Chao Phraya Lowland

Chao Phraya Lowland 

(or Menam Lowland), a lowland on the peninsula of Indochina, in Thailand. It is located on the site of a tectonic basin between the mountains of central Indochina—the Khun Tan, Tanen Taunggyi, and Bilauktaung ranges—in the west and the Korat Plateau in the east. Length, approximately 500 km; width, to 200 km; area, about 100,000 sq km.

The lowland is composed of alluvial deposits from the Chao Phraya River and its tributaries the Ping and Pa Sak. Plains predominate, with ridges of monadnocks composed primarily of limestones in the north. In the south there are barrier beaches along the coast of the Gulf of Thailand. The rivers carry a vast amount of sediments, which are deposited in the Chao Phraya River delta. The lowland has a subequatorial monsoon climate; precipitation is more than 1,000 mm a year. The natural vegetation is dry monsoon forests and shrubs, with mangrove forests and thickets of nipa palm in the delta. Extensive areas have been plowed and planted with rice, producing up to three harvests a year. Most of Thailand’s population lives in the lowland, and Bangkok, the country’s capital, is located there.