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Aerial inspection of river protection zones

The use of phytosanitary products along rivers is forbidden and grass strips and/or buffer zones may be required to limit the transfer of pollutants to the river. In the farming plain of Limagne (Puy-de-Dôme department), a test was run to check compliance of these zones with protection regulations using aerial means.

To check compliance with regulations, i.e. that phytosanitary products are not spread near rivers, Onema personnel generally travel along the rivers on foot or by car. An aerial photo taken during treatment periods is a means to rapidly identify conforming zones that do not need further inspections and thus concentrate efforts on areas requiring more in-depth checks.

“Bird’s-eye” experiments

An experiment was included in the departmental inspection plan for two tributaries of the Allier river, the Jauron and the Litroux rivers located in farming areas. The water police in the Puy-de-Dôme department and the Pélican jaune* association flew over approximately 40 linear kilometres of river at a low altitude, taking frequent pictures to cover the entire itinerary.

The photographs were taken in just forty minutes, thus saving a great amount of time. The geolocated photos were overlaid on Land Register documents to identify the fivemetre zones where phytosanitary products are forbidden. Using software to assemble the photos, it was possible to obtain an overall view of the itinerary. This data will serve to more efficiently organise the necessary inspection work in the field.

* The Pélican jaune association gathers data on aquatic ecosystems using aerial means.