River restoration - Nutrient neutrality private mitigations

River restoration involves manipulating an existing watercourse channel and its features to re-naturalise, restore, and improve a stream/river by reinstating natural processes.

It can be used to mitigate flood risk, deal with sediments, and improve the storage of nutrients. It should be noted that nutrient removal rates are extremely challenging to quantify due to the complexity of these systems and therefore it may be difficult to achieve certainty for use in nutrient neutrality credit systems.

• Biodiversity enhancement
• Carbon sequestration
• Flood mitigation
• Improvement to river water quality/health

• Not widespread in use and high complexity. Would require a multidisciplinary whole catchment modelling
• High cost

1. Phosphorus
2. Nitrogen
3. Sediment

• Medium-long term potential for substantial carbon sequestration when fully restored
• Disturbances to already existing floodplain ecosystems have the potential to increase methane emissions

• Changes take years for initial decrease in removal of nutrients/ organic matter as the river bed is shaped. As vegetation colonises removal rates will go up. However, these are difficult to quantify for a credit system. Although there are other substantial benefits to the natural environment/ecosystem

• Should not require any maintenance as self-reinforcing natural processes are reinstated

Not applicable

The use of river restoration for nutrient removal is not widely used. It would require a bespoke design that considers:

• Upstream flows and land management to ensure self-reinforcing natural processes are reinstated
• Monitoring of nutrient concentrations and flows
• Must take into account climate factors and climate change, such as droughts and dry weather, or water gains from rainfall, etc. as well seasonal dynamics and differences in flows through different seasons

ICRA. (n.d.). In-Stream Restoration. Retrieved from https://snapp.icra.cat/factsheets/25_In%20stream%20restoration.pdf

J. Thompson, C.E. Pelc, W.R. Brogan, T.E. Jordan. (2018). The multi-scale effects of stream restoration on water quality. Ecological Engineering.

Roderick W. Lammers & Brian P. Bledsoe . (2017). What role does stream restoration play in nutrient management? Critical Reviews in Environmental Science and Technology.

Zachary C. Johnson, J. J. (2015). A numerical investigation of the potential impact of stream restoration on in-stream N removal. Ecological Engineering.