1001 Smart Cities
🇫🇷 Nice

Paillon, Magnan and Cagne-Malvan: the Métropole's hydrometeorological watch

🤖 AI-generated summary of the sources below · 🔎 Last verified · ◆ 13 sourced claims, none individually verified yet

This overview was generated with AI from the public sources listed below and checked against them before publication. It has not had a complete human fact-check — treat it as a starting point and follow the sources.

How this atlas is made · What “last verified” means · What “source-checked” means · The full record behind this page

Because the state only forecasts the big rivers, Nice and later the Métropole built their own gauging network on the coastal streams that flood the city. Instrumentation started in 1983 on the Paillons, when the Liautaud tunnel was dug into the river bed: the Métropole lists nine rain gauges, ten water-level stations and four cameras added to support crisis management on that basin, and, separately, a flood alert device whose job is to evacuate and close that tunnel before flooding reaches street level. The Magnan, which runs through the Madeleine district, was equipped from 2013 with two rain gauges, two level stations and three cameras used for image processing, with alert thresholds set inside an experimental hydrovideo forecasting project fed by radar rainfall. As metropolitan assets the Métropole counts 14 rain gauges, 20 limnimetric stations and 7 cameras — more gauges and stations than its own per-basin lists add up to, since it also runs rain gauges in urban areas — telemetered to a flood supervision system and watched by a dedicated engineering team on a 24/7 on-call rota; the Var itself stays with the state's Vigicrues service.

Live 📅 since 1983
Outcome🔄 Ongoing
Evidence🏛️ Officialgrades the sourcing — this entry states no impact figure
what does this mean?The strongest source is the operator's or the city's own reporting — an official report, dataset or press release. It grades who did the looking — not how well the project went. All four grades →
Run byMétropole Nice Côte d'Azur — gestion des risques / GeMAPI, with the TRGP tunnel alert operated from the Centre Multimodal des Déplacements
Scale🗺️ Regional

🎓 Lesson

The network is honest about how far a reading travels. On the Paillon a duty team at the metropolitan traffic centre watches the readings and closes a tunnel — no source describes the closure following a measured level by itself; on the Magnan the forecasting layer is still described by its operator as experimental; and on the Cagne and Malvan, whose monitoring network was completed in 2019, the local alert system is, in the Métropole's own words, still being defined. No published evaluation says how often any of it has been triggered, or with what result.

🌱 EnvironmentFlood resilienceWaterSensors & IoTSafety & security

Sources

↗ Métropole Nice Côte d'Azur — La surveillance hydrométéo et la supervision des cruesOperator's own page and the source of every figure used: instrumentation of the Paillons from 1983 with the Liautaud tunnel, nine rain gauges / ten limnimetric stations / four doubt-clearing cameras there, the Magnan equipped from 2013 (two + two + three cameras, experimental hydrovideo forecasting with radar rainfall), the Cagne-Malvan network completed in 2019 with its local alert system "en cours" of definition, totals of "14 pluviomètres, 20 stations limnimétriques et 7 caméras", real-time telemetry into a flood supervisor over GPRS/RTC/ADSL/fibre, a dedicated engineer team with a 7/7 24/24 on-call rota, and the state (DREAL / Météo-France, Vigicrues) keeping the Var.
↗ Ville de Nice — Le risque d'inondationUpdated 18 June 2025City page, updated 18 June 2025. Names the operational pieces from the city's side: the TRGP tunnel alert system run by the Métropole from the Centre Multimodal des Déplacements 24/7, the RAINPOL platform whose virtual rain gauges raise an alert when a threshold is likely to be reached within the next hour, the PANORAMA water-cycle supervisor, and the use of CSU cameras plus field reconnaissance teams during events.
↗ Tenevia — Flooding detection system on the Magnan river, Nice (case study)Supplier case study — treated as vendor material, used only for the technical description that the Magnan stations measure level and discharge by camera (CamLevel / CamFlow) and were operational from 2013 for the City of Nice. Its performance framing is not used.
Show your work What this page rests on and what it can’t tell you · all 13 claims with their sources · the forensic record

Evidence Passport · public beta 13 addressable claims, 3 source dossiers, one permanent baseline. The passport is unreviewed — an AI-assisted structural migration, not a human or expert endorsement. Every revision keeps a permanent copy under revision history.

