Thanks to the data provided by the authorities and on initiatives such as embalses.netwe have at our disposal complete information of the state of the hundreds of reservoirs that populate our environment. However, for some time the experts have noticed us with a problem that make this data in principle precise and observational into something more similar to estimates.
It is the problem of sediments.
Decades of accumulation. The reservoirs, in addition to accumulating water accumulate sediments. This involves a problem since they occupy a growing proportion of the volume of Spanish swamps, with the aggravating fact that it is very difficult to estimate the exact proportion in each case.
Fortunately, the echoes of drought have abandoned us (for now), but during the last months of water bonanza, some swamps even had to release water after their filling. Part of that water could have been used if their place had not occupied these sediments. It is for all this that the sediments have been called the “silent thief” of the reservoirs.
Difficult solution. This accumulation is due to dynamics associated with the very nature of these great reserves and the architectural barriers that create them. That is why impossible to prevent this accumulation from being more or lesser extent, so we only have two options left: living with sediments or performing periodic dredging operations to clean up these sediments occasionally.
Living with sediments. Coexistence with sediments is not synonymous with ignoring the problem. Quite the contrary, it requires more accurately to document the magnitude of this phenomenon. The speed at which sediments accumulate in the reservoirs in the form of sludge, sand and other materials depends great
Considering all these variables is complicated, so observational studies are also an option. The study of the lacuestre bed through batimeters would allow us to know the status of the bottom of the reservoir without having to empty it or resort to indirect estimates.
Knowing the degree of accumulation of sediments in reservoirs can help us adjust your real capacity and to know more accurately what are the real water resources we have and what is the rhythm to which we spend them. Of course, this solution does not solve the problem of loss of reservoirs capacity, but at least allows us to work with it.
Studies. We do not have a general idea of the state of the sediments in our reservoirs but we do have a record of some studies and estimates carried out over the last years. The problem today is that the number of studies is limited and its diverse results.
We have an example in the study conducted in 2018 by the Tajo Hydrographic Confederation, which estimated an insignificant accumulation of sediments. At the other extreme, a batimetry study conducted by the Safe Hydrographic Confederation indicated a loss of capacity in the basin between 10% and 40%.
A third study offers us a somewhat more global vision. Made through 110 reservoir analysis, this third work estimated a loss of capacity of our reservoirs of about 5%, an intermediate result between those described above.
Dranging the reservoirs. The solution to the problem could be in the dredging of the reservoirs. This option would allow them to recover their original capacity but at the same time raised a challenge due to the number of swamps existing to the country. A challenge and considerable investment.
These types of operations are not, however, a mere utopia. In 2024 the Ebro swamp began dredging operations to release one of the disaggers of the dam, useless as a result of the accumulation of sediments. The budget of the work: 2.5 million euros.
In WorldOfSoftware | The time of truth of the Spanish reservoirs: how are they going to endure the heat after rains that has left them overflowing
Image | Pilar Flores
