Start planning now for the next deluge

Tunnels to carry water instead of people would be an important part of any successful flood management plan in Thailand’s future and here are some examples to consider:

1. The Channel Tunnel is a 50.5-kilometre undersea rail tunnel beneath the English Channel that links the UK and France; at its lowest point it is 75 metres deep and it has two 7.6-metre diameter rail tunnels and a 4.8-metre diameter service tunnel.

2. The Seikan Tunnel is a 53.85-kilometre railway tunnel in Japan with a 23.3-kilometre long portion under the seabed; track level is about 140 metres below the seabed and 240 metres below sea level;

3. The Gotthard Base Tunnel now under construction will be a pair of railway tunnels beneath the Alps in Switzerland; the western tunnel will be 56.978 kilometres, the eastern tunnel will be 57.091 kilometres and the diameter of each of the tubes will be 8.8-9.5 metres.

It would take less than one kilometre of tunnel to link the northern part of the Chao Phraya River with the southern part of the Chao Phraya at the “loop” in the river near Klong Toey port – in order to substantially increase the current and flow of the river – but tunnels can be used just about anywhere at any length to carry water.

The relevant authorities should look at the capabilities of the newest tunnel boring machines.

Every major river and klong in Thailand should be dredged or lowered so that the bottom of each is at least at sea level at low tide (for those that are not lower than that already);

When feasible, every river and klong on the sea should have “locks” to prevent “backfill” when the river or klong water level is lower than sea level.

The water tunnels from the Chao Phraya River to a “super klong” south-southwest of the Chao Phraya should be built to carry water to the sea (noting that cooperation from environmental groups would be necessary for this). 

The super klong would be as wide as the Chao Phraya River  and its bottom would be as low as sea level at low tide (or lower if pumps are used to pump out the lower water).

The water tunnels could be built incrementally, perhaps one per year; the super klong could be built with capabilities for expansion if needed and would also serve as a dam to protect the area below and beside the Chao Phraya (the delta). Of course, these types of projects could apply to other Thai rivers also.

Please start planning something today – as next year would be much too late.

Guy Baker

Bangkok