Spillways on River Levees

Foreword

Introduction

1. Background, definitions, various configurations

Typology of flood protection levees on rivers

Protected areas and flood expansion areas

Typology of spillways on levees

2. The historical background of spillways in France

1584 to 1891: The first spillway constructions on the Loire and Vidourle Rivers

20th century: Several scattered constructions and major development of the Rhône River

21st century: A relative acceleration in construction

3. The hydraulic design of spillways

The spillway’s impact on the flooded river’s waterline

Impact of the spillway on the waterline in the protected area

The spillway’s flow law

Spillway location

Protection, safety, and danger floods

The principle of flood attenuation or flood hydrograph flattening

General hydraulic design principles

The required modelling

4. Spillways and river geomorphology

Overview of sediment transport

Overview of morphological changes in watercourses

Morphological changes in leveed watercourses

The spillway’s influence on sediment transport (riverbed)

Sedimentation behind spillways

The influence of bed change on spillway performance

Torrents

5. Civil engineering design for levee spillways

Safety criteria for levee spillways

Principles of fuse plugs or movable devices

The plan shape of the levee spillway

Types of straight weirs and constituent materials

Fuse plugs or movable devices

Continuous maintenance tracks

Overflow erosion on earthen levees

6. Emergency management of the levee system

The benefits and limitations of spillways in emergency management

The types of emergencies to manage

Considerations before drafting an Emergency Management Plan

Emergency management and levee managers

Local Emergency Action Plan (LEAP)

Special Emergency Management Plan for Flooding

7. Economic aspects

8. Summary and Conclusion

The benefits and limits of a spillway in a protected area

Spillway features

Is a spillway always required in a protected area?

Concluding remarks

Appendix 1. Spillway types on river levees, according to their hydraulic function and their purpose in flood management

Appendix 2. A history of spillways on the Loire River

Appendix 3. Overflow levees and spillways in the CNR’s Rhône River development

General principles

Example 1: The Chautagne plain and Lac du Bourget

Example 2: The Printegarde plain in Livron-sur-Drôme

Glossary

Reference List