Interview with Enrique Velasco and Arnau Cangros Department of Water Management, Area of Water Supply, Catalan Water Agency

Enrique Velasco and Arnau Cangros
Department of Water Management, Area of Water Supply, Catalan Water Agency

The Catalan Water Agency (ACA) is a public company responsible for the planning and management of the complete water cycle in the inner river basins of Catalonia, Spain.

We interviewed Enrique Velasco (head) and Arnau Cangros (technician) of the department of water resources management at the ACA.


1. How would you describe the ACA's mission in a few words? What is your own role within the agency?

The ACA has the mission to manage the integral water cycle of river basins which includes planning, provisioning, sanitation and environmental aspects. We are part of the water supply area that has the aim to guarantee water supply to the different users in the Catalan River basins. One aspect of our daily work consists of monitoring the water supplied to hydropower plants while avoiding water flow oscillations (higher and lower than normal water levels) that could affect the functioning of the hydropower plants themselves, the environmental quality of the basin or the performance of drinking water treatment plants (WTPs) located downstream. Controlling these types of oscillations is important, on the one hand, to avoid the waste of excess water that ends up in the sea and, on the other hand, to sustain the minimum flow required for the water treatment plant functioning.


2. Many of your daily decisions at work depend on climate conditions. Do you use climate information in your work? If so, how often and which kind of information?

We use climate information regularly in our work. Following the official procedure, we check the predictions of the Catalan Meteorological Service (Servei Meteorològic de Catalunya, SMC) for precipitation alerts. The aim of doing so is to identify emergency situations that could lead to possible flooding events and to provide a corresponding alert to the Catalan Civil Protection. Based on the predictions from the SMC, we are able to generate two different types of alerts: precipitation alerts that account only for the meteorology and river alerts taking into account both precipitation and run-off. The latter are more precise and in general tend to predict flooding events better.

On a day-to-day basis, we use meteorological predictions to manage basin user demands. Looking at the prediction up to two days and the forecasted demand we can manage reservoir water to fulfill user needs. The daily management allows us to adapt to changes while saving water. Additionally, every six months takes place the reservoir withdrawal commission, which has the obligation to render an account of its management and agree with users on the future water consumption for the next six months.


3. How do weather and climate forecasts help with the professional decisions that you make? Which decisions can they inform?

Different types of decisions can be informed according to the scope of the forecasts provided. For example, forecasts of up to 2 days (which is the average travel time from the reservoir to the point of demand, i.e. drinking WTP) are used to plan short-term reservoir management. We need these predictions at high spatial and temporal resolution to have information about the volume of water carried by the river upstream and downstream to the point of demand. For instance, if we are able to know with a high level of reliability that tomorrow it is going to rain, we can decrease reservoir water releases and save this water for the future, since part of the demand downstream will be already covered by rainwater.

Forecasts for the next 4-6 days are used for reservoir safety and planning in the case of extreme events. If reservoirs are full and an extreme rainfall episode is predicted to occur, we can decide to release water in a controlled way during the 4-5 days previous to the episode. In this way, we empty some reservoir space that can be used to store the run-off water generated during the rainfall event and therefore, we can avoid damages downstream. A key point in the management of water reserves is that, at the end of the episode, reserves in the reservoir should be equal or higher than before the rainfall event.

Seasonal predictions for the next 1-6 months are used to define how to distribute the water that is stored in the reservoirs for the different uses existing in the river basin during the reservoir withdrawal commissions. These forecasts are critical to manage, for example, the uncertainty in the occurrence of possible drought episodes. In order to be prepared for droughts, the ACA is working on a plan to manage water reserves in a totally innovative way using the Special Drought Plan (Pla Especial de Sequera, PES).

These levels of the PES shown in Fig. 1 are, from low to high, alert, exceptionality and emergency. When reservoir water availability is approaching the alert level, the users would know in advance the water restrictions expected for each scenario. Therefore, the estimation of future water reserves accounts only for past events, with the associated limitation that we cannot predict situations that have never occurred before and that will probably occur under climate change.

Fig. 1: Statistical seasonal forecast for the inner basins of the Ter-Llobregat system
 Fig. 1: Statistical seasonal forecast for the inner basins of the Ter-Llobregat system

4. Given that the aim of the IMPREX is to advance the state-of-the-art of operational hydro-meteorological forecasting systems, by improving meteorological and hydrological models, creating simple climate indices and tailoring climate information to the users, do you think that IMPREX’s work could respond to ACA’s information needs? In which sense?

IMPREX can certainly respond to our needs by improving hydrological models and providing reliable and transparent information that can be readily used by the Agency.

