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Story #1

What Water Can Take from Us

Visualising flooding risk in Spain through high-value datasets

Published on 25 November 2024

This story about flooding risk in Spain is the first in a series that illustrates the power of high-value datasets to inform discussions about issues of public interest. Each story is paired with a visualisation note — an article that introduces the reader to the language of data visualisation.

Climate change and sea level rise are increasing the risk and frequency of fluvial and coastal flooding for millions of people all over the world. In Spain alone, a 2019 study estimated, around 200 000 people may be at risk of coastal flooding in the next few decades. On 29 October 2024, heavy downpours in eastern Spain, particularly in the region of Valencia, caused rivers to overflow and led to catastrophic flash floods resulting in a very heavy deathtoll.

Several high-value datasets — data that the European Commission has recognised to have potential to benefit 'society, the environment and the economy' — identify parts of Spain that may be exposed to flooding in the future and the possible damage that they may face.

Many of these regions are densely populated or have substantial historical, economic or environmental relevance.

This story uses Spain as an example of how to combine different datasets related to flooding risk to build a story to inform public debate about how to face this challenge. This data-driven story could be easily applied to any other European Union (EU) Member State that generates similar datasets.

Let's visualise this data.


These are the main rivers in Spain…

…and these are the parts of Spain that are at high risk of fluvial flooding. They may be hard to see, so…

…let's exaggerate their width a bit so they become more visible.

Some parts of Spain will be more prone to flooding than others. For example, here's the Guadalquivir River basin. A large portion of it is a low-altitude alluvial plain called the Baetic Depression.

Several cities, such as Córdoba...

... and Seville, are located in it.

The Guadalquivir River basin may be at risk not only of fluvial flooding, but also of coastal flooding in the not-so-distant future. Climate change and sea level rise may increase this risk.

Let's now zoom in on the mouth of the Guadalquivir River...

... where it meets the Atlantic Ocean in the city of Sanlúcar de Barrameda.

The Guadalquivir Marshes, from which a large portion of Spain's rice production comes, are located in this area.

The economy of municipalities such as Isla Mayor is greatly dependent on rice.

Doñana National Park, one of the largest remaining wetlands in Europe, home to several endangered species of mammals and birds, will also be negatively affected in the future. Doñana has been a UNESCO World Heritage site since 1994 because of its biodiversity and environmental relevance.

High-value datasets help us identify points that may be at risk of flooding all over Spain. These can be anything from public infrastructure sites to locations of high cultural, historical or economic value.

Properties close to the part of the Guadalquivir River depicted on this map may also be at risk of flooding in the future…

…and so may be the more than 6 000 people who live in the area.

Next, let's zoom out to see the entirety of Spain again and display the areas at risk of fluvial and coastal flooding in the future.

Let's imagine that we could merge all these areas together into a circle.

How big would this circle be? What if we compare it to a region that you're familiar with? In the box below you can search for your town or city and the circle will be positioned around it, to give you a sense of its size. Give it a try!

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High-value datasets used in this story