Impact of managed realignment design on estuarine water levels, London

27 February, 2017 | 18:00 - 20:45

Impact of managed realignment design on estuarine water levels, London

About this event

Based on the Nigel Pontee’s award winning paper, this lecture will look at the impact of managed realignment design on estuarine water levels. Delegates will explore the factors that influence changes in water levels and learn how to design schemes successfully.

In an estuarine context, the term managed realignment is used to describe the process of deliberately removing flood defences and re-introducing tidal regimes to low lying land previously reclaimed from the sea. In the UK, these schemes have been promoted by both the Environment Agency and private developers in order to replace lost habitats or reduce flood defence costs.

The impacts on estuarine water levels have not been widely documented and it is important to rectify this since managed realignment schemes, which are often promoted as reducing flood risk, can cause increases in water levels in some circumstances.

The lecture will provide a brief introduction to managed realignment, explaining how the location of such schemes determines their impacts on water levels and describe results from hydrodynamic modelling carried out as part of design.

The presentation will describe the various options that were explored in the design process. The results confirm that managed realignments schemes that lead to the significant expansion of intertidal areas near estuary mouths can alter the tidal propagation within estuaries leading to increases in water levels. The results also suggest that the design of such schemes needs to carefully consider the location, number and size of breaches since these elements, which are within the remit of the engineer, are also important in determining the impacts. These effects would be expected to apply to other hyper- and macro-tidal estuaries.

These findings suggest that it is necessary to consider the hydrodynamic impacts of schemes when choosing sites an estuary wide scale (e.g. as part of estuary flood risk management strategies) as well as during the detailed design at specific sites.

Event materials

The following materials are available for download:


Nigel Pontee, CEng, FICE, CWEM, CIWEM

John Beswick

Over the last 20 years in coastal consultancy Nigel has spent a large portion of his time working on coastal habitat restoration. Having been involved in approximately 65 such projects, he has contributed to the creation of over 1700ha of new habitat. His work has covered site selection, outline and detailed design, impact assessment, post scheme monitoring and the production of national and international best practice guidelines. He is currently the Global Technology Leader for Coastal Planning and Engineering in CH2M and a Visiting Professor at the Natural and Environmental Science department, University of Southampton.

Ian Townend (Chair)

John Beswick

Ian works as an independent advisor on coastal science and engineering applications and as a Visiting Professor at the University of Southampton. Previously he was responsible for the strategic direction and development of the research capability at HR Wallingford, helping to develop new initiatives within the water sector.  Prior to that he spent 13 years as Managing Director at ABPmer (a research laboratory focussed on the ports industry) and 18 years as a consultant with Halcrow, an international civil engineering company.
He has worked on a wide range of coastal and marine studies in the UK and overseas.  This has included: leading the first regional scale coastal study in the UK that helped frame the subsequent development of Shoreline Management Plans; piloting the application of risk methods to examine coastal flooding at a national scale for the insurance industry; leading the UK estuary research programme; directing the consortium undertaking the UK Climate Change Risk Assessment on behalf of Defra; and working on several major development projects in the UK and abroad.
His own research is largely related to estuaries and coasts and involves a wide range of interests including hydraulics, sediment transport, and geomorphology, as well as the associated habitats and ecosystems.
Ian is currently a Visiting Professor of the School of Ocean and Earth Sciences and the School of Civil Engineering and the Environment, within the University of Southampton, an Honorary Professor of Nanjing Hydraulics Research Institute and a Guest Professor at the State Key Laboratory of Estuarine and Coastal Research at East China Normal University in Shanghai. He is a fellow of the Royal Academy of Engineering.