Inspect the claims, one by one — verbatim text, sources and caveats for all 13

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-dafb329fca5e2f46 descriptive
Because the state only forecasts the big rivers
Published field
snippet · verbatim
Mapping
mapped · no interpretation or interpolation added by this passport
What the mapping says
The operator's page draws the division of labour itself: "L'État est responsable de la surveillance des grands cours d'eau dont les bassins versants s'étendent sur plusieurs intercommunalités, voire départements. Les services de la DREAL et Météo France assurent donc la surveillance du Var dans le cadre de VigiCrues." On the other coastal rivers, it says, Nice and then the Métropole had to build their own arrangement.
Caveat
The page describes the state's role as monitoring rather than forecasting, and its criterion is a catchment spanning several inter-municipal areas or departments rather than the size of the river as such.

Sources carrying this claim

  1. Métropole Nice Côte d'Azur — La surveillance hydrométéo et la supervision des crues
Claim 2 clm-21193489367001b4 descriptive
Nice and later the Métropole built their own gauging network on the coastal streams that flood the city
Published field
snippet · verbatim
Mapping
mapped · no interpretation or interpolation added by this passport
What the mapping says
The operator writes: "Sur les autres fleuves côtiers, la ville de Nice puis la Métropole ont été conduits à développer très tôt leur propre dispositif de surveillance hydrométéorologique, sur les Paillons, puis le Magnan et plus récemment la Cagne et le Malvan." The page also states that the area is exposed to flooding from coastal rivers, mountain torrents, valleys and surface runoff.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Métropole Nice Côte d'Azur — La surveillance hydrométéo et la supervision des crues
Claim 3 clm-44278964bb759d70 quantitative
Instrumentation started in 1983 on the Paillons, when the Liautaud tunnel was dug into the river bed
Published field
snippet · verbatim
Mapping
mapped · no interpretation or interpolation added by this passport
What the mapping says
The operator dates the start of instrumentation and ties it to the tunnel: "L'instrumentation a débuté en 1983 sur les Paillons lors de la construction du tunnel Liautaud dans le lit mineur du cours d'eau." The French "lit mineur" is the low-flow channel of the watercourse.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Métropole Nice Côte d'Azur — La surveillance hydrométéo et la supervision des crues
Claim 4 clm-de8f2ff3e5306294 descriptive
nine rain gauges, ten water-level stations and four cameras added to support crisis management on that basin
Published field
snippet · verbatim
Mapping
mapped · no interpretation or interpolation added by this passport
What the mapping says
The operator counts the Paillon basin equipment: "Neuf stations pluviométriques pour la mesure de la pluie et dix stations limnimétriques pour la mesure des niveaux des cours d'eau ont été progressivement déployées sur le bassin versant. Quatre caméras de lever de doute sont venues compléter le réseau de surveillance du Paillon pour appuyer la gestion de crise." "Caméras de lever de doute" are cameras used to resolve doubt about what a reading means.
Caveat
The page says the gauges were deployed progressively over the years and does not date the count; the four cameras were added later, to support crisis management rather than measurement.

Sources carrying this claim

  1. Métropole Nice Côte d'Azur — La surveillance hydrométéo et la supervision des crues
Claim 5 clm-7dcd9030ce48498c descriptive
a flood alert device whose job is to evacuate and close that tunnel before flooding reaches street level
Published field
snippet · verbatim
Mapping
mapped · no interpretation or interpolation added by this passport
What the mapping says
The Métropole states the purpose of the device: "Un dispositif d'alerte aux crues a été créé pour évacuer et fermer le tunnel, et prévenir l'inondation en surface." The city page names it and says who watches it: "Le dispositif d'alerte des crues du Paillon géré par la Métropole Nice Côte d'Azur assure la sécurité des usagers empruntant le Tunnel Rive Gauche du Paillon (TRGP). Le système est basé au Centre Multimodal des Déplacements Métropolitains (CMDM) et suivi par 7 jours sur 7 et 24 heures sur 24", and lists it as "Le Système d'Annonce des Crues (SAC) du Tunnel Rive Gauche du Paillon (TRGP) pour le Paillon".
Caveat
Neither page says the closure happens automatically, and neither states that the rain gauges, level stations and cameras feed this particular device: the city describes a system watched around the clock from the traffic control centre, and the Métropole lists the instruments and the alert device as separate items. The French "prévenir l'inondation en surface" can equally be read as preventing flooding at street level rather than as a statement about timing.

