The geomorphology and geology of the Monnet-la-Ville area make it highly susceptible to landslides. BRGM mapped the landslide hazard in the area, using a bivariate statistical method to provide the Departmental Directorate (DDT) with a knowledge base on which to base their risk-prevention strategy.
6 November 2024
Map of the landslide hazard with a close-up of the urban area

Map of the landslide hazard with a close-up of the urban area

© BRGM

The need

Following heavy rainfall, the municipality of Monnet-la-Ville (Jura) experienced a major episode of landslides in January 2018. This susceptibility to landslides had already been highlighted by a multi-criteria mapping study of natural hazards carried out for the whole département by BRGM. In order to better prevent the risks associated with landslides in this municipality, the Jura Departmental Directorate (DDT 39) wanted to improve knowledge of this hazard in the area, and called on BRGM to assist with this.

The results

As part of this study, the geological map was updated to a scale of 1:10,000 using data collected during field campaigns and from the existing literature. A local event database was then developed to document past landslide events. Based on this information, reference scenarios were defined for expected landslides, using descriptive statistical analyses of past events.

Concomitantly, key prediction variables of landslide susceptibility were defined, including geology, slope, watercourses and geomorphology. The assessment of susceptibility was based on a combination of two methods: a quantitative method based on a statistical model (weight of evidence) for low-intensity events, of sufficient number to enable the model to be trained, and a qualitative, empirical method (expert opinion) for medium-intensity events, of which there were fewer. In the end, the hazard map shows that the level of risk is negligible in most cases, covering 58% of the municipality’s territory, while 10% of the area is affected by a very low level of risk, 24% by a low level of risk and 8% by a medium level of risk.

The village of Baume-les-Messieurs, Jura

Thanks to BRGM's expertise, we now have a more detailed map of the hazard, which will be officially submitted to the municipality and which the local authorities will be able to use in their local town planning scheme. Furthermore, the BRGM teams, with their technical and scientific expertise, were able to explain the issues to elected representatives and local residents by comparing our project with what is being done in other areas. This has given local residents a better understanding of our preventive approach.

Olivier Boléat, Deputy Risk Manager, DDT 39
Predictive spatial variables characterised for the implementation of the weight-of-evidence method (Jura, 2023)

Predictive spatial variables characterised for the implementation of the weight-of-evidence method (Jura, 2023)

© BRGM

Using the results

The hazard map produced can be used by the municipality to inform the public. The proposed construction provisions, combined with the hazard map, will also enable the local authority to take account of the landslide risk in its spatial planning policy.

The partners

  • Jura Departmental Directorate (DDT39)
  • Municipality of Monnet-la-Ville