Estimating numbers of properties susceptible to groundwater flooding in England

摘要

In the wake of widespread groundwater flooding that affected properties and infrastructure in southern England during 2014, a review has been undertaken of the number of properties in England that might be vulnerable during episodes of high groundwater levels, and an estimate made of how many properties might be affected in susceptible areas. udGroundwater flooding can happen in many geological environments, but is a particular problem on Chalk and Limestone aquifers, where around 920,000 properties are in areas where groundwater emergence could occur. This represents fewer properties than previously estimated for these areas. However, a further 3,800,000 properties are in areas underlain by other aquifer types that could be affected by groundwater flooding or shallow water tables.udThe actual impact of groundwater flooding on properties is often mitigated by building design or natural/artificial drainage systems which act to lower water tables and move emergent water to rivers. As a result only a small percentage of properties identified above are likely to be impacted by groundwater flooding. Although there is limited observational data, we believe that up to 138,000 properties might be impacted in chalk and limestone areas and up to 151,600 in other areas. udThis means the revised estimate of the number of properties in areas at risk of groundwater flooding is between 122,000 and 290,000.udGroundwater may play a role in the flooding of a further 980,000 properties in areas that are also at risk from river and/or coastal flooding. In addition, groundwater flooding is a significant issue for subsurface infrastructure. Note that this latter issue has not been assessed in this report. udud