Determination of the Interception Volume of Storm Water Based on the Contaminants Transport in Storm Sewers

We constructed a mathematical model to investigate the transport characteristics of storm water volume and contaminant amounts in storm sewers. The key factors controlling the optimal interception volume of storm water, such as water catchment area, recurrence interval, initial contaminant concentration of runoff, and runoff coefficient were discussed. The quantitative relationship between the interception volume of storm water and interception rate of contaminants was analyzed, and the optimization of storm water interception in storm sewers for a specific storm was discussed. The mathematical model revealed that if storm water was intercepted for a period starting from the initiation of the storm and lasting for a part of the time the storm water resides in the sewer, the interception rate of contaminants and the interception volume of storm water both increased with time. The interception rate of contaminants grew rapidly with interception time at the beginning of the storm. After a certain point (the point of inflection), this rate grew more slowly, eventually tending towards 100%. This point of inflection varied according to differences in rainfall conditions. Finally, we suggest optimization methods to obtain the most efficient interception volumes for a given set of rainfall conditions.