Redusert avrenning fra urbane felt – Et eksempel på lokal overvannshåndtering / Restoration of the hydrological regime after urban development
Urbanization of a watershed increases the volume and peak discharge of runoff. This paper shows how the use of low impact development (LID) best management practices (BMPs) influences site hydrology by comparing two newly established residential areas in Connecticut, USA. The watersheds were 2.0 and 1.7 ha for the traditional storm water management and LID area respectively. Best management practices used in the LID include swales, permeable pavement, rain gardens and a bio-retention area (area for short time flooding). Results show that the LID area increased the lag time from rainfall to runoff for “small” rain events. For “large” rain events the effect on the lag time was not as clear. However, LID significantly decreased the runoff volume and intensity. In addition, the precipitation required to induce runoff in the LID was twice as large as from the traditional housing area.