Sussex County is in the Atlantic Coastal Plain. Its relatively flat, featureless topography is characterized by two terrace-like surfaces; the lower one rises from sea level to about 40 feet above sea level, and the higher one rises inland from 40 to about 60 feet above sea level. Peculiar landforms of low relief, broad ovals, similar to the "Carolina bays," and to the "New Jersey basins" are common on the sandy flat divides in Sussex County. Hydrologically, they are sites of much ground-water discharge, by evapotranspiration, from meadow and marsh of lush vegetation.
Northern Delaware, the area above the Chesapeake and Delaware Canal in New Castle County, is an area of rapidly growing population and expanding industry. In some places the demand for water has reached or exceeded the capacity of the existing facilities creating apparent water shortages. Many agencies, both public and private, are attempting to alleviate these shortages; studies are being made and reports prepared for immediate action as well as long-term planning. It is the purpose of this report to examine on a long-range basis the water resources of the northern Delaware area. This examination indicates that the surface-water and groundwater resources of the area far exceed the 72.8mgd (million gallons per day) used during 1955. The amount of ground water potentially available in the area is estimated to be at least 30 mgd and the amount of surface water potentially available depends principally on the amount of storage that may be feasible economically. Storage of 3 million gallons per square mile would provide an allowable draft rate of 140 mgd with a deficiency at average intervals of ten years, while storage of 30 million gallons per square mile would raise the allowable draft to 250 mgd, which is about half of the mean annual discharge. In addition to the fresh-water resources, saline water from the Delaware River and its tidal estuaries is available in almost unlimited quantity for cooling, fire fighting, some types of washing, and other purposes.
B2 Geology and Ground-Water Resources of the Newark Area, Delaware with a Section on the Surface Water Resources
This report describes the geological and lithological conditions in the Newark area, and the occurrence, quantity, and quality of the available ground-water supply. Newark is located on the Fall Line, the boundary between the rolling hills of the Piedmont on the north and the gentle slopes of the Coastal Plain on the south. Because the Piedmont is underlain by dense crystalline rocks and their weathered clayey soils, which are of low water-bearing capacity in contrast to the more permeable silts and sands of the Coastal Plain, the exploration for ground water was confined to the Coastal Plain south and southeast of Newark.
Water-level records from 13 observation wells in Delaware for the period July, 1966 - December, 1977 provide the bases for the analyses of water-level fluctuations. Water levels in shallow water-table wells generally rise from November to March, when recharge exceeds discharge, and decline during the warm growing season from May through September. Although water-levels in individual wells changed by as much as 11.17 feet during the 11.5 year period studied, the water-table system remained in a state of dynamic equilibrium and exhibited no permanent changes in aquifer storage. However, the water levels in three artesian observation wells have declined during the same 11.5 year period in response to high demands for ground water while levels in the other two artesian wells have risen slightly due to a reduction in ground-water discharge, or increase in ground-water recharge, or both. Nevertheless during the past several decades, water levels have declined, cones of depression have enlarged, and reductions in aquifer storage, have occurred in the Potomac aquifer in central and southeastern New Castle County, and the Piney Point and Cheswold aquifers in the Dover-Dover Air Force Base area. Therefore, future groundwater development in the artesian aquifers must be carefully planned and managed.
A two-dimensional digital model was developed to simulate the effects of increased pumping on the Piney Point aquifer in Kent County, Delaware. The calibrated digital model was used to predict water-level declines as the aquifer responded to both changes in the distribution and increases in the quantity of pumping to the year 2000.
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).
On October 21, 1878, a hurricane crossed the island of Cuba and headed east of Key West, Florida. On the evening of October 22, it made landfall north of Cape Lookout, North Carolina, as a low Category 2 hurricane with winds around 100 mph. The storm picked up speed after landfall and moved northward at a rate of greater than 40 mph and maintained tropical storm force wind speeds of greater than 60 mph with gusts much higher. On the morning of October 23, it passed up the west side of the Chesapeake Bay near the cities of Baltimore and Annapolis, Maryland, Wilmington, Delaware, and Philadelphia, Pennsylvania. By the late afternoon it had reached Albany, New York, and turned eastward and passed out to sea north of Boston, Massachusetts, on the morning of October 24.
