between the marsh elevation and the water elevation. Positive values are values below the marsh surface, while negative values are values above the marsh surface.

PiermontEfficiencyRggplot.csv - file lists the well number (1-7), distance (a number 1-14, which gives a unique identifier to each combination of well and year), year, which was the year the data was collected. The last field is efficiency. This field refers to the ratio between the change in water level over the course of a tidal cycle in the well to the change in the water level over the course of the tidal cycle at the Battery tide gauge, NYC.

Tidalefficiency.R - file that plots and calculates tidal efficiency during 1999 and 2019 at each well.

(3) Files related to analysis of Battery tide gauge data, Battery tide predictions, and precipitation data
MSL_time.R
3348871.csv
3348873.csv
Battery.csv
Bat_wls.csv
monthly.csv
sin2.csv
predictions.csv
tide_l.csv
wls.csv

MSL_time.R - This R code uses several data files to conduct analysis of change over time in water levels and monthly anomalies in precipitation and water levels. All necessary packages are described.

3348871.csv and 3348873.csv - are weather data from Westchester County airport, station USW00094745 from 1997 to 2001 (3348873.csv) 2017 to 2022 (3348871.csv). The field station lists the station. The field Name is the name of the station, Westchester County Airport. The date is the day data was collected. AWND refers to Average daily wind speed in miles per hour. PGTM refers to peak gust time (hours and minutes, i.e., HHMM). PRCP refers to precipitation in inches, TMAX refers to the maximum daily temperature, in degrees Fahrenheit. TMIN refers to the minimum daily temperature, in degrees Fahrenheit. WDF2 is the direction of fastest 2-minute wind in degrees. WDF5 is the direction of fastest 5-second wind in degrees. WSF2 is the fastest 2-minute wind speed in miles per hour. WSF5 is the fastest 5-second wind speed in miles per hour. Missing data is replaced with -999.

Battery.csv - all high tide levels for 1997 through 2022. The two fields are level, referring to high tide water levels in meters relative to the NAVD88 datum. The second field is year.

Bat_wls.csv is monthly tide levels from the Battery tide gauge, NY. The year field refers to year including fraction. Mean high water (MHW) refers to monthly mean high water relative to the NAVD88 datum in meters. Mean sea level (MSL) refers to monthly mean sea level relative to the NAVD88 datum in meters. Mean tide level (MTL) refers to monthly mean tide level relative to the NAVD88 datum in meters.. Mean Low Water (MLW) refers to monthly mean low water relative to the NAVD88 datum in meters.

monthly.csv - is mean high water and mean sea level from 1980-2022, by month. The field month refers to the month (January =1). MHW is monthly mean high water for all months, relative to the NAVD88 datum, and MSL is monthly mean sea level relative to the NAVD88 datum.

sin2.csv is the monthly mean sea level at the Battery tide gauge (1980-2022), with a 1 year rolling window median smooth added. There are three fields, month, MSL, and year. Month is the number of months elapsed since January 1961. MSL is the monthly mean sea level in meters, relative to the NAVD88 datum, with a one year smoothing function applied. Year refers to the observation month, expressed in years and the fraction of years so January 1980 would be 1980, while February 1980 is depicted as 1980.083.

predictions.csv - tide predictions for the Battery tide gauge, New York City. Fields are y, which stands for year, represented by year, including fractions representing months. High_p is the highest predicted tide of the month, in meters relative to the NAVD88 datum. MHW_p is the predicted mean high tide for the month relative to the NAVD88 datum. MLW_p is the predicted mean low tide for the month relative to the NAVD88 datum. MTL_p is the predicted mean tide level for the month relative to the NAVD88 datum. High_1 is the highest actual tide of the month, in meters relative to the NAVD88 datum. MHW_a is the actual mean high tide for the month relative to the NAVD88 datum. MLW_a is the actual mean low tide for the month relative to the NAVD88 datum. MTL_a is the actual mean tide level for the month relative to the NAVD88 datum.

tide_l.csv is a file with the monthly mean high water (MHW_l), monthly mean tide level (MTL_l), and mean low water (MLW_l) for 1960 -2021.

wls.csv is a file that has monthly water levels from 1999 to 2019, listing year (as a fraction, not just an integer for month), Highest, as the highest tide of the month in meters relative to the NAVD88 datum. MHW refers to the mean high water during the month in meters relative to the NAVD88 datum. MTL refers to the mean tidal level during the month in meters relative to the NAVD88 datum. MLW refers to the mean low water during the month in meters relative to the NAVD88 datum.

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Sharing/Access information

Data was derived from the following external sources:

• Vegetation shapefiles for the Hudson River NERR for 1997, 2005, and 2014, were obtained through personal request to Sarah Fernald,
  Reserve Manager and Research Coordinator. Files should be available through the Reserve website, although the link is not functional at this time: https://hrnerr.org/research-monitoring/mapping/
• The 2018 vegetation shapefiles were obtained from https://data.gis.ny.gov/ under the heading, Hudson River Estuary tidal wetlands.
• We acknowledge the NYS DEC Hudson River Estuary Program, NYS DEC Hudson River National Estuarine Research Reserve, and Cornell Institute for Resource Information Sciences for collection and curation of the Hudson River NERR vegetation data.
• Tide gauge data and tide predictions for the Battery, NY were obtained from NOAA tides and currents website: https://tidesandcurrents.noaa.gov/stationhome.html?id=8518750
• Precipitation data was obtained from the National Centers for Environmental Information, NOAA: https://www.ncei.noaa.gov/. The station for which data was obtained was the Westchester County airport, station USW00094745.

Code/Software

We provide three R files, which we ran using R version 4.3.1 (2023-06-16), in R Studio 2022.02.1, Build 461. All required packages are described in the .R files.

Distancefromsurface.R - This R code utilizes four data files that include low tides during spring tides, low tides during neap tides, high tides during spring tides, and high tides during neap files to compare average and variance in low and high tide water levels during 1999 and 2019 relative to the marsh surface and relative to the NAVD88 datum. Code is also included to produce plots.

Tidalefficiency.R - file that plots and calculates tidal efficiency during 1999 and 2019 at each well.

MSL_time.R - This R code uses several data files to conduct analysis of change over time in water levels and monthly anomalies in precipitation and water levels.