Impact of blockage on flood risk

31 July 2012, 4.00 PM - 31 July 2012, 4.00 PM

Lecture room 1.15QB, Queen’s Building, University Walk, Bristol, BS8 1TR

A two hour meeting of the British Hydrological Society South West Section.

Conveners: Oliver Pollard, Environment Agency

A blockage in a culvert can be very difficult to remove and likely to result in a severe flood risk. For these reasons the provision of a debris screen at the entrance to the culvert is often considered. Such a screen can reduce the risk of a blockage inside a culvert, but introduces a significant maintenance obligation (to ensure that the screen is kept clean) which far exceeds the typical maintenance requirements of an open watercourse. The build-up of trash can be rapid, and the consequences can be severe in terms of flood damage to local properties and infrastructure. Many more problems have been caused by blocked screens than have resulted from blocked culverts. Flood warnings manage the residual flood risk but often ignore the impact of blockage.

This meeting includes four presentations on the various aspects of managing the flood risk due to blockage. The first presentation explores the use of real-time technology such as webcams to monitor flood blockages. The second presentation takes a broad look at good practice in the inspection, maintenance and operation of culverts and refers to the latest guidance provided in CIRIAs recently produced Culvert Design and Operation Guide. The third presentation will look at modelling the impact of blockage on flood risk to provide data useful in both the design and operation of culverts. The final presentation will provide an update on how to design operational flood forecasting models to take account of blockage rather than ignore it.


1545-1600  Registration and Coffee

1600-1605  Meeting introduction - Oliver Pollard, Environment Agency

1605-1630  Flood blockage monitoring - Nik Whalley, Hydro-Logic Consultants

1630-1700  Good practice - Inspection, maintenance and operation of culverts - Matt Balkham, Royal Haskoning DHV

1700-1730 Modelling the impact of blockage on flood risk - Gary Deakin, JBA Consulting

1730-1800 The role of structure blockage in flood risk at Ashton Vale, Bristol - Dr Chris Whitlow, Edenvale Young Consultants


The meeting is free of charge, but register prior to the meeting using this link. A list of attendees is required by the porters for security reasons. There is no need for registration for UoB staff/students.

For further information please contact Oliver Pollard

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