Strong episodes floods of the 2023-2024 campaign highlighted the issue of maintaining the ditches (and watercourse) which border numerous agricultural plots depending on the territory. The role of ditches is to drain plots and reduce the risk of flooding. Their maintenance is the responsibility of the land owners.
The Aisne department is one of the departments affected by the raw. « Before the episodes of 2023-2024, we have already experienced significant rains in July in 2021 which caused flooding in the north of France and in our department with more than 1,000 hectares affected by floods.remembers Hubert Compère, farmer at the time in Mesbrecourt-Richecourt (1). There were significant crop losses, particularly in potatoes and beets. » Ces floods in the middle of summer were a surprise for everyone. Malfunction of ditches had already been highlighted.
Also president of river unionHubert Compère was able to note the lack of maintenance of the ditches: “ In the past, we could use weed killers to clean the edges of ditches. This is now prohibited to preserve the environment and water quality. » Likewise, burning (burning) is no longer authorized. All these practices facilitated the maintenance of ditches. The fear of the administration also weighs on the lack ofmaintenance of ditches. Situations have been reported where farmers have been convicted of illegal practices by carrying out work on ditches when they were not aware of doing wrong. On the other hand, if an owner does not intervene, he is not exposed to penalties, but it is not excluded, in the long term, that a municipality will turn against him if it judges that a flood would be due in part to the non-maintenance of a ditch.
Farmers have lost the habit of maintaining ditches
« Faced with the accumulation of standards and the fear of receiving a sanction, farmers have lost the habit of maintaining ditches over the past fifteen years. », confirmed Charlotte Vassant, president of the Union of Agricultural Unions of Aisne, at the end of August, during an operation “ clean ditches » launched with the local branch of theFrench Biodiversity Office (OFB). Since 2015 (CAEC CAP rules), farmers have had to justify to Brussels that the presence of shrubs in ditches, frozen in aerial photographs on that date, did not correspond to an alignment of trees or a hedge so that their subsequent razing does not result in sanctions on CAP aid. “ They justified it in 2016, 2017, 2018 and then they gave up for fear of being sanctioned, the sanctions sometimes being up to 20,000 euros of withholding on aid. », testifies the farmer. THE ditches then gradually became clogged and lost their usefulness.
« Trees such as willows, bushes and vegetation are found in the ditches. There may also be earth splashes during work in the fields.observes Hubert Compère. Over time, the section of the ditches is reduced with a depth sometimes lost by half. » Result: the water flows too slowly.
The farmer presents a concrete case of impact on crops during spring 2024. “ Our corn seedlings found themselves flooded in a plot at the beginning of June, even though there is a ditch at the edge. On a large part of the field, the water receded within a few days, allowing the corn to grow without problem. But in another area of the plot, the water remained for a long time, causing the plants to die. The ditch that has not been maintained for years has not played its role against this water stagnation. »
Good flow in a maintained ditch accelerates the decline
If a flood is not avoidable when rainfall is very high, the water must be able to quickly withdraw from the field in the event of crue. « Good drainage in a well-maintained ditch saves a few days on the recession and can allow the vegetation to pass this stage without incident. », underlines Hubert Compère. The shorter the duration of flooding, the greater the crop’s chances of survival.
« A point of vigilance is not to let trees grow at the bottom of ditches. If a tree in the ditch obstructs the flow of water, it must be removed by grubbing it “, says Romuald Marandet, of theOFB in Aisne. Marsh willows, for example, quickly become invasive in humid environment if we are not careful. “ If they are on the edge of ditches, they can be pruned or cut. The feet then recover easily. If the trees constitute a hedge, the farmer can cut them (outside the bird nesting period), but not eliminate them. »
A cost for maintenance, but a return on investment
There is no financial aid for the maintenance of ditches. « But by cleaning the ditch, there will be a return on investment with less damage caused to crops by floods.underlines Hubert Compère. It still costs around 800 euros for a day of crane (tracked excavator) which will work over a length of between 400 and 800 meters, depending on the state of the ditch. But then we can rest easy for twenty years ”, according to the farmer. It is up to the different owners to agree on sharing maintenance costs. THE river unions can intervene to point out areas that require maintenance, without having the power to impose work.
To raise awareness of the need to cleaning of ditchesa demonstration zone was installed outside the village of Mesbrecourt-Richecourt two years ago. A document has been drawn up to specify the procedure to follow for any type of owner, whether a farmer or not, to maintain the ditches and enable them to fulfill their beneficial role. In addition to the impact on flooding, a well-maintained ditch will be a source of biodiversity and will contribute to the preservation of the water quality.
(1) Now retired, his son Baptiste has taken over the exploitation of 170 hectares of field crops.
