Believe it or not, it’s a rainy type of drought

26 April 2012

Even if the rainy weather keeps up for the next weeks, the south and east of England will still be in drought. This might sound contradictory, but actually floods and droughts are two sides of the same issue

Our climate is becoming more extreme, with long dry periods and sudden downpours. And when intense rain hits hard dry ground, it soaks up quickly or causes surface flooding, rather than replenishing water supplies.

After two dry winters in a row much of England is now in drought. However, April has been one of the wettest on record with much of the country experiencing heavy rainfall and localised flooding.

Unfortunately this rain – heavy as it is – won't make much difference to the underlying drought conditions; it would take about 50 days of solid rain to make the soil wet enough to allow the water to percolate down and start refilling the underground rocks.

Most of the water supply in the south and east of England comes from wells sunk into chalk rocks. These rocks or aquifers are normally replenished over the winter so it is winter rain (from 1 October to 1 April), that is most valuable in terms of refilling the underground stores of water. Due to the lack of rain over the past two winters, the rocks in some areas are at their lowest level since records began.

Summer rain (1 April to 1 October) either evaporates or is used by plants – it very rarely penetrates into these substrata. Most rivers in the south and east are fed by water coming from the underground rocks so while this rain will help a bit it won't restore flow to normal levels.

In the UK we use on average 150 litres of water a day. If everyone used less the impacts of the drought would be much less. So the rain will keep the surface – and you – wet, but it won't stop the drought. On the upside, this rain will help water gardens, refill water butts and do a bit to top up reservoirs. So do your best to enjoy it while it lasts – but don’t let up on your water efficiency measures.

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