Green and Grey Drainage Infrastructure: Costs and Benefits of Reducing Surface Water Flood Risk

In the UK, flooding has been identified as one of the biggest challenges the nation currently faces, with surface water and fluvial flooding considered the dominant contributors to this (RGS, 2016). Surface water flooding occurs when infiltration rates and/or capacity are exceeded, leading to surface water runoff that collects in a given area, and is of particular concern when this results in damage to land or property. Urban drainage infrastructure is regularly constructed to prevent and alleviate this build-up of water, and thus reduce flood risk, but is expensive (both in terms of money and resources) to develop and maintain these. Sustainable urban drainage systems (SuDS) are considered an alternative to this, mimicking natural ecosystems and so reducing both construction and maintenance costs (Brown, Keath & Wong, 2009). How effective these systems are compared to their 'grey' counterpart, however, has not yet been fully analysed and understood, nor has their large-scale implementation been assessed.
The proposed study, therefore, will look to address these challenges and offer an informed insight into regions requiring further investment in drainage infrastructure. To do so, it will address the research aims outlined below, forming a comprehensive picture of current flood risks, infrastructure developments and drainage effectivities, on which investment recommendations can then be based. Well-targeted improvements in drainage infrastructure could ultimately reduce the risk posed by surface water flooding in the UK, and decrease the cost of damages during flood events.