Indonesia and Malaysia have banned sand exports to Singapore. Now, Cambodia has followed suit (Cambodia bans sand exports to Singapore after pressure from environmental groups; July 13).

There is no guarantee that our other suppliers - such as China, Vietnam and Myanmar - will not do the same in future, citing environmental issues.

As sea levels rise and urban populations swell, sand can be considered a strategically important material.

It is needed in the construction industry and reclamation work. Much of the modern global economy depends on it.

With limits on the export of sand, the prices will rise. Illegal sand mining has also been taking place in nearby countries.

Singapore must think of a substitute for sand and prepare to be self-reliant.

For instance, mud could be used for reclamation, straw and wood for building houses, and crushed rock for concrete. Asphalt, concrete and glass can also be recycled.

Artificial or manufactured sand is fast emerging in other countries as an alternative as well.

Environmentalists in many places are calling on their governments to rein in sand mining. Singapore needs to plan ahead for alternatives.

Francis Cheng