INTRODUCTION
In an effort to reduce the effects of non-point source pollution, which includes overland runoff
from agricultural, industrial, and urban areas and accounts for almost 50% of the total water
pollution in the developed world (Novotny 1994), engineers and highway administrations have
placed an emphasis on cost-effective methods to control runoff pollution. One such LID
technology that has been employed for the conveyance of stormwater runoff in highway designs
for many years is grass swales. Water quality enhancements can be realized in these swales
through sedimentation (due to the low velocity induced by the vegetation), filtering by the grass
blades, infiltration, and likely some biological processes. Swales are commonly used on
highway projects because they represent an aesthetically pleasing method for linearly conveying
runoff. While recent studies have revealed them as an effective stormwater management
technology, good performance data and mechanistic understanding of swale design parameters
are not available.