Investigation of the Relationship between Event Pollutant Load and Rainfall and Runoff Characteristics

This paper investigates the relationship between event diffuse pollution loads from impervious surfaces and storm related variables. The event loads are estimated as power functions of total storm rainfall, total storm runoff, rainfall intensity and runoff rate. Total suspended solids, total phosphorus and total nitrogen data from three residential catchments in Brisbane and Melbourne are used. The results indicate that washoff of particulate pollutants from impervious surfaces is governed more by the rainfall intensity and runoff rate than the total storm rainfall or runoff volume. The results also show that, where there are sufficient data to calibrate the parameters, pollutant washoff from storm events can be estimated reasonably accurately using a simple power function of rainfall intensity and/or runoff rate.