The Spanish Levant has once again suffered a tragedy due to flooding due to DANA, the worst of the 21st century. Beyond adverse atmospheric phenomena, increasingly ferocious and frequent, according to climate change experts, and warning systems activated with little margin, there is the adversity that a large portion of the population lives in potentially flood-prone areas.
In Spain, four million people live in a flood zone. In the Júcar basin, which practically covers the entire Valencian Community, the south of the province of Teruel, the north of Murcia and the western halves of Cuenca and Albacete, there are more than 470,000 people, according to estimates by the Hydrographic Confederation of the Júcar (CHJ). The majority in the Valencian Communitywith 420,000 people exposed.
The following map prepared by ABC shows the river and marine danger, as recorded by the hydrographic confederations. Consult a municipality or address and check the risk level, street by street, on the following interactive map, both in the Valencian Community and other areas affected by this DANA and for the rest of Spain.
Check the flood risk in your area
Search the map for the danger level, street by street
Source: MITECO and hydrographic confederations
The municipalities most affected by DANA this week have a large portion of their urban area in potentially floodable areas. Chives, Chirivella, Paiporta and Letur, some of the most damaged, were already marked as risk areas. Valencia, in fact, is one of the provincial capitals with the highest percentage of land covered at risk of flooding.
No one can know when, where and how much it will rain in advance enough to avoid all disasters; But it is perfectly known where the water will flow when the downpour and the overflow of the riverbed occur. The knowledge of its course is so precise that there are official maps that delimit meter by meter where the runoff will break in the highest risk areas. They are flood-prone areas, exposed to the danger of suffering the natural phenomenon that causes the most destruction, economic damage and deaths in Spain each year.
Júcar Basin, greater risk
The torrential rains, the warming of the water of the Mediterranean Sea, the relief and the typology of the terrain make the Júcar basin one of the areas most historically affected by floods. Deforestation due to climatic causes or human action is another factor, since it eliminates water retention.
The Júcar basin is one of the areas with the highest risk in Spain. The orography of the terrain, with very mountainous areas close to the coast followed by very flat areas, make up a high torrentiality in very small ravines. Coupled with the pronounced rainfall due to isolated depressions at high levels, the DANA, flooding becomes a frequent phenomenon. But, at the same time, in the Júcar basin there is an enormous concentration of population and socioeconomic activities close to the riverbeds, with the risks that this entails.
In the Levant, there are many large municipalities with very high percentages of surface area covered by flood risk, such as Alfafar, Algemesi, Catarroja, Cullera, Swedish either Chirivellain the province of Valencia. In regions such as the Mediterranean coast, where rivers and streams remain dry for much of the year, the population is unaware of their danger, and it is not uncommon for the channels to be used for vehicle access or parking. “There is a lack of knowledge of the real risk,” lamented the then Water Commissioner in the report published in March 2023 by ABC “Four million Spaniards live in a flood zone: are you one of them?”
Hazard is the possibility of the event occurring, risk is the possibility of it causing harm. The danger cannot be addressed: flooding is typical of our climate. The risk, on the contrary, can be minimized. The Flood Risk Management Plans (PGRI) are the instrument of the hydrographic confederations to address the problem. These plans include the updating of hazard maps, and an estimate of the affected population.
Urban planning is the key that increases the risk of damage. Before there was a gradual invasion of river spaces, also during the real estate boom. For just under two decades, urbanization in risk areas has been on the rise. We have many homes, facilities and infrastructure located in high-risk areas, built in the second half of the 20th century and the first years of the 21st century.
Flood zones in Alfafar, Paiporta, Chirivella and surrounding areas
Although what may happen in the future may be resolved with more restrictive legislation, especially since the 2008 Land Law, which requires the preparation of risk maps in urban plans, everything that is poorly built remains, in areas high risk, of the past, because there was no legislation that prevented it, together with the eagerness to transform the territory at all costs, even in areas of high risk of flooding. The problem is who holds the promoter of some homes or the mayor who authorized them accountable in some events that may occur in the long term.
This is how risk maps are created
The interactive map of the report shows the flood zones in Spain due to river or marine causes according to the delimitation and level of risk defined by the respective hydrographic basins. The risk level is based on the probability of the event occurring. Very high in the preferential flow zone immediately to the channels; high in the so-called zone with a return period of 10 years, that is, a 10% probability of a flood occurring; frequent, at 50 years (2% probability); occasional, 100 years (1% probability); and exceptional at 500 years (0.2% probability). This is a medium probability; Floods can occur at any time, regardless of how much time has passed since the last flood.
The Flood Risk Management Plans (PGRI) are the instrument of the hydrographic confederations to address the problem. They are renewed every six years. The last ones, for the period 2023 – 2027, have been approved or are being approved now. In the preliminary evaluation of the risk of flooding, the first phase is to identify in each hydrographic basin the sections or Areas of Significant Risk of Flooding (ARPSI), which are the ones that have mandatory flood hazard and risk maps.
Risk levels are established through models that calculate risk based on numerous factors, such as rainfall, historical floods, slope of the land, buildings or soil type. These studies are carried out by areas; Hence, in some cases the map presents an artificial smooth section, marked by the delimitation of the area studied, and not by the risk situation of that specific area.
The limits included in the risk maps are under constant review. Hazard maps are updated when significant new information becomes available that justifies recalculating flood maps. In the event that works not included in the previous maps have been carried out, records of exceptional avenues must be available and a calculation technique highly evolved compared to that previously applied.
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