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| Publications— Scientific Investigations Reports |
In cooperation with the Delaware River Basin Commission
U.S. Geological Survey Scientific Investigations Report 2006-5125--Version 1.1
By Ronald A. Sloto and Debra E. Buxton
This report is available online in Portable Document Format (PDF). If you do not have the Adobe Acrobat PDF Reader, it is available for free download from Adobe Systems Incorporated.
Errata sheet--5/25/07
Download the report--Version 1.1 (18.3 MB)
Ground-water availability using a watershed-based approach was estimated for the 147 watersheds that make up the Delaware
River Basin. This study, conducted by the U.S. Geological Survey in cooperation with the Delaware River Basin Commission
(DRBC), supports the DRBC’s Water Resources Plan for the Delaware River Basin. Different procedures were used to estimate
ground-water availability for the region underlain by fractured rocks in the upper part of the basin and for surficial
aquifers in the region underlain by unconsolidated sediments in the lower part of the basin. The methodology is similar
to that used for the Delaware River Basin Commission’s Ground-Water Protected Area in Pennsylvania.
For all watersheds, ground-water availability was equated to average annual base flow.
Ground-water availability for the 109 watersheds underlain by fractured rocks in Delaware, New Jersey, New York, and
Pennsylvania was based on lithology and physiographic province. Lithology was generalized by grouping 183 geologic units
into 14 categories on the basis of rock type and physiographic province. Twenty-three index streamflow-gaging stations were
selected to represent the 14 categories. A base-flow-recurrence analysis was used to determine the average annual 2-, 5-,
10-, 25-, and 50-year-recurrence intervals for each index station. A GIS analysis used lithology and base flow at the index
stations to determine the average annual base flow for the 109 watersheds. Average annual base flow for these watersheds
ranged from 0.313 to 0.915 million gallons per day per square mile for the 2-year-recurrence interval to 0.150 to
0.505 million gallons per day per square mile for the 50-year-recurrence interval.
Ground-water availability for watersheds underlain by unconsolidated surficial aquifers was based on predominant surficial
geology and land use, which were determined from statistical tests to be the most significant controlling factors of base
flow. Twenty-one index streamflow-gaging stations were selected to represent the 13 categories of predominant surficial
geology and land use for the 38 Coastal Plain watersheds. A base-flow-recurrence analysis was used to determine the average
annual 2-, 5-, 10-, 25-, and 50-year-recurrence intervals for each group of predominant surficial geology and land use.
Average annual base flow for these watersheds ranged from 0.465 to 1.169 million gallons per day per square mile for the
2-year-recurrence interval to 0.178 to 0.670 million gallons per day per square mile for the 50-year-recurrence interval.
Estimated 2-, 5-, 10-, 25-, and 50-year annual base-flow-recurrence interval values for each watershed in the Delaware
River Basin are considered to be the quantity of ground water available for each watershed over a range of climatic
conditions. The recurrence intervals are considered to be relative indicators of climatic difference; the 2-year-recurrence
value represents wetter years, and the 50-year-recurrence value represents drier years. The remaining available ground water
in each watershed was determined by subtracting current (1997-2000) ground-water withdrawals and consumptive domestic use
and adding water recharged by agricultural irrigation and land application of treated-sewage effluent. Ground-water use
ranged from 0 to 60.8 percent of available ground water for the 2-year-recurrence interval; it exceeded 25 percent in four
watersheds and 50 percent in two watersheds. Ground-water use ranged from 0 to 75.9 percent of available ground water for
the 5-year-recurrence interval; it exceeded 25 percent in five watersheds and 50 percent in three watersheds. Ground-water
use ranged from 0 to 84.5 percent of available ground water for the 10-year-recurrence interval; it exceeded 25 percent in
seven watersheds and 50 percent in four watersheds. Ground-water use ranged from 0 to 103 percent of available ground water
for the 25-year-recurrence interval; it exceeded 25 percent in nine watersheds, 50 percent in three watersheds, and
100 percent in one watershed. Ground-water use ranged from 0 to 127 percent of available ground water for the
50-year-recurrence interval; it exceeded 25 percent in 11 watersheds, 50 percent in 6 watersheds, and 125 percent in
1 watershed. If ground water pumped for quarry dewatering is not considered as a withdrawal, the ground-water use
percentage in some watersheds would drop substantially.
Abstract
Introduction
Purpose and Scope
Study Area
Ground-Water Availability
Watershed Characteristics
Geologic Units
Ground-Water Withdrawals
Ground-Water Recharge
Domestic Water Use
Assumptions and Limitations
Estimation of Ground-Water Availability for Fractured Rock
Index Stations
Precambrian to Ordovician Crystalline Rocks of the Piedmont Physiographic Province
Triassic Clastic Rocks and jurassic Diabase
Precambrian and Cambrian Crystalline Rocks of the Reading Prong
Ordovician Clastic Rocks of the Ridge and Valley Physiographic Province
Cambrian and Ordovician Carbonate Rocks of the Ridge and Valley Physiograph Province
Silurian Clastic Rocks
Mississippian and Pennsylvanian Clastic Rocks
Devonian Clastic Rocks
Blue Mountain Section of the Ridge and Valley Physiographic Province
Glaciated Pocono Plateau Section of the Appalachian Plateaus Physiographic Province
Glaciated Low Plateau Section of the Appalachian Plateaus Physiographic Province
Catskill Mountains Section of the Appalachian Plateaus Physiographic Province
Southern New York Section of the Appalachian Plateaus Physiographic Province
Comparison between Base Flow Estimated by Hydrograph Separation and Spatial-Data Analysis
Estimation of Ground-Water Availability for Unconsolidated Sediments
Index Stations
Predominant Surficial Geology and Land-Use Categories in New Jersey Coastal Plain Watersheds
Salt Marsh and Estuarine Deposits and Undeveloped Land Use
Lower and Upper Stream-Terrace Deposits and Undeveloped Land Use
Cape May Formation
Undeveloped Land Use
Agricultural Land Use
Weathered Coastal Plain Formations
Urban Land Use
Undeveloped Land Use
Agricultural Land Use
Bridgeton Formation
Urban Land Use
Undeveloped Land Use
Agricultural Land Use
Predominant Land-Use Categories in the Delaware Coastal Plain Watersheds
Urban Land Use
Undeveloped Land Use
Agricultural Land Use
Ground-Water Availability and Use by Watershed in the Delaware River Basin
Summary
Acknowledgments
References Cited
This report is available online in Portable Document Format (PDF). If you do not have the Adobe Acrobat PDF Reader, it is available for free download from Adobe Systems Incorporated.
Download the report--Version 1.1 (18.3 MB)
For more information about USGS activities in Pennsylvania contact:
Director
USGS Pennsylvania Water Science Center
215 Limekiln Road
New Cumberland, Pennsylvania 17070
Telephone: (717) 730-6960
Fax: (717) 730-6997
or access the USGS Water Resources of Pennsylvania home page at:
http://pa.water.usgs.gov/.
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