Learning from Singapore on How to Build a Sponge City
Release Time:
2016-02-15
Source:
Learning from Singapore on How to Build a Sponge City
As a rain-soaked tropical island nation, Singapore has experienced a steady increase in its annual maximum rainfall over the past three decades—yet urban flooding remains rare. During the rainy season, the city often sees several sudden downpours each day, yet no significant waterlogging or flooding occurs anywhere in the urban area. This remarkable resilience is attributable to a scientifically designed and well-distributed rainwater harvesting and urban drainage system.
I. Preliminary Planning of the Drainage System
Singapore typically plans and designs the underground and surface drainage systems for all new buildings well in advance of construction. As a result, every building—along with sidewalks and roadways—is equipped with a network of drainage channels. These channels are connected to the city’s main drainage system, creating an island-wide rainwater collection and discharge network that ensures large volumes of stormwater are drained efficiently and promptly. At the same time, individual buildings also feature highly sophisticated rainwater collection and discharge systems. For example, in Singapore’s public housing estates, key areas such as rooftops, corridors, and stairwells are fitted with dedicated rainwater collection pipes. Rainwater is channeled through these pipes to external drainage ditches and then routed into the city’s primary sewer network. In terms of design details, Singapore’s surface drainage channels often include multiple connection points to the main urban sewer system, which not only ensures unobstructed flow but also prevents the channels from becoming excessively deep. Furthermore, electronic monitoring systems are installed throughout Singapore’s underground main sewer lines, enabling relevant staff to track conditions in real time—such as water levels, flow rates, and any blockages caused by debris—so that issues can be addressed promptly.
II. Strengthen Rainwater Diversion and Construct Large-Scale Storage Reservoirs
Rainwater collected by the urban rainwater harvesting system ultimately flows into 17 large reservoirs surrounding Singapore, which play a crucial role in managing stormwater runoff and mitigating urban flooding.
The reservoir is separated from the sea by a seawall and is equipped with crown-shaped gates. When heavy rainfall causes the water level in the reservoir to rise while the tide is low, the gates are lowered to allow excess rainwater to flow directly into the sea. Conversely, when the reservoir’s water level is high and the tide is rising, large-capacity drainage pumps can be used to discharge the surplus rainwater back into the ocean. According to reports, if all the seawall’s giant drainage pumps are activated simultaneously, the entire drainage process takes only nine seconds. The Marina Barrage in Singapore has effectively mitigated localized flooding in low-lying urban areas such as Chinatown, Boat Quay, Jalan Besar, and Geylang, and this project has even won awards in international environmental engineering competitions.
III. Establishing Strict Drainage Standards for Ground-Level Buildings
To ensure timely drainage of rainwater during periods of heavy rainfall, Singapore’s Public Utilities Board has repeatedly revised and tightened standards for surface drainage systems, mandating that all new buildings raise the height of their waterproofing thresholds. Developers are required to install water-storage or “water-absorption” facilities in buildings that can capture 25% to 35% of surface runoff, thereby reducing the burden on structures during intense downpours.
IV. Future Development Plan
Currently, Singapore’s Public Utilities Board is conducting a feasibility study on the construction of a new underground integrated drainage and water-storage system in the country. According to reports, the new system will serve three key functions—drainage, water storage, and power generation—to help Singapore achieve greater self-sufficiency in both water and energy supply.
Conclusion: A sponge city is not achieved through a single measure; rather, it is the result of the coordinated operation of multiple systems, including underground drainage systems, detention ponds, Pervious concrete Both the ground-level implementation and stringent standards are indispensable components; sponge city development represents a fundamental shift in development philosophy and approaches, paving the way for a new path of Chinese modernization.
