Restoring watercourses and wetlands – Practical cases from the SMBV Pointe Médoc
- Käyttötapaukset
The Syndicat Mixte des Bassins Versants of the Pointe Médoc (SMBV Pointe Médoc) is a public inter-municipal organisation responsible for managing and protecting aquatic environments and preventing flooding within its jurisdiction.
This organisation oversees 23 municipalities and 2 inter-municipal communities (CC Médoc Cœur de Presqu’île and Médoc Atlantique), covering a territory of around 600 km², with approximately 500 km of watercourses.
To manage aquatic environments and reduce flood risks, the SMBV Pointe Médoc uses Scalgo Live as a key planning and analysis tool. In this blog, Noémie Robichon and Marion Montecot, project managers for aquatic environments and wetlands at SMBV Pointe Médoc, share how they have used Scalgo Live in their restoration projects.
Project 1 Restoring the natural channel of the Deyre
In Vendays-Montalivet, the Deyre, a small stream in the Gua catchment, has been heavily modified over the years. Much of it has been channelised, but a section of its natural channel remains intact.
This remaining branch is connected to the main channel by a culvert that is poorly sized and incorrectly positioned, limiting water flow and preventing natural exchanges with the main watercourse. This disrupts the ecological continuity of the Deyre.
This area has significant ecological value. For example, it is a critical breeding ground for northern pike. While adult pike can reach this area to spawn, their offspring often become stranded in the spring, unable to make their way back to the main channel.
The plan was straightforward: replace the existing culvert with a larger, better-integrated box culvert, reopen the first 30 meters of the silted-up channel, and allow the stream to naturally reclaim its original path.
In this project, Scalgo Live helped retrace the original channel and provided information for calculating sediment removal volumes. It was also used for analysing profiles and cross-sections, which were then used as input for the final channel design.
On the left, an overview of the terrain and the canal, as well as the natural flow path highlighted from the flow path analysis in Scalgo Live. On the right, a zoomed-in view of the terrain editing.
"With just a few clicks, you get a very visual representation of the effects on flow conditions. Scalgo Live allows both a significant time saving and a better understanding of the challenges and solutions by partners and elected officials".
Noémie Robichon, SMBVPM
Project 2 Restoring a wetland at the edge of Lesparre-Médoc
In Lesparre-Médoc, a 5-hectare wetland sits between two watercourses, just a short distance from the town centre. This natural area plays an important role in protecting the town from flooding. However, it is currently cut off from the surrounding waterways by a maintenance berm, which prevents water from flowing freely into the wetland.
The solution? Create an opening in this berm to restore natural water exchanges and allow the wetland to resume its natural hydrological functions.
By importing up-to-date LIDAR data into Scalgo Live, various scenarios were simulated to assess the effect of potential solutions.
“With just a few clicks, you get a very visual representation of the effects on flow conditions. Scalgo Live allows both a significant time saving and a better understanding of the challenges and solutions by partners and elected officials,” says Noémie.
On the left, the topographic watershed of the wetland, displayed instantly in Scalgo Live based on pre-calculated national analyses. On the right, the areas likely to be flooded, based on local LIDAR data.
“Thanks to the profile tool, you can instantly see the level differences and critical areas. The result is that we can progress more confidently in the planning process”.
Marion Montecot, SMBVPM
Project 3 Restoring historic floodplains in Juran
Also in Lesparre-Médoc, but further south, the Maillarde watercourse crosses former floodplain meadows that historically managed floodwaters, protecting developed areas while also providing critical breeding habitats for species like northern pike.
Today, these meadows are cut off by maintenance berms, preventing water from spreading naturally during heavy rainfall. The goal of the project was to remove these berms, reconnect the floodplain, and restore the natural processes of these valuable habitats.
“Thanks to the profile tool, you can instantly see the level differences and critical areas. The result is that we can progress more confidently in the planning process,” concludes Marion.
