Urban hydrology for small watersheds. 2nd edition




Cronshey, Roger

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U.S. Dept. of Agriculture, Soil Conservation Service, Engineering Division


Technical Release 55 (TR-55) presents simplified procedures to calculate storm runoff volume, peak rate of discharge, hydrographs, and storage volumes required for floodwater reservoirs. These procedures are applicable in small watersheds, especially urbanizing watersheds, in the United States. First issued by the Soil Conservation Service (SCS) in January 1975, TR-55 incorporates current SCS procedures. This revision includes results of recent research and other changes based on experience with use of the original edition. The major revisions and additions are: • A flow chart for selecting the appropriate procedure; • Three additional rain distributions; • Expansion of the chapter on runoff curve numbers; • A procedure for calculating travel times of sheet flow; • Deletion of a chapter on peak discharges; • Modifications to the Graphical Peak Discharge method and Tabular Hydrograph method; • A new storage routing procedure; • Features of the TR-55 computer program; and • Worksheets. This revision was prepared by Roger Cronshey, hydraulic engineer, Hydrology Unit, SCS, Washington, DC; Dr. Richard H. McCuen, professor of Civil Engineering, University of Maryland, College Park, MD; Norman Miller, head, Hydrology Unit, SCS, Washington, DC; Dr.Walter Rawls, hydrologist, Agricultural Research Service, Beltsville, MD; Sam Robbins (deceased), formerly hydraulic engineer, SCS, South National Technical Center (NTC), Fort Worth, TX; and Don Woodward, hydraulic engineer, SCS, Northeast NTC, Chester, PA. Valuable contributions were made by John Chenoweth, Stan Hamilton, William Merkel, Robert Rallison (ret.), Harvey Richardson, Wendell Styner, other SCS hydraulic engineers, and Teresa Seeman.


164 pages; available for download at the link below.


hydrology, watersheds