ACCURACY OF DESIGN FLOOD ESTIMATES FOR MEDIUM SIZE CATCHMENTS IN EASTERN NEW SOUTH WALES

The accuracy of three methods of design flood estimation for minor drainage structures on rural catchments is examined. The methods are, the standard rational method, a statistical interpretation of the rational method in which the runoff coefficient C is determined from rainfall and streamflow records for catchments in the region, and a regional flood frequency method in which recorded flood peak discharges are related to catchment physical and climatic characteristics using multiple regression equations. The methods are tested by comparing flood peak discharges estimated using each technique with recorded values of the annual maximum flood series. Ten medium size catchments in eastern New South Wales are used for testing. The standard rational method gives very poor flood estimates for low return periods on these medium size catchments. This occurs as a result of the very low or zero values of runoff coefficient which are predicted for these conditions. The statistical interpretation of the rational method and the regional flood frequency method are of similar accuracy with respect to random errors. The statistical interpretation of the rational method slightly underestimates the annual maximum flood series (A). (TRRL)

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 22-29
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00310173
  • Record Type: Publication
  • Source Agency: ARRB Group Limited
  • Files: ITRD, TRIS, ATRI
  • Created Date: Oct 8 1980 12:00AM