The Mekong

Where it is

The Mekong rises on the Tibetan Plateau and runs about 4,900 kilometres through China, along the Myanmar and Laos borders, through Laos, Thailand and Cambodia, and into the sea through a delta in southern Vietnam. Six countries, and a flow regime dominated by the monsoon: most of the year's water arrives in a few months. Its most unusual feature is the Tonlé Sap in Cambodia, a lake whose feeder river reverses direction each wet season as the Mekong backs up into it, expanding the lake several-fold and then draining it again.

The land and water around it

• The Tonlé Saplake

  A lake in central Cambodia connected to the Mekong by a river that reverses each monsoon. The flood pulse drives one of the most productive inland fisheries anywhere, and it depends on the river rising enough to push water back into it.

• The Mekong Deltadelta

  A low, intensively farmed delta in southern Vietnam laced with distributaries and canals. Rice, fruit and aquaculture, on ground barely above sea level.

• The Khone Fallsriver

  A wide series of rapids and cataracts near the Laos–Cambodia border. They are why the river is not navigable through to China, and they defeated the French expedition that went looking for a route.

Its history, in short

The river fed the Khmer Empire's rice economy, carried French colonial ambitions upstream in the nineteenth century — an expedition that established, expensively, that the Mekong is not navigable from the sea to China — and now supports one of the world's largest inland fisheries and a very large delta agriculture. Its modern history is a dispute about who gets to change the flow. China has built a cascade of large dams on the upper river; Laos has built and is building more on the mainstream; and the countries downstream depend on a flood pulse that those dams smooth out.

Timeline

Dates are shown on a timeline rather than as changing shapes on the map. The globe draws modern boundaries only, and tinting a modern outline to stand for a historical one would state something we cannot source.

Places that carry meaning

• Angkor9th–15th centuries

  North of the Tonlé Sap, built around an engineered water landscape that redistributed the monsoon across the year.

• The Cửu Long distributariesPresent day

  The Vietnamese name for the delta means Nine Dragons, for the river mouths. Fewer than nine now reach the sea, which is itself a record of how the delta has changed.

Learn the language here

1. 1Understand which languages are spoken hereThe Mekong is multilingual. Start with which languages are used, by whom, and for what — the phrase list only covers one of them.Written by Globe Quest
2. 2Practise with people: Vietnamese practice · Ho Chi Minh CityAn in-person practice circle. It is a prepared plan and needs a host before it runs.Run by members

Check yourself

• What is unusual about the Tonlé Sap?

  Its feeder river reverses direction each monsoon, expanding the lake several-fold

  The Mekong backs up into it in the wet season and it drains again in the dry — the flood pulse the fishery depends on.

• What is genuinely contested about the Mekong's recent low flows?

  How much of the change is dam operation and how much is drought

  Both factors operate. Their relative contribution is disputed between governments and researchers.

Worth arguing about

• Six countries share this river and only four are in the commission. What would a body that could actually settle a dispute look like?
• A flood that farmers, fishers and a lake all depend on is also a flood that dams exist to remove. Whose interest should set the release schedule?

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