:This formula is used to calculate peak rates of runoff when designing drainage LID BMPs in urban area. It is useful in estimating runoff on relatively small areas (roofs, parking lots, medians, road right-of-ways, etc.) | :This formula is used to calculate peak rates of runoff when designing drainage LID BMPs in urban area. It is useful in estimating runoff on relatively small areas (roofs, parking lots, medians, road right-of-ways, etc.) |