Video experiment shows why flooding is more likely after droughts
This experiment by a meteorologist shows the effects of droughts - and how they increase the risk of flash floods after rainfall.
The video, made by Dr. Robert Thompson from the University of Reading, shows three glasses of water being poured on wet grass, moist grass and dry grass.
The experiment was carried out in Harris gardens, at the University of Reading.
The water from the first glass is absorbed into the ground in about ten seconds, the second almost 50, and the third takes so long that Dr. Thompson gives up.
Dr. Thompson explained that this is because dried out soil repels water rather than absorbing it, causing rain to pool on the surface.
He said: "Dry compacted soils repel water rather than letting it soak in as wet soil would."
"This means rain pools on the surface and runoff rates increase – leading to a greater risk of flash flooding," he continued.
Last Friday, eight areas of the country were declared to be in official drought status by the National Drought Group.
The effects of droughts on soil do not only increase the risk of floods, but they also threaten crop yields, according to Dr. Thompson.
He added: "Soil dryness has a serious negative impact on agriculture, especially if they cannot irrigate crops."
The recovery of our soil is still up in the air, as according to Dr. Thompson it "entirely depends on the amount and types of rain that fall."
There are heavy rains forecast for later on this week, but unfortunately according to forecasts they are the wrong type of rain to tackle the driest spell in almost 50 years.
The ideal type of rain is a light drizzle over several hours which is not the downpours that the Met Office has predicted to begin this week.
"With a world where droughts and intense rainfall are both expected to become more extreme, the combination becomes a greater threat."
Although as of the 15th of August there are three active flood alerts in the UK, there is little that can be done to reduce this effect poses, according to Dr. Thompson.
"The best advice is to keep an eye on weather forecasts, sign up for warnings and make a flood plan."