Probably everyone has read at least once in the past few days, or seen it themselves, that the largest tidal wave in the last decade has reached the Danube, so many settlements in Hungary managed to save a serious problem in the entire central Europe only by building dams and filling sandbags from the causative current.
However, according to some experts, it would have been possible to save on the costs of subsequent cleaning of the shoes of politicians who often appear on the dam only for a photo (with respect to the exception), because if the natural bends of the rivers had not been regulated and straightened earlier, there would not have been such a risk of flooding now.
Over the past decades, straightening river bends has become a common practice all over the world, but more and more experts claim that restoring natural river bends can provide more effective flood protection than the latest technological solutions, and also provide a habitat for wildlife. In light of the current wave of floods, which also affects Hungary, this natural solution is especially worth considering, because restoring bends can not only provide long-term flood protection, but can also play an important role in improving water quality and preserving biodiversity.
River meanders, or bends, are the result of the natural movement of water. However, over the centuries some rivers have been artificially straightened to increase agricultural use of the surrounding land and reduce the risk of flooding. In the UK, 97% of rivers are cut off by artificial barriers such as dams and weirs, according to the World Health Organisation. BBC.
However, these interventions often do not achieve the desired effect: by disrupting the natural flow of rivers, the risk of flooding increases and the quality of habitats deteriorates.
In the short term, of course, regulating this way can lead to faster water discharge, but in the long term it can have disastrous consequences. In straight rivers, water flows at a higher speed, which also increases the rate of erosion and carries more sediment with it. This worsens the quality of the water, while the rivers are less able to spread water naturally over the floodplains. Due to more frequent and intense rainfall, also exacerbated by climate change, the rivers are less able to handle the increased amount of water, which – it is not difficult to guess – leads to flooding.
Restoring natural riverbeds may be the key.
It is therefore not surprising that restoring the natural curves of rivers, i.e. rewilding, is becoming an increasingly popular solution in water management. In the UK and other European countries, more and more rivers are being restored to their original natural state, thus transforming them back into their natural floodplains. These types of restoration projects not only improve the protection of waterways from flooding, but also create habitats for wildlife such as fish, waterfowl and insects.
The example of the Swindle Beck River in England illustrates the benefits of restoring bends. The river was regulated about 200 years ago to make way for more farmland. But in 2016, a project was launched to restore the river to its natural state. As a result of the project, the river has regained its former bends, improving water flow, and wildlife that had previously disappeared into the river has begun to flourish again.
This type of restoration also reduces the speed of water and spreads the water over a larger area, so that water flows more slowly in meandering rivers, reducing the possibility of flooding and submerging cities and villages.
In addition to recycling, other natural flood management techniques have become more popular recently, including leaky damming, the restoration of tree- and shrub-covered river banks, and the retention of dams created by beavers. Ultimately, all of these techniques slow the movement of water and allow rivers to deal with flooding naturally, thus avoiding flooding of cities and towns.
Restoring natural river bends helps prevent flooding, improve water quality, and create habitat for wildlife. While these solutions may not be feasible in all situations, they can be effective in many. Natural flood management and recycling is not only an environmentally friendly solution, it can also provide long-term security in areas affected by climate change.
Climate change and river regulation
Although it may seem trite, it is important to note that river regulation has a significant impact on the consequences of climate change, and vice versa, that is, climate change also affects the condition of rivers.
It is already known.who Extreme weather events, including heavy rainfall and flash floods, are increasing due to climate change. When rivers For example with dams They are regulated or straightened using dams or channels, and these interventions often reduce the natural capacity of floodplains. River floodplains are natural buffer zones that help absorb and drain larger amounts of water.
Restoring floodplains and restoring natural river bends can help reduce flood risk.
It is also important to highlight that regulated rivers, especially those that have been straightened or deepened, flow faster, which can lead to increased coastal erosion. Faster water flow carries more sediment, which can damage habitats and worsen water quality. Increased flooding and rainfall caused by climate change will only exacerbate this process.
Furthermore, river regulation often results in the disappearance of habitats such as marshes, wetlands, and floodplain forests. These habitats are important for maintaining biodiversity and preserving water quality. Fluctuations in water levels and temperatures due to climate change also affect aquatic life, and regulated rivers are less able to adapt to these changes.
Of course, the rise in average temperatures due to global warming also affects the temperature of rivers, especially in the case of slow-moving, regulated rivers. Higher water temperatures reduce the levels of dissolved oxygen in the water, which is harmful to fish and other aquatic life. On the other hand, natural meanders and slower-flowing sections of rivers help maintain lower temperatures and better water quality.
Climate change is not only increasing rainfall, but also causing more frequent droughts. Regulated rivers are unable to hold water effectively, while natural river courses and floodplains can store more water, which can be used even during droughts.
Natural flood management techniques, such as restoring river meanders, rehabilitating floodplains, and installing natural barriers (such as trees and dams), can help mitigate the effects of climate change. These solutions slow the flow of water, help prevent flooding into cities, and allow water to naturally infiltrate and be stored in the soil.
In general, it can be said that river regulation and climate change can reinforce each other's harmful effects, but these effects can be mitigated through natural solutions, improving river health and environmental resilience.
Of course, it doesn't hurt to act on this, but as soon as possible.
(Cover image: Danube River water level on September 21, 2024. Photo: Bence Tovesi/Index)
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