Analytical Determination of Pollutant Wash-Off Parameters

Abstract

The wash-off algorithm in the Storm Water Management Model has been widely used to simulate the wash off of sediment and pollutants from impervious areas. This algorithm indicates an exponential relationship between pollutant wash off and runoff volume. To simulate water quality, the initial mass of sediment or pollutant at the beginning of the storm and an empirical wash-off coefficient need to be determined. A simple analytical technique is developed for evaluating these parameters from measured water quality and runoff data. The proposed method is based on an expression of the exponential wash-off equation in terms of concentration rather than pollutant mass, and it can be applied to parameter evaluation without recourse to complex numerical models or optimization techniques.