A field study on the first flush effect of copper roof runoff

The runoff of four copper roof surfaces with different aspects were monitored in a field study in order to identify the existence of the first flush effect and to determine the influences. It was found that almost 40% of all sampled precipitation events exhibited a moderate first flush effect regarding the distribution of copper mass in the roof runoff. There was a significant impact of the roof aspect on the presence and on the magnitude of the first flush. No correlation was found between the first flush effect and weather parameters, such as rain height, rain intensity, and antecedent dry weather period.