01367664

Component

Pervious pavements underlain by infiltration beds have been used as stormwater control measures (SCMs) for several decades. As a design practice, runoff volume reduction in those systems is attributed exclusively to subsurface infiltration. Neglecting evaporation in the hydrologic cycle of pervious pavement systems is based on the perceived insignificance of this factor, rather than on scientific evidence. This paper presents research designed to fill the knowledge gap in evaporation behavior of pervious concrete SCMs. A laboratory simulation was conducted to identify parameters affecting evaporation from pervious concrete systems and to obtain the evaporation rates typical for summer months in the Philadelphia area. Considerations used in the experiment design, methodology, the experimental program, and the results are presented here. The results were placed into the context of the year-round hydrologic performance of the SCM. The effect of initial depth to water surface on evaporation rates was found to be one of the governing factors. The concept of influence depth was established and characterized as approximately 10 inches (254 mm). A predictive empirical equation describing 24-hour evaporation rates as a function of initial depth and the time since rainstorm event was developed. Depending on the design of the system, the evaporation share in a yearly water budget was found to range from 3 to 30 percent. The paper includes a discussion on evaporation behavior and optimization of the design parameters to promote evaporation from pervious pavement systems.

01362476

12-0074

English

16p

2012

Transportation Research Board 91st Annual Meeting

Digital/other

Figures; References; Tables

Evaporation; Experiments; Hydrology; Laboratory tests; Porous pavements; Runoff

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

Transportation Research Board Annual Meeting 2012 Paper #12-0074

TRIS, TRB

Feb 8 2012 4:52PM