COASTAL LANDSCAPE AS STORMWATER MANAGEMENT INFRASTRUCTURE

Kong Lingchang

Over flooding of stormwater runoff is a common issue in highly developed urban areas where impervious surface treatment and hard engineering infrastructure for stormwater management often conflict with natural water flow. The project serves as a green-blue plan for the future residential area along the Pandan River to reorganize the problems regarding the water flow in high-dense urban context and mimicking the natural capacity of flood conveyance and storage of the land with three proposed strategies.

First, the design attempts to decentralizing stormwater management by diversifying water catchment areas based on natural water flows. Traditionally, as rainwater is unable to be absorbed by previous mediums, it will then become surface runoff which will be received by conventional drainage system on site, canalized to the main canal and finally get discharged into the sea. However, by discharging the surface runoff directly limits its potential for ecosystem services. A more ecological way is to retain the water on site and follow the natural water process which reduces the volume of surface runoff and its discharge rate, facilitating its infiltration. In this case, the design fully respects the natural landform and decentralized the catchments by following the nature catchment boundary.

Additionally, optimizing in the capacity of stormwater management by using strategic designs of the green-blue network directs water to water-centric zones. Different from conventional treatments which hide water channels, this project inserts green spaces combined with ABC water features to receive the surface run-off from buildings and pathways to form a greenblue network which is visible where people can appreciate.

Lastly, the project provides more habitat areas for coastal biodiversity through thoughtful plant selection. For a unique coastal land, the existing pump station of Pandan river separates the merged water conditions into freshwater and seawater which generates both constraints and opportunities for my design. With the unique mangroves growing on the tidal mudflat, these factors can potentially provide various species habitat which the project identifies to create additional buffer zones to mitigate the extreme flooding and provide more coastal habitat.

The project envisions Sungei Pandan to be an ecological and multifunctional urban community where the water feature could be integrated into the coastal infrastructure to effectively manage stormwater runoff.

Water Management

singapore managed

Annual maximum hourly rainfall intensities in Singapore singapore Terrain map singapore rainfaLL inTensiTy map(2011) singapore peak run-off CoeffiCienT map masTer pLan

Valuable vegetation along the coastline: Coastal Mangrove Diverse water salinity environment

Water Management Scinarios

Maximal elevation difference:7m(exclude the depth of canal) long conveyance route

50%

75% scheme3(Selected) 1 2 3 4 5 6 good balance between retaintion and discharge surfaCe runoff CaLCuLaTion gree-bLue infrasTruCTure arrangemenT separated catchments S=8.29ha Q=1.14m³/s V(/h)=4103m³ green space water body

S=6.32ha Q=0.87m³/s V(/h)=3128m³ S=4.65ha Q=0.63m³/s V(/h)=2268m³ S=7.29ha Q=1.03m³/s V(/h)=3708m³ S=8.58ha Q=1.16m³/s V(/h)=4176m³ S=5.05ha Q=0.69m³/s V(/h)=2484m³

100% Legend 6

MLA publication_Helen edit.indd 124-125 2018/2/28 14:31:54

Strategy 1

Decentralizing stormwater management by diversifying water catchment areas based on natural water flows

Strategy 2

Optimizing capacity of stromwater management by strategic designs of green-blue network

Strategy 3

Providing habitat for coastal biodiversity through thoughtful flora selection.

10 Years Return Period: 90mm/h

Catchment area=2.81ha

Q(surface runoff)=0.32m³/s

V(water capacity/h)=1138m³ greening rate:45% Internal Retantion capacity: over 52%

Bioretention

Roof water flow

Swale water flow

Surface water flow