Improved methods for design and pollution abatement evaluation of urban highway drainage facilities require not only the average rainfall intensity of the storm but also the time distribution of the rainfall. Since the temporal pattern of rainfall varies with storms and the patterns of future storms cannot be predicted exactly, the design hyetograph can only be determined probabilistically using statistical values of past events. By using the moments of the statistical values nondimensional hyetographs can be established and then used to produce the design hyetographs. The nondimensional triangular hyetograph method is based on the statistical mean of the first moment of recorded rainstorms and triangular representation of the hyetographs, and nondimensionalized using the rainfall duration and depth. An analysis of 9,869 rainstorms at four locations indicates that for a given season the nondimensional triangular hyetographs for heavy rainstorms are nearly identical, having only secondary effects from the duration of rainfall, measurement accuracies of standard U.S. National Weather Service precipitation data, and insignificant effect of geographic locations. Simple procedures of how to use the nondimensional triangular hyetograph to produce the design hyetograph are outlined. The possibility of using trapezoidal nondimensional hyetographs is also discussed. However, it is recommended that more rainstorms from other locations should be analyzed to verify the conclusions of this study. The computer programs together with user's manual for the statistical analysis of rainstorms are presented. /FHWA/

  • Supplemental Notes:
    • Sponsored by the Department of Transportation Federal Highway Administration.
  • Corporate Authors:

    University of Illinois, Urbana-Champaign

    Urbana, IL  United States  61801
  • Authors:
    • Yen, B C
    • Chow, V T
  • Publication Date: 1977-11

Media Info

  • Pagination: 280 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00185272
  • Record Type: Publication
  • Source Agency: Federal Highway Administration
  • Report/Paper Numbers: FHWA-RD-78- 65 Final Rpt.
  • Contract Numbers: DOT-FH-PO-6-3-0160
  • Files: TRIS, USDOT
  • Created Date: Mar 14 1979 12:00AM