Accumulated sediments are a huge problem for reservoirs. And in the Ebro they have taken drastic measures

The reservoirs, both those for hydroelectric use and those for consumptive use, are a vital element in the hydrological panorama. However, for some time, experts warn of a problem that is aggravated over time and affects their functionality. He sediment problem.

Half year of works. The works initiated last August to recover the drain of the Ebro reservoir will extend, predictably until 2026, according to They have indicated from The Montañés newspaper. The works, in addition to introducing improvements into one of the swamp drains, intend to recover their functionality from the accumulation of sediments in this.

The tasks, explains the local newspaper, will require a team of divers for 3.5 meters of accumulated silt next to the drain gates. The works, with a budget of 2.5 million eurosthey will imply the installation in each of the ducts of the security gates with By-Pass and gates for the regulation of flows.

The Arija swamp has two drains, one side and the other located in the dam. It is the latter that, as a consequence of the accumulation of sediments, has lost the ability to perform its function.

Key reservoir. The Ebro or Pantano de Arija reservoir is a key element in the Ebro hydrographic basin. It is one of the largest reservoirs in this hydrographic demarcation (behind those of Mequinenza and Canelles).

Located in the immediate vicinity of the Cantabrian city of Reinosa, the border between this Autonomous Community and that of Castilla y León in the province of Burgos. According to the latest datathe reservoir Albeca now 348 hm³ of water, 64.3% of its capacity (541 hm³).

Some data that do not always reflect reality, precisely due to the problem of sediments.

Limiting the capacity. The problem of sediments Not only does it affect the functionality of the drains of the reservoirs: they also limit their capacity. Decades of use have led to a significant accumulation of sludge and sediments in the reservoirs, sediments whose volume implies a significant reduction in the storage capacity of the swamps.

Estimates of this loss vary significantly, but the most pessimistic talk about a loss of up to 40% of the volume In some basins. A study in 110 reservoirs launched a more optimistic but still alarming estimate, A loss of 5%.

The latest rains seem to have helped reverse the drought situation that still affected some areas. However, our ability to prepare for the next drought is limited by this accumulation of sediments in the reservoirs.

Where the sediments are missing. As if this were not enough, the problem of the sediments left over on one side is the problem of those missing in another. In this case, In the Ebro Delta. The Ebro delta is nothing more than the result of the accumulation of sediments dragged by the river current.

The installation of numerous dams in this hydrographic basin has reduced the arrival of this matter to the mouth, which, together with the natural coastal erosion, has put the delta ecosystem at risk. An ecosystem on which not only depends the local fauna, but also a part of the agriculture and the economy of the region.

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Image | Josu Aramberri, CC by-SA 3.0