First Flush Phenomenon and Its Application for Stormwater Runoff Management

This paper summarizes the results of the comprehensive first flush characterization study performed on three highly urbanized highway sites in Los Angeles, California. The study was performed from ۲۰۰۰ through ۲۰۰۵ and a total of ۹۷ storm events were monitored ranging from ۰.۵ to ۱۳۷ mm with an average rainfall of about ۲۵.۵ mm. First flush characterization was performed based on contaminant concentration and mass loading. To determine the first flush effect, multiple grab samples were obtained throughout the storm event with an emphasis on collecting additional grab samples during the first hour of storm event. Topics presented and discussed in this paper include: (۱) meaningful definition of first flush characterization, (۲) strategic method of collecting first flush sampling, (۳) uniform method and interpreting first flush results, and (۴) the implication of first flush results for urban stormwater runoff management.

Keywords:

Flush Phenomenon , Stormwater , Runoff Management