Techniques are presented for estimating the magnitude and frequency of flood discharges on rural, unregulated streams in New York, excluding Long Island. Peak discharge frequency data and basin characteristics from 313 streamflow gaging stations in New York and adjacent States were used to develop multiple linear regression equations for floods with recurrence intervals of 2 to 500 years. A generalized least squares (GLS) procedure was used to develop the regression equations. A separate set of equations was developed for each of eight hydrologic regions of New York; standard errors of prediction range from 17 to 51 percent. Significant explanatory variables included in the regression equations are drainage area, main channel slope, percent basin storage, mean annual precipitation, percent forested area, average main channel elevation, and a basin shape index. Drainage areas for sites used in the analyses ranged from 0.41 to 4,773 square miles.

    Methods of computing peak discharges differ, depending on whether the estimate is for a gaged or ungaged basin, and whether the basin crosses hydrologic region boundaries. Examples of computations are included. Results of the GLS equations were statistically and graphically compared with those obtained from previously (1979) published equations and were found to be unbiased and generally more accurate.

    Basin characteristics, log Pearson Type III statistics, and regression and weighted estimates of the discharge frequency relations are tabulated for the gaging stations used in the regression analyses. Sensitivity analyses showed that mean annual precipitation and drainage area are the variables to which computed discharges are most sensitive in the regression equations.

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U.S. Department of the Interior, U.S. Geological Survey Maintainer: New York District Publications URL: http://ny.water.usgs.gov/pubs/wri/wri904197/index.html Last update: 12:48:43 Tuesday 15 April 2003 Privacy Statement || Disclaimer || Accessibility