STORMWATER FLOW ESTIMATION FOR SMALL UNGAUGED URBAN CATCHMENTS

The rational or Lloyd-Davies method is widely recognised as the most appropriate procedure for design flow estimation in urban catchments of less than 20 ha developed area. This method assumes catchments to be uniform ie critical storm duration equal to time of concentration, t(sub C). In the hands of experienced practitioners, flow estimates produced by the rational method in typical urban catchments are found to vary up to plus or minus 20 per cent. Uncertainty in the selection of run off coefficient, C, and in the calculation of t(sub C) is cited as the main cause of this variation. An alternative method for calculating design flow estimates is proposed. For the same uncertainty in C and t(sub C), this method is shown in the case of a typical urban residential development, to yield flow estimates which cover a range about two-thirds of that given by the rational method. The method is based on partial area storm consideration and provides improved flow estimation performance only in catchments which are non-uniform ie where critical storm duration is equal to impervious area travel time, t (sub imp). Uniformity and non-uniformity in typical Australian urban residential catchments is investigated; it is concluded that most but not all developed catchments are non-uniform. The proposed method is uncommitted to any assumption of catchment uniformity or non-uniformity and in the case of non-uniform catchments provides flow estimates from both the assumed uniform and non-uniform domains (A). The number of the covering abstract of the conference is TRIS No. 368448. (TRRL)

• Record URL:
  • http://arrbknowledge.com
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/00050164
• Supplemental Notes:
  • Proceedings of Eleventh Australian Road Research Board Conference, held at the Univerity of Melbourne, August 23-27, 1982.
• Corporate Authors:

  ARRB

  Melbourne, Victoria  Australia 
• Authors:
  • ARGUE, J R
• Publication Date: 1982

Media Info

• Features: Figures; References; Tables;
• Pagination: p. 193-205
• Serial:
  • Australian Road Research
  • Volume: 11
  • Issue Number: PT4
  • Publisher: ARRB
  • ISSN: 0005-0164

Subject/Index Terms

• TRT Terms: Calculation; Conferences; Drainage; Drainage basins; Estimating; Flow; Fluid dynamics; Nonuniform flow; Rain; Residential areas; Runoff; Surfaces; Urban areas; Water
• Old TRIS Terms: Uniform flow
• ITRD Terms: 6464: Calculation; 4318: Catchment area (hydrol); 8525: Conference; 5430: Flow (fluid); 2507: Rain; 4329: Run off; 6438: Surface; 313: Urban area; 4355: Water
• Subject Areas: Highways; Hydraulics and Hydrology; I26: Water Run-off - Freeze-thaw;

Filing Info

• Accession Number: 00368452
• Record Type: Publication
• Source Agency: ARRB
• Report/Paper Numbers: V11, Pt2
• Files: ITRD, TRIS, ATRI
• Created Date: Dec 30 1982 12:00AM