Mekong River

The Mekong is one of the world’s major rivers. It is the 11th-longest river in the world, and the 12th-largest by volume. Its estimated length is 4,880 km, and it drains an area of 810,000 km². From the Tibetan Plateau it runs through China's Yunnan province, Burma, Thailand, Laos, Cambodia and Vietnam. All except China and Burma belong to the Mekong River Commission. A south Asian regional association, Mekong-Ganga Cooperation is named after this river. The extreme seasonal variations in flow and the presence of rapids and waterfalls have made navigation extremely difficult.
The river's source, and therefore its exact length, is uncertain, due to the existence of several tributaries in an inaccessible environment. According to the China Science Exploration Association survey, the source is the Lasagongma spring, at an altitude of 5,224 meters. This spring is located on Mount Guozongmucha, and forms the Zayaqu, which has been identified by the Chinese Academy of Sciences as the headwaters of the Mekong, within northwestern China's Qinghai Province. An earlier expedition by Michel Piessel had identified the Zanaqu as the headwaters, at the Rupsa-La pass (further west, at an altitude of 4,975 m). As a consequence of the difficulty in determining the location of the headwaters, figures for the Mekong's total length vary from 4,350 km to 4,909 km.
About 90 million people rely on the river. The area they live in, known as the Greater Mekong Subregion (GMS), comprises Yunnan and Guangxi Provinces in China, Burma, Lao PDR, Thailand, Cambodia, and Vietnam. The main livelihood of the people of the GMS is rice production. Approximately 140,000 km² of rice are grown in the GMS. A huge number of rice varieties are grown along the Mekong. Of approximately 100,000 rice accessions in the Rice Gene Bank of the International Rice Research Institute, about 40,000 come from the GMS.