AQUEDUCTCONTRACT I
The Ochre Valley
for the vicus of Verrae
- Demand
- 140 l/s
- Fall left
- 25.0 m
- Chest
- 3 900
- Flattest
- —
- Arrival
- —
- Delivered
- —
ground 210 m below
—
Settling basin here
Channel section
—
the front is at the intake
Work gangs
THREE CONTRACTS · A VALLEY, A LONG APPROACH, A GORGE
AQUEDUCT
Water does not flow uphill and it does not flow fast, and the two facts between them decide where the city gets its water. Choose the line, spend your height where you have it, and get the whole flow over the lip of the castellum before the silt closes the channel.
↑↓ fall
SPACE lay the reach
123 section
B basin
T tunnel
←→ look
ESC pause
M sound
No line laid yet.
THE WATER WAITS
Paused.
The line, the fall and the silt are all where you left them.
THE ENGINEER'S NOTES
Two facts and a third.
- Fall
- Water runs downhill, and how fast it runs is set by the fall, the width of the channel and how rough it is. The flattest reach on the line decides what the whole line can carry. Below about 0.75 m/s the channel drops its load and silts itself in.
- Arrival
- The water must reach the castellum over its lip. Arrive below the lip and the town draws nothing. Arrive far above it and you have thrown away fall that was yours to spend on gradient.
- Silt
- Every basin is a filter. A big one catches most of what the water is carrying, a small one catches a third. A basin fills from the bottom, and a full basin throttles the whole line behind it — dredge it before it does.
- Sections
- A smooth rendered channel carries on a gentle fall but fouls quickly. A narrow ashlar box is cheap and keeps the load moving but eats fall. A ballasted run swallows silt in its gravel and will not choke.
- Tunnels
- A tunnel cannot be scraped out. If it silts, the only way to save it is to catch the sediment before it gets there.
SPACE lay the reach · ↑ ↓ fall · ← → look along the line · W S pull back · C camera · B basin · T tunnel · 1 2 3 section · D dredge the selected work · ESC pause · M sound · R start the contract again
THE CONTRACT IS CLOSED