Winter hydrology in a cold climate rain garden

This paper evaluates the performance and winter hydrology of two small scale rain gardens in a cold climate costal area, in Trondheim, Norway. The rain gardens received runoff from a small residential watershed over a 20 month study period. The objective of the study was to investigate to what extent the cold climate conditions would influence the hydrology and performance of the rain garden. The hydraulic retention, storm lag time and peak flow reduction was measured and compared between the seasons. No significant difference was found on either hydraulic retention time, lag time or peak flow reduction between the seasons. The hydraulic retention time for the rain garden was 0.83 week with runoff inflow and 2.22 weeks with precipitation only. The rain garden performance with respect to hydraulic function was not impacted by the climatic factors experienced during the cold season.