Completed

Low-tech regeneration of functional processes in waterways and wetlands based on beaver ecology and differentiated management of driftwood and woody debris. A gentle, non-intrusive, adaptable, and reversible operation. The project was carried out on the Lierne and Véore rivers (Drôme, France) to restore degraded river sections by using low-tech structures inspired by beaver dams. Over three one-week phases (spring 2023 and twice in spring 2024), river agents from Valence Romans Agglo built around fifteen structures using only local wood and hand tools. These interventions aimed to reconnect incised channels with their alluvial terraces and rehydrate former side channels. The works were performed without heavy machinery or imported materials, during a practical training led by Association Rivière Rhône Alpes Auvergne (ARRA²). Visible results include lateral river reactivation, aggradation of the riverbed, slower flows, and restored hydrological complexity. Several secondary channels and wetland areas have been permanently reconnected. The site now shows a clear diversification of aquatic, subaquatic, and wetland habitats, including backwaters, forest ponds, sediment deposits, and newly humidified vegetation zones.

This study assessed saturated hydraulic conductivity (Ksat), surface runoff (SR) and soil erosion (SL) under rainfed conditions, at plot scale, over two years, under four different management practices: total soil cover with netting (SP), mechanical tillage (MT) and mulching with plant residues at doses of 3.5-10³ and 17.5-10³ kg ha-¹ of dry matter (NTR350 and NTR1750), in an olive grove in Calabria (Southern Italy). Overall, the results quantified the impact of mulching with pruning residues, applied at different doses, providing useful guidelines to control and mitigate the hydrological response of clay and sloping soils in Mediterranean olive groves, analysing the environmental benefits and associated economics.
Hypothesis – that not working the soil and mulching with pruning residues can significantly reduce runoff and water erosion and improve soil properties compared to conventional tillage – has been confirmed.

The Pesnica river catchment is characterized by intensive agricultural production, mainly cattle/pig breeding and arable farming. In spring and summer, the catchment is exposed to drought, while in autumn and winter to severe precipitation events. Soils with a high proportion of clay, which are subject to rapid surface runoff, erosion and nutrient leaching, are further contributing to unfavourable conditions. Market requirements regarding quality and reliability of production are leading towards changes in the tillage technology, but also towards searching for reliable water sources and economically efficient, yet sustainable measures for the longest possible retention of water in the soil.

Dotnuvėlė river basin covers 192.7 km2. Four reservoirs are situated in the area: near Mantviliškis, Akademija, Dotnuva and near Kėdainiai. The Dotnuvėlė basin is in the Central Lowlands of Lithuania, which is rich in moist soils. Agricultural areas account for 69.2%, forests and other natural areas for 24.5%, artificial surfaces - 5.8%, and water bodies make up only 0.5%. State river monitoring is carried out for this river. The ecological status of the Dotnuvėlė river corresponds to poor (upstream) and medium (downstream) classes.

The OPTAIN project will support the case study team with identifying and developing efficient land management strategies and small technical solutions to improve the soils’ infiltration and water holding capacities as well as its capacity to filter, buffer and transform pollutants.

Bas-Rhin is highly exposed to muddy runoff during spring–early-summer storms, impacting villages downstream of cropped slopes. Since 2008, the Chamber of Agriculture and local authorities diagnose erosion risk at commune scale and co-design preventive measures (concerted crop rotations, a gradual shift to no-till) and curative “soft hydraulics” (dense hedges and live/dead fascines, grass or miscanthus strips), implemented by municipalities or intermunicipal bodies.

Since 2018, the Eurométropole de Strasbourg holds competence for runoff/erosion control. With BRGM, it uses the WATERSED model to rank 96 catchments across 14 at-risk communes and update priorities each year; modelled sediment reductions are typically 50–95% (and >60% for a 10-year storm once devices are in place). Implementation is formalised through 10-year contracts with farmers, with standard annual compensation per area. By 2019–2023, about 129 devices (~9.9 km) were (re)installed under 53 conventions. Recent municipal programmes combine agronomy with hedges/fascines/miscanthus and resized swales (e.g., Eckwersheim), while other communes report site-specific packages (e.g., Lampertheim: 600 m of live fascines and 200 m of grass strips). Regional guidance (DREAL Grand Est) and AERM support frame the approach at departmental/basin scales.

