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The University of Southampton
Geography and Environmental Science

Managing and restoring our river environments

Pioneering research by a Southampton Professor of Physical Geography is transforming the way river management and restoration is tackled around the world by exposing centuries-old flaws in traditional methods.

Research challenge

For centuries, rivers have been dredged to ensure waterways remain navigable, to minimise the risk of flooding and to prevent rising water tables from damaging farmland. Yet, until recently, no-one knew the total cost of digging out sediment from rivers or measured the extent to which the physical processes and form of our rivers were being disturbed.

Researchers were committed to understanding the causes and consequences of the processes of water and sediment movement in river catchments so that they could minimise the need for expensive and disturbing maintenance and management whilst delivering environmentally acceptable and sustainable solutions.

Context

Historically river management had treated the symptom and not the cause of channel movement and sedimentation, but from the early 1990s there was a move to adopt a more holistic approach to managing and restoring our rivers.

Our solution

Novel research by David Sear, Professor in Physical Geography at Southampton, and colleagues from Southampton University’s GeoData Institute along with other UK universities, led to a new approach that sought to ‘audit’ the processes and historical changes behind river management problems such as bank erosion or the infilling of channels with sediments.

Drawing on principles and theory developed in fluvial geomorphology (the study of the form, processes and sediments in river systems), David and others applied these to engineering problems that had traditionally been managed by ‘hard’ techniques based on bank protection and dredging.

First the team identified the scale of the problem – conducting the first national survey to assess UK river management agencies’ approaches to riverbank erosion and sediment accumulation. Their research findings revealed that in 1992 these agencies were spending about £20m a year on removing sediment from rivers – with many projects simply based on rolling programmes of maintenance regardless of whether they were necessary.

Using field surveys, historical data, mapping and modelling, David and the team collated data on sediment dynamics, and developed new ways of managing and restoring the rivers by looking at the issue strategically, rather than focusing on the specific problem site.

Concurrent research aimed to convince river agencies not to rush into dramatic and costly changes to rivers and landscapes without first setting clear benchmarks for what they wanted to achieve.

Extensive investigations into river restoration and the effect of these projects on biodiversity, including studying the impact of 2009’s extreme flooding in Cumbria, has helped develop the theories behind the latest approaches in restoration policy.

What was the impact?

The research, led by David, has helped radically change the approach of river authorities around the world to the management and restoration of waterways.

River management agencies and environmental engineering consultants now routinely apply fluvial geomorphology in the scoping, assessment and planning of their projects.

David and his collaborators have helped develop tools, guidebooks and e-learning training packages that are currently shaping the river management policy and practice of the Environment Agency (EA); the Department for Environment, Food and Affairs; Natural England and the Scottish Environment Protection Agency. He is also involved in reviewing the EA’s policies on sediment management and has trained more than 200 EA staff in fluvial geomorphology.

These training materials are also being used by river agencies around the world, as well as by academics to train the next generation of river managers.

The Fluvial Audit methods developed by David and his colleagues at the GeoData Institute and Newcastle University have been adopted by commercial environmental consultancies and have guided projects on more than 50 rivers in the UK, as well as rivers in the United States, Argentina, Australia and India.

Restoration of watercourses

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