Flood Map - A map produced by the Environment Agency providing an indication of the likelihood of flooding within all areas of England and Wales, assuming there are no flood defences. Only covers river and sea flooding.
Floodplain - A Floodplain is flat or nearly flat land adjacent to a watercourse, an estuary or the sea, that experiences occasional or periodic flooding, or would flow but for the presence of flood defences where they exist.
Flood risk management strategy - A long-term approach setting out the objectives and options for managing flood risk, taking into account a broad range of technical, social, environment and economic issues.
Flood risk assessment (including regional, sub-regional/strategic, and site specific) - A study to assess the risk to an areas or site from flooding, now and in the future, and to assess the impact that any changes or development on the site or area will have on flood risk to the site and elsewhere. It may identify, particularly at more local levels, how to manage those changes to ensure that flood risk is not increased. PPS25 differentiates between region, sub-regional/strategic and site specific flood risk assessments.
Flood risk management measure - Any measure which reduces flood risk such as flood defences.
Flood Zone - A geographic area within which the flood risk is in a particular range, as defined within PPS25.
Fluvial Flooding - Flooding from rivers, streams, watercourses etc these flood when the amount of water in them exceeds the flow capacity of the channel.
Freeboard - The difference between the flood defence level and the design flood level.
Greenfield land - Land that has not been previously developed.
Hold the line - Maintaining the existing flood defences and control structures in their present positions and increase the standard of protection against flooding in some areas.
Internal Drainage Board (IDB) - Public authority and are responsible for providing a service in land drainage and flood protection in areas of the UK.
Local development framework (LDF) - A non-statutory term used to describe a folder of documents which includes all the local planning authority’s Local Development Documents (LDDs).
Local Development Documents (LDDs) - All development plan documents which form part of the statutory development plan, as well as supplementary planning documents which do not form part of the statutory development plan.
Main River - A watercourses designated on a statutory map of Main Rivers, maintained by Defra, on which the Environment Agency has drainage and flood control management responsibility.
Ordinary Watercourse - All rivers, streams, ditches, drains, cuts, dykes, sluices, sewers (other than public sewers) and passages through which water flows which do not form part of a Main River. Local authorities and, where relevant, Internal Drainage Boards have similar permissive powers on ordinary watercourses, as the Environment Agency has on Main Rivers.
Overland flow flooding - Otherwise known as pluvial flooding. Intense rainfall, often of short duration, that is unable to soak into the ground or enter drainage systems can run quickly off land and result in local flooding.
Planning Policy Statement 25: Development and Flood Risk (PPS25) - A statement of policy issued by central Government on flood risk to replace Planning Policy Guidance 25: Development and Flood Risk (PPG25).
Precautionary principle - Where there threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation.
Previously-developed land (often referred to as brownfield land) - Land which is or was occupied by a permanent structure, including the curtilage of the developed land and any associated fixed surfaces infrastructure (PPS3 annex B)
Regional Spatial Strategy (RSS) - A broad development strategy for a region for a 15 to 20 year period prepared by the Regional Planning Body.
Reservoir (large raised) - A reservoir that holds at least 25,000 cubic metres of water above natural ground level, as defined by the Reservoirs Act 1975.
Resilience - Constructing the building in such as way that although floodwater may enter the building its impact is minimised, structure integrity is maintained and repair, drying and cleaning are facilitated.
Resistance - Constructing a building in such as way as to prevent floodwater entering the building or damaging its fabric. This has the same meaning as flood proof.
Return period - The long-term average period between events of a given magnitude which have the same annual exceedance probability of occurring.
Residual risk - The risk which remains after all risk avoidance, reduction and mitigation measures have been implemented.
Risk Management Solutions (RMS) Pluvial Flood Map - The RMS data model does not take into account Coastal/Storm Surge Flooding, Dam Failure Flooding, Sewer Overflow Flooding or risk of flooding from the sea. The source data is created using 0.0005 decimal degree grid cells which represent the ground surface which have been obtained by flying over the UK and sending a radar signal down to the ground which then bounces back up to the plane. This has been translated into British National Grid - as a result of the translation, the data does not appear as a regular grid. Due to this re-projection cell sizes will vary across the country.
River basin management - A management plan for all river basins required by the Water Framework Directive.
Shoreline management plan (SMP) - A plan providing a large-scale assessment of the risk to people and to the developed, historic and natural environment associated with coastal processes. It presents a policy framework to manage these risks in a sustainable manner.
Standard of protection - The design event or standard to which a building, asset or area is protected against flooding, generally expressed as an annual exceedance probability.
Sustainable Drainage Options (SUDS) - SUDS are alternatives to traditional piped drainage systems that utilise natural drainage processes to convey, and improve the quality of surface water runoff generated by urban development. Including: green roofs, water butts, swales , rainwater harvesting, filter strips, wetland areas, infiltration basins, detention basins, retention ponds, porous and previous paving.
Surface water run-off - The flow of water from area caused by rainfall.
Tidal Flooding - Flooding to low-lying land from the sea and tidal estuaries is caused by storm surges and high tides.
Vulnerability class - PPS25 provides a vulnerability classification to assess which uses of land maybe appropriate in each flood risk zone.
Washland - An area of the floodplain that is allowed to flood or is deliberately flooded by a river of stream for flood management purposes.
Water Framework Directive - A European Community Directive (2000/60/EC) of the European Parliament and Council designed to integrate the way water bodies are managed across Europe.
Windfall sites - Sites which become available for development unexpectedly and are therefore not included as allocated land in a planning authority’s development plan.
