Drones at the cutting edge of technology at the confluence of the Lergue and Aubaygues

In the context of a hydraulic study conducted by the intermunicipal body on the river and its tributary to the south of Lodève, in a sensitive area in the event of heavy floods.

Enedis uses drones to inspect its power lines in hard-to-reach areas. The Massif Central departmental road authority, for example, has used them to survey and monitor the cliffs of the A75 north of Lodève.

As part of a hydraulic study initiated last month by the Lodève Larzac community of communes and its Gemapi competence (management of aquatic environments and flood prevention), two drones from the Biterrois company Instadrone surveyed an area between Lodève, Le Puech, and Olmet-et-Villecun midweek.

A sector severely affected in 2014 and 2015

“This study is part of the actions of the third multi-year plan for watercourses and aquatic environments management from 2026-2036 of the Lodève Larzac. And the Papi Hérault (flood prevention and action program). The objective is to better understand the functioning of the Lergue and Aubaygues at the confluence on an area particularly affected by the floods of 2014 and 2015,” explained Mathieu Thelen, Gemapi manager of the community. “We are dealing with a complex sector, with a tributary that flows into the river almost against the current. And a main channel in which the two watercourses border in case of floods. That’s why modeling is necessary 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 topographical manager of the company based in Villeneuve-lès-Béziers, where we have 27 employees, with a study office and a sector for flight regulations. We have 50 branches and 50 pilots in 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. For example, 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 just tested a new bathymetric device in Lodève?

“Yes, for this study, we are testing one of the latest Lidars from the company YellowScan, based in Montpellier, known worldwide for making measurement devices. We work together to help them with their tests, and this time, they provided us with this innovative device to test it in real conditions. It avoids us having to go into the Lergue riverbed. It did the surveys in 20 minutes on the watercourse, where it would have taken us two weeks. It’s a time, money, and safety saver.”

The study, conducted by the Hydrétudes bureau, will last about a year. It will then enable the implementation of solutions to reduce impacts, damages, and risks in case of an exceptional event.

Near 90 hectares and 2.5 km of rivers inspected

“We take care of the entire topographical part, with a Lidar and a camera,” confirms Arthur Marcel, one of the Instadrone company’s managers, 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, and the other, with a bathymetric Lidar, has performed terrestrial and underwater measurements.

In one day, the company covered nearly 90 hectares and 2.5 km of rivers, south of Lodève.

The Lodève Larzac community of communes has exercised Gemapi competence for the municipalities since 2018. The majority of its territory covers the upstream side of the Lergue river.