Amphibious homes, such as those in Maasbommel, the Netherlands, which stay on the ground during dry times but float when water comes, were brought up as an alternative approach in dealing with rising sea levels (Holding back the tides; May 28).

I had discussed the concept with a Dutch friend a few years ago as a possible idea to propose to Malaysia for flood-hit areas in Kelantan. However, it is unsuitable for Singapore, for two reasons.

First, we have less than 200km of coastline, much of which is intensively developed. There just isn't space to accommodate amphibious homes near the coast.

Second, such houses are built on small pontoons, which have insufficient buoyancy to support any structures other than small buildings.

Larger buildings would require a larger footprint and freeboard. We would need deeper water, which means the structure will not be amphibian but fully floating.

Raising the height of coastal roads is also problematic because of flash floods that occur when heavy rain coincides with high tides.

Having the elevation of our coastline higher than the inland terrain would keep the seawater out, but it would also keep flood water in, as a hydraulic gradient is required to flush the water in our monsoon drains into the sea.

Unless we have large drainage pumps to deliver water to the sea, we would succeed only in creating a lake out of our little red dot every monsoon season. Low-lying areas, including underground carparks, MRT stations and shopping malls, would be threatened.

The only satisfactory solution is very large floating structures, like those I have been advocating in my past pieces.

Until then, we will just have to live with the prospect of a rising sea level.

Lim Soon Heng