Use of intercepted runoff depth for stormwater runoff management in industrial parks in Taiwan

First flush of stormwater runoff plays an important role in water quality management. Since stormwater runoff during the initial period of precipitation events carries a greater portion of pollution loads, appropriate strategies are needed for effectively controlling the non-point source loads (NPS). In the present study, case studies were performed in two industrial parks for correlating the relationship between pollutant mass and the runoff volume. Three precipitation events were used for calibration and verification of a deterministic model, Storm Water Management Model. The model was then used to simulate all rainfall events in a particular hydrological year to determine the relationship between interceptive amounts of initial runoff and their corresponding reduced portion of annual NPS loads. The results indicate that the first 6-8 mm of a storm runoff depth includes more than 60% NPS loads. If the depth is increased to 10 mm, 80% NPS loading can be contained. The interceptive volume for eliminating 80% NPS loading in Guan-Tian and Yong-Kong industrial areas are 7 and 12 mm, respectively.