Do you think I need to take a brolly?

I mentioned a few posts ago that it hasn't rained a lot recently around here. Whenever if does rain someone always says -"Well, we need it," and that is about as true a truism as anyone could want. Spain is in the middle of a prolonged drought.

Drought occurs when, over an extended period, rainfall is lower than normal. Eventually, despite reservoirs, desalination plants, water recovery and the like, this results in a hydrological drought or lack of water resources. When this water scarcity affects agricultural, industrial and other economic activity we get to a socio-economic drought which is when your average Joe starts to notice. That's about where we are.

For some reason, presumably to do with the normal pattern of rainfall in Spain, the hydrographic year here runs from the start of October to the end of September. Between 1980 and 2010 the average rainfall in Spain was about 650 litres on every square metre. In the last hydrographic year the figure was 550 litres or some 16% down. There have been bad years in the past, in 2004 for instance it was just 430 litres, but the problem is that it's been drier than usual for four years in a row and that means that the amount of water stored in reservoirs has been steadily falling, we're in a hydrological drought.

In fact the reservoirs are well below 40% of their storage capacity. To be honest this figure seems a strange way to report water capacity. Spain has the highest per capita reservoir capacity in the world. To say that the reservoirs are at 37% of capacity means nothing - do we have a lot of capacity, so there's plenty left for me to drink and for the farmers to pour onto their crops, or are we down to the last few cupfuls? The mug I drink tea from is pretty big, about half a litre, plenty of tea to wash down my breakfast toast but if I needed to drink a bucket of tea every morning, and presuming that the blue 15 litre bucket in our garage is typical, that mug would represent just over 3% of my tea habit needs.

Hydrologically Spain is divided into river basin areas. The one that affects us, in sunny Culebrón is the Jucar and the one next door, the Segura. They're at around 25% and 14% of capacity - the lowest figures in the whole of Spain. Again though that percentage figure has to be analysed rather than taken at face value. Up in Galicia for instance, where it normally rains a lot, there is not, usually, the need to store so much water because the stuff falls out of the sky pretty regularly. The storage figure for the Miño-Sil basin in that region is just over 42% but that represents much more of a supply problem than the 32% capacity for the Guadalquivir basin in Andalucia.  That's because it's often pretty dry in Andalucia so they have lots of reservoirs to store the water when it does come. In fact some restrictions on water use have been put into place in some of the traditionally wetter parts of Spain like Galicia and Castilla y León. Apparently they haven't had any rain at all in Valladolid, not a drop, in over 100 days for instance.

Last year at this time there were just short of 28,000 cubic hectares of water stored in reservoirs. This year it's about 22,000 cubic hectares, some 22% down. The water stored has three principal uses. For agriculture, for the urban centres and for hydroelectric generation. Agriculture uses about 85% of the water and the urban centres about 15%. The hydroelectric generation just borrows it for a moment or two. It's been a bad year for agriculture. The sector has had trouble with frosts, with hailstone damage (I've told you about the horrible hailstorms before) and the drought. Farmers reckon they've lost about 2,500,000,000€ of retail sales because of those three things. Mind you it's not all one way traffic. Farmers are allegedly responsible for an estimated half a million illegal water wells which use about the same amount of water as 58 million people in a year. Hydroelectric generation is down about 50% this year because the dams don't have the flows to drive the turbines. This means that other, non renewable and more costly, forms of energy, like gas and coal, have to be used to fill the gap and that, in turn, means more greenhouse gases - up 37% for this year over 2016.

I wondered how much rainfall would be needed to turn this situation around. None of the articles I read had a figure. It took me a long time to work out why. The answer is that nobody can really say without lots of ifs and buts. For instance Spain has systems for moving water from one river basin to another. Water is often moved from the Tajo to the Segura for instance so, I suppose, if the drought persisted in Murcia but it poured down in the Tajo basin then Murcia would be fine. Also you would need to establish what's normal in the way of full and empty reservoirs and whether the reservoirs or aquifers are the main source of supply. The highest figure I can see for reservoir capacity seems to be 70% in 2013, just before the dry spell started. If you were one of those half empty people, rather than half full people, then I suppose you could, quite rightly, point out that even in the fattest years the reservoirs were 30% below full. I'm pretty sure though that, a few years ago, one of the complaints in the North was that they had run out of storage capacity because all the reservoirs were full. That ties in with the point above about the Miño-Sil river basin. Full to overflowing in the lusher parts, still only at 50% in the drier parts but, in fact, all well and good. Actually I did find an article that said in Galicia it needed to start raining now and not stop until they had about 600 litres per square metre or about half a years average rainfall to bring things back to normal. That doesn't sound good.

But not to worry the Government has said that no cuts in supply are envisaged until 2018 - hang on isn't that just a bit short of 40 days away?