Many developments will change the natural existing drainage pattern so stormwater systems are typically designed and constructed to manage this change and any potential adverse effects which may include increased runoff, flood damage, erosion, sedimentation, water pollution and damage to ecosystems.
The primary goals of a stormwater drainage system are to collect, convey and treat surface runoff to minimise flood damage and adverse effects on the environment and other property. There are several ways this can be done. Low Impact Design features such as planted swales, rain gardens, larger grass verges and detention ponds can allow groundwater recharge, slow the movement of water and reduce the amount of pollutants in receiving water bodies. These areas may also be used to enhance a development, contributing to the wider environmental quality of an area.
Understanding the impact of site development, such as the extent of site coverage (including paved surfaces), is important and options such as narrower carriageways and semi-permeable paving for on-road parking can help to reduce runoff.
Stormwater systems may also integrate with the natural drainage system and this can help mitigate environmental effects, as well as enhance amenity and ecological values.
Definitions in this section
Low impact design
Stormwater drainage system