Following on from previous posts with a water management bent, let's look at the situation in England.
The popular image of England is drenched and sodden. As the saying goes, if you're on top of the Dover cliffs and can't see France it's going to rain; if you can, it's already raining.
However, this constant, uniform perception of rain over the UK is misleading. Parts of the UK, especially London and the south east (my home area), regularly experience drought. The most recent was in February 2012, leading the Environment Secretary to announce drought control measures. The Environment Agency maintains a drought management guide outlining publicity campaigns, hosepipe bans, restrictions on agricultural spray irrigation and further measures.
Droughts can be induced by low levels of rain, and/or by low levels of groundwater, itself caused by irregular or low precipitation. A drought in 2003 was driven by low rainfall (Marsh, The UK drought of 2003, Dec 2006). From 1961 to 1995, rainfall has increased in the winter but decreased in the summer (Osborn et al., Observed trends in the daily intensity of UK precipitation, Mar 2000). This has a large bearing on the UK's groundwater levels, since most groundwater recharge occurs during the winter when evaporation is lower. In summer, by contrast, higher temperatures lead to depleting groundwater levels. This suggests that groundwater may become more important to the UK's water supply.
Chalk reservoirs are found in East Anglia and Southern England. A 2011 model of the effects of climate change on UK groundwater in the reservoirs predicted no significant change, but with lots of sources of uncertainty (Jackson et al., Modelling the effects of climate change and its uncertainty on UK Chalk groundwater resources from an ensemble of global climate model projections, Mar 2011). Christopher Jackson was also the primary author of a recent review of ten studies, each looking at future climate change impacts on groundwater, which demonstrated the large uncertainties in groundwater level predictions. There were also "significant differences in current projections" between each study (Jackson et al., Changes in groundwater levels in the UK over the 21st century, 2013).
It would seem that there is good reason to investigate the extent to which groundwater should become a larger source of water for southern England.
It is interesting to learn that some areas in UK have regular drought episodes. I was wondering if there may be some data on demand and supply of water in these regions, and if conservation of water use could potentially be a strategy that could help alleviate the water stresses in these drought-prone regions.
ReplyDeleteThanks for the interesting post. I wasn't aware that it was common for parts of the UK to experience drought - I learnt a lot through your post on the topic. My question is similar to Joon's - are there any strategies in place for areas to dealing with drought-stress?
ReplyDeleteCheers,
Katherine
Thanks for your comments, Joon & Katherine! The Environment Agency's guide is a good place to start, as it outlines what the UK government does. There's several places to go for water demand/supply data - the EA has reports, as do the regional water suppliers. Ofwat policy also discusses supply/demand, efficiency, leakage and climate change effects.
ReplyDeleteIt's also worth noting that, in SE England at least, water leakage from pipes makes a non-negligible contribution to groundwater levels.