Monitoring Line Hole Well Field, San Salvador Island, Bahamas

San Salvador Island is a small isolated carbonate platform on the southeastern edge of the Bahamian Archipelago. The Line Hole well field is located on an eogenetic karst aquifer on San Salvador Island's northern coast. The island's negative water budget and extensive lake cover have resulted in the upconing of saline water that has fragmented the once continuous freshwater lens. The Line Hole well field consists of several 15-cm diameter wells drilled into the fresh-water lens and arranged in a line perpendicular to the shore. The well field also has two monitoring wells (LH 1, and LH 13), that penetrate approximately 7 m below the water table into higher salinity groundwater. The well field was abandoned in 2016 upon saltwater intrusion to the aquifer.

To evaluate the connectivity between the eogenetic karst aquifer monitored by the Line Hole well field and the ocean, we instrumented wells with HOBO U20L-04 loggers to measure pressure and temperature timeseries. We instrumented wells LH4, and LH8, in addition to the monitoring wells LH1 and LH13.

To evaluate the degree of connectivity between the aquifer and the ocean, we recorded a timeseries of water level and temperature within four of the abandoned Line Hole wells. We monitored Line Hole wells 1, 4, 8, and 13 with HOBO U20L-04 loggers in 2015-2017 with sampling rates ranging between 30 seconds and 15 minutes. See below for details on the datasets within this archive, for associated data sets and publications, and contact information.

Data Files

Header

Each data file has a single header

Header description

Date, UTC-5 (str): Timestamp, index, format "YYYY-MM-DD hh:mm:ss" with minute percision. Times are reported in the timezone UTC-5.
P_kPa (float): Water pressure in kilopascals.
Temp, C (float): Water temperature in degrees Celsius.

Unit Abbreviations

kPa : Kilopascal
C : Degree Celsius
UTC : Coordinated Universal Time
UTC-5 : Time offset from UTC of -05:00. In North America, this is the Eastern Time Zone during standard time. The western Caribbean uses UTC-5 year round.

Null Values

While files with null (or no value) are rare for this dataset, we have specified the string "NaN" to be used to fill in missing values. We use this convention across all files.

Well Monitoring Records and Sampling Rates

LH 1 -- Monitoring well
``` Well_LH01.csv start 2015-07-24 11:06:00
end 2015-07-27 07:55:00
sampling rate 1 minute

        start    2017-02-20 10:00:00  
          end    2017-02-21 09:45:00  
sampling rate    5 minutes

```

LH 4
``` Well_LH04.csv
start 2015-07-24 11:11:00
end 2015-07-27 08:14:00
sampling rate 1 minute

        start    2019-01-06 10:00:00  
          end    2019-03-27 12:55:15  
sampling rate    15 minutes

```

LH 8
``` Well_LH08.csv
start 2015-07-24 11:23:00
end 2015-07-27 08:15:00
sampling rate 30 seconds

        start    2015-07-24 11:29:00  
          end    2015-07-27 08:21:00  
sampling rate    1 minute

```

LH 13 -- Monitoring well
``` Well_LH13.csv
start 2017-02-05 12:00:00
end 2017-02-19 08:25:00

        start    2017-04-24 17:00:00  
          end    2017-05-31 13:55:00

        start    2017-11-04 20:00:00  
          end    2017-11-07 17:35:00  
sampling rate    5 minutes

        start    2016-01-12 09:00:00  
          end    2016-01-15 11:17:00  
sampling rate    1 minute

```

Site characteristics

Well | Bottom Elevation | Distance from coast
------- | -- |
LH 1 | -2 m | 180 m
LH 4 | +1 m | 302 m
LH 8 | +1 m | 424 m
LH13 | +1 m | 544 m
||

Age at depth for all wells was MIS 5 Marine Isotope Substage 5 (~80-130 ka)

Associated Datasets

• GRC Weather Station Data, San Salvador Island, Bahamas.
• LineHole Well Field Monitoring, San Salvador Island, Bahamas.
• Pressure, Temperature, and Specific Conductivity from Lakes on San Salvador Island, Bahamas.

See Gulley et al., 2015 for a description of water chemestry for the Line Hole well field.

See Brithaupt et al., 2020 for results and analysis with this data.

Contact Information

For general questions about this dataset please contact Dr. Jason Gulley of the University of South Florida.
jdgulley@usf.edu, website

HydroShare data archive and readme.md compiled by J. Mejia on 24 May 2021