Flood risk assessment

Flooding in the UK has been in the news recently particularly since the severe floods of winter 2014. Such events are often attributed to changing weather patterns due to climate change. This in part is true but for many cases it has been the lack of consideration of flooding during the development process that has resulted in problems.

Development on areas classified as ‘functional floodplain’ has resulted in a large number of properties at high risk of flooding. Also the effect of development elsewhere in the catchment on ‘downstream’ developments has also been neglected.

Climate change predictions, suggest that flood events will become more prevalent and more severe. With this in mind legislation has tightened in order to protect future development.

The National Planning Policy Framework (2012) states that Local Plans should take account of factors affected by climate change such as flood risk. New development should be planned to avoid increased vulnerability to the range of impacts arising from climate change, however, if new development is brought froward in such areas, care should be taken to ensure that risks can be managed through suitable adaptation measures.

Inappropriate development in areas at risk of flooding should be avoided but where development is necessary, it should be done safely without increasing flood risk elsewhere. Local Plans should be supported by Strategic Flood Risk Assessment and develop policies to manage flood risk from all sources taking account of advice from the Environment Agency and other relevant flood risk management bodies, such as lead local flood authorities and internal drainage boards.

Local Plans should apply a sequential, risk-based approach to the location of development to avoid where possible flood risk to people and property and manage any residual risk.

Will I be asked to undertake a flood risk assessment on my planning proposal?

The Environment Agency has undertaken flood mapping since 2000 for the whole of England and Wales. The mapping classifies Flood Zones 1, 2 and 3.

If the site where development is proposed lies within Flood Zone 2 or 3, the local planning authority is likely to ask for a flood risk assessment to be undertaken.

If it is known that the site lies within an area of frequent historical flooding (particularly relating to groundwater which is not considered by the Environment Agency mapping), a flood risk assessment may also be requested. Further information can be found on the government website GOV.UK.

What we do?

Apple Environmental can undertake flood assessments for potential developments at risk from fluvial, coastal and groundwater flooding. Our reports utilise Environment Agency modelling data and historical data to assess the likelihood and potential impacts of future floods and advise on mitigation strategies where required.

Flood Zone 3 covers an area where, neglecting the effects of flood defences, the probability of flooding from the sea by a flood has a 0.5% (1 in 200) or greater chance of happening each year or from a river by a flood that has a 1% (1 in 100) or greater chance of happening each year.

Flood Zone 2 where the likelihood of flooding is 0.1% (1 in 1000) or greater chance of occurring each year.

Flood Zone 1 includes all other areas where the probability of flooding from the sea or rivers is considered to be less than 0.1%.