However, something happened that the water could not be stopped…
— We must make it clear that periodic water fluctuations are a natural phenomenon of our climate that has always occurred and will always occur. However, it is important to note that through our impact on the environment, we are intensifying the negative effects of this phenomenon. What I mean here is the continuous transformation of the catchment area and the sealing of ever larger areas. It is also important that we often want to build our houses near rivers. We must avoid all this in the future.
But there are opinions among those looking for someone to blame, for example, about plans to build more retention reservoirs in the Kłodzko Valley, which were blocked during the previous government. The question is whether these reservoirs would be able to hold back such a large flood wave?
— I cannot answer this question specifically at such a high level of generality. It all depends on the details, the specific situation, the specific reservoir. However, the solution to the risk of flooding is certainly not just the construction of water reservoirs, nor the regulation of riverbeds, and so on. We must strive to ensure that the entire catchment area, that is, the area from which water flows to a given point, functions as naturally as possible. To be able to retain as much rainwater as possible at the place where it falls. Of course, with such heavy rainfall as we are currently experiencing, it is impossible to retain all the rainwater.
This excess will need to be drained or it will run off the surface of the land. This brings us back to the question of providing our rivers with places where they can flow naturally and safely for everyone. Could dedicated tanks help? I assume they could, to some extent, but let us remember that, in addition to the issue of flooding threats, we also have purely ecological issues, because we want our rivers to function in a natural way, consistent with nature. Tanks are usually more or less an obstacle in this regard.
Today, the most talked-about reservoir has been built, on which the fate of many people, the inhabitants of Opole and Wrocław, depends. This is the Racibórz Dolny reservoir. Why is this object so important in this whole puzzle?
— First of all, it is a new tank. A dry reservoir that has not had the opportunity to be used in such a significant way until now. And this is, in fact, the facility that the residents of Wrocław are looking at in particular, hoping that it will help to avoid the situation of 1997.
However, it is also said that saving Wrocław may also mean making difficult decisions, such as releasing water for polders, for example near Oława, where people also live. Could we face such dramatic dilemmas as those of the 1990s?
— I am not familiar with the different variants of crisis management in Lower Silesia in such detail, so it is difficult for me to say to what extent such an option is being considered, but here I see hope in what I said at the beginning. Those responsible for crisis management now have incomparably better tools at their disposal than they did more than 20 years ago. We have flood risk maps and simulations that show what will happen if embankments or dams fail intentionally or due to water pressure in certain sections.
However, let us remember that this water has to find its outlet somewhere, so if those managing the situation can find an area that will have to be flooded with water in a safe way that does not pose a threat to people’s lives and health, it may be a justified action to protect areas with intense development, inhabited by many people.
Yesterday we saw Kłodzko almost entirely under water, today there is practically no water left there and the clean-up is just beginning. Will this flood be like this? Move north, haunt cities and quickly leave them?
— In mountainous areas, these changes are indeed very dynamic, and there the water should recede quickly when the precipitation in a given river basin stops. However, the further south you go, the slower the wave will travel and the longer it will take. This is for two reasons. Firstly, the slopes of the terrain are decreasing, so the speed of the water flow – although still enormous – is no longer as high as in these mountainous areas. Secondly, the further down you go, the more tributaries of the Oder there are, and it is known that it is these small tributaries that currently pose the greatest danger. And they will also influence the extent of the flood wave.
However, it should be stressed that the possible return of rains, both in Poland and in the Czech Republic, in the catchment areas of the rivers flowing into Poland, will result in a rapid return or intensification of the threat in Lower Silesia.
We are facing the reconstruction of a large part of Głuchołazy, Lądek-Zdrój and Stronie Śląskie. Rebuilding for a while? Today, experts almost unanimously say that something similar could happen again, for example, in 10 years.
— The outlook is certainly not good, but I hope that we will all learn from our experiences, sooner or later. Just as the experience of 1997 allowed for the dynamic development of threat monitoring and warning systems, we will be able to draw the same conclusions after the current crisis. We will have new information about how the collision between what actually happened and what the models previously told us looks like. How accurate were these models and to what extent do they need corrections?
For several years now, we have been increasingly talking about the need to adapt to climate change and the need to pay attention to the way we develop our cities and villages. We have drawn attention, among other things, to the need to stop and retain rainwater. I hope that all these activities will lead to a gradual reduction of this threat. However, we must be clear: these phenomena will continue to occur regardless.
But should people leave these areas that could be flooded? Shouldn’t you run a business in the center of Kłodzko when the water could overflow there too? This is an extremely difficult, even impossible, task.
— Of course, the best and ideal solution would be a scenario where we move away from the riverbeds, human settlements move away, businesses move away, and then there would be no future losses. However, realistically speaking, this would be a difficult solution. So what we can focus on is the safety of the riparian areas where human settlements are, but also on preventing further development in areas that are currently undeveloped but that may be attractive, for example, for scenic reasons. And designating places where large rivers can periodically overflow in a safe and non-hazardous way.
What places could these be?
— They do not have to be areas completely excluded from the human economy, because they can be green, agricultural or recreational areas, whose flooding would obviously entail some losses, but these losses will be incomparably smaller than in the case of areas inhabited by humans.
It is also important that we do not leave the burden of preventing similar threats solely to the towns or villages that are directly on the banks of the river. Because it is not as if their inhabitants are to blame for everything and can prevent future threats. We must always look at the entire catchment area, the entire area. Everyone in this location should try to safely stop and retain rainwater in a way that is as close to nature as possible. This will reduce the risk of flooding and the risk of drought, which we also talk about a lot. The water will simply be collected and can be used by both humans and the environment. That is why these small retention objects, imitating the natural way of retaining water, are so important here.
Has the recent drought contributed to the severity of the situation now, after heavy rains?
— The drought could have played a small role. When rainwater hits a very dry area, the vast majority of it runs off the surface and does not infiltrate into the groundwater. Most of us have experienced a similar process in a flower pot. When we come back after a vacation, it is a bit dry and it is not so easy to hydrate it, the water usually just runs off. Soil behaves in a similar way after a drought.
What about logging near the Śnieżnik massif? This is also pointed out by some as a stone in the garden of disaster added by human activity.
— All deforestation certainly has a negative effect, because the forest is a place that can retain large amounts of water. When vegetation is cut down, natural waste is also destroyed during forestry work, and this increases the flow of rainwater to the surface. However, let us remember: these are elements that, of course, can have a significant impact, but the key in the situation in question is that catastrophic rainfall occurred. This is the most important thing in the discussion about the causes of this flooding.
