Last edited 21 Apr 2019

Flood risk

Contents

[edit] Introduction

The National Planning Policy Framework considers flood risk to be the combination of the probability and the potential consequences of flooding from all sources, including:

[edit] Flood zone and flood risk tables

The Environment Agency has produced a Flood Map for Planning which has three zones of flooding and refers to the probability of the river and sea flooding but does not consider the presence of any defences.

The zones and definitions are as follows:

  • Zone 1 Low probability: Land having a less than 1 in 1,000 annual probability of river or sea flooding.
  • Zone 2 Medium probability: Land having between a 1 in 100 and 1 in 1,000 annual probability of river flooding; or land having between a 1 in 200 and 1 in 1,000 annual probability of sea flooding.
  • Zone 3a High probability: Land having a 1 in 100 or greater annual probability of river flooding; or land having a 1 in 200 or greater annual probability of sea flooding.
  • Zone 3b The Functional Floodplain: This zone comprises land where water has to flow or be stored in times of flood.

[edit] Planning and flood risk

The National Planning Policy Framework (NPPF) sets out policies to avoid inappropriate development in areas at risk of flooding. This includes requiring new development to be flood resilient and resistant where appropriate. The NPPF defines tests that local planning authorities are expected to abide by in order to protect people and property. If the tests cannot be met, new development should not be permitted.

The steps are:

[edit] Building Regulations

Approved document C, Site preparation and resistance to contaminants and moisture, suggests that when building in flood prone areas, buildings can be constructed to mitigate some of the effects of flooding:

It references: Improving the flood performance of new buildingsFlood resilient construction, Communities and Local Government, Defra and the Environment Agency, May 2007, as a source of further information.

[edit] Flood and Water Management Act 2010

The Flood and Water Management Act was introduced on 8 April 2010 to implement Sir Michael Pitt’s recommendations following the widespread flooding of 2007 when more than 55,000 homes and businesses were flooded (see Pitt Review).

The Act requires better management of flood risk, it creates safeguards against rises in surface water drainage charges and protects water supplies for consumers. It gives a new responsibility to the Environment Agency for developing a National Flood and Coastal Risk Management Strategy, and gives a new responsibility to local authorities, as Lead Local Flood Authorities (LLFA's), to co-ordinate flood risk management in their area.

For more information see: Flood and Water Management Act .

[edit] Related articles on Designing Buildings Wiki.