01090489

Component

https://doi.org/10.3141/2060-15

http://scholar.google.com...bber&publication_year=2008

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.

01114752

English

pp 133-140

2008

Transportation Research Record: Journal of the Transportation Research Board

9780309113304

Print

Figures (4) ; Photos (2) ; References (22) ; Tables (8)

Asphalt; Clay; Concrete; Grasses; Laboratory tests; Rainfall; Regression analysis; Runoff; Slopes; Soil water; Terrain; Time; Watersheds

Antecedent moisture conditions; Overland flow

Data and Information Technology; Highways; Hydraulics and Hydrology; I26: Water Run-off - Freeze-thaw

TRIS, TRB

Jan 29 2008 2:37PM

• Assessment of Sag Curve Design Criteria Considering Modern Headlamp Performance
• Community Context and Strip Mall Retail: Public Response to the Roadside Landscape
• Construction Specification Framework for Utility Installations
• Culvert Hydraulics: Comparison of Current Computer Models and Recommended Improvements
• Determining the Length of the Right-Turn Lane at a Signalized Intersection
• Development of a Tool for Utility Conflict Data Management in the Project Development Process
• Do Context-Sensitive Solutions Really Work?
• Effect of Median Design on Rural Freeway Safety: Flush Medians with Concrete Barriers and Depressed Medians
• From Arterial to Asset: Examining the Role of the Multiway Boulevard in Coordinated Transportation and Land Use Planning
• Length Requirements for New Single-Arc Unsymmetrical Vertical Curve: Crest Type
• Midwest Guardrail System Adjacent to a 2:1 Slope
• Safety Evaluation and Improvements for Highway Intersections
• Safety Grates for Cross-Drainage Culverts
• State of the Practice of Cable Barrier Systems
• Students’ Perceptions of Difficulties in Cycling to School in Urban and Suburban Taiwan
• Three-Dimensional, Probabilistic Highway Design: Sight Distance Application
• Two-Level Signalized Intersection