Understanding groundwater storage and transport is critical for resolving potential impacts on this important resource. By determining the nature of groundwater in coastal and nearshore environments CMG research can help address such issues as the transport of pollutants and the encroachment of saline seawater into freshwater aquifers.
USGS Northern Gulf of Mexico (NGOM) The goal of the USGS Northern Gulf of Mexico project is to understand the evolution of coastal ecosystems on the Northern Gulf Coast, the impact of human activities on these ecosystems, and the vulnerability of ecosystems and human communities to more frequent and more intense hurricanes in the future. Posted: 2009-05-28
U.S. Geological Survey Karst Interest Group Proceedings, Bowling Green, Kentucky, May 27-29, 2008 The concept for developing a Karst Interest Group evolved from the November 1999 National Ground-Water Meeting of the U.S. Geological Survey (USGS), Water Resources Division. As a result, the karst Interest Group was formed in 2000. The Karst Interest Group is a loose-knit grass-roots organization of USGS employees devoted to fostering better communication among scientists working on, or interested in, karst hydrology studies. Posted: 2009-05-01
Open-File Report 2008-1342: Examining submarine ground-water discharge into Florida Bay by using 222Rn and continuous resistivity profiling Estimates of submarine ground-water discharge (SGD) into Florida Bay remain one of the least understood components of a regional water balance. To quantify the magnitude and seasonality of SGD into upper Florida Bay, research activities included the use of the natural geochemical tracer, 222Rn, to examine potential SGD hotspots (222Rn surveys) and to quantify the total (saline + fresh water component) SGD rates at select sites (222Rn time-series). To obtain a synoptic map of the 222Rn distribution within our study site in Florida Bay, we set up a flow-through system on a small boat that consisted of a Differential Global Positioning System, a calibrated YSI, Inc CTD sensor with a sampling rate of 0.5 min, and a submersible pump (z = 0.5 m) that continuously fed water into an air/water exchanger that was plumbed simultaneously into four RAD7 222Rn air monitors. To obtain local advective ground-water flux estimates, 222Rn time-series experiments were deployed at strategic positions across hydrologic and geologic gradients within our study site. These time-series stations consisted of a submersible pump, a Solinist DIVER (to record continuous CTD parameters) and two RAD7 222Rn air monitors plumbed into an air/water exchanger. Repeat time-series 222Rn measurements were conducted for 3–4 days across several tidal excursions. Radon was also measured in the air during each sampling campaign by a dedicated RAD7. We obtained ground-water discharge information by calculating a 222Rn mass balance that accounted for lateral and horizontal exchange, as well as an appropriate ground-water 222Rn end member activity. Another research component utilized marine continuous resistivity profiling (CRP) surveys to examine the subsurface salinity structure within Florida Bay sediments. This system consisted of an AGI SuperSting 8 channel receiver attached to a streamer cable that had two current (A,B) electrodes and nine potential electrodes that were spaced 10 m apart. A separate DGPS continuously sent position information to the SuperSting. Results indicate that the 222Rn maps provide a useful gauge of relative ground-water discharge into upper Florida Bay. The 222Rn time-series measurements provide a reasonable estimate of site- specific total (saline and fresh) ground-water discharge (mean = 12.5±11.8 cm d-1), while the saline nature of the shallow ground-water at our study site, as evidenced by CPR results, indicates that most of this discharge must be recycled sea water. The CRP data show some interesting trends that appear to be consistent with subsurface geologic and hydrologic characterization. For example, some of the highest resistivity (electrical conductivity-1) values were recorded where one would expect a slight subsurface freshening (for example bayside Key Largo, or below the C111 canal). Posted: 2009-04-21
Scientific Investigations Report 2007-5101: The Coral Reef of South Moloka‘i, Hawai‘i—Portrait of a Sediment-Threatened Fringing Reef In this landmark volume, U.S. Geological Survey researchers and their colleagues have developed and applied a remarkably integrated approach to the reefs of Moloka‘i, combining geology, oceanography, and biology to provide an in-depth understanding of the processes that have made these reefs grow and that now limit them. They have joined old fashioned natural history of marine animals and plants with study of the geological evolution of the island, hydrology, meteorology, and land-use history, to an arsenal of new methods of remote sensing, including aerial photography, laser ranging, infrared thermal mapping, seismic reflection, in-situ instrumentation to measure chemical parameters of water quality, and direct measurements of the physical driving forces affecting them—such as wave energy, currents, sedimentation, and sediment transport. They provide a level of documentation and insight that has never been available for any reef before. Posted: 2008-11-19
Index for Open file report 2006 1169 This USGS Open-File report presents continual resistiviy profiling data collected along the Cape Cod National Seashore. This report also contains a description of the processing techniques used with these data. Groundwater samples data and core data are also included in this report. Posted: 2008-11-17
