Flood-hit United Kingdom

CASE STUDY: SEASONAL WATER

Flood-hit United Kingdom

Seasonal water extent has increased significantly in the United Kingdom due to various drivers, such as precipitation pattern changes, temperature changes, increasing river flows and sea level rise. Six of the 10 wettest years on record have occurred in the country since 1998, with the top 10 warmest years having occurred since 2002 (Kendon and others, 2020).

In recent years, the United Kingdom has experienced a series of record temperatures, droughts, floods and heavy rain (Watts and Anderson, 2016). Although regional rainfall trends are not yet discernible due to the high variability of rainfall throughout the country, recent studies are beginning to evidence how climate change may impact certain types of extreme events (Herring, 2015; McCarthy, 2020). For example, climate change has very likely increased the risk of extreme rainfall events and ensuing floods, as seen in northern England and Scotland in December 2015, and more recently in Lincolnshire and South Yorkshire in June and November 2019, respectively. Heavy rainfall is often linked to flooding, yet the mechanisms behind the magnitude and severity of flood events are more complex and related to infiltration capacity, increased run-off rates and evapotranspiration. The United Kingdom has become more urbanized in the past decades, with many recent flood events at least partly attributable to the increased run-off from these new impermeable built environments (Rubinato and others, 2019). However, other land-use changes are also responsible. Agricultural practices, such as grazing, may contribute to soil degradation and increased overland flows, with smaller-scale practices, such as deforestation, reducing the water storage capacity of soil and evapotranspiration rates (Weatherhead and Howden, 2009). Climate change and increasing water demand will continue to impact the scale and frequency of floods and droughts both directly and indirectly in the United Kingdom, and as a result the country’s seasonal surface-water extent. Heavy and intense rainfall events, together with bigger storm surges due to sea level rise, are expected to greatly intensify flood risks in the United Kingdom (Pidcock, 2014).

Figure 15. Seasonal water changes (left) and percentage of rainfall anomalies (right) for 2019

Sources: UNEP (n.d.); United Kingdom, Met Office (2019).

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