Up to one-third of Bangkok could be permanently under water by 2050 unless Thailand reforms its water management, an expert has warned. Speaking at a seminar on October 7, Sonthi Kotchawat urged the government to reform water management now. Drawing lessons after each flood is not enough, he said. Bangkok is especially vulnerable because of its low, basin-like terrain, sinking land, and rising seas.
Parts of the city are sinking by one to two centimeters a year, while the Gulf of Thailand rises by about four millimeters annually. By 2050, the Gulf could rise by 20 to 30 centimeters, or as much as 75. That could submerge about a third of the city and force 11 to 12 million people to move. By 2100, seas could be 1.5 to 1.7 meters higher, threatening coastal areas in 24 provinces. Sonthi proposed seawalls, tidal barriers at river mouths, underground flood storage, and large drainage tunnels. He also called for a ban on building in natural flood-retention areas and limits on groundwater pumping, which worsens subsidence.