In the context of a hydraulic study carried out by the intermunicipal authority on the river and its tributary, south of Lodève, in a sensitive area in case of heavy floods.
Enedis uses drones to inspect its power lines in hard-to-reach locations, for example, the Massif Central regional road department used them to survey and monitor the cliffs of the A75, north of Lodève.
As part of a hydraulic study launched last month by the Lodève and Larzac communities and its Gémapi competence (management of aquatic environments and flood prevention), two drones from the Béziers-based company Instadrone surveyed an area between Lodève, Le Puech, and Olmet-et-Villecun midweek.
A sector heavily affected in 2014 and 2015
“This study is part of the actions of the third multi-annual plan for watercourses and aquatic environments management 2026-2036 of the Lodève Larzac. And the Papi Hérault (program of flood prevention and action). The objective is to better understand the functioning of the Lergue and the Aubaygues at the confluence in an area particularly affected by the floods of 2014 and 2015,” explains Mathieu Thelen, responsible for Gémapi at the community. “We are dealing with a complex area, with a tributary that flows into the river almost against the current. And a major riverbed in which both rivers border in case of floods. That’s why we need to model to understand the flow.”
Arthur Marcel: “A bathymetric drone tested for the first time”
Arthur Marcel, can you introduce your company Instadrone?
“Yes, I am the topographic manager of the company based in Villeneuve-lès-Béziers, where we have 27 people, with a study office and a regulatory sector for flights. We have 50 branches and 50 pilots across France. Our job is to fly drones for topographic surveys, inspections of structures, thermography on photovoltaic panels, or agriculture.”
With cutting-edge technologies?
That’s right. We have autonomous drones in boxes, placed in strategic locations that work automatically or can be piloted and controlled remotely to alert and prevent.
And you have recently tested a new bathymetric device in Lodève?
Yes, for this study, we are testing one of the latest Lidar from the YellowScan company, based in Montpellier, known worldwide for making measuring devices. We work in collaboration to help them with their tests, and they have provided us with this innovative device to test it under real conditions. It saved us from going into the Lergue on foot. It surveyed the river in 20 minutes, where it would have taken us two weeks. It’s a time, money, and safety saver.
The study, conducted by the Hydrétudes office, will last about a year. It will then enable the implementation of solutions to reduce the impacts, damages, and risks in case of exceptional events.
Nearly 90 hectares and 2.5 km of rivers inspected
“We take care of the entire topographic part, with a Lidar and a camera,” confirms Arthur Marcel, one of the managers of the Instadrone company, accompanied by pilot Olivier Gelis to cover the area with two drones. The first is equipped with a camera to create a large photographic map of the area, the other with a bathymetric Lidar, conducted terrestrial and underwater measurements.
In a day, the company covered nearly 90 hectares and 2.5 km of rivers, south of Lodève.
The Lodève and Larzac community has been exercising the Gémapi competence for the municipalities since 2018. The majority of its territory covers the upstream slope of the Lergue.
