Case Study of River Restoration

++ Habitat Restoration on the River Thames, Central London ++

River Thames, Central London

A leading threat to aquatic biodiversity is loss of habitat. Nowhere is this more apparent than on the Central London reaches of the tidal River Thames. Despite improvements in water quality in the 1960’s, the tidal Thames remains one of the most challenging ecological aquatic environments. In Central London the river has been channelled along hard vertical walls which have removed the natural habitat of plants and animals. In addition the narrowed channel has lead to an increase in tidal velocity and range to 6 meters. Additional building work encroachment and other physical changes have also changed patterns of water flow, erosion and deposition, increasing the loss of inter-tidal vegetation and associated wildlife.

The creation of new habitat to support biodiversity and endangered species is a challenging task on the Tidal Thames due to the longstanding nature of the alterations to the river, and continuing intense usage and demands of the capital city on its banks. In the last three years Thames21 has tested and introduced a variety of habitat restorations, which have been beneficial small scale initiatives, attracting native plants, insects and other species.

This initial work has enabled the project to develop to the stage where the present larger scale programme could be planned. Funding from the Esmee Fairbairn Foundation has allowed the present collaborative research and demonstration programme between Thames21 and King’s College London to be initiated. The two year research, consultation and trialling programme commences in Spring 2007.

Thames21 is an environmental charity running a programme of sustainable community engagement and volunteering to deliver practical activities which protect and improve waterway environments. It was first set up as a project within Encams ten years ago and has been an independent Registered Charity for two years.

Environmental improvement activities include removing litter and graffiti from the network of waterways across Greater London, creating new habitat for flora and fauna, installing community waterside art, promoting safe public access to watersides and foreshores, educational work with community groups and schools, angling projects to engage young people in their local waterways and education campaigns to change attitudes and behavior and prevent littering, pollution and other threats to the biodiversity of London rivers.

Thames21 aims to increase the community’s sense of value and responsibility for the waterways so that sustainable environmental improvement can be achieved.

++ River Restoration Design ++

There are some research in concerning of the initiation and early development of a river channel within a newly-cut, sinuous, trapezoidal corridor. The restoration design aimed to provide the river with a corridor of appropriate size and sinuosity to give it both the energy and flow complexity to build its own bed and bank forms and reseed its banks. When it is possible to adopt such an approach to restoration, it minimizes costs and maximizes the naturalness of the end product.

A simple approach to restoration


Post-project monitoring is integrating numerical flow simulations with observations of river morphology and dynamics, and with evolving riparian habitat and community structure, providing the first integrated study of hydraulic, sedimentological and vegetation influences on the initial development of a river channel and its margins. The project is providing scientific insight into the mechanisms of river channel and margin establishment and is informing future corridor design.

The success of self-restoration in river-cole, UK

The project has been extremely successful. Bedforms and particle size distributions of the riffle crests evolved within the first winter. Feedbacks between the self-sown bank vegetation and river bank profiles occured within 2 years rather than the 10+ years that were anticipated. Aquatic vegetation was well established within three years.

A diverse vegetation has colonised the banks as a result of transport of seeds and vegetative propagules from upstream. Despite an extensive cover of the alien invasive species, Himalayan balsam, immediately upstream of the restoration site, there has been no significant development of this species within the study reach. Instead the diverse vegetation covering the evolving banks is comprised of largely native species.


++ Riparian Trees and River Dynamics ++

Riparian trees along semi-natural river

Riparian trees and 'natural' river characteristics

A model of island dynamics has been proposed, based upon research on the 'pristine' Fiume Tagliamento, Italy. The model incorporates different island types and trajectories of development in response to interactions between wood debris, living vegetation, sediment calibre, erosion and deposition. This project investigates the influence of alpine, transitional and mediterranean environmental contexts and reach hydraulic characteristics on the nature and trajectories of island dynamics as a basis for tailoring the model to specific environments and providing an input to riparian vegetation management along more impacted systems.

Riparian trees and river engineering


Riparian trees are critical to the characteristics of river channels, banks and floodplains. Many tree species that are capable of colonising and establishing around the margins of rivers have important impacts on the river environment.

Riparian tree species are capable of growing on unstable, often waterlogged sediments. Their growth protects the sediment surface from erosion and also encourages surface sedimentation. Their root systems reinforce the sediment on which they are growing and as the sediment accumulates many species can send out adventitious roots from their buried trunk, offering further reinforcement. These properties of riparian trees make them very useful in artificial bank protection works and so they are widely used in 'soft' engineering schemes.

However, while we know a great deal about the general engineering performance of riparian trees, we know less about the subtle differences in environmental requirements and related growth performance of particular species. Our research is assembling this type of information through laboratory and field experiments and observations, to enable us to:

• guide selection of the most appropriate species, propagule types and planting times to maximise the potential success of planting schemes
• assess the longer term ecological as well as engineering impacts of the artificial introduction of individual species to particular river environments
• forecast likely changes in species performance as a consequence of climate, river flow and management changes.

++ Vegetation Trapping of Fine Sediment ++

Interaction between vegetation and sediment


This NERC-funded project investigates interactions between vegetation, river flows, and sediment / vegetation propagule dynamics in complex, groundwater-fed rivers. It aims to identify how vegetation growth influences fine sediment and organic matter retention in these channels, the feedbacks this has on landform and vegetation development, and the implications these have for physical habitat dynamics and diversity.

Measuring fine sediment and propagule movements

The project integrates observations of flow, fine sediment and propagule transfer processes with vegetation biomass and channel morphology dynamics in 6 reaches (2 on the River Tern, Shropshire and 4 on the River Frome, Dorset), through the assessment of the hydraulic signature of different reach types and the application of ordination techniques to the ecological and sedimentological data. These outputs are being combined with the classification to give insights into the impact of vegetation on sediment and propagule dynamics to support the development of management guidelines.