Morphological restoration of temporary watercourses in the National Forest of Chaux

National Id
The Chaux forest is a silvicultural production area and is covered by a large number of small streams, originally winding and of small size. In 2008, the LIFE program "Ruisseaux de têtes de bassins et faune patrimoniale associée" ([Pond head creeks and associated heritage fauna]) carried out restoration work at the head of the catchment area on part of the small ditches of the Chaux national forest. Based on the experience and results obtained, the National forest office (ONF) proposed a new project to restore 45 km of watercourses in three 15-km sections (2015, 2017 and 2018) with the objective of significantly restoring the hydraulic functioning of the Clauge and improving the conservation status of the species covered by the Habitats Directive. Indeed, all the temporary tributaries of the Clauge were transformed in the 1960s into deep straight ditches via canalization works.
The in-depth description of the case study
Location description
The Chaux forest is covered by a large number of small streams, originally winding and of small size (more than 400 km). They are located at the head of the catchment area and are tributaries of the Clauge.
The lime forest is a silvicultural production area (mainly oak), the environment is described as quite common.
RBD code
Light or indepth?
Monitoring parameters
A monitoring protocol was set up in 2017 with the University of Franche-Comté (technical assistant) and the ONF (National Office of Forest), with the help of 2 master trainees.
Entomological monitoring
Monitoring is carried out in the spring, at the net and in the watercourses and is led by the University. Entomological monitoring is carried out before and after, at a control site, and at restored sites, with a time grid every two and three years. The control shows that the observed changes are not due to climatic variations.
Piezometric monitoring (individual or online).
About twenty piezometers have been installed with weekly automatic readings.
Dendrometric monitoring
At the level of the piezometers, vegetation monitoring plots are placed by the ONF (height, diameter, health status, dominance) on control plots of 1000m². The population evolution will be monitored over the long term.
Biophysical impact assessement method
Comparison with a control site.
Project scale
Application scale
River Basin
Installation date
Area (ha)
2 700 ha
Area specifications
Restored watercourse represents 45 km
Favourable preconditions
Almost all the temporary tributaries of the Clauge being originally meandriformes, a remeandering operation is justified following their transformation in the 1960s into deep rectilinear ditches, so that they can regain a hydrological functioning that allows them to support an associated biodiversity.
Design contractual arrangement
Arrangement type Responsibility Role Comments Name
Design consultation activity
Activity stage Key issues Name Comments
Design land use change
Land use change type
Design authority
Authority type Role Responsibility Name Comments
Initiation of the measure
National office of forest (ONF)
Research institute / University
Franche Comté science university
Success factor(s)
Success factor type Success factor role Comments

The fact that the streams are very degraded allowed to have a very degraded zero state and therefore a strong reaction after the works.

Financing type Comments
Barrier type Barrier role Comments
Legal obligations / restrictions
main barrier
The main constraint was the completion of the public inquiry, since it represents a significant cost, and also a duration of 6 to 8 months.
Driver type Driver role Comments
main driver
The fact the habitat was seriously degraded and other experience of successful restoration of habitat on a similar area was a key driver, as positive results were already forecasted from the beginning.
Financing share
Financing share type Share Comments
Policy description
The naturally straight portions were either overburied, widened or both; the downstream flow velocity of the floods was accelerated accordingly.
This channelization resulted in a lowering of the altitude of the associated surface water tables, but also in a spreading of the flow water slide in the stream, excluding flood peaks, as well as an increase in energy in the minor beds during high water periods.
The expected results were: Restoration of water flows and Overall habitat improvement
Policy target
Target purpose
Policy pressure
Pressure directive Relevant pressure
Policy area
Policy area type Policy area focus Name Comments
Policy impact
Impact directive Relevant impact
Policy wider plan
Wider plan type Wider plan focus Name Comments
Policy requirement directive
Requirement directive Specification
Information on Ecosystem improved biodiversity
Biodiversity monitoring reveals a better attractiveness of the spawning sites for amphibians (frogs, salamander, newt, reproduction multiplied by 10) and amphibians because the river was not initially biogenic;
It also reveals an improvement in habitat for entomofauna, with the number of taxa multiplied by 2, a recovery by ephemeropterans, perlids and trichopterans protected at the European level (e. g. Hagenella clathrata classified as endangered (EN) on the IUCN Red List). There is also an improvement in quality (i.e. more demanding species that are dependent on wetlands).
Information on Increased groundwater level
Piezometric monitoring shows an increase in the hydroperiod (+15 days) because the time of presence of water in the watercourse is longer, as these are surface aquifers that are in silts and dry in summer, water is more available for trees in spring. When the time of presence of water in the stream is extended, it is also extended in the groundwater table.


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