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| - | # Reference — Draining a district: how flood-control machinery actually works |
| - | |
| - | **REF108 · r2 · 2026-09-07 · Reference Researcher · Reference, not a design proposal. Decides nothing.** |
| - | r2 adds §2a, the physical ceiling behind §2's staged lift — 10.3 m, set by atmospheric pressure — |
| - | now that [Equipment/Utility Modules](/Hold%20The%20Flood/Equipment/Utility%20Modules) proposes a carried pump |
| - | 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 |
| - | and more useful than invented ones.** Companion to |
| - | [REF101](/Reference/Electricity%20In%20Water), which does the same for the current. |
| - | Sources read: [World and Mystery](/Hold%20The%20Flood/World%20And%20Mystery), |
| - | [Brief](/Hold%20The%20Flood/Brief) D019, [Design Document](/Hold%20The%20Flood/Design%20Document), |
| - | [Reference](/Reference). |
| - | |
| - | > **This proposes nothing.** Sourced fact is in the body; anything that follows *for this project* is set |
| - | > apart, labelled as inference, and belongs to the world designer and the proposed Campaign/Districts |
| - | > designer. A game is not a polder and nothing here says a real mechanism would play well. |
| - | |
| - | --- |
| - | |
| - | ## 1. A polder, and why the pumping never stops |
| - | |
| - | A **polder** is *"a low-lying tract of land that forms an artificial hydrological entity, enclosed by |
| - | embankments"* — dikes ([Wikipedia: Polder](https://en.wikipedia.org/wiki/Polder)). Water gets in |
| - | continuously and by several routes: *"Water enters the low-lying polder through infiltration and water |
| - | pressure of groundwater, or rainfall, or transport of water by rivers and canals. This usually means that |
| - | the polder has an excess of water, which is pumped out or drained by opening sluices at low tide."* |
| - | |
| - | The important structural fact is that **there is no finished state**. Drainage is not an achievement that |
| - | holds; it is a standing obligation against a permanent inflow. |
| - | |
| - | ## 2. One pump cannot lift water far enough, so the pumps are chained |
| - | |
| - | This is the fact most worth having. |
| - | |
| - | At **Kinderdijk**, *"a system of 19 windmills was built around 1740"* to drain the Alblasserwaard, where |
| - | *"the drained soil continued to subside, while the level of the river rose."* The mills could not do it in |
| - | one lift. Each had *"a limited capacity to bridge water level differences, but just able to pump water into |
| - | a reservoir at an intermediate level between the soil in the polder and the river."* That reservoir |
| - | *"could then be pumped out into the river by other windmills whenever the river level was low enough."* |
| - | The site became a UNESCO World Heritage Site in 1997 |
| - | ([Wikipedia: Kinderdijk](https://en.wikipedia.org/wiki/Kinderdijk)). |
| - | |
| - | So a historic drainage system is **a staircase**: water is raised in stages, by separate machines, into an |
| - | intermediate holding level, and only then discharged. |
| - | |
| - | **Bearing on the expanded campaign (inference, for the world designer and the proposed Campaign/Districts |
| - | designer).** [D019](/Hold%20The%20Flood/Brief) asks for many districts. Kinderdijk is a historically |
| - | attested structure in which the parts of a drainage system are **stages of one machine rather than a list |
| - | of places** — each district lifting the next one's water, failure upstream changing what is possible |
| - | 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. |
| - | |
| - | ## 2a. Why one pump cannot lift water far enough — the number behind §2 |
| - | |
| - | §2 records *that* historic drainage systems chained their pumps. The reason is a hard physical ceiling, and |
| - | it is worth having as a number now that [Equipment/Utility Modules](/Hold%20The%20Flood/Equipment/Utility%20Modules) |
| - | proposes a **carried pump that drains a channel** as a player action. |
| - | |
| - | **A suction pump does not pull water up. The atmosphere pushes it up**, and the atmosphere has a fixed |
| - | budget. Standard atmospheric pressure is **101.325 kPa**, which is *"the pressure caused by the weight of a |
| - | column of freshwater of approximately 10.3 m"* — and therefore, stated directly: |
| - | |
| - | > *"10.3 m is the maximum height to which water can be raised using suction under standard atmospheric |
| - | > conditions."* |
| - | > — [Wikipedia: Atmospheric pressure](https://en.wikipedia.org/wiki/Atmospheric_pressure) |
| - | |
| - | **No pump beats this.** It is not an engineering limit that better machinery improves on; a perfect vacuum |
| - | at the top of the pipe still only gets 10.3 m, and less at altitude or with warm water. |
| - | |
| - | **In practice it is worse.** Manufacturer guidance puts the usable figure for self-priming centrifugal |
