Analysis of Flood-Magnitude and Flood-Frequency Data for Streamflow-Gaging Stations in the Delaware and North Branch Susquehanna River Basins in Pennsylvania [open pdf - 395KB]
"The Delaware and North Branch Susquehanna River Basins in Pennsylvania experienced severe flooding as a result of intense rainfall during June 2006. […] In response to this flooding, the Department of Homeland Security, Federal Emergency Management Agency (FEMA) Region III, and the U.S. Geological Survey (USGS) Pennsylvania Water Science Center began a study to analyze flood-magnitude and flood-frequency data for streamflow-gaging stations (stations) on tributaries within the Delaware and North Branch Susquehanna River Basins in Pennsylvania. This study updates and compares flood frequencies deter-mined from annual maximum series (AMS) data from continuous-record stations to flood discharges obtained from previously published Flood Insurance Studies (FIS) to determine whether there were any major differences in the flood-discharge data. The study also computes flood frequencies using partial-duration series (PDS) data to determine how the use of this PDS data may affect the flood frequencies compared to those deter-mined using the AMS data. The potential effects of regulation and urbanization also were included in the study. […] This report presents the results of (1) a comparison of updated AMS-derived flood-frequency discharges and flood discharges from previously published FIS, (2) a comparison of flood-frequency discharges computed using updated AMS and PDS peak-flow data, and (3) an analysis of the potential effects of regulation and urbanization on updated AMS-derived flood frequencies in the Delaware and North Branch Susquehanna River Basins. A flood-frequency analysis with recurrence intervals of 2, 5, 10, 50, 100, and 500 years (Q2, Q5, Q10, Q50, Q100, and Q500, respectively) was performed for 41 stations in the Delaware and North Branch Susquehanna River Basins in Pennsylvania (fig. 1) (appendix 1). Thirty-six of the 41 stations had 30 or more years of continuous record; the other 5 stations had 25 or more years of record."
U.S. Geological Survey: http://infotrek.er.usgs.gov/pubs/