Mapping the risk of groundwater flooding

September 11, 2015 6:07 am

It’s not long until Flood Re is implemented, which is aimed at providing affordable flood insurance for everyone – even those in high-risk areas. As part of this, insurers want more accurate flood data to help calculate risk, and this has highlighted what in the past has been a weak area: mapping the risk of groundwater flooding.

There are four types of flooding: fluvial (from rivers): pluvial (surface water from rain); coastal; and groundwater. The latter occurs when water rises up from below ground – for example, from underlying rocks or from abnormal springs. This tends to happen after prolonged periods of heavy rainfall and as a result the water table rises above normal levels. One key difference compared with other types of flooding is that groundwater floods tend to take longer to dissipate. There’s a very good explanation of it all on the UK Groundwater Forum website.

According to a recent article in Post magazine, groundwater flooding is more difficult to predict than the other types of flooding. But work has now been carried out which should lead to improved groundwater risk modelling: specifically, flood risk consultancy Ambiental has produced a ‘Groundwater Flood Risk Map’, which can be used by insurers to assess flood risk to even individual properties.

On the subject of Flood Re, the Association of British Insurers (the ABI) has put together a really good explanation of what the scheme is all about, which you can find on its website.