Why are we in drought?

13 03 2012

Rainfall amounts across many parts of the UK have been below average for the last two years. Importantly, this includes two dry winters – the periods when we would normally expect our rainfall to replenish river, reservoir and groundwater levels.

2010 was the eleventh-driest year in the series from 1910 and the driest since 2003. The dry weather continued during 2011 with large parts of central, eastern and southern England having well below average rainfall – several Midland counties – such as Shropshire, Nottinghamshire, Leicestershire and Warwickshire – had their driest year on record.

Map showing the rainfall seen between Nov 2010 and Feb 2012 compared to the long-term average for the same period

This emphasises why there are concerns about drought in parts of England and Wales.

There is no one reason for the dry weather over the last few years; it’s all part of the natural variability of the UK climate. However the dominance of high pressure systems over Europe has been a significant influence. These areas of high pressure effectively block the path of the Atlantic weather systems that bring us our usual wind and rain and this has happened relatively frequently over the last couple of years.

Looking back to the drought of 1976 we can see that in contrast to this year, the whole of the UK was subject to a prolonged period of below average rainfall. Between May 1975 and Aug 1976 only parts of the Western Isles and Western Highlands saw rainfall even a little above normal. Many parts of England and Wales saw only half or less of the rainfall that we could normally expect in that time.

Map showing the rainfall seen between May 1975 and Aug 1976 compared to the long-term average for the same period.

This table shows how much rainfall fell across the UK in 1975-76 compared to 2010-12:

Region/district May 75-Aug 76 total (mm) % of 61-90 average Nov 10-Feb 12 total (mm) % of 61-90 average
UK 1018 72 1502 99
England 689 64 929 82
Wales 1097 62 1658 84
Scotland 1527 82 2386 117
Northern Ireland 1098 78 1638 108
England & Wales 745 64 1030 82
N England 855 69 1212 94
S England 601 60 780 74
N Scotland 1742 86 2564 114
E Scotland 1062 74 1730 113
W Scotland 1734 83 2843 123
E & NE England 666 67 901 88
NW England & N Wales 1160 71 1690 96
Midlands 622 61 780 74
East Anglia 524 65 579 72
SW England & S Wales 907 59 1383 81
Central S & SE England 584 59 824 78

We are working closely with the Environment Agency, Government, local authorities and water companies to ensure that the UK best manages the need for water, while protecting agriculture, horticulture and the environment.

Our role includes providing forecast information to the public; government and the water companies on when, and how much rain, is expected from the next few days to a month ahead. We also maintain observations of how much rainfall there has been and where. This can be compared with our historical database of rainfall, which goes back to 1910, to provide an understanding of the current rainfall situation. The Met Office also provides the UK’s only real-time assessments of rainfall, evaporation and soil moisture for water resource specialists.

Rob Varley, Operations Director at the Met Office, said: “The last two years have been very dry across many parts of England with some areas seeing as little as 60% of their normal rainfall in that time.

“Even sustained rainfall over the next few months would have a limited impact, however we are working with the water industry to make sure they have the best weather forecast information available to help them manage their resources.”

Howard Davidson, Environment Agency South East Regional Director said: “We will continue to work with water companies to meet the challenges of a continued drought.

“The Environment Agency’s role is to balance the water needs of people, businesses and the environment. Using water efficiently will help to ensure we all have enough water for our homes, to produce food, products and services, and to protect our valuable natural environment and wildlife.”

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