Revisions to EA Climate Change Allowances

In July 2021, the Environment Agency (EA) revised their previously published climate change allowances.

Using UKCP18 projections, the EA update the peak river flow allowances basing them upon management catchments rather than river basin districts as was previously the case. Management catchments are sub-catchments of river basin districts.

The EA have also revised their guidance on how to apply the river basin flow allowances within Flood Risk Assessments and have simplified their approach. The majority of assessments will now only need to consider the ‘central allowance’.  The central allowance should also be able to calculate flood storage compensation, except where essential infrastructure is affected.

 

 

 

Climate change allowances

The climate change allowances for peak river flows are based upon percentiles and they show the anticipated changes to peak flow by management catchment. A percentile describes the proportion of possible scenarios that fall below an allowance level. The central allowance is based upon the 50th percentile, which is the point at which half of the possible scenarios for peak flow fall below it, and half fall above it.  Therefore, the central allowance is exceeded by 50% of the projections in the range.

 

For developments in Flood Zones 2 and 3 it will be necessary to determine the impact of climate change on rivers flows and assess the potential impact of flood risk over the developments lifetime as part of a Flood Risk Assessment.

Get in touch!

To speak with us further about how Cole Easdon can help with the assessment of climate change as well as the preparation of Flood Risk Assessments please contact: Dean Frosoni, Technical Director –  waterteam@coleeasdon.com / Tel: 01793 619965

Return to Insights

What our clients say…

“CE carried out the work we commissioned exactly as we would have wanted it in a courteous, friendly and professional manner.”

John Stuart Grant, Grantham Bros Ltd

“CE are great to deal with, their knowledgeable and professional approach was key to helping us achieve a very positive outcome.”

Robin Uttley, United Utilities

“Wonderful service, fast, thought-out and accurate. Assisted us greatly in getting our project scoped out and costed quickly and efficiently.”

Dominic Fry, Avebury Sports & Social Club

“CE offered our design practice a very thorough, friendly and professional highways report service that fully met our brief and within the timescales requested.”

Andrew Jackson, Sylva Group

“The consultant was knowledgeable, professional and efficient. Good value for money. I would highly recommend them.”

Julie Jeanes, Linwood School

“I work regularly with Cole Easdon on a variety of projects for different house builder clients. I have always found them to be very reliable and very pro-active when dealing with highway and drainage authorities.”

Roger Smith, Savills (Oxford)

“Without the professional support from Cole Easdon we would not have been able to challenge and prove the local planning department were incorrect regarding their comments made about our flood zone status.”

Rob Charman, Cuddra Aquatics

“It’s the personal (not corporate) approach you take on projects that I like.”

James Bulley, Trivandi

"CE are very professional, promote good relationships with Clients and provide good civil/drainage solutions on time."

Cidalia Teixeira, Clegg Associates

"They are a thoroughly professional and reliable company. They provide expert advice and support and their reports are first class. They are very willing to engage and give an opinion as to the best way to overcome a problem. Delightful to deal with too."

Andrew Bond, Client

"It's always a pleasure working with Cole Easdon, they understand what's being asked of them and provide accurate detailed information, to which we are extremely grateful."

Philip Jenkins, Clegg Associates