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How to understand a flood risk map to design your flood defence wall

Flooding map for planning, Flood risk map

Obtaining a flood risk map is the first step to protect your property.

Welcome to our comprehensive guide on understanding flood risk maps and how to protect your property. Floods are one of the most common and destructive natural disasters worldwide, and being prepared is crucial. By familiarizing yourself with flood risk maps, you can gain valuable insights into the potential risks to your property and take steps to mitigate them. In this guide, we will explore what flood risk maps are, how they are created, and how to interpret the information they provide.

We will also discuss the different types of flood zones, such as high-risk areas and floodplains, and the precautions you can take to safeguard your property.

With the increasing unpredictability of weather patterns and the impact of climate change, understanding flood risks has never been more important.

By utilizing flood risk maps, you can make informed decisions about where and how to build, purchase flood insurance, and implement effective flood prevention and mitigation strategies.

A step-by-step guide to finding your flood risk

Step 1: Carry out a flood map assessment to check the flood zone risk. You can carry out the assessment yourself by going to https://flood-map-for-planning.service.gov.uk/ if you are based in England. Go to https://naturalresources.wales/?lang=en if you are based in Wales and go to https://www.sepa.org.uk/environment/water/flooding if you are based in Scotland. Go to https://www.nidirect.gov.uk/articles/check-risk-flooding-your-area if you are based in Northern Ireland.

Follow the instructions to obtain the flood map for your location. We can do it for you if you find it too complex.

Zone 1 – Locations in flood zone 1 have a low probability of flooding. This means that in any year, land has a less than 0.1% chance of flooding from rivers or the sea.

Zone 2 – Locations in flood zone 2 have a medium probability of flooding. This means that in any year, land has between a 1% and 0.1% chance of flooding from rivers and between a 0.5% and 0.1% chance of flooding from the sea.

Zone 3 – Locations in flood zone 3 have a high probability of flooding. This means that in any year, land has a 1% or more chance of flooding from rivers or a 0.5% or more chance of flooding from the sea.

Step 2: If the flood risk is in zone 2 or 3, carry out a full risk assessment that includes the topographical levels around the site and flood zone risk levels.

For England, you can request a detailed environmental flood assessment that includes levels. The information can take up to twenty days to be received; from previous investigations, the time is more like seven to fourteen days.

Step 3: If the topographical survey lacks good data and information, obtain a topographical survey for the site.

Step 4: Work out the height that the flood defence wall needs to be to cover the flood risk you wish to protect your property from.

Step 5: Design the flood wall and other flood defences that may be required, such as flood gates, non-return drainage valves, sump and sump pumps, and headwall construction.

Step 6: Prepare a bill of quantities to obtain an accurate budget. Use the bill of quantities to decide the construction strategy; build it yourself or have a contractor build it. If you decide to have a contractor build it, use a blank bill of quantities to obtain competitive prices.

Step 7: Project manage the construction of the flood defence works. This can be done by yourself, with the support of a project manager or by a contractor.

If the work is being managed by the contractor, you may want some support from a project manager to guide you through the process and to make sure the contractor fulfils his obligations.

We can support you with the process to design and build your flood defence wall.