As urbanisation continues to encroach upon the natural landscape, the transformation of watercourses to fit human needs has become all too common, writes our Project Manager, Tarun Ingvorsen. In the quest for development and progress, many rivers and waterways in urban environments have been extensively altered by man, with detrimental consequences, both for the natural environment and the communities there. In contrast, the preservation and protection of natural watercourses, particularly lowland British rivers, like the Beverley Brook, offer a multitude of benefits that outweigh any short-term gains derived from altering them.

Over centuries, these waterways have shaped their surroundings, not just by providing habitat for plant and animal life, but in the layout of towns, place names and the locations of cities. Mortlake, for example, is so named because of the waterways that run past it: Mort, meaning a 3 year old salmon and Lacu, meaning small stream. This makes sense with old maps which show the Beverley Brook often entering the Thames at Mortlake and the fact that Beverley Brook means Beaver Meadow Brook (beaver habitats are beneficial to salmon, providing food, shelter and spawning habitats). Alas, the Beverley Brook is no longer home to either.

The continuous alteration of rivers and watercourses disrupts the natural flow and habitat connectivity of these blue (and often green) corridors, leading to the loss of biodiversity and the decline of numerous species, as highlighted in our recent Beverley Brook Lost Nature Trail. However, are we seeing a change in this? Last year our Conservation Team carried out some work on the stretch of brook which runs through Barnes Common. Previously, due to the levels of silt caking the riverbed and the limited amount of in-channel features (rocks, logs, overhanging branches, etc.), most fish were washed further and further downstream with each high water. This year, because of the works reinstating in-channel features and a more natural watercourse we have seen a large increase in fish fry and larger fish remaining in this stretch after high waters. Not only is this good news for us (our plans are working), but for the resident kingfisher, too, who is often seen perching on a branch, zeroing in on its next target. The heron has also found a new fishing hole, discovered by the ’whitewashing’ (the white streaks of bird guano) of a certain patch of riverbank.

In an era of unpredictable climate patterns and extreme weather events, witnessed locally over the past 3 years with droughts and floods, the importance of flood mitigation cannot be overstated. Natural watercourses have an innate ability to handle and dissipate water during heavy rainfall, thus reducing the risk of flooding in urban areas. When the Beverley Brook was altered, its natural floodplains were cut off and developed upon, exacerbating the severity and frequency of floods. Lowland British rivers, in their natural state, have floodplains that provide storage for excess water during floods or high tides, minimizing the impact on urban settlements.

Additionally, riparian vegetation along natural watercourses acts as a buffer, stabilizing riverbanks and reducing erosion, which further contributes to flood resilience. This flora and associated wetlands even act as natural filters, removing pollutants and excess nutrients, thereby improving the overall water quality. Common reed, as we are hoping to enhance on Barnes Common, can even filter out and break down some heavy metals and radionuclides. In contrast, altered watercourses often suffer from pollution due to urban runoff, industrial discharges, and sewage discharge, compromising the health of both the ecosystem and the people relying on the water for various purposes. Reports of people and their dogs getting sick from the Beverley Brook’s water are increasing. I have firsthand experience of this, myself.

In an era of climate change, urban areas are particularly vulnerable to rising temperatures and the heat island effect. Natural watercourses contribute to climate resilience by cooling the surrounding environment through evaporation and transpiration from vegetation. These waterways also promote the growth of trees and other plants, which further mitigate the heat island effect and improve air quality. The same cannot be said for modified sections of river.

Natural watercourses, especially lowland British rivers, represent a priceless heritage that sustains biodiversity, enhances urban resilience, purifies water, and offers recreational and aesthetic value to people. The importance of preserving and protecting these natural features cannot be overstated, as they contribute to a more sustainable and liveable urban environment. As we navigate the challenges of urbanisation and climate change, embracing the value of natural watercourses and making conscious efforts to safeguard their integrity will ensure a brighter future for both the environment and the communities that thrive alongside these precious waterways. Where we can, here at BCL, we are working towards this goal of a more natural Beverley Brook. This is a whole spectrum approach, from monitoring the river with Citizen Science and community engagement to appropriate tree management and planting and river renaturalisation. If you want to find out more, or get involved, please email me at [email protected].