Inland Bays

Scientists study flow of groundwater into bays - results may help track pollution


Scientists study flow of groundwater into bays. Results may help track pollution.

On a small, homemade barge, built from the skeleton of an old ship, a gray slurry of bay bottom sand flows out of a pipe into a bucket. Two scientists, a well driller and two student interns drill a hole in the floor of the Indian River Bay. They’ll install a very long pipe into the hole and use it to monitor groundwater – how much flows into the bay, how salty it is and how many nutrients it carries with it.

Wastewater Reuse: Benefits and Risk Assessment in Inland Bays Indian River Basin

Project Contact(s)

The goal of this project is to develop a three-dimensional (3D) numerical groundwater flow model to evaluate the potential impacts to surface- and groundwater resulting from the disposal of treated wastewater in a portion of the Inland Bays drainage basin.

By developing a sub-regional, fresh, groundwater flow model and analyzing results, several issues will be addressed that are related to state policy, regulation revision, and proposed projects associated with land-based wastewater disposal (LBWD) in Sussex County.

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Quantifying Geologic and Temporal Controls on Water and Chemical Exchange between Groundwater and Surface Water in Coastal Estuarine Systems

Eutrophication is one of the most common and most severe problems facing coastal bays in
populated and agricultural areas. Unnaturally high quantities of nutrients enter fresh groundwater and surface water as a result of human activities. These nutrients contribute to the overpopulation of phytoplankton and macroalgae in coastal surface waters, which results in deterioration of water quality and animal habitat. This is a particular problem in the Delmarva region, where poultry farms, agricultural activity, and growing human populations have contributed to rapidly declining populations of blue crabs, striped bass, and many other species which live and breed in estuarine waters. The economic value of these species has, in part, prompted political action and efforts to manage nutrient inputs to groundwater and surface water, the primary pathways for nutrient loading to coastal waters. Despite significant reductions, coastal water quality has largely remained poor. A better understanding of the processes that moderate nutrient loading to coastal waters, particularly via groundwater, which is much more difficult to monitor than surface water inputs, is essential for improved management methods that will result in healthy coastal ecosystems. This project will improve understanding of where nutrients are coming from and how loading may be reduced, and may aid in identification of activities that exacerbate negative impacts.
The final DGS report on this project has been released and is available at:…

MS6 Cross Section of Pliocene and Quaternary Deposits Along the Atlantic Coast of Delaware

Exploration for sand resources for beach nourishment has led to an increase in the amount of geologic data available from areas offshore Delaware's Atlantic Coast. These data are in the form of cores, core logs, and seismic reflection profiles. In order to provide a geologic context for these offshore data, this cross section has been constructed from well and borehole data along Delaware's Atlantic coastline from Cape Henlopen to Fenwick Island.

RI68 Estimation of the Water Table for the Inland Bays Watershed, Delaware

A geographic information system-based study was used to estimate the elevation of the water table in the Inland Bays watershed of Sussex County, Delaware, under dry, normal, and wet conditions. Evaluation of the results from multiple estimation methods indicates that a multiple linear regression method is the most viable tool to estimate the elevation of the regional water table for the Coastal Plain of Delaware. The variables used in the regression are elevation of a minimum water table and depth to the minimum water table from land surface.

RI73 Analysis and Summary of Water-Table Maps for the Delaware Coastal Plain

A multiple linear regression method was used to estimate water-table elevations under dry, normal, and wet conditions for the Coastal Plain of Delaware. The variables used in the regression are elevation of an initial water table and depth to the initial water table from land surface. The initial water table is computed from a local polynomial regression of elevations of surface-water features. Correlation coefficients from the multiple linear regression estimation account for more than 90 percent of the variability observed in ground-water level data.

OFR44 Storm-Water and Base-Flow Sampling and Analysis in the Delaware Inland Bays Preliminary Report of Findings 1998-2000

This report provides initial research results of a storm-water and base-flow sampling and analysis project conducted by the University of Delaware College of Marine Studies (CMS) and the Delaware Geological Survey (DGS). Base-flow samples were collected from six tributary watersheds of Delaware’s Inland Bays on 29 occasions from October 1998 to May 2000. Water samples were filtered in the field to separate dissolved nutrients for subsequent analysis, and a separate sample was collected and returned to the laboratory for particulate nutrient determinations.

SP27 Water Table in the Inland Bays Watershed, Delaware

This poster shows three different map views of the water table as well as information about how the maps were made, how the depth to water table changes with seasons and climate, and how the water table affects use and disposal of water. The map views are of depth to the water table, water-table elevation (similar to topography), and water-table gradient (related to water flow velocity).