River channelisation, wetland drainage, the disconnection of rivers from their floodplains and the construction of dams and weirs have transformed the natural character of waterways over many decades. Experts warn that these interventions have reduced the landscape’s natural capacity to retain water in many areas, intensifying the consequences of both droughts and floods.
Restoring rivers and expanding blue-green infrastructure could help communities adapt to climate change and increasingly frequent extreme weather events.
“For hundreds of years, we viewed nature as an adversary, particularly when it came to river ecosystems. Rivers posed a threat to our cities because we did not know how to deal with rising water levels and flooding,” Dr Kinga Krauze of the European Regional Centre for Ecohydrology of the Polish Academy of Sciences told the Newseria news agency.
“Much of this attitude towards nature remains with us. We later learned how to regulate rivers, but at some point we crossed a critical threshold. Heavily engineered rivers, deeply incised into the landscape, began to drain it. A river that no longer interacts with groundwater, is neither fed by it nor replenishes it, effectively becomes a drainage ditch.”
River engineering has declined, but its effects remain
According to Statistics Poland, the largest volume of investment in river engineering and the regulation of mountain streams over the past 30 years was recorded in 2003, when projects covered 858.5 kilometres of waterways.
The scale of such investment has since declined steadily. In 2023, river and stream engineering projects covered 47.4 kilometres.
The trend is now gradually reversing, with increasing attention being paid to restoring rivers to a more natural state. Experts say this reflects a growing understanding of the long-term consequences of altering river networks.
“On the one hand, a regulated river has little capacity to retain water. On the other, it transports a flood wave very quickly, causing towns and villages along its course to be inundated or flooded,” Dr Krauze said.
“Another element of river regulation was the drainage of wetlands. Around 90 per cent of Europe’s wetlands have effectively disappeared, and the figures for Poland are not encouraging either.”
Wetlands store water during periods of heavy rainfall. This slows the rate at which water reaches rivers, reducing the risk of flash flooding. At the same time, wetlands can gradually release stored water during extended dry periods.
Poland has lost natural water buffers
Wetlands were drained partly to create agricultural land. River engineering also separated rivers from their natural floodplains and from wetland areas that should be replenished during periods of intensive rainfall.
Together, these processes have weakened or removed natural systems that once acted as water buffers.
The consequences are being compounded by climate change and rising global average temperatures. According to the Intergovernmental Panel on Climate Change, every additional 0.5°C of global warming leads to a clearly noticeable increase in the intensity and frequency of heatwaves, heavy rainfall and, in some regions, droughts.
Data from Poland’s Institute of Meteorology and Water Management show that the country’s average annual air temperature in 2023 was 10°C. This was 1.3°C above the long-term annual average for the 1991–2020 climate reference period.
“Poland has regions where rainfall is sufficient and others where it is not,” Dr Krauze said.
“Spring rainfall is particularly important. In central Poland, it was almost entirely absent this year, causing significant losses in agriculture.”
She noted that people have become accustomed to water being readily available whenever they turn on a tap. However, different types of water resources are replenished at very different rates.
Groundwater close to the surface may recover over weeks or months, while deeper reserves can take decades or even centuries to rebuild. The deepest artesian water resources may require thousands of years to regenerate.
“These are the resources used by Łódź, where I live. The question is whether they can still be considered renewable,” the researcher said.
“Once they have been depleted, a combination of insufficient spring rainfall and intense summer downpours may mean that we are unable to retain enough water to meet current needs.”
Polish cities are poorly prepared for extreme weather
In Dr Krauze’s assessment, Polish cities are not yet sufficiently prepared to deal with increasingly severe weather events.
Healthy aquatic ecosystems, combined with interconnected blue and green infrastructure, are essential if urban areas are to adapt more effectively to climate change.
“Awareness is growing, and we are beginning to move in this direction. However, the process is very difficult because decisions taken in the past limit the options available to us today,” she said.
“This is a major challenge for planners, urban designers and city authorities, which need to adopt a long-term perspective.”
Restoring rivers will be particularly difficult, and in some cases impossible, in areas where river valleys and floodplains have already been densely developed.
“We allowed areas upstream of major cities to be built over, even though they could have been used to create polders where rivers and flood waves could safely spread,” Dr Krauze said.
“Extreme weather will require much greater flexibility and a reassessment of the business-oriented approach to cities. We need to reconsider what genuinely has value and which elements of the urban environment should be protected for the future rather than assessed solely in terms of short-term profit.”
River restoration becomes a priority in water management
Poland’s State Water Holding “Polish Waters” says river restoration has become one of the most important priorities in modern water management.
The process is intended to restore natural mechanisms in aquatic ecosystems and areas that depend on water. Such measures may include reopening migration routes for aquatic organisms, rebuilding wetlands and restoring the natural functions of river valleys and floodplains.
Restoration projects do not necessarily require rivers to be returned fully to their original state. They can also be implemented on waterways that have been significantly transformed by dams, embankments, weirs and other hydraulic infrastructure.
Experts argue that even partial restoration can slow the movement of water through the landscape, improve groundwater recharge, support biodiversity and reduce the severity of droughts and floods.
As climate change increases the frequency of prolonged dry periods and intense rainfall, rebuilding natural water-retention systems is becoming not only an environmental priority but also an important element of economic and urban resilience.
