A small study in sharing
Common Water.
One river. Many lives downstream.
Follow a year through a fictional delta and decide how its water is shared.
Illustrative model, not measured data.
The Onda delta
April · spring pulse
Million m³ / monthFrom the highlands
33.0 more than a dry April
Wet yearOther yearRiver inflow across the year
112.0 in=37.2 wetlands+22.0 fields+12.0 towns+35.2 sea+5.6 air
BalancedA river is a shared resource.
Spring brings enough water for the wetlands, the towns, and the full demand of the fields. The remaining 35.2 million m³ continues to the sea.
Try a dry July, then change the ecological share. A smaller river makes every choice more visible.
How this river works
A deliberately small model
Onda is a fictional watershed. These values illustrate allocation choices; they are not measured data or a planning recommendation. Each month is independent. There is no stored water, rainfall within the delta, return flow, or groundwater.
All values use million cubic metres (Mm³). One Mm³ is one billion litres. The outlet widths use a common scale; the map is a diagram, not a geographic map.
The order matters
- Five percent of river inflow evaporates.
- The selected ecological share of the remaining water goes to wetlands.
- Towns receive up to 12 Mm³ from what remains.
- Fields receive up to their seasonal demand.
- All remaining water flows to the open sea.
Calculations round to the nearest 0.1 Mm³ at each step; the sea receives the exact remainder. The displayed balance always adds up.
The illustrative inputs
| Month | Wet inflow | Dry inflow | Field demand |
|---|