USGS 01481500 BRANDYWINE CREEK AT WILMINGTON, DE
USGS 01480015 RED CLAY CREEK NEAR STANTON, DE
USGS 01480000 RED CLAY CREEK AT WOODDALE, DE
USGS 01479000 WHITE CLAY CREEK NEAR NEWARK, DE
USGS 01478650 WHITE CLAY CREEK AT NEWARK, DE
USGS 01478000 CHRISTINA RIVER AT COOCHS BRIDGE, DE
The stream-gaging network in Delaware is a major component of many types of hydrologic investigations. To ensure that the network is adequate for meeting multiple data needs by a variety of users, it must represent the range of hydrologic conditions and land-use types found in Delaware, and include enough stations to account for hydrologic variability. This report describes the current stream-gaging network in Delaware and provides an evaluation of its representativeness for the State.
OFR46 Storm-Water and Base-Flow Sampling and Analysis in the Nanticoke River Watershed: Preliminary Report of Findings 2002-2004
This report provides initial research results of a storm-water and baseflow sampling and analysis project conducted by the University of Delaware, College of Marine and Earth Studies and the Delaware Geological Survey. Baseflow samples were collected from four tributary watersheds of the Nanticoke River and one station on the Nanticoke River on 18 occasions from March 2003 to June 2004. Water samples were filtered in the field to separate dissolved nutrients for subsequent analysis, and separate samples were collected and returned to the laboratory for particulate nutrient determinations. On each sampling
date, temperature, conductivity, pH, and dissolved oxygen concentrations were determined at each sampling station. The U.S. Geological Survey made stream discharge measurements at each of these sites under a joint-funded agreement with the Delaware Department of Natural Resources and Environmental Control and the Delaware Geological Survey. Together, the
nutrient and discharge data were used to determine the total nutrient loads at five stations and unit loads (normalized to watershed area) at two of those stations on a quarterly and annual basis. Problems with watershed delineation and low quality discharge data limit these calculations for some watersheds. At the same five stations, storm water was collected during six storms from March 2003 to June 2004. Storm-water loadings of nutrients in each watershed were calculated from the concentrations of nutrients in water samples collected at fixed time intervals from the beginning of the storm-water discharge period until recession to baseflow. Measured storm loads were used as the basis for estimating loads from unsampled storms.
These data provide the Delaware Department of Natural Resources and Environmental Control with a more complete picture of the seasonal dependence of nutrient loading to streams in the Nanticoke River watershed and to Chesapeake Bay receiving waters. These may also be used to establish total maximum daily load goals.
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. On each sampling date, temperature, conductivity, pH, and dissolved oxygen concentrations were determined at each sampling station. Stream discharge measurements at each of these sites were made by the U.S. Geological Survey (USGS) under a joint-funded agreement with the Delaware Department of Natural Resources and Environmental Control (DNREC) and the DGS. Together, the nutrient and discharge data were used to determine the total and unit (normalized to watershed area) nutrient loading from base flow to the Inland Bays from each of these watersheds on a quarterly and annual basis. At the same six stations, storm water was collected during eight storms from May 1999 to April 2000. Storm-water loadings of nutrients from each watershed were calculated from the concentrations of nutrients in water samples collected at fixed time intervals from the beginning of the storm-water discharge period until recession to base flow. These data provide DNREC with a more complete picture of the seasonal dependence of nutrient loading to the Bays from which to establish goals for total maximum daily loads in the Inland Bays watershed.
An explanation is suggested for the origin of thin, laterally persistent pebble beds commonly found in the Columbia Formation of Delaware. The pebbles in the thin beds are usually less than 16 mm in diameter, well rounded, spherical, and composed mainly of resistant material: chert, vein quartz, and quartzite. The process thought to be responsible for the origin of these beds is a combination of erosion and transport of sand and pebbles in suspension by highly turbulent streams resulting in selective deposition of pebbles in thin, laterally persistent layers. An attempt is made to estimate quantitatively the amount of sand that has to be eroded to produce thin pebble beds. The results suggest that such pebble beds mark significant erosional unconformities within the fluvial Columbia sequence.
Data from three streamflow water-quality stations were statistically analyzed to determine the relationships of the major inorganic chemical constituents to specific conductance and to stream discharge. The results show that ion concentrations varied directly with the flow and with specific conductance. A set of regression equations defining these relationships were derived for each of the three stations: Brandywine Creek at Wilmington, St. Jones River at Dover, and Nanticoke River near Bridgeville.
This map shows the saturated thickness of the Columbia Formation. The Columbia Formation covers most of the Coastal Plain of Delaware. Because it consists primarily of coarse sand, it is important to the hydrology of the area. It is an important groundwater reservoir and in most places water must pass through it to reach deeper units. The water budget of the Columbia Formation also influences runoff and baseflow components of streamflow. The saturated thickness was determined through interpretation of data in publications and files of the Delaware Geological Survey, United States Geological Survey, and the Water Resources Center of the University of Delaware. The thicknesses shown on the map represent the best judgment of the authors based on available data. Detailed investigations of specific sites will require additional data.
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.
Digital watershed and bay polygons for use in geographic information systems were created for Rehoboth Bay, Indian River, and Indian River Bay in southeastern Delaware. Polygons were created using a hierarchical classification scheme and a consistent, documented methodology that enables unambiguous calculations of watershed and bay surface areas within a geographic information system. The watershed boundaries were delineated on 1:24,000-scale topographic maps. The resultant polygons represent the entire watersheds for these water bodies, with four hierarchical levels based on surface area. Bay boundaries were delineated by adding attributes to existing polygons representing water and marsh in U.S. Geological Survey Digital Line Graphs of 1:24,000-scale topographic maps and by dissolving the boundaries between polygons with similar attributes. The hierarchy of bays incorporates three different definitions of the coastline: the boundary between open water and land, a simplified version of that boundary, and the upland-lowland boundary. The polygon layers are supplied in a geodatabase format.
Two Pleistocene channel-systems are recognized in New Castle County, (1) a system of straight channels located in the area north of the Chesapeake and Delaware Canal and (2) a braided system occupying the area south of the Canal.
Fluctuations of the flow regime of Pleistocene streams were frequent as evidenced by sedimentary structures and widespread distribution of gravels in the channel deposits.
During high stream flows most of the study area was submerged, while during low flows large interstream areas and islands emerged.
The transporting agents of the Pleistocene sediments were primarily melt-water streams originating below glaciers which at times advanced to within 100 miles north of New Castle County. Thus, the age of the deposits is thought to be glacial, but there is no indication as to which glacial stage they belong. However, the channels appear to have been formed contemporaneously by a major distributary system.
The purpose of this investigation was to obtain data on and study the factors affecting the salinity of the Delaware River from Philadelphia, Pennsylvania to Reedy Island, Delaware. The techniques of analyses of data and results of the analyses are presented.