Bangkok, June 19 (IANS): Thailand’s capital Bangkok is sinking by an average of 10 mm annually and the subsidence could reach a critical level unless the problem is tackled, a leading water engineer said on Friday.

Groundwater extraction, the natural movements of the earth’s crust and construction of high-rise buildings are factors contributing to Bangkok’s sinking, Sujarit Khoonthanakulwong, head of Chulalongkorn University’s water resources engineering department told the Bangkok Post.

Bangkok is at risk of flooding in 30-50 years, unless relevant laws are strictly enforced, he added.

Sujarit suggested that national reforms focus on zoning areas for water retention and town planning, and increase in penalties for illegal use of groundwater.

Currently, the Bangkok Metropolitan Administration's public works department mandates that houses and buildings should not be over 12 metres in height in areas prone to flooding.

Ramkhamhaeng Road in eastern Bangkok has the highest rate of subsidence at two cm per year.