In urban areas heavy rainfall can’t soak away into the ground. It is channelled through drains into rivers. Pollutants are washed with the rainfall into the rivers and groundwater. If the sewage system is overwhelmed sewage can be discharged into the rivers. Carrying the rainfall away from the local area without allowing it to soak into the water table can produce drought conditions later on. If drains are blocked or overwhelmed by a large amount of water in a short space of time localised flooding is the result.
Rain gardens reduce the volume of water flowing through drains by copying the natural water retention of undeveloped land. They help to slow the water flow, filter the run-off and retain water locally. They can be used in conjunction with a rainwater harvesting system and a pond (optional). Even one rain garden can make a difference in addressing localised flooding and water quality.
Basically a rain garden is a shallow depression or large planter, designed to receive rainwater from a downpipe or large paved area. It is filled with absorbent, yet free-draining soil and planted with vegetation that can withstand occasional flooding. The rainwater enters the soil and drains away into the ground or is taken up by the plants and moved into the atmosphere through transpiration. Rain gardens usually absorb all the rainwater that flows into them but are designed to direct excess water following particularly heavy rainfall into the existing drains.
 |
| Rain Garden Planter (from UK Rain Garden Guide) |
 |
| Street Rain Garden (from UK Rain Garden Guide) |
The UK Rain Garden Guide
Rain Garden Kits
Susdrain
Scottish Environment Protection Agency
The Ecologist
Rain Gardens in Puget Sound
depave
Comments
Post a Comment