Methods for Estimating Regional Coefficient of Skewness for Unregulated Streams in New England, Based on Data Through Water Year 2011

Scientific Investigations Report 2017-5037
By: , and 


  • Document: Report (18 MB pdf)
  • Data Release: Data Release - Annual peak-flow data and PeakFQ output files for selected streamflow gaging stations operated by the U.S. Geological Survey in the New England region that were used to estimate regional skewness of annual peak flows
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The magnitude of annual exceedance probability floods is greatly affected by the coefficient of skewness (skew) of the annual peak flows at a streamgage. Standard flood frequency methods recommend weighting the station skew with a regional skew to better represent regional and stable conditions. This study presents an updated analysis of a regional skew for New England developed using a robust Bayesian weighted and generalized least squares regression model. Nineteen explanatory variables for 153 streamgages were tested in the regression analysis, but none were statistically significant and, as a result, a constant model was selected to define the regional skew for New England. The constant model for the New England region has, in log units, a skew of 0.37, a model error variance of 0.13, and an average variance of prediction at a new site of 0.14. An assessment of the selected regional skew model was conducted using a Monte Carlo analysis. The Monte Carlo simulations reveal that the perceived pattern in the station skews among the 153 streamgages is an artifact of the sample variability and the covariance structure of the errors.

Suggested Citation

Veilleux, A.G., Zariello, P.J., Hodgkins, G.A., Ahearn, E.A., Olson, S.A., and Cohn, T.A., 2019, Methods for estimating regional coefficient of skewness for unregulated streams in New England, based on data through water year 2011: U.S. Geological Survey Scientific Investigations Report 2017–5037, 29 p.,

ISSN: 2328-0328 (online)

Study Area

Table of Contents

  • Abstract
  • Introduction
  • Purpose and Scope
  • Study Area
  • Streamgage Data for Regional Skew Analysis
  • Analytical Methods To Generate Regional Skew
  • Data Analysis
  • Regression Analyses
  • Summary
  • References Cited
  • Appendix 1. Assessment of New England Regional Skew Constant Model Through Monte Carlo Realizations   
Publication type Report
Publication Subtype USGS Numbered Series
Title Methods for estimating regional coefficient of skewness for unregulated streams in New England, based on data through water year 2011
Series title Scientific Investigations Report
Series number 2017-5037
DOI 10.3133/sir20175037
Year Published 2019
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Office of Surface Water
Description Report: iv, 29 p.; Data Release
Country Untied States
State Connecticut, Maine, Massachusetts, New Hampshire, New York, Rhode Island, Vermont
Other Geospatial New England
Online Only (Y/N) Y
Google Analytic Metrics Metrics page
Additional publication details