The MFFn(Mass First Flush) was analyzed for various rainy events(monitoring data from 2008 to 2009) in Transportation area(Highway, National road, Trunk road). Estimated MFFn using SWMM was evaluated by comparison with observed MFFn. MFFn was estimated by varying n-value from 10% to 90% on the rainy events. The n-value increases, MFFn is closed to '1'. As time passed, the rainfall runoff was getting similar to ratio of pollutants accumulation. The result of a measure of the strength of the linear relationship between observed data and expected data under model was good (R2=0.89).
Pollutants runoff loads by volume showed Highway 26.6%, National road 44.8%, Trunk road 35.0% at the MFF20(20% by total runoff). A case of MFF30, pollutants runoff loads by volume showed Highway 40.2%, National road 54.3%, Trunk road 46.8%.
According to the results, Initial precipitation basis were Highway MFF30, National road MFF20, Trunk road MFF30 when the Non-Point source control facilities set up.

Abstract
 1. 서 론
 2. 자료 및 방법
  2.1. 연구대상지역
  2.2. 강우유출수 현장 조사
  2.3. SWMM 모형
  2.4. 초기세척 비율
 3. 결과 및 고찰
  3.1. 도로별 현장 모니터링 결과
  3.2. SWMM 유출량 및 수질 검·보정 결과
  3.3. 초기세척비율 산정
 4. 결 론
 참 고 문 헌

• 권헌각(국립환경과학원 낙동강물환경연구소) | Hun-Gak Kwon (Nakdong River Water Environment Research Center, National Institute of Environmental Research)
• 이재운(국립환경과학원 낙동강물환경연구소) | Jae-Woon Lee (Nakdong River Water Environment Research Center, National Institute of Environmental Research) Corresponding author
• 이윤정(국립환경과학원 낙동강물환경연구소) | Youn-Jeong Yi (Nakdong River Water Environment Research Center, National Institute of Environmental Research)
• 신석호(국립환경과학원 낙동강물환경연구소) | Suk-Ho Shin (Nakdong River Water Environment Research Center, National Institute of Environmental Research)
• 이춘식(경남과학기술대학교) | Chun-Sik Lee (Department of Environmental Engineering, Kyeongnam National University of Science and Technology)
• 이재관(국립환경과학원 낙동강물환경연구소) | Jae-Kwan Lee (Nakdong River Water Environment Research Center, National Institute of Environmental Research)