In order to obtain sufficient data which will enable the State to develop its water resources to the fullest extent of which they are capable, a series of systematic investigations is necessary. A long-range plan describing these studies is the subject of this report. A brief discussion of water in Delaware is presented first to provide a proper background for the long-range plan. The plan itself merely outlines the overall objectives and types of investigational work that must be pursued if the State is to develop its water resources wisely.
Analyses of drillers' and geophysical logs, cuttings, and 29 core samples from well Nc13-3 near Greenwood, Sussex County, Delaware indicate that the 1500-foot section penetrated by the drill can be divided into seven rock-stratigraphic units: Matawan Formation, Monmouth Formation, unit A, Piney Point Formation, Chesapeake Group (undifferentiated), Staytonville unit, and the Columbia Formation. The rock units are identified on the basis of texture, mineralogy, color, and interpretation of electric and gamma-ray logs. The oldest rocks penetrated are Upper Cretaceous; Tertiary and Quaternary rocks were also encountered. Correlations of the units encountered in the Greenwood test well with subsurface formations in adjacent parts of the Coastal Plain are explored utilizing lithologies, ages, positions in the stratigraphic column, and geophysical characteristics as criteria. Major time boundaries (Cretaceous-Tertiary; Early-Late Paleocene; Paleocene-Eocene; and Eocene-Miocene) are established by a preliminary study of mainly planktonic foraminifera. The Miocene-Pleistocene boundary was determined on changes in lithology across the unconformable contact.
The increasing population of the State of Delaware is placing severe strains on the quality of ground water in the water-table aquifer by disposing of septic-tank effluent in the soil. At the same time the water resources of this aquifer are being used in greater amounts. The permeable water-table aquifer, containing reserves of 331 million gallons per day, is very vulnerable to contamination by objectionable or toxic fluids and dissolved substances placed on or in the soil.
Information on ground-water quality in Delaware has become critical for three reasons: (1) increased water demand, (2) need for a better understanding of ground-water flow patterns, (3) need for a "base" against which future quality changes can be measured. Analyses of about 150 water quality samples from wells show that Delaware's fresh ground waters are suitable for most purposes. High iron content may occur, however, in wells tapping the Columbia and the Potomac formations. Overall, total dissolved solids in Delaware aquifers are relatively low except in the Cheswold and Frederica aquifers (Miocene), and possibly parts of the Piney Point Formation (Eocene).
The ground-water recharge potential map of Sussex County, Delaware, is a compilation of 1:24,000-scale maps of the water-transmitting properties of sediments in the interval between land surface and 20 ft below land surface. Water-transmitting properties are a key factor in determining the amount of water that recharges Delaware’s aquifers and the susceptibility of aquifers used as sources of water supply to contamination from near-surface pollutant sources. The mapping methodology was developed by Andres (1991) for the geologic characteristics of the Atlantic Coastal Plain portion of Delaware. Mapping and methods development started in 1990 and the final maps were completed in 2002 (Andres et al., 2002). Additional information about the map and methodology and a list of cited references are presented on the reverse side. The mapping program was funded by the Delaware Department of Natural Resources and Environmental Control and the Delaware Geological Survey.
The ground-water recharge potential map of Kent County, Delaware, is a compilation of 1:24,000-scale maps of the water-transmitting properties of sediments in the interval between land surface and 20 ft below land surface. Water-transmitting properties are a key factor in determining the amount of water that recharges Delaware’s aquifers and the susceptibility of aquifers used as sources of water supply to contamination from near-surface pollutant sources. The mapping methodology was developed by Andres (1991) for the geologic characteristics of the Atlantic Coastal Plain portion of Delaware. Mapping and methods development started in 1990 and the final maps were completed in 2002 (Andres et al., 2002). Additional information about the map and methodology and a list of cited references are presented on the reverse side. The mapping program was funded by the Delaware Department of Natural Resources and Environmental Control and the Delaware Geological Survey.
Geology and hydrology of the Chesapeake and Delaware Canal Area, Delaware. There are 2 sheets in this series.