Code
N08
Sector
Hydro Morphology
The complete description of the NWRM
Summary

Riverbed material represents the sediment eroded upstream, transported by the river and deposited on the river floor. It can be composed of coarse and/or fine material. Its re-naturalization consists in recovering the nature-like structure and composition of the bed load, in particular the equilibrium between coarse and fine sediment. In case of deficit of coarse sediment leading to river incision, the main objective is to level-up the riverbed with this type of sediment, by reactivating bank erosion in terrains contributing to this type of sediment. It should be noticed that in case of excess of fine sediment causing inundations, silting of hydro-electric dams or degradation of fish habitats, the main objective is to control erosion on slopes and riverbanks providing this type of sediment.

Illustration(s)

Renaturalized riverbed, (France)

Source: http://www.onema.fr/Les-jeudis-de-la-restauration,1432

Explicative scheme for the principle of riverbed renaturalization (France)

Source: http://www.syndicatdelaseiche.fr/entretenir-et-restaurer-les-cours/restaurer-le-lit-des-cours-d-eau/

Possible benefits with level
Benefits Level
PO1 - Improving status of biology quality elements
High
PO2 - Improving status of physico-chemical quality elements
Medium
PO3 - Improving status of hydromorphology quality elements
High
PO4 - Improving chemical status and priority substances
Medium
PO7 - Prevent surface water status deterioration
High
PO8 - Prevent groundwater status deterioration
Low
PO9 - Take adequate and co-ordinated measures to reduce flood risks
Medium
PO10 - Protection of important habitats
Medium
PO11 - Better protection for ecosystems and more use of Green Infrastructure
Medium
PO13 - Better management of fish stocks
Medium
PO14 - Prevention of biodiversity loss
Medium
ES1 - Water storage
Medium
ES2 - Fish stocks and recruiting
Medium
ES3 - Natural biomass production
Medium
ES4 - Biodiversity preservation
High
ES7 - Flood risk reduction
Medium
ES8 - Erosion/sediment control
High
ES9 - Filtration of pollutants
Medium
ES11 - Aesthetic/cultural value
Low
BP1 - Store runoff
Medium
BP2 - Slow runoff
Medium
BP3 - Store river water
Medium
BP4 - Slow river water
Medium
BP9 - Intercept pollution pathways
Medium
BP10 - Reduce erosion and/or sediment delivery
Low
BP12 - Create aquatic habitat
High
BP13 - Create riparian habitat
High

Case studies per NWRM