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SGEvT: wild deposits scrutinized from space

Created in 2015, the General Society for Territorial Evaluation (SGEvT) has developed a platform bringing together several dozen indicators and decision-making tools intended to support local authorities in the management of their territory. Among these tools, we have recently found a solution to identify, qualify, but also prevent illegal dumping of waste.

An “indicatheque”. This is what has been developed – and continues to be enriched – by the General Society for the Evaluation of Territories (SGEvT), a Toulouse-based company born in 2015 under the impetus, in particular, of Nancy Oliveto, lawyer, urban planner and ex-consultant in sustainable development. Baptized TEREvAL, this library of indicators and decision support tools now includes nearly sixty, intended to guide local authorities in their territorial development projects. The birth of this veritable “dashboard”, like that of the company, is closely linked to the Grenelle de l’environnement. Arnaud André, co-founder and President of the SGEvT talks about it: “The Grenelle de l’environnement gave rise to the obligation for local authorities to develop plans for the sustainable development of the territory.[1]. The number of subjects to be included in these plans has increased sharply, to take into account aspects such as energy efficiency, soil artificialisation, etc. The other obligation was also, for these local authorities, to assess the efficiency of their plans. The company was therefore created on the idea of ​​providing local authorities with tools constituting a dashboard allowing them to monitor the impact of the projects carried out over time”.

Scalable, this platform is constantly enriched over the needs expressed by the customer communities of the SGEvT. “As the projects progressed, different subjects appeared, such as that of the urban envelope, that is to say the limits of the city. We have therefore created algorithms to help establish this envelope, but also to verify compliance with the prescriptions that are made.”, explains Arnaud André. Recently, the SGEvT also tackled a subject of growing importance: illegal dumping.

Identify, qualify, but also prevent illegal dumping

Led by Ademe, a survey carried out in 2018 among 2,652 local authorities revealed that nearly 90% of them were then faced with the problem of illegal dumping. However, as the Agency noted in the report published following the completion of this investigation[2], “no exhaustive inventory of the situation of illegal deposits (quantities and nature of deposits) exists on a national scale”. A tool developed by the SGEvT could, however, change the situation. The company has in fact developed a remote sensing solution aimed at identifying, but also at qualifying these deposits (extent, date of appearance, risks for the environment, etc.) and even at identifying, before the appearance of waste, areas particularly prone to illegal dumping.

Few French communities are not affected by the problem of illegal dumping. However, an inventory on a national scale remains difficult to establish. © SGEvT

“Thanks to the links that we have had for years with the CNES, we proposed to them to set up an offer based on the Pléiades satellite photos, crossed with our contextual knowledge of the territory: relief, occupation of the plots, transport networks…”, reveals Arnaud André. Initiated at the end of 2019, the process culminated in 2021 with the commissioning of this unique remote sensing tool. “The development took time. It is indeed necessary to detect on satellite images forms which could be wild deposits, but which can also be simple rocks, or rivers for example. Algorithms therefore need time to learn, to gradually correct their errors.notes the president of the SGEvT.

A solution that has already proven itself in the field

The spatial resolution of the images captured by the Pléiades satellites allows the detection of deposits from around fifty square meters. © SGEvT

Once detected, each deposit is scored according to criteria such as its proximity to a watercourse, an underground water table, schools or other sensitive places. “This tool that we have developed provides prioritization elements, making it possible to answer the question “which filing should be processed first?” », emphasizes Arnaud André. An interest to which is added that of the identification of sensitive areas, conducive to the appearance of wild deposits. Zones which, once delimited, can thus be the subject of reinforced surveillance. “We also provide intervention tools, adds the co-founder of the company. At the end of 2021, we helped the police to carry out an intervention campaign in Aude, over several hundred km². We produced sheets for them mentioning the size of the depots, the conditions of access to reach them, etc. Thanks to this, the gendarmes went to the field, and in one afternoon, they were able to carry out a job that would have taken them several days, perhaps even more than a week, without our tool. »

Conducted at the end of 2021 by the Aude gendarmerie using data and indicators provided by the SGEvT, an initial campaign of interventions has proven to be particularly fruitful. © SGEvT

In terms of reliability, the tool proposed by the SGEvT proves capable of achieving a detection rate of at least 90% according to the president of the company, who nevertheless concedes: “If the deposit is invisible from the satellite, obviously we will not detect it. This is the case, for example, of what is under plant cover. That said, it depends on the season.”. In addition to this limitation, the size of the deposits is also important: with a resolution of 50×50 cm, the images provided by the Pléiades satellites allow detection of deposits from a few tens of square meters. “A simple plastic bag filled with waste will not be detected”, thus cites Arnaud André as a counter-example. The future Pléiades Neo constellation, with its spatial resolution of 30 centimeters, promises to make the detection threshold a little lower still.

Available via the TEREvAL platform, the tool notably generates intervention sheets to guide the actions carried out in the field. © SGEvT

Expanding its range of tools: the raison d’être of the SGEvT

After the success of the project carried out in Aude, SGEvT now hopes to offer its solution to many other local authorities. “There are a lot of interests, and subjects to be studied. Not only from local authorities, but also from collection manufacturers, who see new opportunities in it”rejoices Arnaud André.

For a subscription of a few tens of thousands of euros per year – depending in particular on the size of the territory to be covered – the functionalities of detection, rating or definition of means of access are thus already available. via the TEREvAL platform. “And there will of course be material to complete these functions with other ideas”provides the president of the company.

An additional string is thus added to the arc of the “indicathèque” developed by the SGEvT. A platform which should also expand a little more soon, with the addition of other tools, as Arnaud André finally reveals: “We have a whole offer in terms of proximity and we are working, for example, on local health contracts[3]which have become an emergency for many territories”. And the manager concludes: “Providing communities with the widest possible collection of tools is our raison d’être”.


[1] Territorial climate-air-energy plans (PCAET), made mandatory by the Grenelle 2 law for communities with more than 50,000 inhabitants, and now mandatory for all intermunicipalities with more than 20,000 inhabitants (threshold lowered in 2018).

[2] ADEME, ECOGEOS. 2019. Characterization of the problem of litter. Report. 84 pages.

[3] Tools jointly carried by the Regional Health Agencies (ARS) and local authorities to reduce territorial and social inequalities in health.

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