Sources carrying this claim

  1. Métropole Nice Côte d'Azur — La surveillance hydrométéo et la supervision des crues
  2. Ville de Nice — Le risque d'inondation
Claim 6 clm-366ab26dc7e48e3e quantitative
The Magnan, which runs through the Madeleine district, was equipped from 2013 with two rain gauges, two level stations and three cameras used for image processing
Published field
snippet · verbatim
Mapping
mapped · no interpretation or interpolation added by this passport
What the mapping says
The operator writes: "Le fleuve côtier Magnan, qui traverse le quartier de la Madeleine à Nice, a été équipé à partir de 2013. Le bassin versant est surveillé par deux stations pluviométriques et deux stations limnimétriques, complétées récemment par trois caméras permettant d'effectuer du traitement d'images." The supplier describes the same three cameras as measuring instruments: "Two CamLevel sensors and a CamFlow sensor have also been deployed on the river (Upstream - Intermediate - Downstream). They send the river's real time water levels (CamLevel) and flows (CamFlow) to the authorities."
Caveat
The supplier dates the first equipment to early 2011 with the stations "operational since 2013", so 2013 is when the network began working rather than when it was installed. The operator calls the three cameras a recent addition and does not date them.

Sources carrying this claim

  1. Métropole Nice Côte d'Azur — La surveillance hydrométéo et la supervision des crues
  2. Tenevia — Flooding detection system on the Magnan river, Nice (case study)
Claim 7 clm-9b57a4dab5bb9ccf descriptive
with alert thresholds set inside an experimental hydrovideo forecasting project fed by radar rainfall
Published field
snippet · verbatim
Mapping
mapped · no interpretation or interpolation added by this passport
What the mapping says
The operator writes: "Des seuils d'alerte ont été définis dans le cadre d'un projet expérimental de prévision des crues utilisant cette technologie d'hydrovidéo et la prévision de pluie à partir de lames d'eau radar." The supplier describes the same rainfall input: the HydroCore simulator "uses spatial measurements and rainfall forecasts on the river Magnan, sent from a dual-polarisation weather radar" produced by Novimet, giving anticipation over roughly the next hour and a half.
Caveat
Neither source publishes the threshold values, and neither says what happens when one is crossed.

Sources carrying this claim

  1. Métropole Nice Côte d'Azur — La surveillance hydrométéo et la supervision des crues
  2. Tenevia — Flooding detection system on the Magnan river, Nice (case study)
Claim 8 clm-007b5a1ca06d5cfb quantitative
As metropolitan assets the Métropole counts 14 rain gauges, 20 limnimetric stations and 7 cameras
Published field
snippet · verbatim
Mapping
mapped · no interpretation or interpolation added by this passport
What the mapping says
The operator gives the totals under the heading on how the work is organised: "Cela représente un patrimoine métropolitain de 14 pluviomètres, 20 stations limnimétriques et 7 caméras, auxquels sont associés les automates d'acquisition de mesures."
Caveat
The page presents these as the Métropole's overall holdings, not as a sum for the three basins, and the two figures do not agree with the per-basin counts on the same page: nine plus two plus eight rain gauges and ten plus two plus three level stations. Only the seven cameras match. The same page also mentions a further network of rain gauges deployed in urban areas for runoff monitoring.

Sources carrying this claim

  1. Métropole Nice Côte d'Azur — La surveillance hydrométéo et la supervision des crues
Claim 9 clm-3e11c000e71fd353 quantitative
telemetered to a flood supervision system and watched by a dedicated engineering team on a 24/7 on-call rota
Published field
snippet · verbatim
Mapping
mapped · no interpretation or interpolation added by this passport
What the mapping says
The operator writes: "Les données de surveillance sont centralisées en temps réel vers un logiciel de supervision des crues. Plusieurs moyens de télécommunications sont utilisés : GPRS, RTC, ADSL, fibre optique"; the software also receives technical alarms for sensor and communication failures. On staffing: "L'ensemble de ces dispositifs est piloté par une équipe d'ingénieurs et de techniciens dédiés. Une astreinte est organisée 7 jours / 7 et 24 heures / 24, avec une mobilisation anticipée par les émissions de Vigilance Météo." The city page names the supervisor as "Le superviseur PANORAMA de la Direction du Cycle de l'Eau et de la GEMAPI".
Caveat
The team is described as engineers and technicians, and the page says the on-call rota is mobilised in advance by the national weather service's Vigilance bulletins, so the trigger for staffing up comes from the state rather than from the Métropole's own gauges.

