The 2010-12 drought and subsequent extensive flooding: a remarkable hydrological transformation

Across most of the UK, the 2010‑12 period was remarkable in climatic terms with exceptional departures from normal rainfall, runoff and aquifer recharge patterns. Generalising broadly, drought conditions developed through 2010, intensified during 2011 and were severe across much of England & Wales by the early spring of 2012. Record late spring and summer rainfall then triggered a hydrological transformation that has no close modern parallel. Seasonally extreme river flows were common through the summer, heralding further extensive flooding during the autumn and, particularly, the early winter when record runoff at the national scale provided a culmination to the wettest nine‑month sequence for England & Wales in an instrumental record beginning in 1766. This report provides comprehensive documentation and hydrometeorological appraisals of a three‑year period which incorporated a number of important regional drought episodes as well as the outstanding runoff and recharge patterns which characterised most of 2012. An examination of the wide range of impacts of the drought and flood episodes is included and the extreme hydrometeorological conditions are examined within an extended historical context. Finally, the recent exceptional conditions are reviewed in the light of observational evidence for trends in temperature, rainfall, river flow and aquifer recharge patterns.