The extreme drought and heatwave that hit the United Kingdom and continental Europe during the summer of 2003 led to substantial social and environmental effects but, in relation to water resources stress, the UK’s general resilience to within-year rainfall deficiencies was well demonstrated.
Drought conditions became established over most of the UK during the late winter and early spring of 2002/2003. The spring period saw record-breaking lack of rainfall and gave way to long, warm summer. Exceptional evaporative demands contributed to the severe drought conditions through the summer and the associated environmental impacts assumed a greater political significance in the context of climate change projections.
Seasonally very high temperatures and well below average rainfall characterised most of the country from late winter to late autumn. For the UK as a whole, the February-October rainfall total was the second lowest in a series from 1900. There were also record-breaking high temperatures through the summer – causing additional heat-stress and evaporation demands; heatwave conditions also affected most of continental Europe.
The next few months from November 2003 onwards saw rainfall totals mostly near, or slightly above average but groundwater levels continued to decline in parts of the South East and the Midlands.
The plot below shows the monthly North Atlantic Oscillation (NAO) Index for the periods before, during and after the drought. The NAO is a prominent teleconnection pattern in all seasons, and strong positive phases tend to be associationed with above-average temperatures in northern Europe, whilst negative phases of the NAO tend to be associated with below-average temperatures. There is more information available here.
The drought began in early 2003 in north-west Britain and became increasingly widespread through western parts of UK, before spreading into north-east Britain through the second half of 2003. This maximum spatial extent of the majority of northern and south-western parts of the UK was sustained through late 2003 and the first half of 2004. The highest values of drought severity occurred in northern and eastern Scotland in the early stages of the event, reflecting the hot dry nature of the driving meteorology in summer 2003. Drought conditions first diminished in north-west Britain in summer 2004, followed by north-east and south-west England in autumn 2004. In southern England, deficiencies established in late 2003 and through 2004 went on to re-intensify as the 2004-2006 drought.
As a relatively short drought in historical terms, there are few catchments which rank amongst the top 10 on record by duration. The exception to this is those parts of southern and south-west England where the 2003/2004 event never fully recovers before the 2004-2006 drought. Despite a wide spatial footprint, the drought minimum ranks amongst the top 10 on record only in Scotland and parts of north-east England. Within these areas, the drought minimum is amongst the top three on record for northern and north-eastern Scotland, ranking second on record in seven catchments. Correspondingly, mean deficits are also most notably in Scotland, particularly in the east; for nine catchments here, the 2003/2004 drought had the highest mean deficit of any event in the historical record. Overall, the 2003/2004 event is more noteworthy for its intensity than its duration, reflected in high rankings for drought minimum and mean deficit. This set of characteristics is typical of a short hot and dry period causing responsive rivers in the north and west to fall below average rapidly.
At a national scale, the 2003 drought had a relatively limited impact from a groundwater perspective – reflecting the very healthy state of groundwater resources in the spring of 2003. However, Marsh (2004) reported that ‘many shallow wells were dry’ by the end of the summer of 2003, and due to the ‘memory’ in groundwater systems the drought was a precursor of the more significant 2004-2006 groundwater drought.
Entering 2003, groundwater levels throughout the UK were at or above normal levels as a consequence of a period of years with normal or above normal winter recharge (Marsh, 2004). Subsequently, the UK’s driest February-October since 1921 brought an early end to the aquifer recharge season and very sustained groundwater level recessions which continued into 2004 in some eastern areas. In northern Britain many springs failed and, to the south groundwater levels in a number of Chalk wells and boreholes had declined to close to their long term minimum dry end to the recharge season from February to May 2003 led to spatial variation in groundwater levels, with areas of Chalk in southern England being particularly affected by reduced groundwater levels (Marsh, 2004). Groundwater levels continued to decline through to late summer and autumn associated with the driest February-October since 1921 and the high associated soil moisture deficits (Marsh, 2004). However, it wasn’t until July 2003 that groundwater levels were reported as being below the average for many sites across southern areas of the Chalk. Despite relatively high levels of recharge in January 2004 at some sites, such as at Dalton Holme in Yorkshire, the legacy of the 2003 drought was that ‘groundwater-level recessions at many index wells and boreholes in central and southern England began at their lowest spring level for seven years’ (Marsh, 2004).
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This drought not only affected the UK but also continental Europe. Yield reductions reported for many crops, as well as quality issues. Abstraction restrictions imposed in many areas. Grass shortages were reported in many locations, with hot weather reducing livestock grass intake. Lamb growth and milk yield were negatively affected. Yield reductions were reported for many crops. About a third of winter oilseed rape failed to establish because of the dry weather in 2003.
“Dry winter conditions have caused many oilseed rape crops to fail this year, particularly in heavy land areas...Up to 70 per cent of oilseed rape has been abandoned in some parts of the eastern counties, and that many more backward crops could suffer further yield loss if not treated with an appropriate fungicide” 'Oilseed rape crops failing in dry winter, Farmers Guardian, 12 March 2004, p24'
In summer 2003, potato futures prices rocketed by over 60%, spurred on by dry weather across the Continent and record low plantings in the UK. Dry weather was also limiting potato yield potential across Europe. In the UK, it caused decreases in tuber size, but generally the quality was very good.
A new economic regulator is established through the Water Act 2003 – Parliamentarians start to think of water resource management as a sustainability issue – the challenge of integrating environmental and economic objectives in the regulation of water resources starts to be recognised.
In February 2003 Parliament started to discuss the introduction of the Water Bill 2003, which was passed later that year. The Water Act 2003 had a significant impact on the reorganisation of the water industry: it established the Water Services Regulation Authority as a principal economic regulator of the privatised water and sewerage industry in England and Wales. It grants increased powers to the Environment Agency in matters linked to water management, for example, when deciding upon applications for abstraction licences.
This legislative change is directly related to experienced and predicted environmental changes and periodic reduced rainfall. The Water Bill stresses the need to link water conservation and efficient water use. The government’s vision is also to better integrate economic and environmental regulation. Throughout the Parliamentary debate about the Water Bill, a new way of thinking about water management becomes apparent: Members of Parliament express concerns about the long-term sustainability of water resources, conservation and efficient water use, and the environmental impact of various phenomena such as droughts and floods.
Water and drought management start to be seen as environmental (or sometimes ‘sustainability’) issues, as well as an economic one.