“The flood in Poland was a symptom of a changing world”

The year 2024 was full of extreme hydrological phenomena in Poland. What we remember most is the September flood that affected some of them Central Europeincluding southwestern Poland. Intense rainfall came over our country on September 14, quickly filling local river beds. On that day, the first evacuations were also ordered in Głuchołazy and Mory.

The rain fell continuously for several days, damaging houses and roads and breaking down bridges. Within 24 hours, high water reached other towns: Stronie Śląskie, Lądek-Zdrój and Nysacausing enormous damage in each of them. The Hospital Emergency Department in Nysa was completely flooded, and in Prudnik there were power problems. A state of natural disaster has been introduced in parts of the Lower Silesian Voivodeship.

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In the following days of September, the flood situation did not improve. The water reached further towns located in the Oder basin, including the Wrocław agglomeration. After the great water passed, banks of rubble, asphalt, garbage and sludge were visible on city streets. Nine people died in floods in Polandand w throughout Central Europe – 24.

– The September flood in Poland was a symptom of this changing world. Although this is still quite a rare phenomenon in our country, it was intensified by climate warming, which has influenced the recent years – said Dr. Sebastian Szklarek, author of the blog “Świat Wody”, ecohydrologist from the European Regional Center of Ecohydrology of the Polish Academy of Sciences under the auspices of UNESCO.

According to the US National Oceanographic and Atmospheric Administration, the average global surface temperature from January to November was the highest in the 175-year history of measurements. It was 1.28 degrees Celsius higher than the average from 1901-2000. According to November data from the EU climate change agency Copernicus, last year the average global temperature was as much as 1.62 degrees Celsius higher than the pre-industrial level.

Dr. Szklarek reminded that the increase in global temperature intensifies weather phenomena, among others by increasing the temperature of ocean and sea waters.

– And if the water temperature is higher, all the processes related to it and occurring in it also intensify – said the expert. A good example of these processes is the September flood in the southern Oder basin. It was caused by a cold low, which periodically flows from around Great Britain south towards the Gulf of Genoa. – It usually gains moisture there and moves towards us. It then collides with warm air from Eastern Europe and the moisture turns into rain. However, this year the low has been strengthened by climate change, because the warmer the waters, the more evaporation, and the warmer the air, the more moisture. Therefore, this famous one could draw more water towards us from the Italian region. And because of this, the rainfall was more intense than would usually be expected – described the ecohydrologist.

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Our region is also characterized by the fact that torrential rainfall occurs more and more often, i.e. when an amount of rain falls in a few hours equal to, for example, monthly norms. Such heavy rainfall causes a flash flood. – If we look back at recent years, most cities have been affected by such phenomena. They too have the right to happen, but if we look historically, the frequency of such phenomena is increasing – noted the ecohydrologist.

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On the other hand, high temperature contributes to the opposite phenomenon – droughtwhich last year, according to the Institute of Fertilization and Soil Science – PIB, occurred throughout Poland between July 11 and September 10. – The increase in temperature means that even if it rains, the water disappears very quickly through evaporation. This factor largely contributes to the development of agricultural drought, said the ecohydrologist. He noted that the wet winter and the beginning of spring 2024 caused the so-called snowmelt surges, which slightly delayed the drought. However, the warmer than usual spring months, and especially summer and autumn, meant that water “started to escape significantly” quite early.

– We think about evaporation mainly in the summer, because then the temperature is high, reaching 30 degrees. However, we pay less attention to the fact that, for example, in winter, when we have positive temperatures, water also evaporates. Of course, this is less evaporation than in summer, but as research shows, winter evaporation is increasing in percentage terms faster than in previous years, the expert explained.

The effects of water evaporation could be seen even by superficially observing the water level in the Vistula. In the first half of September, when southern Poland was struggling with flooding, the water level of the longest Polish river reached record low levels. The smallest amount – 20 centimeters – was recorded at the Bulwary Wiślane hydrological station in Warsaw.

– What the water gauge on the Boulevards shows is a reflection of everything that is happening to water in approximately one quarter of Poland. Everything about Vistula flows from Tatra Mountainsfrom the Bieszczady Mountains, which is later reflected in what is happening on the Vistula River Warsaw. The fact that we had a record low level is the result of the fact that many small streams and small rivers in this area of ​​the country are drying up – emphasized Dr. Szklarek.

The ecohydrologist emphasized that in the face of such phenomena, which are intensifying from year to year, we must prepare for a new reality. These preparations – despite education and communication of threats – do not make us optimistic.

– After all, climate models have been telling us for years what direction the climate will go. And we see the speed at which states and societies respond to these warnings, said Szklarek.

In his opinion, we should prepare for future phenomena with some “headroom”. – If we prepare for what is now, it will soon turn out to be insufficient. We need to prepare not for the rainfall that is happening at the moment, but for twice as intense rainfall, because this is the direction it is heading – noted the expert.

However, as Dr. Szklarek reminded, “slowing down the speeding train” of climate change is not easy, because the key is to reduce the burning of fossil fuels, which contribute to greenhouse gas emissions. Otherwise it won't work. Actions that reduce the negative effects of climate phenomena can be taken a little faster. In the case of protection against floods, the best solution, according to the ecohydrologist, is to “stop water where it falls” – It is also a counteract to drought, because if we stop water, we create moisture in the soil, which will eliminate both the threat of fire in forests and agricultural drought. If we ensure water seepage, it slowly seeps underground towards the nearest river. This stabilizes water flows when it is not raining, which means it reduces the risk of low water levels in rivers” – described Dr. Szklarek.

In lowland areas, retaining water is much easier because its flow is limited by the topography itself. Apart from “deconcreting” cities, which is talked about a lot, it is enough to deepen the area in places such as parks and lawns, creating basins that retain water. – In cities, we usually have lawns above street level, and it would be enough to reverse this trend and we would have large areas that could retain water. It is more difficult in the mountains, so in some mountain regions, the best solution to protect towns would be dry polders, i.e. areas that could absorb excess rain, said Dr. Szklarek. Appropriate solutions can also be used in cities. For example, do not place key infrastructure or important institutions on the lower floors of buildings. Use super waterproof windows on lower floors. In some cities, fast barriers are also used, placed in the rails on both sides of the street in times of danger. – In this way, a barrier is created that redirects water through a given town so that it causes the least possible damage, protecting key and densely populated areas. Of course, it is expensive, but you need to calculate whether it will be cheaper than later rebuilding property that was flooded – emphasized Dr. Szklarek.