Researchers believe that restoring natural river bends can prevent flooding and create healthy habitats for wildlife.
Swindale Beck, a river in Cumbria, located in the heart of the Lake District in England, meanders through fields, farms, and valleys. However, not long ago, the river’s flow was much straighter. A healthy river needs bends, flows freely, and is rich in wildlife. Yet, in England, 97% of rivers are fragmented by artificial barriers such as weirs. Currently, there is at least one artificial barrier for every 1.5 kilometers of river in the country. Over the decades, rivers have gradually become channels, artificially straightened to prevent water from flooding homes and farmland.
Aerial view of Swindale Beck. (Photo: Natural England).
However, removing the natural bends of the river has actually created the opposite effect. Instead, it disrupts the river’s flow, degrades aquatic habitats, reduces water quality, and increases the risk of flooding. As the health of rivers in Europe continues to deteriorate due to declining wildlife, water pollution, and agricultural runoff, many communities are turning to natural solutions to restore flow.
Some rivers are being rehabilitated using natural flood management (NFM) techniques such as building wooden weirs, planting trees, and constructing beaver enclosures. One idea is to add bends to rivers and their tributary systems. Around the world, from the Netherlands to the United States and the UK, rivers are being curved back to their original flow. In England, authorities are beginning to reap the benefits as fish, birds, and invertebrates return to rivers in Cumbria and West Sussex.
Two hundred years ago, Swindale Beck was straightened to create more farmland. However, since 2016, a project has been underway to reverse this process and return the river to its original state. Directed by the Royal Society for the Protection of Birds (RSPB), the project’s goal is to create more diverse habitats, structures, and forms.
After researching the valley to identify the original flow, the charity set up a digging team to reshape and create a new riverbed. The project is a collaboration between RSPB, the Environment Agency, Natural England, and the water company United Utilities, costing over $260,000 to reshape a one-kilometer stretch of the river. Initially, they conducted studies of the area to map the original flow, then arranged for the digging team. Currently, Swindale Beck is about 180 meters longer than the river that had been straightened over the past two decades.
According to Tom Hayek, a flood management expert at the Wildfowl and Wetlands Trust (WWT), adding bends to the river has two advantages. This approach alters both the speed of flow and the volume of water.
First, it reduces the amount of water the river can carry downstream. As the river’s length increases, water spreads out over a wider area, allowing more water to remain upstream rather than rushing into urban areas downstream.
The second impact is on flow speed. The more structures added to the river’s morphology, the slower the water will flow. If the river runs straight, the water rushes through. “The gradual increase in speed and volume due to tributaries flowing in means that at some point, the river cannot contain all the water, leading to flooding,” Hayek explains. In the past, dredging riverbeds to increase capacity was a common practice to address flooding, but this did not solve the underlying problem.
Scientists warn that climate change is causing increased rainfall in some areas of Europe due to warmer weather carrying more moisture. Restoring rivers to their natural state, removing weirs, and managing floodplains can help us cope with the rising risk of flooding.
As the water flow slows down, there are more deep pools for fish to gather and rest. Areas of the river with finer gravel accumulate, creating perfect spawning habitats for salmon. Consequently, aquatic plants also return, providing shelter for young fish to forage. The reshaping of Swindale Beck allows the river to self-clean, as a straightened river flows faster and carries more sediment away. The bends encourage the river to deposit sediment along its banks.