Sources carrying this claim

  1. Métropole Nice Côte d'Azur — La surveillance hydrométéo et la supervision des crues
  2. Ville de Nice — Le risque d'inondation
Claim 10 clm-95fcab724cab93bf descriptive
the Var itself stays with the state's Vigicrues service
Published field
snippet · verbatim
Mapping
mapped · no interpretation or interpolation added by this passport
What the mapping says
The operator writes: "Les services de la DREAL et Météo France assurent donc la surveillance du Var dans le cadre de VigiCrues." The city page confirms the same split from its own side: "Le suivi des hauteurs d'eau et des débits du fleuve Var est assuré par le Service de Prévisions des Crues (SPC) du territoire Méditerranée Est", and lists "Vigicrues Var pour le Var" among the monitoring systems it relies on.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Métropole Nice Côte d'Azur — La surveillance hydrométéo et la supervision des crues
  2. Ville de Nice — Le risque d'inondation
Claim 11 clm-9883bc32a33af1b2 descriptive
On the Paillon a duty team at the metropolitan traffic centre watches the readings and closes a tunnel
Published field
lesson · verbatim
Mapping
mapped · no interpretation or interpolation added by this passport
What the mapping says
Both pages describe a dedicated alert system for the Paillon whose stated purpose is the tunnel. The Métropole: "Un dispositif d'alerte aux crues a été créé pour évacuer et fermer le tunnel, et prévenir l'inondation en surface." The city lists it as "Le Système d'Annonce des Crues (SAC) du Tunnel Rive Gauche du Paillon (TRGP) pour le Paillon" and says it "assure la sécurité des usagers empruntant le Tunnel Rive Gauche du Paillon (TRGP)", operated from the Centre Multimodal des Déplacements Métropolitains and watched every day around the clock.
Caveat
Neither page mentions a threshold for the Paillon. The only thresholds either page names are the alert thresholds set for the Magnan and the ones the RAINPOL virtual rain gauges use for urban runoff. Neither page says the tunnel closes automatically when a level is reached; the city describes a system watched around the clock by staff at the traffic control centre.

Sources carrying this claim

  1. Métropole Nice Côte d'Azur — La surveillance hydrométéo et la supervision des crues
  2. Ville de Nice — Le risque d'inondation
Claim 12 clm-915718d5140d124a descriptive
on the Magnan the forecasting layer is still described by its operator as experimental
Published field
lesson · verbatim
Mapping
mapped · no interpretation or interpolation added by this passport
What the mapping says
The Métropole's own undated page still calls the forecasting work a trial: "Des seuils d'alerte ont été définis dans le cadre d'un projet expérimental de prévision des crues utilisant cette technologie d'hydrovidéo et la prévision de pluie à partir de lames d'eau radar." The same page lists "le développement de la prévision des crues et des inondations" among the works still to come.
Caveat
The page carries no date, so it shows what the operator says today rather than how long the project has been called experimental.

Sources carrying this claim

  1. Métropole Nice Côte d'Azur — La surveillance hydrométéo et la supervision des crues
Claim 13 clm-170349f1cae6b9b0 quantitative
on the Cagne and Malvan, whose monitoring network was completed in 2019, the local alert system is, in the Métropole's own words, still being defined
Published field
lesson · verbatim
Mapping
mapped · no interpretation or interpolation added by this passport
What the mapping says
The operator writes: "Enfin le réseau de surveillance de la Cagne et Malvan a été achevé en 2019. Les enjeux sont essentiellement concentrés dans la partie aval du bassin versant, en particulier la commune de Cagnes-sur-Mer. Le réseau est composé de huit stations pluviométriques et de trois stations limnimétriques. La définition d'un système d'alerte local est en cours."
Caveat
The page is undated, so it establishes that the alert system is unfinished as the operator now describes it, not how long it has been in that state.

Sources carrying this claim

  1. Métropole Nice Côte d'Azur — La surveillance hydrométéo et la supervision des crues
Forensic record — source dossiers, gaps, hashes and the exact revision this page renders

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 2026-08-22-evidence-baseline effective 2026-08-10 · created 2026-08-22

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

sha256:4f6a030c21b91b1d3b559679153d2cc8be866f2c757203e6a8f5358c01769a32
Revision history → Permanent version link → Machine-readable record → Evidence Constitution →
13
of 13 claims mapped
3
source dossiers
0
publication dates recorded
0
archives linked
0
exact locators
0
content captures hashed

Governance facts carried by the record

Operator
Métropole Nice Côte d'Azur — gestion des risques / GeMAPI, with the TRGP tunnel alert operated from the Centre Multimodal des Déplacements
Actor types
city-government
Funding model
Not recorded
Funding description
Not recorded
Cost
Not recorded
Ownership
Not recorded
Decision rights
Not recorded
Exit conditions
Not recorded

3 source dossiers

Métropole Nice Côte d'Azur — La surveillance hydrométéo et la supervision des crues nicecotedazur.org · 13 linked claims

