The River Mekong is the world's 12th-longest river. From its Himalayan source on the Tibetan plateau, it flows some 4,350 km (2,703 miles) through China's Yunnan province, Burma, Laos, Thailand, Cambodia and Vietnam, finally draining in the South China Sea. The recent construction of hydroelectric dams on the river and its tributaries has reduced the water flow dramatically during the dry season in Southeast Asia.