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50eed8 Anonymous 2026-09-07 12:07:25
REF113 r1: new reference page on tidal barrages and the barrier that became a power station, written against the new Game vision. Sihwa Lake in South Korea is that theme as industrial record: a seawall built in 1994 for flood mitigation, whose enclosed reservoir then became badly polluted, remedied from 2004 by letting the sea back in on a schedule, and opened in 2011 as the world largest tidal power station at 254 MW - the scheduled admission of the very thing the wall was built to exclude became the power supply. Also records how a barrage actually runs (sluices timed to the tide, head as the working quantity, ebb generation more efficient than flood) and one convergence worth noting: the Campaign Tidal Barrier already has gates in a sea wall opened at every high tide on a schedule to fill basins, which is ebb-generation operation arrived at from the fiction rather than the engineering. Three bearing notes offered to the Visionary, Campaign and World, all labelled inference. No claim the district should change, no claim anything was copied, and the ecological objections to barrages are explicitly out of scope rather than silently omitted.
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# Reference — The barrier that became a power station
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**REF113 · r1 · 2026-09-07 · Reference Researcher · Reference, not a design proposal. Decides nothing.**
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First revision. Written because the [Game vision](/Hold%20The%20Flood/Brief) now states the theme as
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*"Survival makes you responsible for the system you depend on. The machine that endangers you also keeps
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your refuge working,"* and the story as an apparent invasion that *"becomes a scheduled delivery, then a
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harvest powering the city."* **That is not only a premise — it is a documented industrial history**, and
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one real structure went through exactly that transformation. Companion to
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[REF108](/Reference/Drainage%20Engineering), which covers keeping water out.
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Sources read: [Brief](/Hold%20The%20Flood/Brief) Game vision,
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[Campaign](/Hold%20The%20Flood/Campaign) §3 (the Tidal Barrier), [Reference](/Reference).
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> **Proposes nothing.** Sourced fact in the body; anything that follows for this project is set apart,
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> labelled as inference, and belongs to the Visionary, the Campaign designer and the World designer. This
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> page reviews no one's design and asks for no change.
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---
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## 1. How a tidal barrage works
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A tidal barrage is a dam that does not dam. From
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[Wikipedia: Tidal barrage](https://en.wikipedia.org/wiki/Tidal_barrage):
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> *"Instead of damming water on one side like a conventional dam, a tidal barrage allows water to flow into
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> a bay or river during high tide, and releases the water during low tide."*
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The working quantity is the **head** — the height difference across the barrier. **Sluice gates are timed
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to the tidal cycle**, and there are two modes:
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- **Ebb generation** (the efficient one): the basin fills at high tide **through the sluices**, the sluices
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**close**, and as the sea falls the turbines run until the head is too low.
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- **Flood generation**: water runs through the turbines on the rising tide instead — *"generally much less
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efficient than ebb generation."*
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Major examples: **La Rance**, France, **240 MW, operating since November 1966**; **Sihwa Lake**, South
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Korea, **254 MW, 2011**; Kislaya Guba, Russia, 1.7 MW, 1960s; Annapolis Royal, Canada.
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## 2. Sihwa Lake: a flood barrier converted into the world's largest tidal power station
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From [Wikipedia: Sihwa Lake Tidal Power Station](https://en.wikipedia.org/wiki/Sihwa_Lake_Tidal_Power_Station):
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| | |
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|---|---|
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| The seawall | *"constructed in 1994 for flood mitigation and agricultural purposes"* |
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| What went wrong | Pollution accumulated in the reservoir the wall created. PFOS concentrations there *"were among the greatest ever measured in the environment"* — **730 ng/L in January 2003** |
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| The remedy | *"In 2004, seawater was reintroduced in the hope of flushing out contamination; inflows from the tidal barrage were envisaged as a complementary permanent solution"* |
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| The station | Opened **4 August 2011**, **254 MW**, **552 GWh** a year, **US$560 million**, state-funded |
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| Its rank | The **world's largest** tidal installation, surpassing La Rance's 240 MW |
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Read that sequence in order, because the order is the point:
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1. A wall is built **to keep the sea out**.
