UK (Brunel University London) Campus river clean-up boosts biodiversity and reduces flood risk

The Vice-Chancellor was joined by students, staff, and local residents as they learned about the much-loved water feature.

Staff and students at Brunel University London were joined by members of our local community to learn about the River Pinn, which runs through the university’s Green Flag Award-winning campus, at an event held on 6 June.

The river is a coveted feature and beauty spot, and Brunel’s Vice-Chancellor and President, Prof Andrew Jones, donned waders and gardening gloves to join the clean-up.

As well as clearing the river of its minimal litter, the Vice-Chancellor’s main job was to clear it of any Himalayan balsam, which is an invasive, fast-spreading weed found in riverbanks and ditches. It erodes soil and riverbanks, inhibits native vegetation, and has to be managed and controlled.

Prof Andrew Jones clearing Himalayan balsam from the River Pinn

Simon Carroll, Head of Grounds and Biodiversity at the university, led a ‘talk and walk’ group along the river and spoke about the damage that Himalayan balsam can cause.

Simon Carroll, Head of Grounds and Biodiversity at Brunel, leading a ‘talk and walk’ along the river

“Beekeepers like Himalayan balsam because it’s very good for honey and produces good pollen, but the downside is that there is an ecological issue with it. If you touch the seed pod, they explode and disperse widely,” he said.

“These seeds can spread up to seven metres away and can quickly establish themselves on riverbanks, Simon explained. “It grows quite big and tall and smothers the more native species that might be slow growing. When it dies, it can cover a lot of ground and kill off what is left underneath. It then destabilises the bank.

“There’s very little Himalayan balsam along the river at the moment, mainly because the weather conditions haven’t been the best for it but also because we manage and control it. It’s a fairly loosely rooted plant, so we can pull it out by the root quite easily before it sets seed.

“We’ve gradually eradicated a lot of it over the years because we go into the river and pull them out.”

Prof Trevor Hoey – Brunel’s Pro Vice-Chancellor for International and Sustainability and Professor of River Science – led another ‘talk and walk’, explaining the many features of the river, which is at least 18,000 years old.

Prof Trevor Hoey, Brunel’s Pro Vice-Chancellor for International and Sustainability and river expert (centre) leading a ‘talk and walk’ along the river

“Globally, there are very few rivers like this because there are not many places with chalk, which makes it an important habitat,” he said.

“Parts of the riverbank are stone walls, which are still there, but it’s rather overgrown now with trees and shrubs. The river is very densely vegetated at the moment, and the channel provides diverse habitats with different water temperatures, velocities, and depths. A wide variety of species use these micro-scale ecological habitats, from invertebrates to wading birds.

“Increasingly, we now know about the range of organisms living in the river. It’s a visually attractive habitat with fish and wetland birds, and you can occasionally see herons. We also get some invasive species growing in the riverbed, like algal blooms.”

The River Pinn runs through Brunel University London

Prof Hoey noted that 2023 has been an unusually dry year so far, explaining why the river is currently shallow, at only a few centimetres deep at the bridge. But flooding is a risk to be considered, and he spoke about Brunel’s future flood management plan.

“Only once in the last 10 years has the flow been over the top of the banks. This was in June 2016, when we had an early summer storm,” he said.

“The river has been straightened over the years, which was thought to be good for flood protection.” This increases the velocity of the flow, causing the water level to drop. But, Prof Hoey explained, the unintended consequence is that it can cause bigger floods further downstream, so the modern approach is to try to slow the water down.

“The culture now is for natural flood management, using vegetation to slow the water down,” he said.

“We have an idea to slow the flow, by restoring the river’s natural shape. Our ambition is to make it a meandering river again, which will contribute to flood management.

“On the inside of the bend, there would be a hollow that would store water and help reduce flooding further downstream. This would also create more diverse habitats as well as providing a recreational area.

“It takes quite a lot of planning to create such changes, but as we make the river more natural, it will be a resource for students, staff, and local residents. We already use it for teaching, especially in environmental science and civil engineering.”

Reflecting on the afternoon’s event, Prof Andrew Jones said: “It was great to have so many people and volunteers in the middle of the campus at the River Pinn, and to be able to remove some of the invasive Himalayan balsam.

 “We are really thinking about how we all use the campus and how we look after all the wonderful parts of it, including the river.

“We are considering how all our students and our staff can make more use of the campus when they are here, and how they can get involved in things. I was having an exciting discussion with some colleagues recently about students growing their own food on campus and how we can increase the biodiversity of the species we have on campus overall.”

More information on how the university is committed to environmental issues and sustainability can be found here.