Locating people swept away

A study led by Francisco Vallés Morán, a researcher at the Institute of Water and Environmental Engineering (IIAMA) at the Universitat Politècnica de València, has analysed in detail the flooding caused by the DANA on 29 October 2024 in l'Horta Sud (Valencia) using advanced two-dimensional hydraulic modelling techniques.

The study, published in Cuadernos de Geografía of the University of Valencia, accurately reproduces the dynamics of the event, the extent of the flooding and the overflowing flows that caused serious material and human damage.

Using public information and open-access tools, the research has enabled the reconstruction of the hydraulic behaviour of the Poyo–Torrent and Poçalet–Saleta ravine systems, including extreme flow velocities, arrival times at the affected towns, and depths exceeding four metres in some urban areas.

'The results show the extraordinary speed and violence of the episode, with speeds of up to 8 m/s and response times of less than an hour between the headwaters and the most densely populated areas,' says the IIAMA Research.

Main conclusions

The study confirms that hydraulic modelling reproduces the reality observed during the storm with sufficient reliability, both in terms of the extent of flooding and water levels, as well as the temporal evolution of the process. In addition, it highlights the decisive role of certain transport infrastructures, such as the V-31 motorway, which generated backwater effects and contributed to worsening the flooding upstream.

'The results also show the consistency between the overtopping flows and the historical geomorphology of the territory, shaped by paleochannels and areas of natural water accumulation, which reinforces the robustness of the analysis carried out,' highlights Research Francisco Vallés.

Innovation: a tool for locating missing people

One of the main innovative elements of the work is the development of a tool based on the hydraulic power of the current as an indicator of its carrying capacity.

This approach enables the identification of the trajectories of the most energetic overtopping flows, specifically the areas where this energy is dissipated, which are the most likely to accumulate people or objects carried away by the flood.

"This methodology was applied during the October 2024 episode and proved useful to the emergency services, facilitating the search for missing people. The tool, which can be exported in georeferenced formats for direct use, represents a significant advance in the application of hydraulic knowledge to emergency management," says Professor Vallés.

Additionally, the results offer valuable insights for evaluating existing infrastructure and developing adaptation strategies in response to the increasingly frequent and intense events associated with climate change.

For all these reasons, the work demonstrates that applied hydraulic science can play a key role not only in flood risk planning and prevention but also in operational response during emergencies.

'The possibility of having reliable simulations in near real time opens up new avenues for improving decision-making, optimising the search for missing persons and, potentially, saving human lives in future extreme events,' he concludes.

REFERENCIA:

Vallés-Morán, F. J. (2025). Simulación hidráulica de la inundación y flujos desbordados en la DANA del 29 de octubre de 2024 en l’Horta Sud (Valencia). Cuadernos de Geografía, 114-115, 375-395. https://doi.org/10.7203/CGUV.114-15.32121