Flooding and Drainage
Flood Risk AssessmentsWhat is a Flood Risk Assessment?
A Flood Risk Assessment is a document which identifies whether the site in question could be susceptible to flooding at present or as a result of future development. It will also determine if any proposed development could cause a risk of flooding to neighbouring properties or areas downstream of the site. A Flood Risk Assessment is a vital part of most Planning Applications.
Preparation of Flood Risk Assessments in accordance with National Planning Policy Framework, Flood Risk Standing Advice includes the following processes:
- Obtaining historical or modelled flood level data from the Environment Agency.
- Identifying risk of flooding from fluvial sources
- Identifying the risk of flooding from local drainage infrastructure inadequacies.
- Preparing Drainage Strategies to reduce or maintain flows to downstream watercourses or existing sewer network, including design for flow control, storage and Sustainable Drainage Systems (SuDS) for storms up to 1 in 100 year plus allowance for Climate Change.
- Indentifying flood routes for extreme storm events above the 1 in 100 event.
- Negotiations with Environmental, Planning and Drainage Authorities.
The local planning authority will generally advise whether or not a Flood Risk Assessment is required, either in consultation with the Environment Agency or in accordance with their own policies.
However, as a general rule; if your site is within Flood Zone 2 or 3 you will need a flood risk assessment. If it is outside these zones you may still need one, particularly if the development is over 1ha or in close proximity to a river or other watercourse.
Click here to see if you need a Flood Risk Assessment