In Les Plans, 99% of residents live on shrink-swell clay
The state hasn’t mapped flood zones in Les Plans in detail, yet it has declared 11 flood disasters here since 1982, the last in September 2023. Hazard risk is not graded in France: there is no national flood map, so a town outside the mapped areas can’t be called safe from floods.
What stands out about hazards in Les Plans
From the state’s records on Géorisques. Nothing here is graded.
6 hazards in Les Plans at a glance
Bars show where the town sits among French towns of 2,500+; they are not a grade. Disaster declarations are shown, not compared.
Flood zones
Disasters declared
Clay ground
Earthquakes
Radon
Industrial sites
Why hazards aren’t graded in France
In the UK, the Hazard risk grade is the share of homes in a mapped flood zone; in the U.S., it is FEMA’s modelled yearly damage to buildings. Both rest on maps that cover the whole country. France maps flood zones in detail only in its 125 areas at highest risk (TRI), so most towns have no figure, and a blank would read as “dry”. The state’s disaster declarations don’t fill the gap: they depend on the mayor applying, and they don’t line up with the mapped zones. So Les Plans has no Hazard grade, and its overall grade uses the other six subjects.
Everything on this page is shown as published. We’ll grade it when France publishes a national flood map.
Flood zones in Les Plans on the map
The state’s own layers from Géorisques, drawn over the street map. Tap a layer to switch it on or off.
Les Plans is outside the state’s detailed flood maps, so no flood zone shows here; that doesn’t mean no flood risk (below). The map opens on the clay ground instead.
No detailed flood map for Les Plans
France maps flood zones in detail only in its areas at highest risk (TRI). Les Plans isn’t one, so there is no share of residents to show. That isn’t a clean bill of health: the state has declared 11 flood disasters here since 1982, the last in September 2023.
What the state does have for Les Plans: a flood atlas (Atlas des zones inondables du bassin versant de l'Hérault and Prévention submersion marine) showing where past floods reached.
16 natural disasters declared in Les Plans since 1982, 11 for floods
The state’s register of natural-disaster orders, 1982 to January 2026.
- 2023Floods and mudflowsSeptember 16–17, 2023 · order published October 4, 2023
- 2023Drought: clay subsidenceJanuary 1, 2023 – September 30, 2023 · order published July 2, 2024
- 2015Floods and mudflowsSeptember 12–13, 2015 · order published October 8, 2015
- 2014Floods and mudflowsNovember 27–30, 2014 · order published December 11, 2014
- 2014Floods and mudflowsSeptember 17–19, 2014 · order published November 7, 2014
- 2004Floods and mudflowsApril 29, 2004 · order published May 3, 2005
Show all 14 events
- 1997Mudflow · LandslideDecember 18, 1997 · order published June 11, 1998
- 1997LandslideNovember 5, 1997 · order published June 11, 1998
- 1997Floods and mudflowsNovember 4–5, 1997 · order published June 11, 1998
- 1996Floods and mudflowsJanuary 28–30, 1996 · order published April 17, 1996
- 1996LandslideJanuary 1–31, 1996 · order published September 4, 1996
- 1992Floods and mudflowsSeptember 26–30, 1992 · order published February 27, 1993
- 1992Floods and mudflowsSeptember 21–23, 1992 · order published November 18, 1992
- 1982Floods and mudflows · StormNovember 6–10, 1982 · order published November 19, 1982
Declarations by hazard · 1982–2025
Each line is a state order recognizing a natural disaster in the commune (“CatNat”), which lets insured owners claim. The latest flood began September 16, 2023; 8 flood declarations since 1995.
This count partly reflects how often a mayor applies for a declaration, so it isn’t compared between towns. It is a record of recognized claims, not a flood map. Source: GASPAR, Géorisques, file of 5 October 2026 (orders published to January 2026).
The state lists 4 hazards for Les Plans
Risk plans in force or in preparation, and the prefecture’s list of major risks.
| Hazard | Risk plan (PPR) | Listed by the prefecture |
|---|---|---|
| Landslides and rockfalls | Approved 2008 | ✓ |
| Clay shrink-swell | Approved 2008 | ✓ |
| Forest fire | — | ✓ |
| Radon | — | ✓ |
A risk plan (plan de prévention des risques, PPR) is the state’s map of where building is banned or restricted because of a hazard; it is attached to the town’s planning rules, and a seller or landlord must tell you if the home is in one. The prefecture’s file of major risks (DDRM) lists the hazards it expects in each commune.
Earthquake zone 1 (very low); 99% of residents on shrink-swell clay
What the ground under Les Plans does: national maps, the same for every town.
Residents on shrink-swell clay · share of residents
Clay ground swells when wet and shrinks in drought, which cracks walls of houses on shallow foundations. Since 2020, a soil study is required before selling a building plot in a medium or high zone. 1 drought (clay) declaration here since 1982.
Les Plans is in zone 1 (very low): ordinary homes need no earthquake building rules. The zone sets building rules; it isn’t a forecast.
Clay: BRGM shrink-swell exposure map 2025, residents placed by INSEE’s 200 m grid. Earthquakes: national seismic zoning, decree of 22 October 2010.