Open-File Report 2007-1304: Assessment of Groundwater Input and Water Quality Changes Impacting Natural Vegetation in the Loxahatchee River and Floodplain Ecosystem, Florida, Open File Report 2007-1304 The Loxahatchee River and Estuary are small, shallow, water bodies located in southeastern Florida. Historically, the Northwest Branch (Fork) of the Loxahatchee River was primarily a freshwater system. In 1947, the river inlet at Jupiter was dredged for navigation and has remained permanently open since that time. Drainage patterns within the basin have also been altered significantly due to land development, road construction (e.g., Florida Turnpike), and construction of the C-18 and other canals. These anthropogenic activities along with sea level rise have resulted in significant adverse impacts on the ecosystem over the last several decades, including increased saltwater encroachment and undesired vegetation changes in the floodplain. The problem of saltwater intrusion and vegetation degradation in the Loxahatchee River may be partly induced by diminished freshwater input, from both surface water and ground water into the River system. The overall objective of this project was to assess the seasonal surface water and groundwater interaction and the influence of the biogeochemical characteristics of shallow groundwater and porewater on vegetation health in the Loxahatchee floodplain. The hypothesis tested are: (1) groundwater influx constitutes a significant component of the overall flow of water into the Loxahatchee River; (2) salinity and other chemical constituents in shallow groundwater and porewater of the river floodplain may affect the distribution and health of the floodplain vegetation. Posted: 2008-07-03
USGS Open-File Report 2007-1310: Submarine Ground Water Discharge and Fate Along the Coast of Kaloko-Honokohau National Historical Park, Hawai'i; Part I; Time-Series Measurements of Currents, Waves, Salinity and Temperature: November, 2005-July, 2007 The impending development for the west Hawai‘i coastline adjacent to Kaloko-Honokōhau National Historical Park (KAHO) may potentially alter coastal hydrology and water quality in the marine waters of the park. Water resources are perhaps the most significant natural and cultural resource component in the park, and are critical to the health and well being of six federally listed species. KAHO contains ecosystems of brackish anchialine pools, two 11-acre fishponds, and 596 acres of coral reef habitats, all fed by groundwater originating upslope. The steep gradients on high islands, combined with typically porous substrates and high rainfall levels at upper elevations, make these settings especially vulnerable to shifts in submarine groundwater discharge (SGD) and its entrained nutrients and pollutants. Little is known about the magnitude, rate, frequency, and variability of SGD and its influence on contaminant loading to Hawaiian coastal environments. Recent studies show that groundwater flux through the park is vital to many ecosystem components including anchialine ponds and wetland biota. The function of these ecosystems may be vulnerable to changes in groundwater flow stemming from natural changes (climate and sea level) and land use (groundwater pumping and contamination). Oki and others (1999) showed that increased groundwater withdrawals for urban development since 1978 likely decreased groundwater flux to the coast by 50%. During this same time, the quality of groundwater has been vulnerable to increases in contaminant and nutrient/fertilizer additions associated with industrial, commercial and residential use upslope from KAHO (Oki and others, 1999). High-resolution measurements of waves, currents, water levels, temperature and salinity were collected in the marine portion of the park from November, 2005, through July, 2006, to establish baseline information on the magnitude, rate, frequency, and variability of SGD. These data are intended to help researchers and resource managers better understand the hydrodynamics of the oceanographic environment in the park’s coastal waters as it pertains to the pathway of SGD and associated nutrient and contaminant input to the park’s coral reef ecosystem. Measurements were made of the oceanographic environment (waves, tides, currents, salinity and temperature) using hydrodynamic techniques to characterize and quantify the distribution, input and throughput of freshwater and associated nutrient/contaminant within the near shore environment of KAHO through the emplacement of a series of bottom-mounted instruments deployed in water depths less than 15 m. This study was conducted in support of the National Park Service (NPS) by the U.S. Geological Survey (USGS) Coastal and Marine Geology Program’s Coral Reef Project. These measurements support the ongoing studies of the Coral Reef Project to better understand the transport mechanisms of sediment, larvae, nutrients, pollutants and other particles on Pacific coral reefs. Subsequent reports will address the spatial and temporal variability in groundwater input and the associated nutrient flux in the park’s waters Posted: 2008-03-11
Submarine Ground-Water Discharge: Nutrient Loading and Nitrogen Transformations In coastal watersheds with soils of high hydraulic conductivity and permeable coastal sediments, ground water is a major route of transport of freshwater and its solutes from land to sea. Freshwater flowing downgradient from aquifers may either discharge from a seepage face near the intertidal zone, or flow directly into the sea as submarine ground-water discharge (SGD). Posted: 2008-02-01
Submarine Groundwater Discharge Submarine Groundwater Discharge: Instances, Causes, and Methods and Tools for the Analysis Thereof Posted: 2005-11-10