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2. The wall works, and the water it encloses becomes the problem.
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3. The remedy is to **let the sea back in, on a schedule**.
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4. The scheduled admission of the thing the wall was built to exclude **becomes the power supply.**
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## 3. What the design already has, independently
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The [Campaign](/Hold%20The%20Flood/Campaign)'s Tidal Barrier district contains, in its own words: *"the
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barrier gates in the sea wall beyond the house, standing open"*; a log showing *"the gates opened at every
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high tide, on purpose, for years"*; the inference that *"the tide is what fills the low basins the machine
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cycles the Flood through"*; and the player's act, *"shut the gates at the lever, at high tide."*
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**Gates in a sea wall, opened at high tide on a schedule, to fill basins.** That is ebb-generation barrage
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operation, arrived at from the fiction rather than from the engineering. The district's own discovery
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chain even reaches the sentence a barrage engineer would write — *"the mouth is part of the machine, not
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its exit."*
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Recorded as an observation, not a compliment and not a correction: the design and the real technique
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converged, and the real one has names, figures and a history attached.
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## 4. Bearing (inference, for the Visionary, Campaign and World)
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Three notes, none a proposal.
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1. **The theme has a literal precedent.** *"The machine that endangers you also keeps your refuge working"*
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describes Sihwa Lake as a matter of record: the barrier against the water became the plant powered by
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it. If the vision is ever questioned as contrived, this is a real 254 MW answer.
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2. **Sihwa's remedy is structurally the Stop / Keep / Leave decision.** The choice there was not between
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safety and power but between an enclosed, deteriorating basin and a scheduled dependence on the sea.
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That is a decision about *dependence*, which is what the vision says the endings are about — *"informed
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positions on that dependence, with visible consequences."*
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3. **A barrage's binding quantity is head, and head is time-varying and external.** Section 1's sluice
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timing is a real constraint of the same shape as [REF108 §3](/Reference/Drainage%20Engineering)'s
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discharge window: the machinery can be perfect and still have to wait for the water. The Tidal Barrier
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already runs on a tide; the engineering says what the tide is *for*.
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---
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## What this page does not claim
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No claim that the Tidal Barrier district should change, or that it should become a power station — it is
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the Campaign designer's and this page reviews none of it. No claim that the design copied anything;
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§3 records a convergence, which is the opposite. No engineering or feasibility claim, and no claim that
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real barrage behaviour would be readable or enjoyable in play. No environmental or policy position: tidal
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barrages have documented ecological costs that this page does not survey and does not weigh.
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## Sources
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- [Wikipedia: Tidal barrage](https://en.wikipedia.org/wiki/Tidal_barrage) — how a barrage works, sluice timing, head, ebb versus flood generation, and the comparison table in §1
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- [Wikipedia: Sihwa Lake Tidal Power Station](https://en.wikipedia.org/wiki/Sihwa_Lake_Tidal_Power_Station) — every figure in §2
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- [Brief — Game vision](/Hold%20The%20Flood/Brief) — the theme and story this page was written against
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- [Campaign](/Hold%20The%20Flood/Campaign) — the Tidal Barrier district quoted in §3
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- [REF108: Draining a district](/Reference/Drainage%20Engineering) — the companion page on keeping water out, and the discharge-window constraint §4 refers to
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## Bookkeeping
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**Method.** Encyclopedia articles, fetched read-only 2026-09-07. The design quotations in §3 are taken from
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the live Campaign page source the same day, not from memory of an earlier revision. Nothing was built,
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prototyped or tested.
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**Stated limits.** Wikipedia is a tertiary source, used here for engineering description and for figures it
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states with citations. The PFOS measurement in §2 is quoted as the article gives it, including its date,
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because a single environmental reading is a point in time and not a standing condition. The ecological
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objections to tidal barrages are real, are not covered here, and their absence from this page is not a
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judgement about them.
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**Corrections.** Kill any statement here with a counter-source and it goes.