The urban river that crosses Veules-les-Roses (Seine-Maritime) in Normandy. isamiga76/Flickr , CC BY-NC-SA

Laurent Lespez , Paris-Est Créteil Val de Marne University (UPEC) and Marie-Anne Germaine , Paris Nanterre University – Paris Lumières University

As the 2024 Olympic Games approach, swimming in the Seine is back in the news . Although it raises new challenges in terms of improving water quality, this objective follows on from projects centered on rivers and large rivers which have consisted of enhancing water fronts in towns as was the case with the banks of the Seine in Paris, the banks of the Rhône in Lyon or the Garonne in Bordeaux.

In the shadow of these waterways, small urban rivers have long been neglected. However, they represent the main part of the hydrographic network which crosses the large agglomerations (73% in Île-de-France) and the living environment of a large part of the city dwellers.

They can offer a response to the growing demand for nature in the city exacerbated by the health crisis by providing a connection with local nature, but also contribute to issues made urgent by climate change such as the reduction of the heat island. urban or thepreservation of biodiversity .

Degraded and forgotten waterways

Badly treated over time , small urban rivers are often buried, channeled, rectified and have ended up being forgotten, because they are assimilated to a sewer or a ditch like the Bievre that we are rediscovering today .

Swallowed up by urban sprawl and associated with a negative image due to their artificialisation, they also constitute one of the least studied dimensions of water in the city . Hydrological analyzes have long shown that they suffer from the urban stream syndrome linked to the increase in impermeable areas, drainage networks and canalization .

The increase in runoff leads to an amplification and acceleration of floods , aggravating the vulnerability of local populations. It also causes the incision and widening of minor beds, threatening the balance of the river system and the safety of infrastructure (bridges, developed banks) and riverside land .

Small urban rivers are also subject to a decrease in summer flow or even dryness. Finally, they are distinguished by a generalized degradation of the quality of water ) and habitats and therefore of aquatic biodiversity .

Often classified as heavily modified water bodies, they are considered globally as “our least restorable ecosystems” .

A renewal of the gaze

Yet, small urban rivers are one of the few natural infrastructures still available in cities to provide ecosystem services . For the past fifteen years, they have again become [issues of the urban project].

Some are the subject of emblematic open-air sheds, re-meandering, restoration of the banks or even removal of thresholds. Encouraged by the Water Framework Directive and aimed at “repairing” these rivers, these projects are often part of a flood control strategy.

Accompanied by the restoration of flood expansion areas and plantations, these projects also aim to participate in the preservation of biodiversity. The generic tools used by managers (CARHYCE, I2M2, etc.) are however struggling to define improvement trajectories for these rivers.

It therefore appears necessary to develop more appropriate hydro-ecological diagnoses taking into account the local conditions specific to each watercourse and each section in order to propose avenues for sustainable improvement rather than standardized solutions. This involves, for example, going beyond the preferential diagnosis of aquatic environments at the scale of the channel to promote indicators integrating terrestrial biodiversity (turquoise frame) and integrating ecological corridors providing major services ).

A fragmented management

Paradoxically, suburban waterways are the most suitable for involving local populations in the ecological project. Unlike large navigable rivers, which are managed by the State, the ownership of the banks and the bottom of the bed of small watercourses is fragmented between a multitude of owners forming a mosaic of public and private spaces, making it more complex their management. The project must therefore be multidimensional, including the improvement of the recreational potential and the living environment and integrate residents and local populations in the definition of objectives as well as in the action.

While the 1992 law recognizes water as the common heritage of the nation, the State undertakes to improve the quality of water and environments without land control, while the riparian owners are absent from the governance bodies of the the water.

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The upkeep and management choices of these small rivers thus raise many challenges questioning the French model of water governance. These singularities make small urban rivers an archetype of ordinary environments and lead to questioning the modalities of a co-construction of a common good integrating all the actors of the river .

Reenchantment

While the car switching of peri-urban households has contributed to the disconnection of daily living places and in the perspective of "the quarter-hour city" , small urban rivers offer local amenities whose valuation has hitherto been neglected. Their restoration is an opportunity to integrate the concerns of inhabitants and users in terms of the environment, landscape, access or even values ​​and to build knowledge of these waterways, their functioning and their history. .

However, the practices of the riparian owners, the first managers, remain very poorly known. New knowledge is based on the characterization of the social connectivity of small urban rivers which integrate indicators such as the visibility and accessibility of banks and water defining potential uses. Studies rooted in the field of political ecology have analyzed the place given to local communities, particularly disadvantaged ones, in these projects and the way in which they can respond to the challenges of environmental justice .

Finally, it is a question of going beyond the proposal of a decor or a natural infrastructure unrelated to the spaces crossed by considering that ecological restoration defines a new materiality that takes place in living hydrosocial territories . But while the city-river relationship is well documented for large rivers, it remains poorly studied for small rivers.

Reconstituting the trajectory of these environments makes it possible to reconstruct the evolution of the relationship with the river while they are characterized by a renewal of the local populations limiting the transmission of the memory of the places (risk of flooding, heritage, attachment). This dimension makes it possible to compensate for the concept of generational environmental amnesia and contributes to making the river a community beyond the riparian owners to promote the emergence of an attachment to this urban nature and to develop a culture of the river.

Faced with the ecological emergency, our work carried out in particular within the Parisstreams group aims to "make visible what others no longer know how to see, make people feel what they are no longer sensitive to", from macroinvertebrates to floods, from hydraulic heritage to riparian vegetation, in order to re-enchant the management of small urban rivers to promote a sustainable socio-environmental transition .

Laurent Lespez , Professor, Paris-Est Créteil Val de Marne University (UPEC) and Marie-Anne Germaine , Teacher-researcher in geography, Paris Nanterre University – Paris Lumières University

This article is republished from The Conversation under a Creative Commons license. Read the original article .