Mekong River
Southeast Asia's lifeline, from the Tibetan Plateau to the sea
The Mekong threads six countries on its way from the Tibetan Plateau to the South China Sea, and few rivers on Earth feed so many people so directly. Its annual flood pulse drives one of the most productive inland fisheries in the world and fills the great lake of Cambodia, the Tonle Sap, which famously reverses its flow each year. From cold Himalayan headwaters to the warm, fertile delta of southern Vietnam, the river is the spine of mainland Southeast Asia.
The Mekong runs roughly 4,909 kilometers, third longest in Asia. In its upper reaches, known in China as the Lancang, it cuts deep parallel gorges through the eastern Himalaya. Downstream it becomes a tropical river braided with rapids, islands and seasonal channels, dropping over the wide Khone Falls on the Lao-Cambodian border. Its defining rhythm is the monsoon flood: rising waters back up into the Tonle Sap, briefly making it one of Asia's largest lakes, before draining out again and flushing nutrients through the delta to the sea.
More than sixty million people in the lower basin depend on the river for food and farming, and its delta is the rice bowl of Vietnam. That dependence is now under strain. A cascade of large dams on the Chinese upper river and on tributaries has begun to alter the flood pulse and trap the sediment that builds the delta, while the delta itself is sinking and salting as the sea rises. The Mekong has become a test case for how to share a great river among many nations.