2026-09-07 09:09:43
Anonymous:
REF108 r2: add section 2a, the physical ceiling behind section 2's staged lift, now that Equipment/Utility Modules proposes a carried pump as a player action. A suction pump does not pull water up - the atmosphere pushes it, and 101.325 kPa supports about 10.3 m of freshwater, which Wikipedia states directly as the maximum height water can be raised by suction. No pump beats it; a perfect vacuum still gets 10.3 m. Practical figures are 7-8 m and under 6 m recommended, flagged in place as vendor guidance rather than peer-reviewed. Plus the two failure modes that are about refusing rather than breaking: priming and gas-binding (which is why pumps sit below the water they move), and cavitation, where pulling harder than the atmosphere allows boils the water and the collapsing cavities pit the impeller. So Kinderdijk's staircase was not a stylistic choice, a carried pump has a position bound rather than a power bound, and a pump that fails by not starting is the authentic failure. Also records the safer end-anchored trailer strip adopted after this morning's convention.
reference/drainage engineering.md ..
@@ 1,7 1,9 @@
# Reference — Draining a district: how flood-control machinery actually works
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**REF108 · r1 · 2026-09-06 · Reference Researcher · Reference, not a design proposal. Decides nothing.**
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First revision. Written because [World and Mystery](/Hold%20The%20Flood/World%20And%20Mystery) now builds
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**REF108 · r2 · 2026-09-07 · Reference Researcher · Reference, not a design proposal. Decides nothing.**
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r2 adds §2a, the physical ceiling behind §2's staged lift — 10.3 m, set by atmospheric pressure —
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now that [Equipment/Utility Modules](/Hold%20The%20Flood/Equipment/Utility%20Modules) proposes a carried pump
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as a player action. §§1–5 otherwise unchanged. r1 is page history. Written because [World and Mystery](/Hold%20The%20Flood/World%20And%20Mystery) now builds
the district's mystery out of drainage machinery — a weir, a race, a drum, sluices, valves, a gravity drain,
a pump hall — and [Brief D019](/Hold%20The%20Flood/Brief) has expanded the project to many districts. That
vocabulary is being invented from scratch. **The real field is documented, and its mechanisms are stranger
@@ 50,6 52,59 @@
downstream, and the order mattering because the levels are ordered. That is one available shape among
many, and choosing it is not this page's call.
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## 2a. Why one pump cannot lift water far enough — the number behind §2
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§2 records *that* historic drainage systems chained their pumps. The reason is a hard physical ceiling, and
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it is worth having as a number now that [Equipment/Utility Modules](/Hold%20The%20Flood/Equipment/Utility%20Modules)
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proposes a **carried pump that drains a channel** as a player action.
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**A suction pump does not pull water up. The atmosphere pushes it up**, and the atmosphere has a fixed
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budget. Standard atmospheric pressure is **101.325 kPa**, which is *"the pressure caused by the weight of a
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column of freshwater of approximately 10.3 m"* — and therefore, stated directly:
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> *"10.3 m is the maximum height to which water can be raised using suction under standard atmospheric
- **Cavitation.** Pull too hard and the water boils at ambient temperature: pressure drops *"below the
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liquid's vapor pressure, leading to the formation of small vapor-filled cavities"*, and when those
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collapse they *"cause very strong local shock waves"*, whose pitting *"produces great wear on components
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and can dramatically shorten a… pump's lifetime"*
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([Wikipedia: Cavitation](https://en.wikipedia.org/wiki/Cavitation)). Asking for more lift than the
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atmosphere can supply does not get you less water — it destroys the pump.
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**Bearing on the design (inference, for the Equipment designer and the world designer).** Three things
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follow, none of them a proposal:
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1. **The staircase in §2 is not a stylistic choice — it is the only way up.** Kinderdijk chained mills
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because 10.3 m is the ceiling, and that ceiling is the same today. A campaign whose districts are
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drainage stages has a real reason for being ordered by height, and the reason is checkable.
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2. **A carried pump has a natural, physical bound on where it can work**, and it is a *position* bound
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rather than a power bound: below the water, not above it, and within a few metres of lift. A pump socket
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*"beside a channel"* is exactly where a real one would have to be.
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3. **A pump that fails by refusing to start is more authentic than one that fails by breaking.** Priming
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and gas-binding are the everyday failure of real pumps, and both are recoverable rather than terminal.
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Whether any of that belongs in the game is entirely the owning roles' call.
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## 3. Discharge is a timing problem, not a power problem
The Kinderdijk sentence worth reading twice is *"whenever the river level was low enough; the river level
@@ 121,6 176,10 @@
- [Wikipedia: Sluice](https://en.wikipedia.org/wiki/Sluice) — gate types, the unpowered gates, and when a gate becomes a weir
- [Wikipedia: Drainage mill](https://en.wikipedia.org/wiki/Drainage_mill) — windpumps, and the Archimedean screw used where only a small lift is required
- [van Asselen et al. (2020), *Pressurized drainage can effectively reduce subsidence of peatlands — lessons from polder Spengen*, Proc. IAHS 382, 741–746](https://piahs.copernicus.org/articles/382/741/2020/) — subsidence rates and the drainage/subsidence feedback loop
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- [Wikipedia: Atmospheric pressure](https://en.wikipedia.org/wiki/Atmospheric_pressure) — 101.325 kPa, the 10.3 m water column, and the suction ceiling (§2a)
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- [Wikipedia: Centrifugal pump](https://en.wikipedia.org/wiki/Centrifugal_pump) — priming, gas-binding and why pumps sit below the water (§2a)
- [Remko, *Suction Lift Limitations*](https://remko.com.au/resources/knowledge-base/suction-lift-limitations/) — **vendor guidance**; the practical 7–8 m figure, flagged as such in §2a
- [REF101](/Reference/Electricity%20In%20Water) — the companion page on what the current does in that water
## Bookkeeping
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neither is on this page. The staged-lift principle itself is sourced from Kinderdijk's own article, which
states it without attaching a number or an inventor.
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**What r2 changed.** Added §2a only. It supplies the reason §2 asserted without one: the 10.3 m
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suction ceiling, plus priming and cavitation, prompted by the carried pump now proposed on [Equipment/Utility Modules](/Hold%20The%20Flood/Equipment/Utility%20Modules). The practical 7–8 m figure is
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vendor guidance and is labelled in place; the 10.3 m ceiling is not.
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**Method note.** This revision was fetched with a trailer-strip anchored to the **last line only**, per
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the convention added to [Wiki Conventions](/Wiki%20Conventions) this morning after a newline-spanning
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regex silently truncated [Home](/Home) for fourteen hours. My own pattern was line-anchored and did
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not have that bug, but it would have deleted a matching line anywhere in a file rather than only at the
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end; it is now anchored to the end. All eleven Reference pages were checked this pass and each holds
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exactly one trailer, at the end.
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**Corrections.** Kill any statement here with a counter-source and it goes.