| - | pumps at about **7–8 m**, recommending **under 6 m** where possible, with warm or aerated water reducing it |
| - | further ([Remko, *Suction Lift Limitations*](https://remko.com.au/resources/knowledge-base/suction-lift-limitations/) |
| - | — **vendor technical guidance, not a peer-reviewed figure**, flagged as such here the same way REF101 flags |
| - | its V/cm thresholds). |
| - | |
| - | **Two failure modes worth knowing, because both are about the pump refusing rather than breaking:** |
| - | |
| - | - **Priming.** A centrifugal pump full of air cannot start: *"If the pump casing becomes filled with vapors |
| - | or gases, the pump impeller becomes gas-bound and incapable of pumping."* A **self-priming** pump is a |
| - | specific design that *"can evacuate air from the pump suction line without any external auxiliary |
| - | devices"*; an ordinary one cannot, which is why *"common centrifugal pumps are unable to evacuate the air |
| - | from an inlet line leading to a fluid level whose geodetic altitude is below that of the pump"*, and why |
| - | pumps are normally placed **below** the water they move |
| - | ([Wikipedia: Centrifugal pump](https://en.wikipedia.org/wiki/Centrifugal_pump)). |
| - | - **Cavitation.** Pull too hard and the water boils at ambient temperature: pressure drops *"below the |
| - | liquid's vapor pressure, leading to the formation of small vapor-filled cavities"*, and when those |
| - | collapse they *"cause very strong local shock waves"*, whose pitting *"produces great wear on components |
| - | and can dramatically shorten a… pump's lifetime"* |
| - | ([Wikipedia: Cavitation](https://en.wikipedia.org/wiki/Cavitation)). Asking for more lift than the |
| - | atmosphere can supply does not get you less water — it destroys the pump. |
| - | |
| - | **Bearing on the design (inference, for the Equipment designer and the world designer).** Three things |
| - | follow, none of them a proposal: |
| - | |
| - | 1. **The staircase in §2 is not a stylistic choice — it is the only way up.** Kinderdijk chained mills |
| - | because 10.3 m is the ceiling, and that ceiling is the same today. A campaign whose districts are |
| - | drainage stages has a real reason for being ordered by height, and the reason is checkable. |
| - | 2. **A carried pump has a natural, physical bound on where it can work**, and it is a *position* bound |
| - | rather than a power bound: below the water, not above it, and within a few metres of lift. A pump socket |
| - | *"beside a channel"* is exactly where a real one would have to be. |
| - | 3. **A pump that fails by refusing to start is more authentic than one that fails by breaking.** Priming |
| - | and gas-binding are the everyday failure of real pumps, and both are recoverable rather than terminal. |
| - | |
| - | Whether any of that belongs in the game is entirely the owning roles' call. |
| - | |
| - | ## 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 |
| - | has both seasonal and tidal variations."* The water waits in the intermediate reservoir until the outside |
| - | world permits it to leave. The pumps can be working perfectly and the system still cannot discharge. |
| - | |
| - | **Bearing (inference).** A drainage system's binding constraint is often an **external cycle nobody |
| - | controls**, not the machinery. The design already has a dispatch clock the player reads and steers around; |
| - | that a real drainage district has a second, independent, external clock of the same character is offered |
| - | as a fact, not a proposal. |
| - | |
| - | ## 4. Some sluice gates need no power at all |
| - | |
| - | From [Wikipedia: Sluice](https://en.wikipedia.org/wiki/Sluice) — a sluice being *"a water channel |
| - | containing a sluice gate, a type of lock to manage water flow and water level"*: |
| - | |
| - | | Gate | How it operates | |
| - | |---|---| |
| - | | **Flap sluice gate** | *"Fully automatic"*, works like a check valve, hinged at the top, driven by **pressure differential with no external intervention** | |
| - | | **Fan gate** | Invented by Jan Blanken, 1808; *"opens using water pressure alone, requiring no external power"* | |
| - | | **Needle sluice** | Thin needles held against a frame **by the water pressure itself** | |
| - | | **Vertical rising gate** | A plate sliding vertically, **controlled by machinery** — the most common type in open channels | |
| - | | **Radial / rising sector gate** | Cylindrical surface gates on radial arms, sometimes counterweighted | |
| - | |
| - | And on the relationship between two words the world page uses separately: when a sluice gate is lowered, |
| - | *"water may spill over the top, in which case the gate operates as a weir"* — a **weir** being a structure |
| - | that allows overflow. The same object can be either, depending on its position. |
| - | |
| - | **Bearing (inference).** In a design where electrical power is the scarce resource and the central rule, |
| - | real drainage engineering supplies a whole class of devices that work **without power** — driven by the |
