Alkaff Lake@Bidadari Park

Innovative solution to mitigate flood risk

Alkaff Lake, situated in the new Bidadari estate, is a first-of-its-kind multi-functional drainage infrastructure for stormwater management, enhancing flood protection for Bidadari estate and the surrounding areas. In dry weather, it looks like a regular lake and forms part of the recreational and aesthetic community space for the public. During heavy rainfall, it plays an important role in controlling stormwater runoff.

To cater for the development of the new Bidadari estate, there was a need to address an increase in stormwater runoff. Alkaff Lake was conceived in close collaboration with agencies such as Housing & Development Board (HDB) and National Parks Board (NParks) as an innovative solution that balances the need for drainage improvements, while also enhancing the overall liveability of the area by incorporating blue and green spaces. The 1.8-hectare lake is designed to hold up to 30,000 cubic metres of water, the equivalent of 12 Olympic-sized swimming pools.

During a heavy storm, runoff from half of Bidadari estate (43.5 hectares) will be diverted into Alkaff Lake, which is the lowest point in the area. This allows for large amounts of stormwater to enter the lake, which has outlet points to control the release of stormwater. By capturing and retaining the stormwater from nearby areas, the lake regulates and slows down the amount of runoff that flows into the downstream drainage system, which cannot be widened further due to space constraints. This helps to mitigate flood risk in the areas downstream of the Bidadari estate.

Alkaff Lake incorporates PUB’s Active, Beautiful, Clean Waters (ABC Waters) design features such as terraced wetlands and swales, which are integrated with our drainage infrastructure where feasible to create more liveable spaces that bring the public closer to water. Visitors can take in the panoramic view of the cascades and lake from the nest shelter or the large viewing deck which extends over the water.

To ensure good water quality in the lake, the terraced wetlands and swales help to cleanse and filter pollutants from stormwater runoff. Gross Pollutant Traps (GPT) are installed to trap pollutants such as litter and silt that are accumulated in the runoff, while aerators within the lake improve water circulation and increase the amount of dissolved oxygen in the water.