Losses from the September flood are still being counted, and the flood wave is passing through the Odra. However, there is more and more talk about whether such consequences could have been avoided and what to do to be better prepared for the next flood.
We must begin with the fact that we were dealing with an extreme phenomenon in the full sense of the word.
– It must be clearly stated that floods have always occurred, but with the ongoing climate change they will most likely occur more often and become more intense. We must try to limit their negative effects – said Michał Marcinkowski, chief specialist at the Department of Adaptation to Climate Change at the national Institute for Environmental Protection, in an interview with Gazeta.pl.
In some areas on the border between Poland and the Czech Republic, significantly more than 300 mm of rain (or 300 litres per square metre) fell in three or four days, with an average annual total rainfall of about 600 mm. With such rainfall, the threat of flooding was certain. The terrain played its part – rapid water runoff from the mountains.
We don't talk about this enough
The question of whether we were prepared for the flood is difficult to answer with anything other than “no”, as evidenced by the losses in many towns, the destruction of infrastructure, and the loss of life. The questions of “what could have been done better” and, above all, “what should we do now” are much more complicated. And it will take time to answer them in detail. However, experts are presenting the first conclusions. These are slipping away black and white presenting the case as “for/against retention reservoirs”.
We talk a lot about reservoirs and flood embankments, but we miss the basic thing: we cannot look at the problem from the perspective of one threatened city or one reservoir. It is necessary to look at the entire catchment area. If we want to reduce the risk of flooding for specific locations, we must take into account the entire area from which water flows into them.
– Marcinkowski pointed out. Secondly – he said – we must consider the full range of solutions that slow down the flow of water on the surface of the ground or retain it in place. – Of course, when we are dealing with catastrophic rainfall, it is impossible to retain or stop it in its entirety – he added.
Experts – such as Prof. Piotr Skubała of the University of Silesia in an interview with Gazeta.pl – draw attention to the role of both natural, green water retention and grey, concrete infrastructure.
– The so-called “grey” infrastructure, i.e. technical solutions such as dams, reservoirs and polders, should be the next step. The first are solutions based on nature: giving rivers space to spread, natural retention, rain gardens, basins, green areas. Forests, especially those with a diverse species structure, also retain water very well – and conversely, deforestation can accelerate its runoff – said Michał Marcinkowski.
Sebastian Szklarek, hydrologist and author of the blog Świat Wodny, in an article about the recent flood draws attention to the possibilities of natural retention by forests and delaying water runoff. According to various studies, the possibilities of retaining water in a forest are from a few to a dozen or so percent per year, but only a few millimeters (or liters per square meter) during one rainfall. With a rainfall of 200-300 mm, there is no way that a forest will “stop” a flood. However, it can mitigate it somewhat – which shows the need to combine different solutions.
Give the rivers a place
The expert from the Institute of Environmental Protection points out that “some people would like to fix the effects of changes in the environment that we have been introducing for hundreds of years – cutting down forests, regulating rivers – with even greater interference”. – I do not believe that reservoirs are not needed in any case, but they should be used as the next stage of reducing the risk of flooding, after the application of solutions based on nature – he said.
Piotr Bednarek, hydrologist and naturalist, in analysis film flooding in several places – Głuchołazy, Kłodzko Valley – drew attention to both the advantages and limitations of hydrotechnical structures. Reservoirs on the Nysa Kłodzka retained a huge amount of water, but at some point a quick discharge was necessary, which led to the flooding of, among others, the hospital. – It's amazing, by the way, that we have buildings such as hospitals in areas at risk of flooding – the hydrologist notes in the film. In Stronie Śląskie, a breach of a dam led to the rapid flooding of the areas below.
Bednarek also commented on claims that, for example, in Głuchołazy, the flood would be reduced by regulating the river. The Biała Głuchołaska – the hydrologist pointed out – is a mountain river that is already regulated, and its banks are built up. The mountain landscape and the development of the river banks mean that there is no room for retention reservoirs – at least not without flooding currently inhabited areas. Bednarek also pointed out that the weir located in Głuchołazy itself may increase the risk of flooding. – I am not saying that all such structures should be demolished. But in this case, this structure undoubtedly had an impact on how the water behaved – he says in the film.
– Quite common images on the internet comparing the functioning of regulated rivers in straight channels and those flowing in natural meandering channels are of course a simplification, but in my opinion they well show the effects of our interference in the environment in the event of heavy rainfall – said Michał Marcinkowski.
For this reason, “the only guarantee that the flood will not flood homes is to move away from the river and stop building on floodplains”. However, as the IOŚ expert points out, what may be possible in the case of individual buildings is hard to imagine in relation to cities, towns and monuments. – However, where possible, we should leave the river a place where it can flood naturally. This will make it easier for us to protect built-up areas – he emphasized.
Plan the adaptation
In the context of floods, the protests of residents of, for example, the Kłodzko Valley against the construction of reservoirs are recalled, as well as the negotiated consent of the community to the construction of the Racibórz Dolny reservoir. The polarized discussion – either “only concreting the rivers” or “complete renaturation” – may make such talks even more difficult in the future.
According to the IOŚ expert, “it is very important to build awareness of the effects of climate change, which are not limited to flood threats only”. – Adaptation to these changes cannot be imposed from above, but should result from real needs and awareness of society. Actions, from river renaturation to the construction of reservoirs, must be understandable so as not to arouse opposition – he said.
At the moment, the largest cities in Poland already have their own climate change adaptation plans. They describe threats that grow with climate change, such as heavy rains and floods, and plans to prepare for them. – Such documents should also be created for smaller cities on the one hand, and for entire regions on the other – said Marcinkowski.
How Ilona Jędrasik pointed outhead of the organization ClientEarth Lawyers for Earth, the draft act on the preparation of adaptation plans for changes in cities with more than 20 thousand inhabitants was created two years ago. It has been waiting for the first reading in the Sejm since March. – Adopting this bill should now be a priority for the authorities – she said.
Marcinkowski pointed out that the Institute of Environmental Protection – State Research Institute is working on a regional adaptation plan for the Silesian Voivodeship. He emphasized that it is important not only to check off their preparation, but to treat it seriously and focus on the quality of the plans:
It is very important that documents related to adaptation to climate change are prepared reliably and take into account the specific conditions of a given place, and are not based on general information about the effects of climate change and possible actions. The purpose of their development should not be only to meet the statutory requirement (the act introducing the obligation to develop municipal adaptation plans to climate change for cities with a population of over 20,000 is currently being processed), but to strive for a real improvement in the functioning of the city, the comfort of life and the safety of residents in the conditions of changing climate conditions.