On October 29, 2024, an episode of torrential rains shook the Valencian Community, leaving behind a trail of devastation and numerous flooded municipalities. The response of the University of Valencia (UV) was not long in coming: a multidisciplinary team of experts created in record time the first accurate mapping of the areas affected by the DANA. This map not only documents the impact of the disaster, but also seeks to establish the basis for better future emergency management
Coordinated by Professor Carmen Zornoza, from the Department of Geography, the project brought together researchers such as Javier Serrano and Ana Belén Ruescas, with the collaboration of the Image Processing Laboratory (IPL). Using remote sensing tools and citizen participation, the team improved the initial delimitation provided by the European Copernicus program, which offers a quick map of the affected area after emergencies such as the DANA. “Our goal was to provide fast and accurate information to assess damage, manage aid and propose long-term solutions,” explains Zornoza.
The map revealing the true dimension of the DANA
The University of Valencia team's mapping arose from the need to accurately show the extent of the emergency. “Seeing the magnitude of the tragedy, we knew we needed to know how far the flooding had reached. The first Copernicus layers, although fast, did not reflect reality, especially in urban areas. Many towns in l'Horta Sur, such as Massanassa or Sedaví, were completely flooded, but they were not included,” says Zornoza.
The team organized itself quickly, working remotely. “We, who know the terrain and many of the people affected, knew it was urgent to improve that information,” adds Zornoza. Through video calls and remote coordination, each member contributed resources: Serrano used his networks to obtain key data, while Ruescas integrated remote sensing tools. “As coordinator, I was in charge of delimiting the area to publish a more accurate map in the flood,” she concludes.
The result was a more accurate tool, which not only reflects the immediate effects of the DANA, but also serves as a basis for future risk management strategies.
The role of mapping in disaster management
Floods caused by extreme phenomena such as this DANA are increasingly intense and frequent in certain areas of the Mediterranean, such as the Rambla del Poyo, a ravine that has been studied for decades by the Professor of Physical Geography Ana Camarasa, who currently heads the Department of Geography at the UV. For her, ‘mapping is the first step in understanding the magnitude of the disaster and planning for effective recovery. But it should also be an educational tool that helps citizens to know their territory and to act safely in critical situations.
This educational approach is central to the research projects led by Camarasa. The expert warns about the lack of risk perception in usually dry areas: ‘Many people do not understand that they live in flood-prone areas. Social education should aim to change this mentality and encourage self-protection.
"Our aim was to provide quick and accurate information to assess damage, manage aid and propose long-term solutions"
Citizen participation: key to defining the flood map
The work of the Universitat de València in the creation of the flood map was possible thanks to the close collaboration with the citizenship. Javier Serrano, professor and coordinator of this task, stresses the importance of this contribution: ‘Without their help it would not have been possible to delimit areas such as the southern part, Beniparrell and all that area up to the Silla industrial estate. Without being there and seeing it in person, we would not have been able to see the extent of the flooding and the extent of the destruction in the Horta Sud. This process would not have been feasible without citizen collaboration.
Since it was impossible to carry out fieldwork immediately due to the reports blackout, a system was put in place to collect information remotely. ‘We couldn't travel, which would have been the quickest way. So we started contacting people in the affected areas: town councils, social services, friends and even students of the Geography and Environment degree,’ explains Serrano.
The methodology consisted of sharing the preliminary map with these contacts and asking them for corrections or extensions: ‘We said: “This is what we have, can you correct it, extend it or confirm it?” The response was very positive. In just a few days, between 50 and 100 people gave us very quick feedback, which allowed us to refine the delimitation much better’. Citizen collaboration was key to perfecting the map with great precision in record time.
Satellite technology: an indispensable tool in emergencies
Satellite images played a crucial role in this project, as Ana Belén Ruescas, professor at the Department of Geography and member of the Signal and Image Processing Group of the PIL-UV, explains. ‘In emergencies like this, satellite technologies and images are fundamental because they offer a global view of an area that would be very difficult to obtain by physically moving around,’ he explains.
These images allow us to analyse large areas and extract key information using mathematical algorithms applied to different radiation ranges. ‘With them, we can get a very precise view of a very large area, which is very helpful. It is true that the human factor is indispensable to validate these data, but as a research and analysis tool it is extremely valuable,’ adds Ruescas.
Thanks to this technology, the team was able to integrate satellite data with information provided by the citizenship, providing a comprehensive tool to delimit the extent of flooding and act more effectively.
Climate change and resilience
The impact of the DANA highlights the need to integrate climate change into spatial planning. According to Ana Camarasa, Mediterranean wadis, such as the Poyo, are showing more extreme behaviour due to the specialty of the hydrological cycle. ‘Climate change not only increases the frequency of these events, but also alters the natural dynamics of the watercourses,’ she explains. Against this backdrop, he points out that we cannot rely solely on structural solutions: ‘Concrete works give us a false sense of security. Altering the natural cycle also has consequences’.
For Camarasa, it is essential to combine traditional measures with nature-based approaches: ‘A river or a wadi has the task of carrying water and sediment to the sea. If we obstruct their path, they will look for another outlet or cause greater damage. These solutions must allow ecosystems to perform their function without increasing risks to the population.
For the UV team, flood mapping is only the first step towards more effective risk management. Ana Camarasa emphasises the need for better communication and education about these phenomena: ‘What happened during the DANA, with people trying to save their cars instead of protecting themselves, cannot be repeated. This is evidence of a lack of knowledge that we must overcome through teaching, education and dissemination, working from the University and in collaboration with public administrations, firefighters, Civil Protection and other sectors’. Camarasa stresses that promoting risk perception and training citizens to understand the territory in which they live and how to act in the event of an emergency is key to preventing dangerous situations in the future.
Towards a safer future
The cartography created after the DANA has been incorporated into the official viewer of the Institut Cartogràfic Valencià, where it serves as a reference for institutions and public administrations. This achievement not only demonstrates the technical and scientific capacity of the Universitat de València, but also its commitment to the territory and its citizens.
What we have learned from the DANA is that we cannot fight against nature, but we can work with it and prepare ourselves better As extreme rainfall events become more frequent, initiatives such as this mapping become indispensable tools for building resilience and saving lives.
The UV team continues to work on new research and educational strategies to reduce the impact of future disasters. In the meantime, his message is clear: knowledge and prevention are our best defences against the force of nature.