The effects of vegetation on the hydraulic residence time of stormwater ponds

Storm water ponds treat polluted run-off from urban areas, highways and agricultural land. Vegetation plays a key role in water treatment, but further understanding is required to identify how vegetation density and spatial distribution within a pond affect the residence time, an important parameter with respect to water treatment. This paper presents results from a preliminary study where the residence time distribution and discharge of a water treatment pond were measured at two stages within the vegetation’s seasonal growth cycle, representing the minimum and maximum states of the vegetation’s density. The results show clear and significant differences between the residence time distribution for the two cases, and highlight the need for further work on the topic.