Avonmouth and Severnside flood risk management options

Avonmouth and Severnside is part of an enterprise area, which by 2026, could deliver between 6,000 and 12,000 new jobs. To support these new jobs, new offices, factories, buildings and roads will need to be built. It is important that these sites and surrounding communities are protected from flooding or the risk of flooding is minimised.

If we do nothing it could limit the amount of development and jobs that could be provided in the area and lead to individual land owners raising site levels, increasing flood risks to other sites.

The Outline Development Strategy (ODS) for the area identified two potential options (which we are not consulting upon) and then recommended that on the basis of cost and that the second option would be unacceptable for environmental reasons, that the first option should be investigated further. 

  • Option 1: New flood defences to a height of 10.7 metres at an estimated cost of £56.8million
  • Option 2: New flood defences to a height of : 12.7 metres at an estimated cost of £200 to £300million


The council working with the Environment Agency and local landowners have established a Flood Defence Working Group to take look at Option 1, the preferred option in more detail and they have commissioned a stage 1 study on the feasibility of these options. The purpose of this stage 1 study was to:

  • Review existing datasets and identify and gaps in knowledge to be filling in subsequent phases.
  • Examine existing flood risks in Avonmouth/Severnside, both from tidal flood events and from river and stream flood events.
  • Consider the impact of climate change on flood risk in the area.
  • Develop and assess flood risk management options for existing and projected flood risk.
  • Feed these options into a ‘Growth Development Model’ for the Enterprise Area.
  • Ensure that projected growth in the area is in compliance with guidance and legislation relating to flood risk management and environmental protection.

The stage 1 study found that:

  • There is a strong economic and funding case to pursue the next phase of works. This would consist of formal business case submission and consultation with directly affected parties and detailed design studies to progress the recommended scheme option.
  • The study assessed a number of options to deal with the existing flood risks. This included wide-scale ground raising of potential development sites above the tidal floodplain levels, improvements to the existing tidal defences, construction of landward tidal defences (as part of the local road system), and localised banks around or ground raising of potential development sites above the river and stream floodplain levels.
  • The preferred option is to improve existing tidal defences, with localised river and stream flood protection. There are a series of sub options within this general theme.
  • Dependent upon the sub option chosen, the total overall approximate cost of the necessary works is estimated to be between £30m and £70m.
  • The primary constraint on development within the enterprise area is due to climate change.
  • The study provides an indicative timeline  to indicate when certain interventions will be required

It also identified some uncertainties that will require further consideration and analysis:

  • The need to ensure risks and interventions are based on improved data to better refine the risks and costs. This could have a significant impact on predicted phasing and costs. This is particularly the case for fluvial modelling.
  • The preferred sub options are yet to be informed by discussions with key landowners and stakeholders to determine what is deliverable.
  • Flood mitigation recommendations will need to be considered alongside the mitigation of ecological impact, planning constraints (including archaeology and control of major accident hazards zones) and transport implications.
  • Engineering, economic and environmental constraints will need refinement following more detailed investigation (Stage 2).


Have your say

We welcome comments on the stage 1 report before we progress onto the second stage where we will refine the plans and options and explore engineering, environmental and economic constraints in more detail

We are inviting comments until 21 February 2014. Further information is available in the full technical report and the non-technical summary. To tell us your views:

  • Email:  consultation@southglos.gov.uk   
  • Write  to:  FREEPOST RTCT-JXLE-EET, South Gloucestershire Council, Avonmouth and Severnside Flood Options Consultation,  Civic Centre, High Street, Kingswood,BRISTOL,BS15 9TR
  • Phone:  01454 863003

This consultation has now closed and we are analysing the results, which will be published here in due course.


  • Opened
    13 Jan 2014 at 00:00
  • Closed
    21 Feb 2014 at 23:59


Consultation Topic
  • Environment
  • Jobs, careers and employment
  • Local economy & business issues
  • Planning policy & strategy
Geographical area
  • Pilning and Severn Beach
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Target Audience
  • All residents
  • Businesses & employers
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  • General public
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  • Staff
  • Town and Parish Councils
  • Voluntary and community groups / organisations
Contact Details

If you have any questions or wish to respond to this consultation:

email: consultation@southglos.gov.uk

Write to:

South Gloucestershire Council
Avonmouth and Severnside Flood Options Consultation
Civic Centre
High Street

BS15 9TR

Phone: 01454 863003