Long droughts can be disruptive and dangerous for many sectors including agriculture, water supplies, fisheries, health, and infrastructure. They cause river and reservoir levels to drop, making them particularly straining for farmers. The 1976 drought in the UK made an estimated £3,500 million worth of crops fail. They can also be extremely dangerous – it was drought conditions that allowed the so-called ‘King fire’ of California to spread so quickly in 2014.

One of the challenges of managing droughts is that they are hard to predict. Their long, extended nature means current technology can't give more than one month’s warning.

Their drawn-out nature also means that the term ‘drought’ has no exact definition. The common understanding that droughts are a space of abnormally dry weather isn't very useful as what's ‘abnormal’ changes from one region to the next. Bali is so wet that six days without rain is enough to create a drought, while in Libya it is pretty normal for nearly two years to go by without any rain at all.

CEH Fellow Terry Marsh has written this short blog post which examines "What is a drought?"

A drought’s slippery definition means it is sometimes easier to refer to them by their causes or impacts:

  • hydrological drought - refers to a lack of water in all parts of the water cycle
  • meteorological drought - determined by the number of days without rain
  • agricultural drought -focuses on the amount of water in the soil
  • socioeconomic drought - a lack of water means that demand for an economic good exceeds the supply

CEH work on drought

Projects

River flows from the September 2017 UK hydrological summary
River flows generally in the normal range or above across the UK
Drip irrigated potato crop
Achieving efficient water use to feed more people
UK river flows in August 2017 hydrological summary
Groundwater levels remain below normal in areas despite wet summer
Cattle and people on dry ground
HydroSOS - pilot system for warning millions around the world of flood and drought situations
Raindrops on a pond
Assessment of summer 2017 UK hydrological situation
July 2017 river flows in the UK
Imprint of dry winter and spring still apparent despite wet July across the UK

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