A scientific paper published on Friday says a severe storm surge could reach 2.2 metres (7.2 feet) above the local tide datum along parts of Singapore’s eastern coast, placing 46,000 residents in areas that could flood if defences failed. The researchers say planners used the same scenario in engineering calculations, while a public hazard map shows a lower 1.4-metre (4.6-foot) level.
The study, in the Journal of Monsoon Coasts, combined 13 years of tide readings with elevation surveys to model a hypothetical cyclone passing through the South China Sea. It estimates that 18,600 homes and 1,300 hectares (3,200 acres) could lie within the inundation zone by 2050. The authors stress that this is a risk scenario, not a forecast of an approaching storm.
The number missing from the map
Lead author Luděk Filipová, a coastal modeller at the Straits Institute for Marine Research, said the team found the higher surge level in a publicly accessible engineering tender for a planned eastern barrier. The tender sets a proposed crest height of 2.25 metres (7.4 feet), while the government’s public-facing coastal-risk map depicts flooding only up to 1.4 metres (4.6 feet).
The gap matters because the map is widely used by residents and businesses to judge whether their property is exposed, the paper says. The researchers checked the tender against tide-gauge data from the eastern shoreline and ran the model with a cyclone track that would drive water into the Singapore Strait. “The public map stops where the engineering calculation starts,” Filipová said.
The public map stops where the engineering calculation starts.
Luděk Filipová, coastal modeller
The Coastal Safety Directorate said its map was designed to show a planning baseline, not every extreme event, and rejected the suggestion that it had hidden an imminent danger. Alfred Devaux, the directorate’s deputy chief engineer, said the higher figure was a “stress test for infrastructure design” and that the planned barrier would protect key districts. He said a revised map, with clearer explanations of its limits, is due early next year.
A costly question for the coast
At Pasir Ris, a residential district facing the Singapore Strait, the paper’s risk zone includes low-lying streets, a bus interchange and sections of parkland. Fabiana F. Ramos, who runs a small food shop near the coast, said customers had never been told the area could feature in a severe-surge model. “We see high tides, but nobody has explained what this number means for our block,” she said.
The barrier programme is estimated to cost S$1.9 billion (about €1.3 billion), according to the public tender. Devaux said the design would be reviewed against the paper’s findings, but gave no estimate for added costs or a decision date. The researchers say the proposed barrier covers only part of the mapped zone, leaving officials to decide whether drains, raised roads or further walls should protect other areas.
Singapore is not usually struck directly by tropical cyclones, but the authors say a distant storm could still push water into the strait, especially when it coincides with a high tide. The paper models one such track, named Cyclone Soren, and does not claim that a storm of that strength is likely in any particular year.
The directorate has invited public comments on coastal maps until 30 November and says it will publish a technical explanation alongside its revision. Filipová said the team’s next step is to test the model against additional tide gauges; until then, she said, residents should treat the figures as a warning about the limits of the current map, not a prediction that their homes will flood.