Open original source ↗

Stable source ID
src-a47854ce8099af57
Publisher
Name not classified · nicecotedazur.org
Type / language
web-page · language not classified
Published
Not recorded
Updated
Not recorded
Source last checked
No source-level check date
Record last verified
2026-08-10
Dossier created
2026-08-22
Retrieved copy
No local capture recorded
Archive
No archived copy linked
Content hash
No captured content hash
Locator
Open the recorded source note

Operator's own page and the source of every figure used: instrumentation of the Paillons from 1983 with the Liautaud tunnel, nine rain gauges / ten limnimetric stations / four doubt-clearing cameras there, the Magnan equipped from 2013 (two + two + three cameras, experimental hydrovideo forecasting with radar rainfall), the Cagne-Malvan network completed in 2019 with its local alert system "en cours" of definition, totals of "14 pluviomètres, 20 stations limnimétriques et 7 caméras", real-time telemetry into a flood supervisor over GPRS/RTC/ADSL/fibre, a dedicated engineer team with a 7/7 24/24 on-call rota, and the state (DREAL / Météo-France, Vigicrues) keeping the Var.

Descriptive only — not page/paragraph exact
Claims linked
Ville de Nice — Le risque d'inondation nice.fr · 4 linked claims

Open original source ↗

Stable source ID
src-f11d53fa1f1d2b43
Publisher
Name not classified · nice.fr
Type / language
web-page · language not classified
Published
Not recorded
Updated
2025-06-18
Source last checked
No source-level check date
Record last verified
2026-08-10
Dossier created
2026-08-22
Retrieved copy
No local capture recorded
Archive
No archived copy linked
Content hash
No captured content hash
Locator
Open the recorded source note

City page, updated 18 June 2025. Names the operational pieces from the city's side: the TRGP tunnel alert system run by the Métropole from the Centre Multimodal des Déplacements 24/7, the RAINPOL platform whose virtual rain gauges raise an alert when a threshold is likely to be reached within the next hour, the PANORAMA water-cycle supervisor, and the use of CSU cameras plus field reconnaissance teams during events.

Descriptive only — not page/paragraph exact
Claims linked
Tenevia — Flooding detection system on the Magnan river, Nice (case study) tenevia.com · 2 linked claims

Open original source ↗

Stable source ID
src-eb9e20bacbc6833a
Publisher
Name not classified · tenevia.com
Type / language
web-page · language not classified
Published
Not recorded
Updated
Not recorded
Source last checked
No source-level check date
Record last verified
2026-08-10
Dossier created
2026-08-22
Retrieved copy
No local capture recorded
Archive
No archived copy linked
Content hash
No captured content hash
Locator
Open the recorded source note

Supplier case study — treated as vendor material, used only for the technical description that the Magnan stations measure level and discharge by camera (CamLevel / CamFlow) and were operational from 2013 for the City of Nice. Its performance framing is not used.

Descriptive only — not page/paragraph exact
Claims linked
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.

Continue exploring

Compare this project

🇯🇵 Tsunami-Alert Automatic Tide Gate Closure · Osaka Osaka's gates close automatically on a national warning. Nice's Paillon threshold closes a road tunnel; the rest of its network only warns. 🇭🇳 Río Choluteca Real-Time Flood Sensor Network (Sistema de Alerta Temprana) · Tegucigalpa Both gauge the streams the state ignores. Tegucigalpa started in 2024 with four sensors; Nice has been at it since 1983, with 34 stations. 🇫🇷 RAMSES: Real-Time Stormwater and Sewer Control · Bordeaux France gauges what the state ignores: Nice instrumented its coastal streams, Bordeaux automated the pipes beneath them.

Explore the wider context

📟 A Reading Is Not a Decision🌊 Flood resilience guide🏙️ Nice city profile🌱 Environment projects📖 Flood early-warning system📖 Automated speed enforcement (speed cameras)📖 District metering area (DMA)
📎 Cite this project

1001 Smart Cities (2026). “Paillon, Magnan and Cagne-Malvan: the Métropole's hydrometeorological watch” — Nice, France. The Smart City Atlas. https://1001smartcities.org/projects/nice-flood-monitoring/ (last verified 2026-08-10). Data: CC BY 4.0.

The underlying data is free to reuse with attribution — see the open data page.

🚩 Report an error · 🔔 Follow changes to this entry (RSS)

✉️ Get the next source-checked smart-city project in your inbox

One short email a week: the Landmark, one Insight, the new cities. No spam, one-click unsubscribe. About the newsletter · RSS