Stormwater Basin

Stormwater basin is an excavated area designated to collect the stormwater to prevent flooding or erosion in a area adjacent to river, lake or a bay. It can be classified as dry and wet basins.

TUHH Difference between a detention and a retention basin (1)

Detention and retention basin basic difference. Source:

The dry basin, or also called as detention pond, is used mainly to prevent peak flow erosion through creating a temporary space for the water to reside for a short period of time, usually around 24 to 48 hours. It is normally covered in dry grass, except during storm event. Therefore, it can be multifunctional such as used for parks or playing ground during its dry period.

The wet basin, or also called as retention pond, is used mainly to prevent flooding and downstream erosion through retaining the water for a longer period of time. It always has a permanent pool of water, which only excess when rain happens. It promotes pollutant removal through sedimentation or absorbtion of the aquatic vegetation. This pond offers an opportunity for landscape designer to create an aesthetic element for the city. It also can be used for wildlife habitat or as part of a public open space.

Storm water is being directed to the basin through a network of streets or underground pipes. Both type of basin must allow a large volume of water to enter. The dry basin has a small opening in the lowest point of the structure, so the water can pass trough directly. While, the wet basin will only reduce the water through evaporation or excess when there is a major storm event happen. The maintenance of the dry basin is easier than the wet basin. The wet basin needs frequent sediment removal and moving, rather than the dry basin.

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