Tuesday, October 3

Transfer of the Ebro: Arga, Ega and Aragón make the Ebro male

In the times of María Castaña, schoolchildren had to memorize the rivers of Spain and their tributaries. In the case of the Ebro river, a mnemonic rule was used that read like this: Arga, Ega and Aragón make the Ebro male. Indeed, in these days of rainy and snowstorms in Navarra, the Arga river (with a peak flow of 961 m3 / s at 5 hours on the 11th) swelled the Ebro so that in Zaragoza it reached a flow of 2,118 ms / s at 17 hours on the 14th. To serve as a reference, the normal average flows in these rivers are usually 30 in Arga and 100 in Zaragoza in m3 / s. Is it possible to take advantage of these extraordinary floods to make a transfer to the dry southeast coast ?

In the first place, it is evident that this transfer could not prevent the floods produced in the towns and orchards of the Ribera Alta and Ribera Baja de Aragón, but the Ebro River continues to flow downstream and finally a high number of cubic hectometres of water will go to the sea. The water is actually stored in the Mequinenza reservoir located almost on the border between Aragon and Catalonia. But, due to the fact that this reservoir contains more than 1000 cubic hectometres all year round, on stormy days when a strong flood is expected, the measure is taken of discharging of the order of more than 1000 m3 / s and thus have the capacity to retain the water that comes from Zaragoza. In short, the water from the flood is stored in the reservoir and it is the discharged water that finally goes to the sea. Through Tortosa, for 6 days, the river flow has been 1,300 m3 / s, which means about 674 hm3 discharged into the sea. This is practically twice what the old transfer project designed (350 hm3). One of the objections made to the transfer was that, in the few days that the flood lasts, 350 hm3 cannot be pumped through an infrastructure of normal dimensions designed to transfer that volume of water over months. The solution is an adequate hydraulic management of the reservoir that would allow the 350 hm3 to be extracted from Xerta, downstream of the reservoir, little by little, for months, before and after the floods. The more than 1000 hm3 of Mequinenza maintained throughout the year would be the guarantee of this operation.

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Another of the objections of those who oppose the transfers is that the sea needs the rivers to pour water into it, because, otherwise, its high salinization could put life in its bosom at risk. Regarding the high salinization, a simple calculation can be made to determine the variation in the salinity of the Mediterranean (water volume 2500 million hm3) due to stopping 350 hm3 of water being discharged into the sea (transferring) in one year. The overall effect on the entire Mediterranean would be ridiculous.

I propose two alternatives: one, diverting a quantity of fresh water to the south, and two, letting that same quantity of water pour into the sea and later, in the south, extracting the same quantity from the sea, but salinized, and treat it in a desalination plant to convert it into sweet, but consuming a high amount of energy, higher than that used in pumping the transfer. What is the most sustainable process?

Snow and rain storms over Navarra usually occur almost every year, sometimes in autumn (like this year), sometimes in winter. That is why this article is redundant with the several that I wrote years ago, in which I gave a lot of quantitative data on the transfer. As examples, I will cite two published in INFORMATION: “A round with the Ebro (I)”, 9/5/2006, “A round with the Ebro (and II), 9/20/2006.

In other times, scholars like Joaquín Costa and Lorenzo Pardo and even politicians like Indalecio Prieto were in favor of the redistribution of river waters in solidarity with dry Spain. However, now politicians, and also to be politically inclusive, they oppose the transfer of the Ebro and also the Tajo-Segura. Some use the climate change mantra as an argument. But, with or without climate change, snow and rain storms in Navarra will occur for many years so that Arga, Ega and Aragón will continue to make the Ebro male.

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