STUDY GUIDEClimate
Shared rivers and drought
When a river crosses borders, every country upstream affects every country downstream. How shared rivers are measured, divided and argued over when the water runs low.
Start here
- 1
One river, several governments
The Ilvar runs between Valdoria and the Kesh Federation before reaching the Merovan Sea through its delta. What one country withdraws upstream changes what reaches the other and the delta. That makes water a diplomatic question as well as a technical one.
- 2
Data comes first
Countries cannot agree on sharing water if they do not agree on how much there is. Gauges along a river measure flow, and a data protocol sets how those readings are shared. This is usually the least contested part of any deal.
- 3
Allocation is the hard part
Allocation means agreeing each country's share, especially in a drought. Some argue for triggers agreed in advance, so cuts happen automatically when flow drops. Others say fixed shares lock in today's users and prefer flexible local arrangements.
- 4
Glaciers and lakes upstream
In the Basin, glacial lakes such as Teyla Lake in Saranth feed rivers through the dry months. When they shrink, summer flows fall downstream, which is why highland data matters to delta towns.
Timeline
2010
Lake baseline
The year against which Teyla Lake's late-summer level is now compared.
2022
Ilvar at 410
Lowest August flow at the Aldermere gauge is 410 cubic metres per second.
2026
Ilvar at 270
The August low falls to 270, about a third below 2022.
2026
Teyla Lake record low
The lake's late-summer level is 3.1 metres below its 2010 average.
Autumn 2026
Port Alder summit
Six governments meet to discuss data, drought plans and the Ilvar.
Glossary
- A fixed station that measures a river's level and flow.
- The smallest volume of water passing a gauge in a period, often the August minimum.
- An agreed share of water each country or user may withdraw.
- A pre-agreed reading that sets off planned cuts in withdrawals.
- Water taken from a river for farms, towns or industry.
Where
Lowest August flow by year, as reported by Delta Hydrology Review.
| Label | Value (cubic metres per second) |
|---|---|
| 2022 | 410 |
| 2023 | 380 |
| 2024 | 345 |
| 2025 | 300 |
| 2026 | 270 |
Who is who
place
Neutral host of Basin summits in Port Alder.
institution
Statutory body that monitors glaciers, lakes and river gauges in Saranth.
institution
Proposes pre-agreed drought cuts on the Ilvar.
institution
Backs data sharing but opposes binding allocation.
Common questions
Why not just divide the river equally?
Countries differ in population, farmland and how much of the river's water starts in their territory. Each argues for a share based on different principles.
What would a data protocol change?
It would make gauge readings available to all governments on agreed terms, so disputes start from the same numbers.
Why do glaciers matter to a river delta far away?
Melting ice and lake storage feed rivers in dry months. If that store shrinks, summer flows fall all the way to the sea.
Live stories on this topic
Further reading from the sources
- Summit agenda: river data, drought plans and the IlvarMeridian Wire · Wire
- Agency to present Teyla Lake melt data at Port AlderSaranth Water and Hazards Agency · Primary / official
- Ilvar summer low flow has fallen by a third since 2022Delta Hydrology Review · Specialist
- Valdoria to press for shared drought rules on the IlvarThe Valdorian Herald · Reported journalism
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