Khorat Plateau

The Khorat Plateau also Korat Plateau, is a plateau in the northeastern region of Thailand, also called Isan. It is named after the biggest city in the area, Nakhon Ratchasima, which is often called shortly "Khorat".

The average elevation is 200 m and it covers an area of about 155,000 km². The saucer-shaped plateau is tilted towards the south-east, and is drained by the Mun and Chi rivers, tributaries to the Mekong, which also is the boundary of the area. It is separated from Central Thailand by the Phetchabun mountain range, and to the south from Cambodia by the Dongrek mountains. The Khorat Plateau was formed from a sudden fault slip, probably around AD 700, where most of the ground around it fell hundreds of feet. The area eventually flattened out, but the effects are seen in the Mekong tributaries.

These together with the Truong Son Cordilliera in the north-east catch a lot of the rainfall, so the South-West monsoon has much lower intensity then in other regions - the mean annual rainfall in Nakhon Ratchasima is about 1150 mm, compared with 1500 mm in Central Thailand. The difference between dry and wet season is much stronger, which makes the area less fertile for rice.