How can we get high school students to work on the phenomenon of erosion and its risks? Cédric Metge, SVT teacher at the Marcelin Berthelot high school in Toulouse, creates 3D models with his students using digital software. “This practical work follows a geological excursion in the streets of Toulouse.” Dam and water level are taken into account to study the risk of flooding. With the model, “high school students visualize the altitude in relation to a geological map”. Cédric Metge explains his approach and gives advice.
What is this project on landslide risks and prevention using 3D models?
The article presented on the Toulouse academy website results from a session organized in four separate workshops. It focuses on one of these workshops in particular.
This practical work follows a geological excursion in the streets of Toulouse. This urban walk offers us the opportunity, through construction materials, to grasp the geological context of the region.
During this outing, the students were able to observe various protection measures against the risk of flooding, as well as panels representing the water level during the historic flood of 1875. The dikes and a cofferdam gate were particularly highlighted in the neighborhood.
Why did you specifically choose to use the ElevationAPI and Cura?
Cura software is standard software for cutting STL files for printing on a 3D printer. It stands out for its ease of use and above all for its free nature.
The API elevation, designed by Xavier Fischer, constitutes the most remarkable aspect of this activity. The API (Application Programming Interface) is a set of functions developed by Xavier Fischer. Its principle lies in the recovery of digital terrain models (DTM) provided by organizations such as NASA or IGN, in order to produce two types of images: a 3D image viewable on the screen and an STL file printable using in Cura.
The models thus produced benefit from remarkable quality, making it possible to represent the geological structures associated with a geological map or risk models, such as the one produced during the activity in question.
How does this activity allow students to understand the concepts of erosion, landslides and natural risk prevention?
This workshop highlights the notion of flood risk such as the historic flood of 1875, caused by heavy precipitation and heavy snowmelt. Here, we emphasize that mountain landslides can also contribute to flood risks.
Indeed, this activity allows students to identify, from the official document of major risks of the city of Toulouse, that the Cap-de-Long dam can cause a risk of flooding of the Garonne in Toulouse. Initially, students may think that the only danger lies in the dam breaking. However, this activity teaches them that landslides can also play a role, causing the dam to overflow, as happened in Italy at the Vajont dam.
The notions of alteration, erosion and landslide will be addressed during the following session.
What are the advantages of 3D modeling? Pitfalls to avoid?
The main advantage of 3D modeling is visualizing elevation in relation to a geological map. For example, on the model of the Toulouse region, we can distinguish three molasse complexes and the different alluvial terraces. On the map, the difference in colors allows us to distinguish the different alluvial terraces but on the 3D modeling, we can clearly distinguish the vertical lines of the different terraces.
On the flood risk model, thanks to the topography, we can easily simulate a flood, by depositing water in the bed of the Garonne. We gradually notice the rise in the level of the Garonne. Submersion of the filter meadow takes place first and then the water can rise to the level of Avenue de la Garonnette, a former branch of the Garonne that was abandoned for reasons of urbanization. Thus, we understand the interest of this famous cofferdam gate, which helps preserve the neighborhood.
How do you evaluate students?
As mentioned previously, this session is made up of four separate workshops. The first workshop aims to present the different geological structures of the city of Toulouse, such as molasse complexes and alluvial terraces, using a Geoportal section and 3D modeling of the geological map of Toulouse by Elevation API. The second workshop explores the origin of the city’s various construction materials, notably highlighting its famous bricks. The third workshop highlights the importance of man’s use of these construction materials, by identifying the different sand and gravel pits around the city of Toulouse. Finally, the last workshop focuses on the risk of flooding.
Each group has one hour to solve their workshop, then the students are evaluated on their ability to solve their problem during an oral presentation.
Comments collected by Julien Cabioch
SVT Toulouse resource link
API elevation
API elevation data sheet
Video using the model
Video link to participate in the 2024 Geosciences competition based on the workshop
In the coffee
Cédric Metge: The ecological transition in high school
