The basic cause of all droughts is insufficient rainfall. Often this is prolonged over a period of several months or even years.
Short-term droughts, such as those experienced in the UK, can also be caused when high pressure systems persist over, or close to, the UK for a prolonged period.
This weather pattern blocks the usual passage of low pressure systems that bring bands of rain and showers, especially to western parts.
The 2014 weather summaries show how the UK weather has varied in the past year.
Roles and responsibilities
The Met Office works closely with the Environment Agency, Government, local authorities and water companies to ensure the effects of droughts are minimised. We aim to help ensure that the UK manages the need for water of consumers, including farmers, abstractors, and other users, while protecting agriculture, horticulture and wildlife from damage.
As the UK's official weather service we have a statutory duty to:
- provide forecast information on when, and how much rain, is expected. These are for the public; relevant Government agencies, such as the Environment Agency and Cabinet Office, and the water companies;
- 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.
The statutory body that has a duty to manage water resources in England and Wales. The Environment Agency:
- monitors environmental indicators such as river flows, groundwater levels, reservoir levels and river ecology to recognise the onset and development of droughts;
- reports the state of water resources during a drought to the public, media and Government;
- determines water company drought permits;
- ensures water companies are following their own drought plans;
- provides advice to abstractors and enforces licence conditions to protect the environment.
Water companies are responsible for monitoring and controlling water supplies. When there is a drought they implement their Drought Plan, which outlines a series of actions that a water company can take to effectively manage the water resources available during a drought.
These can include:
- Running publicity campaigns to encourage customers to use water wisely.
- Working with large businesses to reduce their water use.
- Increasing work to find and fix leaks and reduce water pressure.
- Implementing water conservation schemes.
- Introducing hosepipe or sprinkler bans.
- Asking the Government/Welsh Assembly for permission to issue 'Non-essential use ban drought order' - banning things like cleaning windows and the filling of ornamental ponds.
- Issuing an emergency drought order - imposing standpipes, tanks and bowsers, and possibly even rotas for water consumption.
Drought and climate change
Dr Richard Betts explains the different definitions of drought and what we might expect to see under climate change in our Climate change and drought video (YouTube).