The month of March 2013 was the rainiest since recordkeeping began (around 1947, according to the Spanish Meteorology Agency, AEMET). We all probably realised this because of the number of days we had to bring our umbrellas with us, and also because of the images of water discharges and full reservoirs on the TV news. The fact is that reservoirs play a decisive role in ecosystems, although people are not generally aware of this.
As the main hydroelectric operator in Spain, Iberdrola makes a significant contribution towards mitigating the damage caused by the heavy rainfall, as it manages 8,232 megawatts in four different river basins. This means it operates 73 power plants, 69 dams and 119 weirs, with a maximum capacity of 11,500 Hm3.
Precisely because of the significant value of these ‘hidden services’ provided by reservoirs, I would like to talk to you about the Biovalora project. This initiative was started by the Basque Ecodesign Centre (IHOBE) a year ago and has been supported by Iberdrola throughout. It aims to define a methodology for assessing the economic impact of these services.
The project was carried out in the Tera river basin (Zamora); to be more specific, at the following power plants: Cernadilla (installed capacity of 30 MW and reservoir capacity of 255 Hm3), Valparaíso (68 MW and 162 Hm3) and Agavanzal (24 MW and 34 Hm3). These facilities were selected because they combined a representative number of the ecosystem services to be assessed, such as supplying water for fire prevention, irrigation and human consumption, flood control, recreational tourism, water treatment, etc. In order to ensure the most reliable results, it was decided to cover the longest possible period of time. For data availability reasons, the period chosen ended up being the last 10 years.
I must say that I myself was the first to be surprised by the results of the project, because I wasn’t aware of all of the effects of reservoirs or just how important they are. For example, I was struck by the fact that some qualitative considerations obtained in the study were almost more relevant than the economic assessment, such as the importance of supplying water for irrigation purposes. This is one of the most important services provided by reservoirs, because it allows for development in irrigated areas that would not be possible under normal conditions. This in turn has enabled economic development in countries that would otherwise have been affected by serious economic and population decline, if they had been solely reliant on rain-fed agriculture.
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Another very important function worthy of notice is supplying water for fire prevention purposes. The Biovalora project calculated that a surface area of 590 hectares of land is saved from fire every year because of the water siphoned from reservoirs and discharged by hydroplanes, in the area of Zamora and part of León and Salamanca.
Flood control is another key function of reservoirs, perhaps the best known by the general public. It consists of controlling the torrential rain run-off so that most of it is stored. This reduces the impact of the excess water. The study revealed that the flood control capacity for the Tera system was 50%, with a 31% reduction in the impact caused. In other words, the reservoirs included in the study reduce the number of floods that would occur in the area under normal conditions by half. As regards those that cannot be avoided, they allow to reduce by a third the value of the economic damage caused.
This data is not directly replicable for the rest of the river basins, as every reservoir system provides different services and in varying proportions. However, I believe that the results obtained illustrate the importance of these services, which are sometimes not known about but are nonetheless crucial for their local ecosystems.
Personally speaking, the Biovalora project has helped me to realise the sheer scale of the assets and the work we do in the Hydraulic Generation Department. It has also helped me to learn more about an area, the Tera river basin, which I would encourage you all to visit. The Sierra de la Culebra mountains and Puebla de Sanabria are two examples of these incredible landscapes, which are very rich in terms of nature and culture.
Finally, I would like to thank everyone that took part, as their experience and generosity made it possible to successfully complete the Biovalora project. I would especially like to thank the staff in charge of the Duero river basin, the Environment team at Iberdrola, and the staff of IHOBE, who organised the initiative.