Radon potential in Les Plans: category 1 of 3 (low)
Radon is a natural radioactive gas from granite and volcanic rock; it builds up indoors.
Les Plans is in category 1, the lowest: the rocks here release little radon.
The category describes the rocks under the commune, not any home: a test is the only way to know.
Source: radon potential by commune, IRSN (now ASNR), 2019.
No industrial risk plan reaches Les Plans
Hazardous sites whose danger zone reaches the town, and the technological risks the prefecture lists.
Seveso sites store or use large amounts of dangerous substances; upper-tier sites have a risk plan around them. Distances are from the town’s center.
Sources: GASPAR (PPRT, DDRM), Géorisques, 5 October 2026; Seveso sites from Géorisques’ register of classified installations.
Hazards in Les Plans’ neighbors
Towns of 2,500+ within 30 km. Tap one to open its hazards page.
| Town | Flood zone* | Seismic zone | Radon |
|---|---|---|---|
| Les Plans | — | 1 | 1 |
| Lodève 7,251 · 4 km | — | 1 | 3 |
| Bédarieux 5,804 · 18 km | — | 1 | 2 |
| Clermont-l'Hérault 9,461 · 18 km | — | 2 | 3 |
| Saint-André-de-Sangonis 6,427 · 21 km | — | 2 | 1 |
| Canet 3,619 · 23 km | — | 2 | 1 |
| Gignac 6,651 · 24 km | — | 2 | 1 |
* Share of residents in a mapped medium-probability flood zone; a dash means no detailed map, not no risk. Radon: category 1 to 3.
Being ready in Les Plans
Where France publishes warnings, and what to ask before you buy or rent.
- Météo-France’s vigilance map gives the day’s warnings by département, from yellow to red.
- Vigicrues shows river levels and flood warnings for the main rivers, updated twice a day.
- FR-Alert sends emergency alerts to every phone in the area; no sign-up needed.
- The seller or landlord must give you a risk statement (état des risques) for the address, listing the plans it is in.
- They must also tell you about any natural-disaster claim paid on the home.
- Géorisques gives the same statement for any address, free.
- Don’t drive or walk through floodwater.
- Go upstairs, not to the cellar or car park.
- Call 112 if you’re in danger.
- Ask for the risk statement and read which plans the address is in.
- Ask the town hall for its risk booklet (DICRIM) and safety plan (PCS).
- For a house, look for cracks and ask about the foundations: much of the town is on shrink-swell clay.
- Check that home insurance includes natural-disaster cover (it comes with fire cover).
What this data can and can’t tell you
- Not graded. France has no national flood map, so we don’t grade hazard risk. Comparisons on this page are with other French towns of 2,500+, shown for context.
- Mapped areas only. Flood shares exist only where the state has mapped flooding in detail (the TRI areas). A town without a figure has no map, not no risk.
- Disaster declarations. A CatNat order recognizes a disaster so that insurers pay; it follows the commune’s application. The count partly reflects how often a mayor applies, so we show it but don’t compare towns on it.
- Plans. A risk plan maps where building is limited; it doesn’t say any one home will flood.
- Clay, earthquakes, radon. National maps of the ground: they describe susceptibility and set building rules, not damage or forecasts.
Questions about hazards in Les Plans
Does Les Plans flood?
The state has declared 11 flood disasters in Les Plans since 1982, the last starting September 16, 2023. The town has no detailed flood map, so check a specific address on Géorisques.
Is Les Plans at risk of earthquakes?
Les Plans is in seismic zone 1 of 5 (very low). The zone sets building rules for new construction; it isn’t a forecast.
Is there radon in Les Plans?
Radon potential is category 1 of 3 (low). It describes the ground under the commune; only a test tells you a home’s level.
Are there dangerous industrial sites near Les Plans?
No industrial risk plan reaches Les Plans; 0 Seveso sites lie within 5 km.
Why doesn’t Les Plans have a Hazard grade?
France maps flood zones in detail only in its areas at highest risk, so most towns would have no figure, and a blank would look like no risk. We show the data instead, and will grade it if France publishes a national flood map.
Sources: Géorisques (Ministry of Ecological Transition), GASPAR file of 5 October 2026: CatNat orders, risk plans (PPRN, PPRT, PPRM), flood atlases, DDRM, DICRIM · flood directive maps, 2020 (TRI 2nd cycle) and 2024 outlines · BRGM clay shrink-swell map 2025 · seismic zoning, decree of 22 October 2010 · ASNR (formerly IRSN) radon potential 2019 · INSEE 200 m income grid 2021 (where residents live) · map: Géorisques layers over © OpenStreetMap contributors · Seveso sites: Géorisques register of classified installations. Licence Ouverte / Open Licence (Etalab). Not graded.
Contains public sector information under the Licence Ouverte / Open Licence 2.0 (Etalab): INSEE, DGFiP, the Interior Ministry’s statistics service (SSMSI), the Ministry of Education (DEPP), the Health Ministry’s statistics service (DREES) and the Housing Ministry (Carte des loyers). Commune boundaries: IGN Admin Express.