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In this series of photographs in La Vanguardia Readers’ Photos I show the before and after of the Vallvidrera reservoir. Everything changes and nothing remains –remember the article on Heraclitus of Ephesus–, since everything is subject to continuous change.
In this case, the after is the consequence of the simultaneous occurrence of two events: the intentional emptying of the swamp to eliminate an invasive species and the persistent drought.
Two events that from their beginnings were the chronicle of a death foretold, the death of the Vallvidrera reservoir. There is no water left in the swamp. It’s completely dry.
There are no more fish, no turtles, no kingfishers, no herons and the local fauna can no longer quench their thirst there. At the time of making this photographic report I was able to walk on what years ago was the bottom of the swamp.
I have taken the photographs from the deepest part at the base of the retaining wall. The mud is dry although occasionally there are areas where it retains some moisture and grass and bushes begin to make their way over land that was once submerged.
I have been able to confirm that the reservoir has two limnimeters or water level measuring devices. The old one is engraved on the same wall with tiles with a number that marks the depth. There are four tiles placed vertically and marked with the numbers 1, 2, 3
and 4 respectively, it being understood that the unit of measurement is the meter. In the middle of each pair of tiles there is a rectangular plate without a number, consequently, this device measures the water level with an accuracy of 0.5 meters.
Right next to it is the modern limnometer, a metal bar (made of aluminum to prevent corrosion) located vertically and graduated in the decimal metric system (every 5 centimeters has a mark, therefore, its precision is 0.05 meters).
When it comes to making measurements to minimize errors, the same measurement is usually carried out several times with the same or different measuring devices. What does not fit into anyone’s head is that the devices with which it is measured are poorly calibrated or are out of phase.
I personally trust the ancient device more because the tiles were placed when the reservoir was built, a marvel of engineering at the time, and they indicated the actual bottom of the reservoir at the time it was built.
The bottom of the swamp is above the rectangular mark between 0 and tile 1 of the old limnometer, that is, approximately 60 centimeters from the actual zero level, a distance that coincides with the phase difference between both devices. This means that there is exactly 60 centimeters of sediment accumulation and that the modern limnometer was placed 60 centimeters above the actual zero.
I must point out that at the time it was stated that the invasive species, Paramisgurnus dabryanus, is capable of surviving by burying itself in mud to avoid drying out. If it does not rain, next summer the sludge will finish the drying process and the bottom should be cleaned, sludge removed, in short, maintenance that is already needed.
There is a detail that has not gone unnoticed: the fountain next to the reservoir, next to the watchman’s pink house, exactly where the picnic area is with some wooden tables and chairs anchored to the ground.
At that fountain someone, probably the owner of a dog, I don’t know if intentionally or by forgetfulness, left a plastic container (tupperware) so that the animals could drink.
The truth is that, since the swamp is empty, the animals benefit from that container full of water. I noticed a robin and a Eurasian jay quenching their thirst.
Days after taking the photographs I returned to the Vallvidrera reservoir with the new year. And, upon arriving, I was able to verify that the plastic container was still there, although not in the fountain, but lying on the floor and empty.
So I took it, I filled it with water and I placed it on one of the tables in the picnic area, I sat right next to it, after which I began what every photography fan should have: patience and know how to wait
In less than 5 minutes the first visitor appears, a robin that perches on a branch of a tree in front of me.
The robin has a characteristic that differentiates it from other birds. It is extremely sociable, it is not afraid of the presence of man, so it did not hesitate to come down from the tree and perch on the table a few centimeters from me.
He then went towards the plastic container, started drinking and this allowed me to take the second photograph, which is not easy to achieve due to the pose that the bird adopts and which I also share.
Other small birds came close to perching on the tree in front of me but were not able to come down to drink. They were more fearful and when they saw me move they fled.