What is happening in the Neuquén river is a explosive mixture of a premature melting of snow, the result of not so low temperatures and heavy rains, which cause a flood that the long period of drought had been denying it. They will not be super extraordinary levels like those of 2006, but they will force the complex of Cerros Colorados dams and reservoirs to be managed very precisely to absorb what comes down from the north of the province.
The consequences of this phenomenon began to be seen on Friday in the rivers in the north of the province of Neuquén, which like capillaries are giving shape to the channel that gave the province its name.
This large amount of water is already reaching the only hydraulic work that regulates the Neuquén River, Cerros Colorados. It is estimated that the flow will go from the 123 cubic meters per second that it had until Friday to about 5,500; Such is the magnitude of the flood.
Flooding of the Neuquén river: A flow that will rise in an extraordinary way
This Sunday the Interjurisdictional Basin Authority reported that these 5,500 cubic meters per second is a medium estimate; There may be higher flows depending on the time of day.
In order to drive such a mass of water towards the Cerros Colorados reservoirs (Los Barreales and Mari Menuco) it is gates need to be opened downstream of the damsThis is why the river will reach Centenario and Cinco Saltos with up to 600 cubic meters per second during the week (today it is around 80).
The Neuquén river is less mighty than the Limay (even less in the last 20 years), but due to the characteristics of that area, with high peaks, sparse vegetation and a height difference that becomes abrupt, this type of flood is not ( or was not) strange. In fact, since there are records, he has been responsible for several extraordinary situations, such as the one in 1899, which reduced the General Roca Fort to ruins.
17 years ago, a very similar but larger phenomenon put the management of the basin to the test. And the result was successful because the first of the Cerros Colorados dams, Portezuelo Grande, was able to divert a mass of water never before recorded towards Los Barreales: more than 10,000 meters per second.
In 2016, the Portezuelo Grande dam endured the maximum flood recorded in history (Photo: AIC)
The Interjurisdictional Basin Authority (AIC) issued an alert that must be corrected hour by hour, not because it is wrong, but because the records in the rivers are giving a higher estimate than expected.
Another basin in the north of Neuquén, that of the Colorado River, also receives extraordinary contributions during these hours for the same reason. The corresponding interjurisdictional committee, Coirco, announced that there will be a significant increase in flows, that even Casa de Piedra (north of Roca) has no other regulation than the small Divisaderos dam, between Catriel and 25 de Mayo.
Without Cerros Colorados, the situation would be serious because there would be no way to stop such a flow. What is planned is within the containment possibilities of the complex, but for that the reservoirs must enter what is called the “flood attenuation strip”: open the gates downstream.
It is very probable that towards the south of El Chañar there are complications with the supply of water for human use; It has already happened other times due to the turbidity that usually causes a sudden change in flow.
On the Limay River there are five dams with their reservoirs, two of them large, to absorb the flood. Like a domino effect, the plants can be operated so that the greatest flows reach El Chocón, whose lake has low levels, without problems.