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Base-flow frequency characteristics of selected Pennsylvania streams

Water-Resources Investigations Report 90-4160

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Abstract

Streamflow hydrographs of 309 streamflow stations in Pennsylvania were analyzed by using three computer-assisted empirical methods--local-minimum , fixed-interval, and sliding-interval--to separate the ground-water and surface-runoff components. The 2-, 5-, 10-, and 25-year base-flow-recurrence intervals were determined for each station. The 50- and 100-year recurrence intervals were determined for stations with minimums of 25 and 50 years of record, respectively. All active and inactive continuous-recording Pennsylvania streamflow stations with 10 or more years of record through water year 1986 were analyzed. Stations on the Delaware River in New York and New Jersey also were included. Hydrograph analysis by computer provides consistency of results by removing the subjectivity inherent in manual analyses and considerably reduces the time required to make the analyses. Estimates of the 25-year base-flow-recurrence interval made by using the local-minimum technique, which gives the most conservative estimate, range from 0.069 to 0.888 million gallons per day per square mile. Base flows estimated by using the three computer-assisted techniques compared well with published base flows estimated by using manual methods for three studies in southeastern Pennsylvania. Examples of the effects of geology, climate, regulation, and urbanization on base flow are provided.

Additional publication details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Base-flow frequency characteristics of selected Pennsylvania streams
Series title:
Water-Resources Investigations Report
Series number:
90-4160
Year Published:
1990
Language:
English
Publisher:
U.S. Geological Survey
Contributing office(s):
Pennsylvania Water Science Center
Description:
vi, 67 p. :ill., map ;28 cm.
Country:
United States
State:
Pennsylvania