Sources of Flooding

The Nottingham and Nottinghamshire LRF Area is potentially at risk to flooding from a number of sources.

River Flooding
Reservoirs Breach
Groundwater Flooding
Surface Water Flooding
Sewer Flooding

River (Fluvial and Tidal) Flooding

A river overtopping its banks or flood defences leading to flooding is usually caused by prolonged periods of heavy rainfall. Fluvial flooding can be both deep and high velocity, depending on the nature of the river catchment. The areas possibly affected by fluvial and tidal flooding have been mapped by the Environment Agency.

Are you at risk of being flooded?

See the following link to see if you are at risk of flooding:

Environment Agency - Am I at risk?

The Environment Agency will monitor and warn for fluvial flooding where systems and procedures are in place.

Reservoirs Breach

This refers to a collapse of a reservoir dam, there are a number of these within the Nottingham and Nottinghamshire area.

Some reservoirs hold large volumes of water above ground level, contained by walls, or 'dams'.  Although the safety record for reservoirs is excellent, it is still possible that a dam could fail.


In Nottingham and Nottinghamshire LRF area there are approximately 40 identified Reservoirs (over 25,000m³).

Are you at risk of Reservoir Flooding?

See the following link to see if you are at risk of reservoir flooding:

Environment Agency - Am I at risk of Reservoir Flooding?

Groundwater Flooding

Occurs when water levels in the ground rise above surface levels. It is most likely to occur in areas underlain by permeable rocks, called aquifers. These can be extensive, regional aquifers, such as chalk or sandstone, or may be more local sand or river gravels in valley bottoms underlain by less permeable rocks.

The Nottingham and Nottinghamshire LRF area is not at significant risk from this type of flooding.

Surface Water Flooding

Occurs when heavy rainfall overwhelms the drainage capacity of the local area.  It is difficult to predict and pinpoint, much more so than river flooding. It will be most problematic when catchments are already saturated or frozen and in urban areas with impermeable surfaces. It will usually occur rapidly, but be relatively short lived.

Accurately predicting and mapping surface water flooding is currently not possible. The best available information is provided by the Met Office Severe Weather Warnings and a local understanding of the most commonly effected areas.

Met Office - Severe Weather Warnings

Sewer flooding

Occurs when sewers are overwhelmed by heavy rainfall or when they become blocked.  The likelihood of flooding depends on the capacity of the local sewerage system. Land and property can be flooded with water contaminated with raw sewage as a result. Rivers can also become polluted by sewer overflows.

Page last updated: 22 May 2012 11:35AM