Find out why drought occurs and how you can help by using water wisely.
What is drought?
There is no single definition of drought. Whilst a drought will be caused by shortage of rainfall, the nature, timing and impacts vary according to location and the different sectors affected such as public water supply, agriculture and industry.
A long drought in winter may not be obvious as the weather is cold, but it can cause problems for public supply if groundwater and reservoirs don't refill. A short drought in summer may be very visible as soil and small streams dry out, affecting farmers and the environment first.
Why do we still get floods during a drought?
We have issued flood alerts and flood warnings about flash flooding in some parts of the country. A combination of heavy rainfall and poor drainage has caused some rivers to rise quickly and overflow.
- Despite the flooding, the soil is still very dry because of the current drought. Even where there have been heavy downpours, the water is either absorbed very quickly or it runs off the surface of the soil.
- We need a few months of above average rainfall to replenish our groundwater reserves deep beneath the soil. Only then will we be out of drought.
Definitions
Across England and Wales we apply these three categories relating to water shortages:
‘Temporary Use Restrictions’
Water company drought plans have required them to implement restrictions, such as hosepipe bans, to help conserve supplies. In addition, farmers, other abstractors and the environment are likely to be adversely affected. Groundwater stores will not be replenished by short-lived periods of rainfall.
‘Environmental Stress due to Rainfall Deficit’
Farmers, other abstractors and the environment are at risk of adverse affects by long-term, significantly below average rainfall. Rivers and lakes may show short term responses due to rainfall but groundwater stores remain in deficit.
‘No Environmental Stress due to Rainfall Deficit’
Rainfall and the water environment within normal ranges. No significant impacts on either the environment, farmers or other abstractors.
How does the Environment Agency determine drought?
- We consider a range of hydrological and environmental triggers across the different sectors and the geographic area affected.
- We look at drought prospects and how likely it is the situation will get worse. This will include the timing and season.
- We assess the level of actions we and water companies are taking or are about to take in line with our drought plans.
- We consider the extent of public and media interest so that people are well informed and can help - for example by saving water.
The decision to move to drought status is an expert judgement based on all these factors.
The main aspects of drought and the impacts, risks and triggers we monitor are set out in our drought plans. They include the following aspects and will tend to occur in the order below:
- Meteorological - shortage of rainfall and actual evaporation.
- Hydrological - reduced river flows and low groundwater levels.
- Environmental - dry soils, stress on habitats and wildlife.
- Agricultural - dry soils, need for irrigation and stress on plants.
- Public supply - low reservoir storage, high demands, customer appeals and restrictions, and drought permits and orders.
More information
Find out more about the different kinds of drought and their effects:
