Apart from the obvious risk of flooding in coastal areas, the main risk of flooding to London and the South East is from rivers, groundwater saturation, surface water run-off and leaks from water mains pipes. Apart from the Thames, there are various other smaller rivers running through London and the Home Counties. In times of heavy and prolonged rainfall, these rivers can burst their banks causing flooding to nearby land/buildings. River flooding can be exacerbated by groundwater saturation, where the ground is unable to contain and disperse rainwater due to its sheer volume, which results in the groundwater level (or table) rising. Any additional rainwater cannot be absorbed and will flood the land above. Surface water flooding (often referred to as pluvial flooding) is caused by sudden, heavy rainfall (typically summer thunder storms) falling on impervious paved surfaces (such as roads, hard paved parking areas). The surface water drainage systems are unable to cope with and disperse the large volume of rainwater, causing flooding to nearby land/buildings. Leaking water from burst mains water pipes can cause flooding to nearby land/buildings, as it can take several days for the affected water main to be repaired/replaced. Properties in low lying areas or at the base of a hill will always be at a greater risk of flood damage than properties on more elevated sites. Similarly, any below ground level accommodation such as basement conversions and cellars will be more prone to flood damage. The Environment Agency’s flood risk website can be useful in assessing the flood risk of a particular location, by inputting the full postcode of the property in question. However due to climate change, forecasting models based on past flooding events, may not prove very accurate. They should be used for guidance only.
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