The worst affected areas were found along the Gulf of Thailand in seven southern provinces, after a survey by the Natural Resources and Environment Ministry.

"Out of 18 surveyed sites, we found seven of them were seriously damaged geologically," geologist Somsak Wathanaparueda said.

"Five-metre-high waves hit the coast from December 18-22 and brought massive amounts of sand on shore from the seabed. In some places the deposits were as thick as five to 10 metres," he said.

In Nakhon Si Thammarat, some parts of Laem Talumphuk beach lost up to three metres. In other areas the damage extended as much as one kilometre in length.

In Prachuap Khiri Khan, similar damage was found at Had Naresuan and nearby beaches in Sam Roi Yod district.

In Chumphon, serious erosion was found in Lang Suan district. Several areas in Surat Thani's Don Sak and Tha Chana districts were also hard hit, with 50-centimetre-high piles of sand deposited on coastal roads for distances as long as one kilometre.

In Songkhla's Pakklong Samroeng area, erosion extended over one kilometre, while in Pattani, Taloh Kapo-Laem Pho Road was badly damaged, the geologist said.

"This is an extremely unusual phenomenon, caused by the growing impact of global climate change," Somsak said.

Normally, erosion happens along the west coast of Thailand at a rate of three to five metres per year, and is due to the seasonal northeastern monsoon.

The unusual severity of the damage over the past two weeks worried geologists that this year's erosion rate would be a lot more serious, especially as the monsoon season would last till March, Somsak said.

"This serious erosion should be temporary, we expect. However, a long-term preventative plan is needed, including city planning that bans the construction of buildings along coastal areas," he said.

Janjira Pongrai

The Nation