The recent downpours of heavy rain have provided welcome relief for gardeners, farmers, and the environment in our drought-hit region. Unfortunately, though, it won’t have done much to help replenish groundwater supplies. These are the underground aquifers that supply almost half of all the drinking water we supply.
Seeing floods and swollen rivers, it’s hard to believe that there can still be a shortage of water anywhere. But after the driest 18 months in a century, we need more than a few wet weeks to cancel out the deficit brought on by months of below average rainfall.
“The irony of having a hosepipe ban in place while floods and burst riverbanks cause so much damage isn’t lost on us,” said Ciaran Nelson, from Anglian Water. “This rainfall is helpful because it means people don’t need to water plants and they are dissuaded from washing their cars, so it does suppress demand for water. And it’s going to have refilled everyone’s water butts, too.
“But, unfortunately, it’s not going to make much of a dent on underground water levels unless it persists for many more weeks, possibly months.
“We’ve taken the opportunity to refill our reservoirs, and some of them are recovering quite well. But the challenge we have is that they are starting from a very low level, following so many months of below average rainfall.
“Our aquifers – the water stores that you cannot see – are also starting from a very low level. The difficulty we have is that they take longer to be affected by rainfall, and that’s why these downpours won’t fundamentally change the situation.”
What happens to the rain?
- At this time of year, a lot of rainfall is absorbed by growing trees and plants. When the weather gets warmer, much is also lost to evaporation.
- The ground is very hard, because of the lack of rain over the last two years. This means that it takes longer for water to soak into the ground, with more water ‘running off’ into drains, rivers, and streams.
- Once the soil does start to absorb the water, it acts like a dry sponge, recharging itself. Only once this ‘sponge’ is saturated can excess water start to make its way into aquifers.
- Anglian Water captures a lot of the rain that flows into the rivers, and pumps it into reservoirs. Most of these have recovered well following the recent rainfall – but reservoirs only supply half of the drinking water we need in our region.
Ciaran continued: “We’ve got to be careful not to let the recent rainfall mask the ‘hidden drought’ that still exists in our groundwater stores. These aquifers are still notably low. It takes longer for them to be affected by drought, but it also takes longer for them to recover when it rains – many months, in some cases.
“We may have had the wettest April on record – one of the few recent months with above average rainfall – but that follows the driest March since 1953, which comes at the end of the driest 18 months in a century.