The Disappearing Rivers Returning This Season
If you’ve been out walking in the countryside recently, you’ll almost certainly have noticed it: water returning to places that have been dry for months, with streams and channels reappearing across the landscape following recent heavy rainfall and flooding.
These aren’t ordinary rivers. In many cases, what you’re seeing is the seasonal reawakening of a winterbourne - one of the rarest and most interesting habitats found in our chalk stream landscapes.
As autumn and winter rainfall replenishes the aquifer, groundwater levels rise and winterbournes begin to flow again, bringing life back to places that, during summer, can look as though a river never existed at all.
What is a winterbourne?
Winterbournes are very rare. They are temporary headwater streams most commonly found in the uppermost tributaries of chalk catchments, though they can also occur in other geological settings. They only flow when the underlying aquifer is full enough for groundwater to reach the surface.
Not all winterbournes have a clearly defined channel. Some appear instead as seasonal groundwater emergence, where water rises and flows along the valley bottom — one reason why the question of “what is a winterbourne?” remains an active and evolving area of discussion.
This means winterbournes can:
- Flow beautifully during wetter months
- Dry up completely during summer
- Vanish for long periods, leaving only a dry channel or valley feature behind
During their dry phases, winterbournes can appear almost invisible. But they remain ecologically significant even when no water is present.
Why are winterbournes so special?
The unique wet–dry cycle of winterbournes creates a habitat unlike any other.
Some species have evolved specifically to thrive in these changeable conditions. For example, the scarce purple dun, a rare insect, depends on winterbourne environments for survival.
When winterbournes are flowing, they can also provide:
- Important spawning grounds for wild brown trout
- Nursery areas for juvenile fish
- Seasonal refuge and feeding habitat for a wide range of aquatic wildlife
Whether wet or dry, winterbournes are precious parts of the wider river network, supporting biodiversity in ways we are only beginning to fully understand.
Vulnerable in their dry phases
One of the greatest challenges facing winterbournes is that when dry, they are often overlooked.
A dry winterbourne can be mistaken for:
- A ditch
- A dry depression
- A forgotten streambed
This can leave them vulnerable to unintentional damage, including sediment build-up, vegetation loss, trampling, or inappropriate land management. Protecting winterbournes means recognising their value even when water is absent.
Restoring a winterbourne at National Trust’s Hinton Ampner
This autumn, as part of our Watercress & Winterbournes programme, we delivered a winterbourne restoration project at National Trust’s Hinton Ampner — the first time we have undertaken a restoration on a dry channel.
Winterbourne restoration is a vital step in improving the resilience and health of chalk stream catchments. At Hinton Ampner, work focused on enhancing habitat quality and supporting natural processes in this unique seasonal river environment.
The images from the project tell a powerful story:
- The winterbourne channel before restoration
- The site just after works were completed
- And now, water returning once again as the winterbourne refills and flows
Seeing water come back into a restored winterbourne is a vivid reminder of how dynamic and extraordinary these habitats truly are — and as vegetation establishes, the winterbourne will only continue to evolve.
With thanks to the Wild Trout Trust for their support and expertise in delivering this project.
New guidance for caring for winterbournes
In response to growing calls for practical advice on winterbourne management, a new Winterbournes Guidance Document has now been launched.
Developed in partnership with The Environment Agency, Hampshire & Isle of Wight Wildlife Trust, Nottingham Trent University, The Wild Trout Trust…the guidance brings together shared expertise to support those managing winterbournes or land surrounding chalk streams.
It includes practical recommendations on key issues such as:
- Sediment and erosion
- Flooding and flow dynamics
- Grazing and land use
- Non-native invasive species
- Vegetation and habitat management
This document is an important tool in helping ensure winterbournes are protected and restored for the future.
Looking ahead
Winterbournes may be hidden for much of the year, but they are among the most valuable and specialised habitats in our landscapes.
With continued restoration work, shared guidance, and community awareness, we can help winterbournes thrive — whether flowing or dry.
