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Characterization and investigation of submarine groundwater discharge from a coastal aquifer into the nearshore environment Caulkins, Joshua Lee
Abstract
The current trend of global populations moving increasingly to high density, coastal cities places a greater emphasis upon the water quality of aquifers supplying those cities. Problems that affect coastal aquifers (e.g. saltwater intrusion, non-point source pollution) will be amplified as this trend increases. The goal of this research project is to understand the processes that control freshwater/saltwater interactions in the coastal zone, specifically in areas of high submarine groundwater discharge (SGD). A site in NW Florida along the Gulf Coast is a well-documented SGD locale and provides an excellent opportunity to examine how tidal fluctuations, differential pressure in the seabed and groundwater seepage rates are interrelated. Experiments at the site focus on characterization of the nearshore aquifer, submarine groundwater discharge at the seabed and numerical modeling of the system. New onshore wells at the field site show that hydraulic conductivities in onshore region are similar to those in the offshore region. Slug tests and water level monitoring of the onshore wells are used to measure a seaward, horizontal hydraulic gradient. Direct measurements of discharge are conducted with an automated seepage meter, which shows that peak discharge rates tend to occur at the transition between high and low tides. A new apparatus called a differential piezometer system (DPS) is designed and used to measure differential hydraulic head in the seabed created by seepage and tidal interactions. This system failed to accurately portray differential head fluctuations in the seabed as a result o f calibration error. Salinity samples are collected from on and offshore wells and from a newly installed multi-level well, the data of which are made into salinity profiles. These profiles define the boundaries of a saline wedge and mixing zone in the nearshore region. FRAC3DVS is flow and transport groundwater model that is used to design and run a 1-dimensional numerical model. The model results confirm the temporal effects of tidal elevation on discharge rates observed in the seepage meter.
Item Metadata
Title |
Characterization and investigation of submarine groundwater discharge from a coastal aquifer into the nearshore environment
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
2004
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Description |
The current trend of global populations moving increasingly to high density,
coastal cities places a greater emphasis upon the water quality of aquifers supplying those
cities. Problems that affect coastal aquifers (e.g. saltwater intrusion, non-point source
pollution) will be amplified as this trend increases. The goal of this research project is to
understand the processes that control freshwater/saltwater interactions in the coastal zone,
specifically in areas of high submarine groundwater discharge (SGD). A site in NW
Florida along the Gulf Coast is a well-documented SGD locale and provides an excellent
opportunity to examine how tidal fluctuations, differential pressure in the seabed and
groundwater seepage rates are interrelated. Experiments at the site focus on
characterization of the nearshore aquifer, submarine groundwater discharge at the seabed
and numerical modeling of the system. New onshore wells at the field site show that
hydraulic conductivities in onshore region are similar to those in the offshore region. Slug
tests and water level monitoring of the onshore wells are used to measure a seaward,
horizontal hydraulic gradient. Direct measurements of discharge are conducted with an
automated seepage meter, which shows that peak discharge rates tend to occur at the
transition between high and low tides. A new apparatus called a differential piezometer
system (DPS) is designed and used to measure differential hydraulic head in the seabed
created by seepage and tidal interactions. This system failed to accurately portray
differential head fluctuations in the seabed as a result o f calibration error. Salinity
samples are collected from on and offshore wells and from a newly installed multi-level
well, the data of which are made into salinity profiles. These profiles define the boundaries of a saline wedge and mixing zone in the nearshore region. FRAC3DVS is
flow and transport groundwater model that is used to design and run a 1-dimensional
numerical model. The model results confirm the temporal effects of tidal elevation on
discharge rates observed in the seepage meter.
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Extent |
12146392 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-11-21
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0052755
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
2004-05
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.