When Will the Drought End?

The UK is currently experiencing a severe drought, with many areas affected by hosepipe bans. However, the question on everyone's mind is when will the drought end, and how much rain will it take for things to return to normal?

Contrary to public perception, a drought does not end with a few days of rain. Water must flow back into rivers, reservoirs, and the stores beneath our feet in the tiny spaces between soil, sand, and rock. This can take months.

According to scientists, the key question is not "Has it rained?" but "have water resources recovered?" Dr. Katie Facer-Childs from the UK Centre for Ecology & Hydrology explains that the drought has not been caused simply by a lack of rainfall, but also higher than average temperatures.

The drought has been classified into four stages: meteorological drought, soil moisture drought, river flow drought, and groundwater and reservoir drought. While we have not yet reached severe groundwater and reservoir drought, there is still hope.

The British Geological Survey reports that no groundwater sites around the UK are currently reporting record lows, with nearly half at normal levels.

So, when will we know the drought is over? The first clear indication usually comes in late autumn and winter, when we typically see more rainfall and experts can assess whether that water is moving through rock layers into underground stores, known as aquifers.

Dr. Kevin Collins, senior lecturer in environment and systems at The Open University, warns that even when autumn rains arrive, people often assume the drought is over. However, sustained rainfall is needed over months rather than a few heavy rainfalls.

Hydrologists should know by February or March whether aquifers and human-made reservoirs have been replenished. But recovery from the environmental impacts can take years.

A dry winter will make the current drought worse and heighten government concerns. Prof. Tim Palmer of Oxford University warns that it will be "catastrophic" for the UK next year if the rains do not come.

There is some hope, however. Over Europe, there are signals for a wetter-than-average autumn, potentially influenced by global ocean changes, including the developing El Niño weather phenomenon. However, there remains considerable uncertainty.

The government needs to start planning for a worst-case scenario where the rains don't return in sufficient amounts this winter, and next summer is similar to the last two, according to Prof. Palmer.

Heavy rain after drought brings new challenges. Parts of the UK have experienced a flash drought - a type of drought that develops very rapidly, driven by extreme heat, very low rainfall and exceptionally high water demand.

The problem is that once conditions become extremely dry, subsequent heavy rainfall can trigger flash flooding because the land is unable to absorb the water effectively. This creates a cycle of rapid swings between drought and flooding, which is what people mean by weather whiplash.

As the climate warms, scientists say rapid swings between wet and dry conditions are increasing and are expected to get worse. A recent study found the UK is likely to experience faster transitions between droughts and floods, especially in south-east England and parts of the north-west of the country.

Researchers warn this growing "volatility" could make water supplies, agriculture and infrastructure harder to manage as conditions switch rapidly between extremes.

Neil Entwistle, from Rebalance Earth, argues that floods and droughts are "two sides of the same coin." He believes that the UK needs to see a fundamental shift in how it thinks about water, and that we are in the "new normal" where we will get a lot of heavy rain and short amounts of rain.

This is a wake-up call that we do need to adapt to the changing climate and think about water in a new way.