Whereas in many cases weather and climate predictions cannot provide accurate enough information for decision-making, variables like the future water volume stored in reservoirs can better inform reservoir’s management along with the final decisions taken by water users. In this sense, a big qualitative improvement will result from integrating seasonal climate predictions in the estimation of future reservoir water volumes. This will probably narrow the probability distribution curve based on climatology that we currently use to estimate future water reserves.

Besides water volume, having information on drought indices could also be extremely useful for the ACA. Actions taken during long periods of drought tend to be drastic and expensive. Having information on the length of the drought period can therefore support the selection of management measures (i.e. if we know that in two months there is a high chance of rain in the basin, the measures that we will apply will be softer than if the drought season is known to be much longer. In the latter case, extreme solutions, such as the construction of new and costly infrastructure, would need to be proposed instead.


5. What would you list as main barriers that prevent a wider application of climate information within the water sector?

The lack of a direct relationship between precipitation and river flow is one of the greatest barriers that we face. River flow does not depend only on the water that comes from the rain but also on other characteristics of the river basin.

The water content in the soil plays a very important role, since it determines the run-off and the total volume of water that reaches the river channel. With the same amount of rainfall, a huge increase in river flow could be experienced if the soil is already saturated with water. Conversely, the increase in river flow could be almost imperceptible if the soil is dry and therefore water infiltrates and does not become run-off.

Other parameters like land use are also important in this process. For example, forests (especially non-managed forests) act as water sinks, increasing water evapotranspiration and therefore avoiding this water to reach the river channel. In fact, it is known that forests can take up to 80% of rain water.

Spatial resolution is also another issue. The size and heterogeneity of the river basins that the ACA manages are not captured in the model outcomes that provide predictions at 80km cell resolution.

All these things need to be taken into account when predicting the amount of water that will be available in the future, and they are neglected when looking exclusively at weather and climate prediction data.


6. What do you see as being the impact of better climate predictions in terms of business? Who do you think will most benefit from better climate predictions in your region?

Better climate predictions will allow for increased trust in the predicted future scenarios. In the case of the ACA, we don’t have the responsibility to take the final decision, but we make all the information available to support the decision-making of water users.

Every six months, reservoir withdrawal commissions are organized to accommodate the water demands of the different economic sectors in the basin (farmers, industry, recreation, hydropower production, environmentalists, etc.). Water is distributed among the sectors based on the predicted availability of the future water resources in the reservoirs. For this reason, the more accurate the prediction, the more benefits users will obtain, since their decisions will be safer. Imagine a farmer that would ideally need 0.1 Hm3 of water to irrigate crops. If water reserves are not enough, it can be that his initial demand cannot be covered and that only half of it is guaranteed. At this point he is confronted with an important decision: i) take the risk and invest in planting the planned amount anyway, ii) plant only one half of the crop and do not risk too much, or iii) go for another crop that requires less water. Although the first option is more risky, if finally the season is more humid than predicted, the farmer would benefit from choosing the first option. However, more conservative options like the second and third, would be more beneficial in the case of a dry season. In summary, better climate predictions could reduce the risks taken by farmers and other sectors that depend on water availability in the basin’s reservoirs.


7. How do you see the future of weather and climate predictions? Are you optimistic about their potential to support water management?

We are optimistic about the application of future weather and climate predictions to the water management sector. However, it is crucial that these predictions are accurate enough to reduce the risk of taking wrong decisions, since this can result in economic losses and loss of credibility.

From our experience, there is a need to integrate weather and climate predictions in the development of models and indices that are particularly tailored to the needs of the water sector. By this, we mean providing information on water volumes or drought indices that are readily usable to inform the regular decisions that the ACA faces every day. As we used to say regarding planning, “the next drought is starting tomorrow”.


For more information, you can visit the ACA website and social networks:


Note to readers:

Enrique Velasco

Civil Engineer, Head of the Water Resources Management Department in the Catalan Water Agency (ACA) and Coordinator of the Hydrological Observation and Emergency team for floods and droughts and management of infrastructure for water users (dams, reservoirs, irrigation, drinking, hydropower, fishing, recreation, environment, etc.). Enrique Vasco is responsible for various ACA FP7 and H2020 research projects and other EU programmes related to water management and associated risks. He is passionate about all that is hydrology, especially floods and droughts.

Arnau Cangros

Civil Engineer and Degree in Administration and Business Management. From 2009, Expert Technician in the Department of Water Resources Management in the Catalan Water Agency (ACA) working in the management of the telecontrol of hydropower plants and supporting the sections dealing with hydrological resources, droughts, innovation projects and corporative communication. He participates in various ACA FP7 and H2020 research projects. A very good narrator, enthusiastic about his work and interested in learning from the results of other research projects.

Enrique Velasco and Arnau Cangros


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