A New Approach to Sediment Transport in the Design and Operation of Irrigation Canals : UNESCO-IHE Lecture Note Series

Understanding the behavior and transport of sediment allows efficient planning and reliable water delivery schedules, and ensures the controlled deposition of sediments, making maintenance activities more manageable. This book presents a detailed analysis of sediment transport in irrigation canals, together with physical and mathematical descriptions of the behavior. The authors use a mathematical model to predict the sediment transport, deposition and entrainment rate for various flow conditions and sediment inputs. The model is particularly suitable for the simulation of sediment transport in irrigation canals where flow and sediment transport are determined by the operation of flow control structures. Read more... Abstract: Understanding the behavior of sediment allows efficient planning and reliable water delivery schedules, and ensures the controlled deposition of sediments, making maintenance activities manageable. This book presents an analysis of sediment transport in irrigation canals, together with physical and mathematical descriptions of the behavior. Read more... Content: Table of Contents LIST OF FIGURES LIST OF TABLES 1. INTRODUCTION 2. OPEN CHANNEL FLOW 2.1 Introduction 2.2 Flow types and characteristics 2.3 Geometry 2.4 Basic hydraulic principles 2.5 Velocity distribution 2.6 Uniform flow 2.7 Non-uniform steady flow 2.8 Some general aspects of unsteady flow 2.9 Basic differential equations for gradually varied unsteady flow 2.10 Solution of the de St. Venant equations 2.11 Rectangular channels and the method of characteristics 3. SEDIMENT PROPERTIES 3.1 Introduction 3.2 Density and porosity 3.3 Size and size distribution 3.4 Shape 3.5 Fall velocity 3.6 Characteristic dimensionless parameters 4. DESIGN CRITERIA FOR IRRIGATION CANALS 4.1 Introduction 4.2 The role of sediment transport in the design of irrigation canals 4.2.1 Regime method 4.2.2 Tractive force method 4.2.3 Permissible velocity method 4.2.4 Rational method 4.3 Final comments 5. SEDIMENT TRANSPORT CONCEPTS 5.1 Introduction 5.2 Friction factor predictors 5.2.1 Bed form development 5.2.2 Effect of bed forms on the flow resistance 5.2.3 Determination of the friction factor 5.2.4 Composite roughness for non-wide irrigation canals 5.2.5 A recommended method for the prediction of composite roughness in trapezoidal canals 5.2.6 Comparison of the composite roughness predictors in trapezoidal canal 5.2.7 Prediction of composite roughness in a rectangular canal 5.3 Governing equations for sediment transport 5.3.1 Sediment transport capacity 5.3.2 Comparison of sediment transport capacity 5.3.3 Sediment transport computation in non-wide canals 5.3.4 Comparison of the procedures for computing the total sediment transport 5.3.5 Sediment transport in non-equilibrium conditions 5.4 Morphological changes of the bottom level 5.5 Conclusions 6. SETRIC, A MATHEMATICAL MODEL FOR SEDIMENT TRANSPORT IN IRRIGATION CANALS 120 6.1 Introduction 6.2 Water flow equations 6.3 Sediment transport equations 6.4 General description of the mathematical model 6.5 Input and output data 6.6 Conclusions 7. THE SEDIMENT TRANSPORT MODEL AND ITS APPLICATIONS 7.1 Introduction 7.2 Case 1 - Changes in the discharges 7.3 Case 2 - Changes in the incoming sediment load 7.4 Case 3 - Controlled sediment deposition 7.5 Case 4 - Flow control structures 7.6 Conclusions REFERENCES LIST OF SYMBOLS APPENDIX A: METHODS TO ESTIMATE THE TOTAL SEDIMENT TRANSPORT CAPACITY IN IRRIGATION CANALS A.1 Introduction A.2 Ackers and White method A.3 Brownlie method A.4 Engelund and Hansen method A.5 Van Rijn method A.5.1 The suspended load transport A.6 Yang method APPENDIX B: METHODS TO PREDICT THE FRICTION FACTOR B.1 Van Rijn B.2 Brownlie B.3 White, Paris and Bettess B.4 Engelund APPENDIX C: HYDRAULIC DESIGN OF IRRIGATION CANALS C.1 Introduction C.2 Alignment of an irrigation canal C.3 Water levels C.4 Earthwork C.5 Design of irrigation canals C.6 Boundary shear stresses C.7 Sediment transport criteria C.8 Transport of the bed material C.9 Final remarks C.10 Computer aided design of canals APPENDIX D: DESCRIPTION OF THE MAIN ASPECTS OF THE REGIME THEORY D.1 Some regime considerations D.1.1 Sediments D.1.2 Maturing of canals D.1.3 Slope adjustments D.1.4 Diversion of the sediment D.1.5 Maintenance aspects D.1.6 Flow capacity D.1.7 Design considerations APPENDIX E: GLOSSARY INDEX The transport of sediment greatly influences the sustainability of an irrigation system. Erosion and deposition not only increase maintenance costs, but may result in an inequitable and inadequate distribution of irrigation water. Understanding the behavior and transport of sediment allows efficient planning and reliable water delivery schedules, and ensures the controlled deposition of sediments, making maintenance activities more manageable. This book presents a detailed analysis of sediment transport in irrigation canals, together with physical and mathematical descriptions of the behavior. The authors use a mathematical model to predict the sediment transport, deposition and entrainment rate for various flow conditions and sediment inputs. The model is particularly suitable for the simulation of sediment transport in irrigation canals where flow and sediment transport are determined by the operation of flow control structures.

These lecture notes present sediment transport in irrigation canals under varying flow conditions and sediment inputs. They include an analysis of sediment transport concepts, a physical and mathematical description and a model that is typically suited