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The Tajo de la Encantada dam in El Chorro in the Guadalhorce valley has successfully released a controlled discharge following the 'Dana' storm which swept through Malaga province two weeks ago. The operation to release sediment that could clog drains and lower the reservoir's storage capacity took place on Monday 11 November, ahead of more rainfall which is forecast to fall on Wednesday 13 November.
SUR was there to witness the operation at the Tajo de la Encantada dam. The water flow was very low in the early hours of the morning, but technical teams and operators were keeping a close eye on the operation at the foot of the small dam and also on the bridge that crosses it, right next to the rural hotel and the train station.
Similar maintenance operations take place dozens of times during the year in Malaga province's reservoirs, however, this one at La Encantada dam was a special one, due to the severity of the Dana storm and the amount of build-up it left behind.
The Junta de Andalucía's deputy director of water infrastructures Óscar Lorente said: "As a result of the torrential rains that occurred in the last days of October, there was a very significant contribution to the three headwater reservoirs of the Guadalhorce. This inflow not only carries water, but also carries a large amount of sediment which, as it enters the reservoirs and slows down, is gradually deposited. The accumulation of these materials carried by the floods can have detrimental effects on the reservoirs. On the one hand, they reduce the storage capacity by modifying the bottom level and they can also have harmful effects on the outflow if they accumulate nearby".
These drainage operations are key for both ordinary situations, for maintenance, and extraordinary situations, for safety, Lorente added.
"The aim of this release was to eliminate sediment. It is a low, controlled flow and it is brought to the attention of the town halls and civil protection groups," Lorente pointed out.
The three headwater reservoirs in the system are the Guadalhorce, Conde de Guadalhorce and the Guadalteba. The waters of the Guadalhorce, Turón and Guadalteba rivers and streams mainly flow into these reservoirs. In turn, on their way to Malaga city and the Guadalhorce valley orchards, they reach the hydroelectric dam of La Encantada, which is operated by Endesa. Downstream there is a canal which divides in two at the Paredones weir (Álora). There, the left bank is used for irrigation and the right bank is shared by irrigation and the water that is sent to Malaga city for urban supply.
The channel starts on the right bank of the La Encantada dam, which also has bottom spillways leading to the river bed, and it is there where the flow was discharged on Monday.
The Paredones weir reached an all-time high on 29 October: 5.84 metres deep. For several hours it was at level three risk of overflow, marked in red. Monday's flow had no affect on it. From the time it began to drain at 10am until about 3pm in the afternoon, the depth was about 60cm. At 4pm, it was increasing with a flow of 4,600 litres per second, and by 5pm it was already 11,000 litres per second, but the depth of the river at that time was 1.30 metres. At 6pm, 12,000 litres per second (1.34 metres) flowed downstream. The level rose slightly at 7pm and the outlet from La Encantada was closed, with the maintenance operation declared a success.
These operations take place in the three headwater reservoirs from time to time, but their effects are not felt in the flooding of the watercourses as they are discharged into La Encantada. All the reservoirs in the province have periodic releases. For example, in El Limonero and Casasola they are vital as they are two safety dams, for flood abatement. They always leave a very large buffer and are filled just enough to provide a margin in the event of flooding. The one located on the Guadalmedina, in Malaga, releases water on the first Wednesday of each month, and the second, on the Campanillas, in Almogía, does so on the last Thursday of each month.
The rise in the level of the province's reservoirs following the Dana has now stabilised, with an overall gain of 50 cubic hectometres. This has been a good boost for the Guadalhorce system, whose headwater reservoirs have exceeded the 71 cubic hectometres which marks the end of severe drought. Before the Dana storm, they were on the verge of dropping below 40 cubic hectometres. However, only the Costa del Sol, thanks to the good state of the La Concepción reservoir near Marbella, can breathe a sigh of relief, being officially outside the drought threshold.
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