In Saint-Léger-les-Mélèzes (Hautes-Alpes), a ski slope stripped by 2015 remodeling linked with works around the upstream Libouze snowmaking reservoir was revegetated to curb erosion, improve snow retention and summer landscape, and allow grazing. The “green hay” transfer (hay harvested nearby and spread fresh) was applied in July 2016 after earlier attempts with commercial seed failed. Monitoring on fixed quadrats recorded rapid establishment of native meadow species; the slope was left ungrazed for two years to ensure rooting. Results reported by local stakeholders indicate reduced erosion and better snowpack persistence compared to conventional seeding. The operation formed part of the Sem’ les Alpes programme on local-provenance seed solutions for Alpine grasslands. Since then, CBNA has documented a second site in the resort (“Pied de station”, ~3,000 m²) using composted sewage sludge plus green hay, and regional partners and media have highlighted the Vernie Rouge case in compilations of ecological engineering exemplars.

Upstream of L’Isle-Jourdain (Gers), the Save’s active floodplain hosts a complex of wet meadows. To safeguard the downstream drinking-water abstraction, restore wetland habitats and slow floods, the Gascogne Toulousaine community acquired a 13-ha riparian parcel (“Quintarets”), leased it under an agri-environmental contract, converted it to permanent natural grassland using late-cut “hay-flower” transfer, and dug shallow detention basins to retain floodwater and favour wetland plants. Since 2013 the municipality has embedded this action within a wider priority wetland area (~468 ha) and a Departmental Sensitive Natural Area (≈456 ha), with ongoing land purchases and site management led by the SYGESave river syndicate. Technical follow-up (2013–2017) reports rapid grassland naturalisation after hay transfer and longer water residence in the excavated basins. A major update is the June 2022 biotope protection order (APPB) for Bellevalia romana, which secures >22 ha within the L’Isle-Jourdain wetland. Overall, the Quintarets restoration is now part of multi-year catchment management that couples biodiversity protection, drinking-water safety, flood attenuation and public awareness.

Chaux Forest is a timber production area threaded by many small, originally sinuous headwater streams. A 2006–2008 LIFE pilot restored two intermittent tributaries; building on those results, the National Forest Office (ONF) scaled up to ~45 km of temporary tributaries from 2015, redirecting flows to former meanders, adding coarse woody material and sediment to counter decades of straightening/drainage that had widened and incised channels, sped floods and lowered near-surface water tables. Since 2021, ONF and the Doubs-Loue river syndicate have restored ~13 km of the Clauge mainstem inside the forest (2021–2023): narrowing/raising the bed with vegetated berms, gravel recharge, selective infilling of over-wide sections and engineered log structures. Monitoring reports a strong hydrological response: depending on context, the hydropériode of the Clauge headwaters and intermittent tributaries now increases by ~2–6 months per year (including +3–12 weeks in spring), alongside recovery of aquatic bio-indicators. In June 2025 the project received the national “Rivière en bon état” distinction and the Nature-based Solutions award from the Rhône-Méditerranée-Corse Water Agency. Next step: design for restoring the Tanche tributary, with works targeted for 2026.

Fourqueux (≈4,000 inh.) requalified its centre with new housing and created the “Jardin des Eaux” to manage stormwater from ~1.7 ha. The park routes runoff through a sequence of dry basins to a planted permanent pond, infiltrating frequent rain and avoiding direct discharge to the separate sewer draining to the Seine via the ru de Buzot. Delivered in 2016 after 2014–15 studies (as part of the Cœur de village programme), the site is both hydraulic infrastructure and neighbourhood amenity. Recent technical records report ~482 m³ of storage and ~5,000 m³/year of volumes kept out of sewers (≈80% of ~700 mm annual rainfall) over ~9,000 m² of active surfaces; typical events up to ~8 mm are handled on site, with measured infiltration times of 15–58 h depending on the basin. The landscaped area itself is ~3,800 m², reconnects clean water to the ru, and supports colonisation by aquatic fauna. The project has been showcased in professional visits and local programming, and remains highlighted by Saint-Germain-en-Laye; it was co-funded by AESN, Île-de-France Region and Yvelines Department.

More than half of the territory of the regional natural park of the Millevaches in Limousin (PNR) is covered with forest, some of which is the subject of intensive forestry exploitation. A peat bog restoration project in the headwater sector of the catchment area was initiated between the PNR (project manager) and the forestry cooperative Bourgogne Limousin (technical partner). The goal was to remove the softwood stand from the single-species plantation on the plot in order to restore the hydrological functioning of the peat bog. The work was carried out by aerial skidding using a cable mast. In addition to initiating collaboration between forestry and environmental management, the project has made it possible to restore the natural hydrological functioning of the bog and the associated specific habitats.