Visitors to Sungei Buloh Wetland Reserve last Thursday and Friday may have found themselves closer to the water than expected.

High spring tides of up to 3.5m submerged the wooden walkway on both afternoons.

The reserve's deputy director, Ms Sharon Chan, said such high tides occur several times a year and added that there are plans to raise the height of the reserve's boardwalks.

"Some sections of the boardwalks may be flooded during the spring tides," she told The Sunday Times. "On these days, signs are put up to inform visitors that the trails are closed."

Spring tides occur when the Sun, Moon and Earth are aligned, according to the United States' National Oceanic and Atmospheric Administration (NOAA).

The gravitational pull of the Sun is "added" to the gravitational pull of the Moon on Earth, causing the oceans to bulge more than usual.

This means that the high tides are a little higher and low tides are a little lower than average.

Tide timetables on the National Environment Agency's website show that the high tides are expected to reach 3.4m on Feb 20 slightly before noon and on Feb 21 at about 12.30pm.

Visitors to the Sungei Buloh reserve were unfazed by the occasional flooding.

"Even if you get there and some parts of it are closed, there are lots of other things you can do," said Ms Georgina Tan, 30, a sales executive.

The reserve recently opened a new extension that includes five lookout points that give people unobstructed views of the reserve and the sea, and a gallery featuring plants and animals found in the mangroves.

Entry to the reserve is free and it is open from 7.30am to 7pm from Mondays to Saturdays, and 7am to 7pm on Sundays and public holidays. For the tidal timetable, call 6794-1401.

zengkun@sph.com.sg