Flood Risk Assessments: Environment Agency’s new climate change allowances

June 8, 20160 Comments

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5 Things You Need to Know about Environmental Agency’s new climate change allowances

Did you know that in February of this year the Environment Agency (EA) changed the way it views climate change and how it will affect flood risk? These changes will have a widespread and immediate effect on planning applications. So what do you need to know?

  1. Climate change has gone regional. Gone is the national blanket 20% increase allowance in river flooding and in is a regional view, based on 11 river basin districts. Want to find out which area you’re in? Use the EA’s catchment data search using place name or postcode here http://environment.data.gov.uk/catchment-planning/
  2. Climate change views have changed for rivers and rainfall Flooding from the sea, however, is currently thought to be largely unchanged (although there is some changes to how many storms are predicted and how high waves will be during storms).
  3. What, Where and How Long For? These things now matter! Climate change allowances now take into account what you’re building, how long the structure will be around and where you’re building it.Homes tend to be classified as ‘more vulnerable’ and are designed to last longer, whereas offices and warehouses tend to be classified ‘less vulnerable’ and have shorter lifespans. Now climate change allowances take this and the area in which you’re building into account by splitting climate change into 3 different timeframes (2015 – 2039; 2040 – 2069; and 2070 – 2115) and 3 different brackets (central, higher central and upper end).For example, using the tables below we can see that to build a new home in the South East in flood zone 3a, you will need to potentially add up to 105% onto the existing river flows to account for climate change up to 2115. However, if you wish to build a warehouse, then you will only need to add 30% to look to 2069. Agreements as to which flows to be adopted should be discussed with the EA. The reasoning is that for when we focus on residential dwellings ‘More Vulnerable’ they fall into the ‘Higher Central and Upper End’ bracketing therefore the flows to be adopted could be 50% to potentially 105%. The effect on the flood plain these flows can have could differentiate whether a development is viable.

    EA Climate Change Allowances table

    Table below shows peak river flow allowances by river basin district for South East and Thames

    EA Flood Risk Assessment - Peak River Flow Allowance Table

  4. There’ll be significant changes to large developments. There’s a greater focus on larger developers re-modelling the flood risks posed by climate change. However, the Environment Agency are open to discussion for small developments as to how to best address climate change without having to re-model. Please do not hesitate to contact our team on how best to address smaller developments.
  5. Last but not least. Ambiental is here to help! Ambiental is in a unique position, with an Environmental Assessment Consultancy working alongside a dedicated technical team who produce flood risk models and maps for governments, research and UK and international insurance providers. This provides a wealth of in-house data available only at Ambiental which can be used to support our work within the planning process.

Still confused? We’d love to help. Why not get in touch with one of Ambiental’s expert Flood Risk Consultants. They have vast experience and expertise in the field as well as a wealth of knowledge relating to any recent policy changes.

Call: Daniel Cook or Natalie James on 0203 857 8540 or email fra@ambiental.co.uk

Filed in: Flood modellingFlood risk consultancyFRA NewsLatest NewsPlanning & property

About the Author ()

Natalie James is a Flood Risk & Drainage Consultant at Ambiental and is involved in the full process of producing flood risk assessments and drainage strategies: from initial contact with a potential client, discussing their individual needs, and producing quotes, to requesting data from the relevant authorities, analysing available data and writing the report.

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