18 Jun 2014

Is a drought even possible this year?

The fickle nature of the British weather has delivered us extremes at both ends of the spectrum in the past few years.

Following two consecutive dry winters in the UK in 2010/11 and 2011/12, water resources were twice deprived of their most important annual replenishment cycle, leading to a large swathe of England gaining official drought status early in 2012.

Several water companies were forced to introduce water restrictions, in order to preserve the limited supplies of water that were present.

lincoln_river_g_wp

However, in typical British style, summer 2012 ended up being the wettest in 100 years, leading to the drought being eradicated by the end of the summer.

Then we had last winter, which saw storm after storm batter our shores, delivering damaging winds and copious amounts of rain, with winter 2013/14 becoming the wettest on record.

Is a drought possible this year?

During the past few weeks, people have jokingly said to me that after such a wet winter, we would probably end up in a drought again later this year. But what are the chances of this?

The Centre for Ecology and Hydrology release a monthly report that looks at the current and projected state of water resources here in the UK. It focuses on four main elements – river flows, soil moisture deficits, groundwater levels and reservoir levels.

River flows, reservoir and groundwater levels

River flows measure the amount of water flowing through the river catchments across the country. As of the end of May, all rivers had flows that were normal or above, except for north east Scotland, where a lack of rainfall has left some rivers below normal.

elan_dam_g_wpReservoir levels across the UK are doing very well, with most reservoirs close to being at full capacity, with only a few slightly less full than normally seen in May.

As would be expected, groundwater levels are still at exceptionally high levels in parts of the UK worst hit by the winter floods – particularly southern parts of England.

However, groundwater levels should continue to decrease in the coming months because rain that falls in summer tends not to reach deep down in the ground. Instead, it is sucked up by growing plants or evaporates in the strong summer sunshine.

Soil moisture deficit

Soil moisture deficit is a measure of the amount of moisture in the soils. The greater the deficit, the less water present and vice versa.

200513218-001Soil moisture deficits are notably below normal in many areas, meaning that the soil is much wetter than would normally be seen at this time of year. In fact at the end of May, soil moisture deficits across much of central England are the lowest since the early 1980s.

With the soils wetter than normal, the ground is more sensitive to heavy summer downpours than usual. This means that surface water flooding could be a little more prevalent to relatively moderate intensities of rainfall.

A positive outlook

With so many aspects of our water resources at average or above, the outlook remains a positive one across the UK.

In the latest hydrological outlook, Simon Parry from the Centre for Ecology & Hydrology said: “With river flows and groundwater levels in the normal range or above (significantly so in areas where the wet winter of 2013/14 is still exerting an influence) and above average reservoir stocks in most impoundments, the water resources situation for the summer and early autumn is favourable.”

So, until the British weather throws us another curve ball, for now, the situation is looking green and a little bit soggy.

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One reader comment

  1. Ashley Haworth-roberts says:

    Might some places soon be declared to be in a meteorological drought – which I believe means 15 consecutive days with daily precipitation less than 0.25 mm? (But not triggering any hosepipe bans.)

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