Guidance on selecting mitigation measures

Key considerations for selecting measures

Selecting measures which alter or support dynamic hydromorphological processes and which will then improve biology requires careful assessment on a case-by-case basis. Some key areas for consideration are highlighted below.

Working with natural processes

Changes in natural processes and forms underpin physical habitat and allowing adjustment to changes in hydrological or sedimentological regimes is crucial in maintaining functioning ecosystems. In many cases, this will also contribute to flood risk management and the strategic approach will assist with this (see below). In some cases recovery from past changes may already be ongoing and either allowing this to continue through no active intervention or assisted natural recovery may be the best option. In the second of these cases, limited intervention will be needed and may involve only modification or structures or some remedial works. Working with natural processes is a concept supported by existing policy and guidance, including Making Space for Water and the new Flood and Water Management Act (2010).

Strategic planning

Changes in one part of the water body result in changes elsewhere and planning modifications and mitigations should take account of this.

A strategic approach, for example sub-catchment or catchment scale planning:

  • solutions of a long-term nature are involved (see adaptive management);
  • works will be implemented over a long time scale;
  • there are hydromorphological process connections and interactions between different projects and measures;
  • several smaller problems could be tackled in an integrated way and sequencing is important to success of measures.
  • the effects of any works, including environmental impacts, are likely to extend over a wide area.

Regional Habitat Creation Programmes and Strategic River Restoration Planning processes follow this approach (Natural England, 2007).

It is also important to note that FRM projects often form part of wider waterside developments incorporating flood and coastal management activities as part of more detailed regeneration or masterplan. Good forward planning will be essential as many issues take time to resolve the land value of the project site and adjacent areas may be key factors which will take time to resolve.

Adaptive management

Assisted natural recovery and restoration projects take time to come to effect, often necessitating active intervention over a number of years informed by monitoring.  The approach to, for example reconnection to the flood plain may take time to adjust and monitoring will help in determining future management.

Six steps of successful adaptive management, (Walters, 1997) Challenges in adaptive management of riparian and coastal ecosystems, Conservation Ecology

Wider environment

A balance is needed between achieving benefits for aquatic habitats and wider environmental value of the area to be influenced by the FCRM activity. Processes of appraisal allow the options to be explored to actively encourage and promote solutions which are best for the whole environment as well as meeting the needs of the WFD. Environmental constraints and opportunities will need to be taken into account. There may well be opportunities for a landscape design that highlights the water body character – this can create exciting landscapes that are not common particularly in urban areas. All elements of masterplanning, including water access and transport routes, wider wildlife corridors, and Sustainable Drainage Systems, should be considered in parallel.

  • Softer solutions should be used where possible.
  • Look to the surrounding area to influence design.

References

Natural England (2007) Rationale for the physical restoration of the SSSI river series in England