Levees, Diversion Canals or Flood Expansion Areas?

R Tourment,G Degoutte,B Beullac,J Maurin,S Patouillard

doi:10.1051/e3sconf/20160712007

Abstract

Risk Flood protection involves works which reduce the hydraulic hazard in protected areas in terms of frequency, duration, water level, water velocity or flood arrival time. These works are parts of protection systems. In this paper, we discuss and compare three structure-based solutions that contribute to flood protection but seem to oppose one another in the mind of general opinion: levees based protection systems, whose purpose is to prevent water from spreading in protected areas; diversion channels that aim to decrease the flow at their downstream; flood expansion areas, whose purpose is to temporary store water, reduce flood peak and spread flow duration. The article also deals with weirs which can be found in addition to dikes in the three types of solutions on which the paper focuses. For each type of these flood protection solutions, the paper describes their functions and limits, details how these solutions are similar, opposite or complementary, and in the end shows that they are globally complementary and not mutually exclusive. It also demonstrates the interest of a multi-scale analysis and of an integrated design and management of these arrangements, taking into account flood risk, morphological changes and associated environmental objectives.

Highlights

Amongst the various measures and tools contributing to flood prevention, protection is the best known, the most visible, and the one which is most likely to be requested by populations and local stakeholders
This paper will discuss and compare three solutions based on structures which contribute to flood protection and are perceived as antagonistic in the public mind: flood protection systems based on levees, diversion canals, and flood expansion areas
Spillways are usually found on the three types of structures that will be examined: levee based flood protection systems, and in relation to with levees in diversion channels and flood expansion areas

Summary

Introduction

Amongst the various measures and tools contributing to flood prevention, protection (sometimes called defence) is the best known, the most visible, and the one which is most likely to be requested by populations and local stakeholders. Protection calls for structures which function is to reduce, in the areas they protect, hydraulic hazards in terms of: - frequency; - duration; - water velocity; - water level; - or of the moment when flooding occurs. These structures can be levees, grouped together or complementing other structures or natural elements in protection systems, or dams, canals, or dynamic retention structures. This paper will discuss and compare three solutions based on structures which contribute to flood protection and are perceived as antagonistic in the public mind: flood protection systems based on levees, diversion canals, and flood expansion areas.

Embankments: dams or levees

Spillways

Levee based flood protection systems

Diversion Canals

Conclusions and perspectives