FINAL REPORT 7 Hazen Drive, PO Box 483 Concord, NH 03302-0483 14
Technical Report Documentation Page 1. Report No. 2. Gov. 3. Recipient's Catalog No. FHWA-NH-RD-14282F Accession No. 4. Title and Subtitle 5. Report Date Estimation of Flood Discharges at Selected Recurrence Intervals for Streams in New 2008 Hampshire 7. Author(s) 8. Performing Organization Report No. Scott A. Olson 9. Performing Organization Name and Address 10. Work Unit No. (TRAIS) U. S. Geological Survey New Hampshire-Vermont Water Science Center 361 Commerce Way Pembroke, NH 03275 11. Contract or Grant No. 14282F, X-A000 (601) 12. Sponsoring Agency Name and Address 13. Type of Report and Period Covered New Hampshire Department of Transportation FINAL REPORT 7 Hazen Drive, PO Box 483 Concord, NH 03302-0483 14. Sponsoring Agency Code 15. Supplementary Notes In cooperation with the U. S. Department of Transportation, Federal Highway Administration 16. Abstract This report provides estimates of flood discharges at selected recurrence intervals for streamgages in and adjacent to New Hampshire and equations for estimating flood discharges at recurrence intervals of 2-, 5-, 10-, 25-, 50-, 100-, and 500-years for ungaged, unregulated, rural streams in New Hampshire. The equations were developed using generalized least-squares regression. Flood-frequency and drainage-basin characteristics from 117 streamgages were used in developing the equations. The drainage-basin characteristics used as explanatory variables in the regression equations include drainage area, mean April precipitation, percentage of wetland area, and main channel slope. The average standard error of prediction for estimating the 2-, 5-, 10-, 25-, 50-, 100-, and 500-year recurrence interval flood discharges with these equations are 30.0, 30.8, 32.0, 34.2, 36.0, 38.1, and 43.4 percent, respectively.
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