Headwaters of three rivers
Where is it?
- Sanjiangyuan is in southern Qinghai Province, on the north-east part of the Qinghai-Tibet Plateau. The land is mostly more than 4,000 m above sea level.
- The area is about 360,000 sq km (more than the size of Germany).
Why is it so cold and wet-green at the same time?
- Temperature falls about 6.5 °C for every 1,000 m you climb. At 4,000 m it is about 26 °C colder than at sea level, so snow and glaciers last, and ice melts slowly into streams.
- Cold air means little evaporation, so lakes and wet meadows (wetlands) hold water for a long time.
The three rivers
- Yellow River (about 5,460 km): its upper streams gather in lakes and marshes; about half of its water starts here.
- Yangtze (about 6,300 km, the longest in Asia): begins as small streams from glaciers; about a quarter of its water starts here.
- Lancang (called Mekong after leaving China): about 15 % of its water in China starts here. It crosses six countries.
Because so many people depend on its water, the region is called the "water tower" (or the "Chinese water tower") of Asia.
Nature
- Grassland and wetlands are home to wild yaks, Tibetan antelope, wild asses, snow leopards and many birds.
Ecological protection
The problems
- Overgrazing: too many sheep, goats and yaks eat the grass faster than it grows.
- Warming climate: glaciers shrink, permafrost (frozen ground) thaws, lakes and wetlands dry in places.
- Grassland degradation: green meadow turns to bare "black-soil patches" and sand; wind and rain wash soil away; less water is stored, so rivers can carry less.
Protection steps
- Sanjiangyuan National Park was set up (trial from 2016, officially in 2021) so that land is managed as one protected area.
- Fewer animals and grazing rest: herders follow limits on grazing, and some graze in turns while the grass recovers.
- Herders become rangers: many families are paid to patrol, collect litter and guard wildlife.
- Restoring grass and wetlands: reseeding bare patches, fencing, and blocking small gullies.
- Better science: satellites and weather stations track glaciers, lakes and grass.
Rule to remember: protecting the source protects every town downstream.
Why protecting the source matters downstream
- Farms, cities, power stations and fisheries along the Yellow River, the Yangtze and the Mekong all use water that began here.
- A healthy source gives steady water in dry months; a damaged source means more floods in the wet season and less water in the dry season.
- The Mekong is an international river, so the source region also matters to other countries.
Try it: a sponge and a bare plate
- Pour water on a flat plate: it runs off at once (bare ground).
- Pour the same water on a wet sponge on the plate: it holds and releases slowly (meadow and wetland).
- Squeeze the sponge a little at a time. That is like a river flowing in the dry season.
- Now tear half the sponge away. How does the "river" change? That is grassland loss.
Key formulas and definitions
- Headwaters: the place where a river begins
- Plateau: a high flat-topped land (Qinghai-Tibet, over 4,000 m)
- Temperature falls about 6.5 °C per 1,000 m height
- Wetland: land soaked with water that stores and slowly releases it
- Shares from here: Yellow River about 49 %, Yangtze about 25 %, Lancang about 15 %
- Overgrazing: more animals than the grass can feed
- Permafrost: ground that stays frozen for years
Worked examples
1. At sea level the air is 20 °C. What is the temperature at 4,000 m (use 6.5 °C per 1,000 m)?
Fall = 4 × 6.5 = 26 °C. Temperature = 20 - 26 = -6 °C. That is why snow lasts on the plateau.
2. Why does wetland help a river in dry months?
Wetland soaks up rain and snowmelt like a sponge and releases it slowly, so the river keeps flowing when little rain falls.
3. A meadow can feed 100 yaks but 150 graze there. What is the overstocking in per cent, and what happens to the grass?
(150 - 100) ÷ 100 × 100 = 50 %. The grass is eaten faster than it grows, roots weaken, bare patches appear and soil is lost.
Common mistakes
- Thinking all three rivers flow the same way. They go in different directions, and the Lancang turns into the Mekong abroad.
- Thinking the plateau is a warm, low plain. It is cold and high, mostly above 4,000 m.
- Thinking a damaged source only matters to the people living there. It affects everyone downstream.
- Believing protection means no people at all. Herders can stay, graze less and become rangers.