Overland Flow Time of Concentration on Very Flat Terrains

Two types of laboratory experiments were conducted to measure overland flow times on surfaces with very low slopes. One was a rainfall test using a mobile artificial rainfall simulator; the other was an impulse runoff test. Test plots were 6 ft (1.83 m) wide by 30 ft (9.14 m) long with slopes ranging from 0.24% to 0.48%. Surface types tested include bare clay, lawn (short grass), pasture (tall grass), asphalt, and concrete. A regression analysis was conducted to construct models for predicting flow times. Results predicted with regressed models were compared with those from empirical models in the literature. It was found that the slope variable in the regressed model from rainfall test data is less influential than that in existing models. Furthermore, the exponent for the slope variable in the regressed model for the impulse runoff condition is only 1/10th of those in existing models. Overall, most empirical models underestimate overland flow time for laboratory plots with very low slopes. The slope variable becomes insignificant in governing overland flow time when the slope is small. Antecedent soil moisture, not included in most empirical models, significantly affects time of concentration, which is included in the regressed models.

• Record URL:
  • https://doi.org/10.3141/2060-15
• Summary URL:
  • http://scholar.google.com/scholar_lookup?title=Overland+Flow+Time+of+Concentration+on+Very+Flat+Terrains&author=M.+Li&author=P.+Chibber&publication_year=2008
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/isbn/9780309113304
• Authors:
  • Li, Ming-Han
  • Chibber, Paramjit
• Publication Date: 2008

Language

• English

Media Info

• Media Type: Print
• Features: Figures; Photos; References; Tables;
• Pagination: pp 133-140
• Monograph Title: Highway Design 2008
• Serial:
  • Transportation Research Record: Journal of the Transportation Research Board
  • Issue Number: 2060
  • Publisher: Transportation Research Board
  • ISSN: 0361-1981

Subject/Index Terms

• TRT Terms: Asphalt; Clay; Concrete; Grasses; Laboratory tests; Rainfall; Regression analysis; Runoff; Slopes; Soil water; Terrain; Time; Watersheds
• Uncontrolled Terms: Antecedent moisture conditions; Overland flow
• Subject Areas: Data and Information Technology; Highways; Hydraulics and Hydrology; I26: Water Run-off - Freeze-thaw;

Filing Info

• Accession Number: 01090489
• Record Type: Publication
• ISBN: 9780309113304
• Files: TRIS, TRB
• Created Date: Mar 21 2008 8:20AM