Francisco Vallés, a researcher at the Research Institute for Water and Environmental Engineering (IIAMA) of the Universitat Politècnica de València (UPV), has developed a new hydraulic model to help locate missing people after torrential episodes such as the one caused by the DANA on 29 October in the province of Valencia.

The model makes it possible to study the trajectory followed by an overflowing flow from a certain point to its mouth and estimate the speed of the water and the height reached. From this information, it obtains the hydraulic power of the overflowed flow, which indicates the current's dragging capacity, the key to this model.

'By overlapping the information layer with the current trajectory one, it is possible to track the current until it loses enough energy to deposit the entrained elements. For this purpose, a threshold of hydraulic power of the flow has been established below, and it is assumed that the current does not have sufficient dragging capacity,’ explains Francisco Vallés.

The UPV researcher has developed a hydraulic model of the Poyo ravine, from the junction with the A3 to its mouth at La Albufera, analysing different parameters and variables recorded in its basin and extending the study to the Gallego, Horteta, Pozalet and Saleta basins as well.

To create the model, Vallés worked with the cartography of the area, accessible at the Valencian Cartographic Institute; he also analysed the rainfall data published by AEMET and AVAMET, as well as the records of the gauging station of the Júcar Hydrographic Confederation located in Ribarroja, just downstream of the junction of the Poyo ravine with the A3 motorway.

‘With all this data, I was able to reconstruct the hydrograph of the Poyo and analyse what is known as the flood stain - how far the water reached - and the behaviour of the flood in the other basins, with the hydraulic power as the final reference value. There is a threshold at which the current slows down and deposits everything it carries; the model helps to determine this limit and thus identify areas ideal for searching for missing persons,’ explains Francisco Vallés.

To generate this model, the IIAMA-UPV researcher worked with a large number of calculation cells, specifically 415,000, to achieve the most precise geographical delimitation possible of the flooding area.

However, Vallés stresses that ‘the model is designed as a support tool. It results from data collection work and many hours of calculation, with data recorded from the dana of 29 October. Still, it could be applied to any similar episode, with one objective: to help from the first moment in the search for missing persons,’ concludes the UPV researcher.