Comparing levees with dams

Overview

The purpose of this evening meeting is to discuss matters of common interest to both the dams and reservoirs industry and those involved in using levees in flood risk management. The meeting flows out of the setting up within ICOLD of a technical Committee on Levees, the first meetings of which were held at the Vienna Congress in 2018. The main justifications for the inclusion of levees within the scope of ICOLD put forward by member countries were:

• Learning from similarities and differences between levees and dam including in areas such as uplift, piping, breach analysis, consequences assessment, flood hydrology, aging of concrete, public education, risk analysis, and use of geomembranes and geotextiles
• In many ICOLD member countries In terms of the infrastructure portfolio, levees have a scale & scope similar to dams
• Dams and levees act as a system to protect against droughts and floods and their presence has a mutual effect

The presentation and the discussion at the meeting will cover two separate aspects:

1. Progress with the Dams vs Levees Inter-comparison Report which was commenced by an EUCOLD WG and is being taken up by the new Levees TC. The report will cover: functions, components and failure modes; dams and levees in flood risk management; governance; design, construction, operation and maintenance; emergency management. The form of the comparison will be to start with brief statements about respective levee and dam practices/properties and the potential lessons to be learned from the similarities and differences. The aim will be to highlight or discuss the areas of levee knowledge that might have added value for the dam community, areas where dam knowledge may or may not be directly applicable to levees. Understanding differences in terminology will be crucial for common understanding. The report is also expected to help to identify key areas where the Levee Committee should aim to co-operate with other ICOLD Committees.
2. Discussion on research being carried out for the Environment Agency on interfaces between levees and flood walls or other hard structures. It is understood from historical floods (both in the UK and internationally) that most levee failures occur around transitions. This is illustrated by well-known cases such as the levee failures in New Orleans during hurricane Katrina, and by the findings from reviews of levee performance during UK flood events since 2007. The research is delivering improved assessment/inspection guidance, quantifying the effects of transitions for use in flood risk analysis via fragility curves and is hoped to provide guidance on retrofitting, which will supplement that available in the International Levee Handbook