Flooding FAQ’s

We operate with a number of clients from varying backgrounds and have compiled answers to our most commonly asked questions.

Q. What is a Flood Risk Assessment?
A flood risk assessment is a report which is carried out in accordance with the current flood risk policy notes, it outlines the main risks of flooding from rivers, groundwater, runoff, and tidal sources. The report presents mitigation measures to reduce the risk of flooding at a site and ensure no increases of flooding within the surrounding area.

Q. What is the purpose of Flood Risk Assessment?
Flood Risk Assessments are required by planning authorities for all developments greater than 1 Hectare in size. Their purpose is to determine the risk of flooding to proposed developments at the planning stage and direct inappropriate development away from high risk flood zones. The assessment ensures that developers are aware of the current regulatory framework and potential mitigation measures which may be appropriate to ensure that a development is sustainable and safe in terms of flood risk.

Q. Do I need a Flood Risk Assessment?
All planning applications for sites greater than one hectare, or sites which lie within a flood zone require a flood risk assessment. You can search the Environment Agency flood zone website by going to the flood risk section and inserting your post code in the box on the right.

Q. Can you guarantee results?
Unfortunately we cannot guarantee a successful application.

Q. Do you have the necessary insurance cover to do the work?
Enzygo carries professional indemnity insurance for our flood risk work, should our clients wish to see a copy this can be provided upon request.

Q. How quickly can a Flood Risk Assessment be completed?
The speed of our flood risk assessments are related to the speed at which we can obtain data. Normally Flood Risk Assessments take from 3 to 5 weeks, as the Environmental Regulators respond within 21 days. However, we have undertaken 2D modelling due diligence within 5 day subject to caveats on available data.

Q. What is the Flood Risk Assessment process?
The process begins at a variety of stages from, pre planning, site acquisition or due to an objection from the Environmental Regulator. Normally we would consult with the Regulator and Local Planning Authority to discuss the major issues at the site. After this stage we can provide a firm methodology, scope of works, timescale and cost. The assessment then continues, flood risk assessments are a cyclical process informing the design architects and other members of the design team with regard to layout, materials and mitigation. After the assessment has been concluded, a draft report is submitted to the client for comment and then issued to the Environmental Regulator and once approved issued as a final top the Local Planning Authority.

Q. How much will it cost?
The cost of a flood risk assessment is dependent upon the risk of flooding at the site and information currently available. Our assessments can cost less than £500 for a simple assessment, however, where data is lacking and modelling is required the cost can be significantly greater.

Q. What area do you cover?
Enzygo operates across the UK, Ireland and Europe.

Q. How does Flood Risk relate to the NPPF
Flood risk is an integral part of the National Planning Policy Framework and it’s accompanying technical guide.

Q. How does Flood Risk fit within the planning process?
Flood risk is an integral part of the planning process and the NPPF makes it a mandatory action for the Local Planning Authority to consult with the Environment Agency on all sites over 1Ha or within flood zones 3 and 2 or critical drainage zones.

Q. Who is the enforcing body for Flood Risk Assessments
The NPPF applies to England only, and as such the enforcing body is the Environment Agency. They have the right to call in any application to the Secretary of State, upon which the Local Planning Authority approves contrary to the Environment Agency’s advise.

Q. Why does climate change affect flood risk?
In the UK, the effects of climate change over the next few decades are predicted to result in milder wetter winters and hotter drier summers. A combination of increasing frequency of heavy, intense precipitation leading to increased peak river flows and rising sea levels will have a major impact on the potential for future flooding. If the affects of climate change are taken into account the maximum flood depths experienced may rise in the future. Sea levels may be up to 1000mm higher than today’s level, peak rainfall intensity could be up to 30% higher than current levels and peak river flow could be 20% higher than current levels. All of which would result in the flood depths being much higher today’s.

Q. How accurate is the Environment Agency’s flood map?
Environment Agency flood zones are the product of modelling output derived from software called JFLOW. This software has been used by the Environment Agency to produce the 100year (1%) and 1000year (0.1%) flood outlines. It is widely acknowledged by the Environment Agency and other consultants that JFLOW is a generalised model, and it does not take into account flood defences or some areas of local topography. Therefore flood outlines should only be used as a rough tool to inform the planning process and indicate where more detailed flood modelling is required.

Q. Can flood zones be challenged?
Yes, since they are based upon a generalised model, they can be challenged through more detailed 1D and 2D flood modelling.

Q. What’s a 2D model and can Enzygo produce this?
A 2D model is a numerical model which allows flood depths and velocities to be modelled for a variety of scenarios.

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