The Llobregat River Basin is located in Catalonia in north-eastern Spain. The Llobregat River, together with the Ter and other small basins (referred to as Ter-Llobregat system), provides water supply to the densely populated Barcelona Metropolitan District, which encompasses a population of approximately 4.4 million inhabitants.

Extreme weather events can jeopardise satisfactory water production. In this case study, a water quality model was developed to represent these events. The model will include several constituents such as dissolved oxygen, organic matter, ammonia, nitrates, phosphorous, and indirect variables such as high turbidity events in the raw water at the inlet of the water treatment plant. These high turbidity events were correlated with rain events that cause erosion of the upstream basins and removal of bed sediments. The water quality model was developed by CETaqua and UPVLC, in collaboration with local water operators (Aigües de Barcelona, Aguas de Terrassa).


This case study tested together with end-users several climate services for better-informed water resources management and planning, especially for urban water supply. Weather extremes and climate have an impact on both the quality and the quantity of water and can compromise the safety of drinking-water.

For example, droughts induce low river flow and high concentration of contaminants; intense rainfall events cause high levels of turbidity, protecting microorganisms from disinfection effects; and rising temperatures increase the probability of development of communities of cyanobacteria releasing toxins into the water.

Drinking-water suppliers are responsible for preparing and implementing water safety plans (WSPs) to manage the risks raised by these hazards. This case study helped in the development of reliable WSPs in this basin and others with similar conditions.

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