Abstract. Drought termination can be associated with dramatic transitions from drought to storms and flooding, and this is certainly true for recent events in the United Kingdom (UK). Attention devoted to these newsworthy and memorable events may be at the expense of drought terminations that proceed gradually and pose a different set of challenges for water resource managers. This paper defines drought termination as a phase of drought in its own right and makes the case for a more systematic approach to its identification and characterisation, applying an objective approach to detect drought terminations in observed river flow records for 52 catchments. The resulting archive of 459 drought terminations provides an unprecedented historical perspective on drought termination in the UK. Nationally- and regionally-coherent drought termination events are identifiable, although drought termination characteristics vary both between and within major episodes. Contrasting drought termination events in 1995--1998 and 2009--2012 are described in greater depth. The dataset is also used to assess potential linkages between metrics of drought termination characteristics and catchment properties. The duration of drought termination is moderately negatively correlated with elevation and catchment average rainfall, suggesting that wetter catchments in upland areas of the UK tend to experience shorter drought terminations. More urbanised catchments have a tendency for gradual drought terminations, contrary to perceptions of flashy hydrological response in these areas, although this may also be related to the type of catchments typical of lowland England. Potential linkages are found between both the duration and rate of drought termination and the duration of the preceding drought development phase, which may have important implications for water resources management during a drought. The dataset helps to place individual events within a long-term context. The drought termination phase in 2009--2012 was, at the time, regarded as exceptional in terms of magnitude and spatial footprint but the Thames river flow record reveals comparable events before 1930. Hence, the approach adopted and the chronologies of drought termination enable objective intercomparison of events. The dataset may in due course provide a basis for better understanding the drivers, long-term trends in occurrence and characteristics, and impacts of historical and contemporary drought termination events.
The influence of long term trends in pollutant emissions on deposition of sulphur and nitrogen and exceedance of critical loads in the United Kingdom