The Chesapeake Bay Bolide Impact: A New View of Coastal Plain Evolution - USGS Fact Sheet 049-98 A spectacular geological event took place on the Atlantic margin of North America about 35 million years ago in the late part of the Eocene Epoch. Sea level was unusually high everywhere on Earth, and the ancient shoreline of the Virginia region was somewhere in the vicinity of where Richmond is today. Tropical rain forests covered the slopes of the Appalachians. To the east of a narrow coastal plain, a broad, lime (calcium carbonate)-covered continental shelf lay beneath the ocean. Suddenly, with an intense flash of light, that tranquil scene was transformed into a hellish cauldron of mass destruction. From the far reaches of space, a bolide (comet or asteroid), 3-5 kilometers in diameter, swooped through the Earth's atmosphere and blasted an enormous crater into the continental shelf. The crater is now approximately 200 km southeast of Washington, D.C., and is buried 300-500 meters beneath the southern part of Chesapeake Bay and the peninsulas of southeastern Virginia. Posted: 2004-03-02
An Overview of Coastal Land Loss: With Emphasis on the Southeastern United States In states bordering the Gulf of Mexico and the Atlantic Ocean, vast areas of coastal land have been destroyed since the mid 1800s as a result of natural processes and human activities. The physical factors that have the greatest influence on coastal land loss are reductions in sediment supply, relative sea level rise, and frequent storms, whereas the most important human activities are sediment excavation, river modification, and coastal construction. As a result of these agents and activities, coastal land loss is manifested most commonly as beach/bluff erosion and coastal submergence. Posted: 2003-08-20
Geology and Human Activity in the Florida Keys - USGS Fact Sheet Live corals on the east side of the Florida Keys are mysteriously dying and algae are taking over that eco-niche. U.S. Geological Survey (USGS) studies and mapping of the Keys and the reef tract suggest that a number of natural factors, combined with effects of human activity, may contribute to the corals' demise. A complete geological study of this ecosystem would provide the kind of information environmental managers need to determine the extent of damage to reefs resulting from human activity. Posted: 2003-03-02
Subsidence and Fault Activation Related to Fluid Energy Production, Gulf Coast Basin The Gulf Coast Basin is a region where subsidence and fault activation are common around large, mature oil and gas fields even though moderately deep hydrocarbon production has generally been disregarded as the primary cause. This project will test the hypothesis that long-term, large-volume oil and gas production in the Gulf Coast Basin has resulted in land-surface subsidence and activation of deep-seated faults around some fields. Posted: 2002-09-18
Chemical Pollutants and Toxic Effects on Benthic Organisms, Biscayne Bay, Florida Through the study of benthic foraminifera in Florida's Biscayne Bay, this project seeks to identify the distribution of pollutants and their effects in the bay. Findings will be used to assist in planning Everglades restoration and to aid in understanding recent change in local coral reef health. Posted: 2002-08-27
Geologic History of Cape Cod Massachusetts Cape Cod is a sandy peninsula built mostly during the ice age and juts into the Atlantic Ocean like a crooked arm. Geologists are interested in Cape Cod because it was formed, by glaciers, very recently in terms of geologic time and because of the ever changing shore as the Cape adjusts to the rising sea. This is an online version of USGS geologist Robert Oldale's popular circular. Posted: 2002-04-23
Lake Pontchartrain, LA, Geochemistry Geology, geologic history, sediments, circulation, satellite imagery, of Lake Pontchartrain, LA, and a sediment database and geochemical assessment of the Lake. Posted: 2002-04-23
Atchafalaya and Mississippi River Deltas Study This study will evaluate the transport and storage of particle reactive, environmentally relevant contaminates through the Mississippi River and Atchafalaya River delta complexes to the near-shore Gulf of Mexico. Posted: 2002-03-18
A Photo Gallery of Florida's Big Bend Tidal Wetlands This collection offers a thematic tour of Florida's Big Bend tidal wetlands, covering aspects of the flora, fauna, and geology of this mosaic of tidal marsh, coastal forest, and winding tidal creeks. Posted: 2001-02-23
Geologic Framework and Processes of the Lake Pontchartrain Basin Lake Pontchartrain and adjacent lakes form one of the largest and most important estuaries in the Gulf Coast Region. The estuary drains the Pontchartrain Basin, an area of over 12,000 square kilometers situated on the eastern side of the Mississippi River delta plain. In Louisiana, nearly one-third of the state population lives within the 14 parishes of the Pontchartrain Basin. Posted: 2000-03-15
Geologic Characterization of Lakes and Rivers of Northeast Florida This study is part of a series of cooperative investigations conducted from 1993 to 1997 of inland and offshore waters and adjacent terrain throughout much of the St. Johns River Water Management District in northeastern Florida. Posted: 2000-03-03
Seismic Stratigraphy of the Central Indian River Region - Open File Report 97-723 The geology and and hydrology of the central Indian River region along the central east coast of Florida is of critical concern to the St. Johns River Water Management District (SJRWMD). In this area the upward migration of deeper, more saline ground water in the lower Floridan aquifer to the shallower, fresher ground water of the upper Floridan aquifer and above, may impact the water quality of this resource. Posted: 2000-02-29
Chesapeake Bay Bolide: Modern Consequences of an Ancient Cataclysm The story of the Chesapeake Bay Bolide, a meteor that hit the earth and formed a crater that is now buried under the mouth of Chesapeake Bay; how it was originally discovered, its effects on the landscape, and its importance to the groundwater supply and to engineering planning in the Norfolk area of Virginia and the lower Delmarva peninsula. Posted: 1997-07-24
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