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Water Level Management

ISIS Professional Case Study

by Vijay Jain, Halcrow

Managing tidal flood risk in London

Cost-effective integrated

modelling solutions. Much of London is built on the floodplain. Notable floods from the River Thames leading to loss of life occurred in 1099,

1236, 1663, 1791, 1928 and 1953. The Thames Barrier and associated flood defences now protect much of London and ISIS is the model of choice for informing the operation of the Barrier. ISIS is also used to support many other flood risk management activities in London and the Thames Estuary.

Key features of ISIS that make it the ideal tool for modelling the Thames include: • Accurate representation of the operation of major structures such as the Thames Barrier.

• Flexibility to select either a one- dimensional representation (1D), two-dimensional (2D)

representation or a coupled 1D (channel) to 2D (floodplain) model.

• Robust and rapid calculation engine.

• Ability to run within the Delft FEWS-based National Flood Forecasting System. • Inclusion of wind shear effects. • High quality support and maintenance.

These attributes mean that those using it to support critical operational decisions, such as when to close the Thames Barrier to protect London, can be fully confident in the model’s ability to provide robust water level estimates on demand.

ISIS has been successfully used on the Thames to:

• Calculate extreme water levels, which are used to inform the design of new defences and assess the risk from breaching to new developments. • Undertake daily operation forecasts of water levels to support operational decision making for the Thames Barrier and associated gates. • Produce design water level boundaries for a TUFLOW model of the floodplain, which

determined the tidal Flood Zones across London.

• Support emergency planning via implementation in the THEMIS software, which enables real-time rapid analysis of breaching and overtopping scenarios.

• Inform the development of the Environment Agency’s Thames Estuary 2100 long term flood risk management strategy (TE2100), by modelling a wide range of future climate conditions and flood risk management responses.

Solutions to modelling complex river structures

Halcrow will be holding their latest ‘Modelling Made Easy’ webinar on Wednesday 16th May at 13:00 (GMT). The free 30 minute (including questions) webinar will discuss the issues associated with modelling complex river structures. It will focus on flow gauging stations for which careful schematisation and modelling is required to accurately represent the often complex hydraulics at these sites. Complex and unusual weirs, out of bank flows, data limitations, modelling approaches, uncertainty and calibration against observed data will all be considered. The webinar will be hosted by Adam Parkes and is aimed towards relatively new users of ISIS, but the more experienced modeller may also pick up a useful tip or two.

Adam has vast consultancy experience and is responsible for a number of ISIS and TUFLOW training courses. He has worked on a wide variety of projects ranging from small site specific flood risk assessments in ungauged catchments through to very large scale flood risk mapping and flood alleviation projects requiring utilisation of large amounts of observed and gauged data. Our free webinar combines real-time desktop sharing with phone conferencing so that everyone can see and hear the same thing. It eliminates the need for travel - all you need is access to the internet and a telephone.

Reserve your place

To reserve your place at the webinar, please contact Alastair Sheppard at Specific information on how to access the session will be provided directly to those wishing to attend.

Please note that spaces are limited and are allocated on a first come, first serve basis. Due to the limited number of spaces, it is recommended that organisations use a conference or meeting room to hold the webinar as this will allow several people to attend at each office via one registration.

More Information

If you have any questions about ISIS, please do not hesitate to contact our dedicated technical support team on +44 (0)845 094 7994 or at Additional information about ISIS can also be found at 25

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