1001 Smart Cities

Permanent project revision

Tsunami-Alert Automatic Tide Gate Closure

Revision 2026-08-26-p1-quality-uplift · effective 2026-08-26

Superseded. A later revision exists: 2026-08-27-source-dating →

unreviewed

Created the first structured Evidence Passport with 7 claims and 5 source dossiers.

sha256:dfa38f9405860a25d13f422c6d1ec5e23863b1e124150b94cdda6f9ffd594834
All revisions → Current entity page →

Change set

  • add /evidencePassport — Added claim-level evidence mapping and source dossiers.
  • add /revisionHistory — Established a permanent, hash-addressed baseline revision.
7
of 7 claims mapped
5
source dossiers
1
publication dates recorded
0
archives linked
0
exact locators
0
content captures hashed

Claims, one by one

The text below is copied verbatim from the published record. Each claim names the source dossiers that carry it; caveats stay attached to the claim they qualify.

Claim 1 clm-48aadbfb3094c2fd quantitative
About 21 square kilometres of western Osaka lie below sea level after decades of industrial groundwater pumping
Published field
snippet · verbatim
Mapping
mapped · no interpretation or interpolation added by this passport
What the mapping says
The prefecture's own page on the area below sea level sets out the extent of the subsided zone in western Osaka and its cause in industrial groundwater extraction.
Caveat
A Japanese-language prefecture page; no locator string is recorded because the figure is presented graphically rather than in one quotable sentence.

Sources carrying this claim

  1. Osaka Prefecture — Osaka, a city lower than the sea
Claim 2 clm-e6174e22efe10a89 descriptive
shielded by seven tide gates on five rivers
Published field
snippet · verbatim
Mapping
mapped · no interpretation or interpolation added by this passport
What the mapping says
The closure notice names all seven gates - Aji, Shirinashi, Kizu, Rokkenyagawa, Shorenji, Sangenya and Dekishima - in its closure-criteria table, and the river facilities page places them on the rivers of western Osaka.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Osaka Prefecture, Nishi-Osaka Flood Control Office — automatic tide gate closure notice
  2. Osaka Prefecture — river facilities of western Osaka
Claim 3 clm-e4906c477f8fc24c descriptive
closes them automatically off the national J-Alert signal
Published field
snippet · verbatim
Mapping
mapped · no interpretation or interpolation added by this passport
What the mapping says
The notice explains the mechanism: on a tsunami advisory or warning issued to Osaka Prefecture, the Fire and Disaster Management Agency emits the J-Alert signal, and on receiving it the office automatically sends a closure signal to each gate.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Osaka Prefecture, Nishi-Osaka Flood Control Office — automatic tide gate closure notice
Claim 4 clm-20c033ab546426fe descriptive
Sangenya and Dekishima shut on a Japan Meteorological Agency tsunami advisory, the other five only on a warning
Published field
snippet · verbatim
Mapping
mapped · no interpretation or interpolation added by this passport
What the mapping says
The closure-criteria table gives a closure for Sangenya and Dekishima in the tsunami-advisory column as well as the warning columns, while the Aji, Shirinashi, Kizu, Rokkenyagawa and Shorenji rows are blank in the advisory column and closed only from the warning column onwards.
Caveat
The atlas previously said any advisory or warning closed every gate. The prefecture's own table shows the threshold differs by gate.

Sources carrying this claim

  1. Osaka Prefecture, Nishi-Osaka Flood Control Office — automatic tide gate closure notice
Claim 5 clm-5d1553034a5f7596 quantitative
The three 1970 arch gates on the Aji, Shirinashi and Kizu rivers joined in April 2023, sounding an eight-minute warning to boats first, and are now being replaced
Published field
snippet · verbatim
Mapping
mapped · no interpretation or interpolation added by this passport
What the mapping says
The notice lists the start of automatic operation by gate - April of Reiwa 5, that is 2023, for Aji, Shirinashi and Kizu - and states that those three warn for eight minutes after receiving the closure signal before shutting. The renewal page covers their replacement.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Osaka Prefecture, Nishi-Osaka Flood Control Office — automatic tide gate closure notice
  2. Osaka Prefecture — renewal of the three great tide gates
Claim 6 clm-3756af1200d045d1 descriptive
a Japan Meteorological Agency tsunami warning is a binary national signal, so a relay can act on it in seconds and the gate shuts without anyone deciding
Published field
lesson · verbatim
Mapping
mapped · no interpretation or interpolation added by this passport
What the mapping says
The notice describes exactly this chain and nothing else in it: the meteorological agency issues the warning, the Fire and Disaster Management Agency emits J-Alert, the office's system receives it and sends the closure signal to each gate automatically. No human decision appears anywhere between the alert and the gate.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Osaka Prefecture, Nishi-Osaka Flood Control Office — automatic tide gate closure notice
Claim 7 clm-da2d2ee56bac5e05 descriptive
the three big shipping gates close only on a warning, not on the lesser advisory, and give boats eight minutes of countdown; the two smaller ones close on an advisory and give three
Published field
lesson · verbatim
Mapping
mapped · no interpretation or interpolation added by this passport
What the mapping says
The notice sets both out: the criteria table shows the advisory column closing only Sangenya and Dekishima, and the text states 'Aji, Shirinashi and Kizu warn for 8 minutes after receiving the closure signal; Rokkenyagawa, Shorenji, Sangenya and Dekishima warn for 3 minutes, after which the gates close.'
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Osaka Prefecture, Nishi-Osaka Flood Control Office — automatic tide gate closure notice

Source dossiers and revision state

This layer records what is known about each source, what is still missing, and the exact snapshot this page is rendering. A missing date, archive or hash stays visible as missing.

unreviewed Revision 2026-08-26-p1-quality-uplift effective 2026-08-26 · created 2026-08-26

Awaiting operator and domain-expert review; publication of this revision implies neither.