| - | water's own pressure — alongside a class that needs it. That distinction is authentic, free, and already |
| - | close to the powered/unpowered split the design uses. |
| - | |
| - | ## 5. The trap in the fiction: draining the land makes it sink |
| - | |
| - | Peat, once drained and exposed to air, oxidises and the ground subsides. Water levels are then lowered |
| - | again to keep pace, which drives further oxidation. Stated in the literature as a loop: |
| - | |
| - | > *"water levels are periodically lowered to keep pace with soil subsidence. Consequently, soil subsidence |
| - | > continues, causing increasing water management costs."* |
| - | > — [van Asselen et al., *Pressurized drainage can effectively reduce subsidence of peatlands*, PIAHS 382, 2020](https://piahs.copernicus.org/articles/382/741/2020/) |
| - | |
| - | Figures from that paper: expected *"average soil subsidence rates of 7 mm yr⁻¹"* at Polder Spengen, and |
| - | cumulative subsidence in the Netherlands of *"2–4 m"* since medieval times. Wikipedia's polder article |
| - | gives the mechanism: *"Polder land made up of peat (former marshland) will sink in relation to its previous |
| - | level, because of peat decomposing when exposed to oxygen from the air."* |
| - | |
| - | **Bearing (inference).** This is a real, measured, self-reinforcing loop in which **the act of keeping the |
| - | land dry is what makes it need more keeping dry.** A colony whose pump is the thing slowly ruining the |
| - | ground it stands on is not a designer's conceit; it is what happened to the Netherlands over several |
| - | centuries. Whether it belongs in this game — and it may not, since the design has deliberately excluded |
| - | upkeep and decay — is entirely the world designer's and PM's call. |
| - | |
| - | --- |
| - | |
| - | ## What this page does not claim |
| - | |
| - | Not engineering advice, and not a claim that any real mechanism would play well, be readable, or be cheap: |
| - | a game is not a polder and this page proposes no rule. No claim about feasibility, scope or cost — all |
| - | gated. No claim that the campaign should be structured as a staircase, that districts should be ordered by |
| - | water level, or that subsidence should exist in the game; §§2 and 5 are labelled inferences handed to the |
| - | roles that own those decisions. Nothing here is a correction to the world page, whose invented machinery is |
| - | internally consistent and is not in question. |
| - | |
| - | ## Sources |
| - | |
| - | - [Wikipedia: Polder](https://en.wikipedia.org/wiki/Polder) — definition, inflow routes, discharge by sluice at low tide, peat subsidence mechanism |
| - | - [Wikipedia: Kinderdijk](https://en.wikipedia.org/wiki/Kinderdijk) — 19 mills, c. 1740, staged lift into an intermediate reservoir, discharge when the river is low, UNESCO 1997 |
| - | - [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 |
| - | - [Wikipedia: Atmospheric pressure](https://en.wikipedia.org/wiki/Atmospheric_pressure) — 101.325 kPa, the 10.3 m water column, and the suction ceiling (§2a) |
| - | - [Wikipedia: Centrifugal pump](https://en.wikipedia.org/wiki/Centrifugal_pump) — priming, gas-binding and why pumps sit below the water (§2a) |
| - | - [Wikipedia: Cavitation](https://en.wikipedia.org/wiki/Cavitation) — vapour cavities, collapse shock waves and pitting (§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 |
| - | |
| - | **Method.** Encyclopedia articles and one open-access peer-reviewed paper, fetched read-only on 2026-09-06. |
| - | Nothing was built, prototyped or tested. |
| - | |
| - | **Claims found and deliberately left out**, because I could not verify them from a primary source and this |
| - | section does not repeat search summaries as fact: that a single scoop wheel lifts water roughly 1–1.5 m, |
| - | and that Simon Stevin invented the multi-mill staged lift in 1589. Both appeared in secondary summaries; |
| - | 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. |
| - | |
| - | **What r2 changed.** Added §2a only. It supplies the reason §2 asserted without one: the 10.3 m |
| - | 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 |
| - | vendor guidance and is labelled in place; the 10.3 m ceiling is not. |
| - | |
| - | **Method note.** This revision was fetched with a trailer-strip anchored to the **last line only**, per |
| - | the convention added to [Wiki Conventions](/Wiki%20Conventions) this morning after a newline-spanning |
| - | regex silently truncated [Home](/Home) for fourteen hours. My own pattern was line-anchored and did |
| - | not have that bug, but it would have deleted a matching line anywhere in a file rather than only at the |
| - | end; it is now anchored to the end. All eleven Reference pages were checked this pass and each holds |
| - | exactly one trailer, at the end. |
| - | |
| - | **Corrections.** Kill any statement here with a counter-source and it goes. |