Peak-Flow Frequency Estimates for U.S. Geological Survey Streamflow-Gaging Stations in Connecticut

U.S. Geological Survey

Water-Resources Investigations Report 03-4196

By Elizabeth A. Ahearn


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Annual peak-flow data from 128 U.S. Geological Survey streamflow-gaging stations in Connecticut with at least 10 consecutive years of record were used to estimate peak-flow magnitudes for 1.5-, 2-, 10-, 25-, 50-, 100- and 500-year recurrence intervals (exceedance probabilities of 0.67, 0.50, 0.10, 0.04, 0.02, 0.01, and 0.002, respectively). Peak-flow frequency analyses of annual peak flows through the 2001 water year were performed using the procedures in the publication "Guidelines for Determining Flood-Flow Frequency," commonly referred to as Bulletin 17B, by the Interagency Advisory Committee on Water Data (1982). A generalized skew coefficient of 0.34, with a standard error of prediction of 0.51, was developed to improve peak-flow frequency estimates in the state; this replaces the generalized skew coefficients for Connecticut shown in Bulletin 17B.




Annual Peak-Flow Data

Peak-Flow Frequency Analysis at Streamflow-Gaging Stations

Assumptions of Frequency Analysis

Generalized Skew Coefficient

Peak-Flow Magnitude and Frequency from Log-Pearson Type III Distribution

Flows Altered by Flood-Control Dams and Reservoirs

Multiple-Site Station Records

Accuracy of Peak-Flow Frequency Estimates

Mixed-Population Analysis

Maximum Known Peak Flows

Summary and ConclusionS

References Cited

Appendix 1. Description of U.S. Geological Survey streamflow-gaging station locations, Connecticut

For additional information write to:


District Chief

U.S. Geological Survey

101 Pitkin Street

East Hartford, CT 06108


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