HYDRAULIC DESIGN OF STEPPED CASCADES, CHANNELS, WEIRS AND SPILLWAYS

1. Introduction 1.1. Presentation 1.2. Applications 1.3. Flow regimes 1.4. Air entrainment on stepped chutes. 2. History of stepped channels and weirs 2.1. Introduction 2.2. History of stepped chutes 2.3. Ancient irrigation canal systems 2.4. Discussion. 3. Nappe flow regime 3.1. Hydraulic Characteristic of nappe flows 3.3. Energy dissipation 3.4. Air entrainment in nappe flow regime 3.5. Design of chutes with nappe flow regime 3.6. Example of application. 4. Skimming flow regime (1) - Hydraulic of skimming flows 4.1. Introduction 4.2. Onset of skimming flow 4.3. Boundary layer growth 4.4. Uniform flow conditions 4.5. Flow resistance 4.6. Velocity distribution 4.7. Examples of application. 5. Skimming flow regime (2) - Energy dissipation 5.1. Presentation 5.2. Head loss calculations 5.3. Residual energy 5.4. Discussion 5.5. Examples of application. 6. Air-water transfer on stepped chutes 6.1. Introduction 6.2. Prediction of air-water gas transfer 6.3. Nappe flow regime 6.4.Skimming flow regime 6.5. Discussion : comparison between nappe and skimming flows 6.6. Examples of application. 7. Design of stepped channel and chutes 7.1. Introduction 7.2. Design of stepped fountains 7.3. Concrete stepped spillways and weirs 7.4. Gabion stepped weirs and chutes 7.5. Earth dam spillway precast concrete blocks 7.6. Timber dams and crib dams 7.7. Debris dams. 8. Accidents, failure and safety of the design 8.1. Presentation 8.2. Failure and accidents 8.3. Safety features for stepped channels 8.4. Discussion 8.5. Example of application. 9. Conclusion. Appendices. Appendix A - Nappe flow trajectory at a drop structure. Appendix B - Physical and chemical properties of fluids. Appendix C - Bubble size calculations at inclined plane liquid jets. Appendix D - Modelling air-water gas transfer in skimming flows. Appendix E - Unit conversions. Appendix F - Corrections

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