“Do not cross flood zones. If you are in a flood zone, look for high areas or go up to a higher floor”. Last Monday the Generalitat Valenciana again sent a message to cell phones in the province of Castellón through the Es-Alert system to warn the population about the risk of flooding during the storm that is battering these days the Comunitat Valenciana.
A very different message to the one that was also sent at 20:11 hours last October 29, 2024, in which it was recommended only to avoid travel. However, as seen in October, many people living in risk areas may not be aware of it.
What is a flood zone?
The classic definition would be that a flood zone is a geographical area that may be temporarily covered by water due to natural phenomena such as heavy rains, river overflows, rising sea levels or failures in hydraulic infrastructures.
In Spain, these zones are delimited by a map of the National Flood Zone Mapping System (SNCZI), which is available for public consultation.
These systems identify both the potential extent of water and the impacts on the population, economic activities and the environment.
Flood-prone areas are identified through flood hazard and risk studies, which consider factors such as the frequency and magnitude of flood events. These areas are classified according to their probability of flooding, expressed in return periods (e.g., every 10, 100 or 500 years).
The Ministry for Ecological Transition offers in the SNCZI a viewer that identifies each of the flood zones throughout Spain and allows to know their danger to avoid them in periods of heavy rains, such as the current one or October 29, 2024, which claimed the lives of 227 people, 219 in the Comunitat.
How do I know if I live in a flood zone?
You may already know, but if you are in doubt, you can check exactly which areas are flood zones near your home using this viewer.
The image above shows a screenshot of the National Flood Zone Mapping System (SNCZI) viewer. In the folder icon is the “Service Tree”, where each of the scenarios are grouped together.
It is the navigation panel of the viewer, where different layers of geographic information can be selected and allows to activate or deactivate different categories of maps related to floods and water resources.
For example, if areas of significant potential risk of flooding (ARPSI) are selected, the viewer will display different colors to indicate the areas with the highest risk of flooding, depending on the layer selected. As well as the flood risk zones according to the chosen return period, which starts from the last 10 years (high) up to 500 (low).
This is just an example of how you can consult the flood zones and analyze the risk of flooding in Valencia or other regions through the SNCZI so that, in this way, before the next warning, we can know exactly in which area we are.