Erratum on this revision's envelope. The snapshot, its hash and its permanent link are untouched.

  • createdAt previously read 2026-08-26T15:00:00Z. The batching script that produced this revision advanced createdAt into the future to satisfy the strictly-increasing order the validator requires per entity. The value never recorded a real event; the corrected value is the moment the revision provably existed in the repository. Corrected to 2026-08-26T14:01:23Z on 2026-08-27; evidence: first appears in commit 292394e4ae, committed 2026-08-26T14:01:23Z.
sha256:dfa38f9405860a25d13f422c6d1ec5e23863b1e124150b94cdda6f9ffd594834
Revision history → Permanent version link → Machine-readable record → Evidence Constitution →
7
of 7 claims mapped
5
source dossiers
1
publication dates recorded
0
archives linked
0
exact locators
0
content captures hashed

Governance facts carried by the record

Operator
Osaka Prefecture, Nishi-Osaka Flood Control Office
Actor types
regional-government
Funding model
public
Funding description
Not recorded
Cost
Not recorded
Ownership
Not recorded
Decision rights
Not recorded
Exit conditions
Not recorded

5 source dossiers

Osaka Prefecture, Nishi-Osaka Flood Control Office — automatic tide gate closure notice pref.osaka.lg.jp · 6 linked claims

Open original source ↗

Stable source ID
src-f7064087841a71e4
Publisher
Name not classified · pref.osaka.lg.jp
Type / language
web-page · language not classified
Published
Not recorded
Updated
2023-04-01
Source last checked
No source-level check date
Record last verified
2026-08-26
Dossier created
2026-08-26
Retrieved copy
No local capture recorded
Archive
No archived copy linked
Content hash
No captured content hash
Locator
Open the recorded source note

The office's own notice: which alert level closes which gate, the J-Alert mechanism, and the countdown each gate runs before it shuts. The page states only a last-updated date, so no publication date is recorded.

Descriptive only — not page/paragraph exact
Claims linked
Osaka Prefecture — renewal of the three great tide gates pref.osaka.lg.jp · 1 linked claim

Open original source ↗

Stable source ID
src-f156e54486e97917
Publisher
Name not classified · pref.osaka.lg.jp
Type / language
web-page · language not classified
Published
Not recorded
Updated
Not recorded
Source last checked
No source-level check date
Record last verified
2026-08-26
Dossier created
2026-08-26
Retrieved copy
No local capture recorded
Archive
No archived copy linked
Content hash
No captured content hash
Locator
Open the recorded source note

The prefecture's page on replacing the three arch gates. The host did not answer automated requests, so no date is recorded here.

Descriptive only — not page/paragraph exact
Claims linked
Osaka Prefecture — Osaka, a city lower than the sea pref.osaka.lg.jp · 1 linked claim

Open original source ↗

Stable source ID
src-48cff65ee8b7f92e
Publisher
Name not classified · pref.osaka.lg.jp
Type / language
web-page · language not classified
Published
Not recorded
Updated
Not recorded
Source last checked
No source-level check date
Record last verified
2026-08-26
Dossier created
2026-08-26
Retrieved copy
No local capture recorded
Archive
No archived copy linked
Content hash
No captured content hash
Locator
Open the recorded source note

Official source for the subsidence framing: heavy industrial groundwater extraction caused subsidence; about 21 square kilometres of western Osaka lie below sea level and about 41 square kilometres below mean high tide.

Descriptive only — not page/paragraph exact
Claims linked
Osaka Prefecture — river facilities of western Osaka pref.osaka.lg.jp · 1 linked claim

Open original source ↗

Stable source ID
src-7fbe387f3963d155
Publisher
Name not classified · pref.osaka.lg.jp
Type / language
web-page · language not classified
Published
Not recorded
Updated
Not recorded
Source last checked
No source-level check date
Record last verified
2026-08-26
Dossier created
2026-08-26
Retrieved copy
No local capture recorded
Archive
No archived copy linked
Content hash
No captured content hash
Locator
Open the recorded source note

Lists the facilities the office runs — three arch gates, other gates, 46 storm-surge steel doors and a pumping station — and names the gate remote monitoring and operation system that carries the closure commands.

Descriptive only — not page/paragraph exact
Claims linked
Mori et al., Field Survey of 2018 Typhoon Jebi in Japan, Geosciences 8(11):412 mdpi.com · background

Open original source ↗

Stable source ID
src-72d10f810611e1b8
Publisher
Name not classified · mdpi.com
Type / language
web-page · language not classified
Published
2018-11-09
Updated
Not recorded
Source last checked
No source-level check date
Record last verified
2026-08-26
Dossier created
2026-08-26
Retrieved copy
No local capture recorded
Archive
No archived copy linked
Content hash
No captured content hash
Locator
Open the recorded source note

Peer-reviewed field survey of Typhoon Jebi's storm surge against the design level of Osaka's coastal defences. Publication date from Crossref.

Descriptive only — not page/paragraph exact
Claims linked
Background source; no baseline claim points here
Known limits of this passport
  • Publisher names and source languages have not yet been classified; domains are recorded without guessing.
  • Existing source notes are descriptive locators, not page- or paragraph-exact citations.
  • A missing archive, publication date or content hash is shown as null rather than inferred.
  • The project-level evidence grade ranks the strongest source in the entry; it is not a truth score for every claim.