a river in Thailand, a right tributary of the Mekong. It is approximately 700 km long and drains an area of approximately 130,000 sq km. The Mun crosses the Korat Plateau from west to east and flows mainly in a broad valley. There are rapids near the mouth. The mean flow rate in the lower course is 630 cu m per sec. There is high water in the summer. The waters are used for irrigation. The city of Ubon Ratchathani is on the Mun.