Sprinkler and Drip Irrigation: Theory and Practice

Description

This textbook is a comprehensive volume on sprinklers and drip irrigation and covers all the basic and fundamentals concepts related to these topics. It is the first book to consider  relative-flow-ratio as an evaluation criterion for both sprinkler and drip irrigation designs.  It also discusses various types of sprinklers (used for irrigation), their complex layouts, design methodologies, selection criteria explained with practical examples, and their operations and maintenance under different conditions. In addition to operation and maintenance of drip irrigation components, the book also explains the drip irrigation hydraulics and various design aspects and the effect of the same on their performance. It also has one important chapter on Rhizosphere modelling which introduces the state-of-the-art technologies in optimal irrigation and fertigation scheduling. Worked out examples and solved problems in the chapters would aid to learning and understanding of the topic among the students. Given the contents, the book will be extremely useful for the undergraduate and postgraduate students of agriculture engineering, irrigation engineering and civil engineering. This textbook will also be useful for researchers, engineers and professionals working in these areas. Foreword Preface Acknowledgements Contents About the Author Main Section Sprinkler Irrigation Types and Components Introduction Advantages Disadvantages Classification of Sprinkler Irrigation Systems Components of a Periodic Move Sprinkler Irrigation System Pump Pipes Pipe Fittings Sprinkler Heads Valves Control Valves Air Release/Vacuum Breaker Valve Non-return Valve Pressure Relief Valve Booster Pumps Desilting Basins and Debris Screens Summary Assessment References and Further Readings Uniform Irrigation with Sprinklers Introduction Sprinkler Discharge Rate Wetted Diameter Spacing of Sprinkler Heads Breaking of Jet Application Rate Application Efficiency Sprinkler Head Selection Uniformity Parameters Design of Sprinklers Spacing Summary Assessment References and Further Readings Layout of Sprinkler Systems Introduction Maximum Area of Land Irrigated from a Water Source Number of Sprinklers Operated at a Time (Nmax) Time of Irrigation Pressure Variation in a Lateral Typical Layouts Summary Appendix Assessment References and Further Reading Design of Periodic Move and Solid Set Sprinkler Systems Introduction Important Observations from This Problem Friction Loss Equation in Sprinkler Lateral for a Uniform Diameter Pipe Scallopi’s Correction Factor for Christiansen’s F Average Friction Loss Pressure Head Distribution in Sloping Laterals Design of Laterals Design of Submains Design of Main Summary Appendix Assessment References and Further Reading Selection of Pumps Introduction Reference States for Components for Energy Pump Total Dynamic Head (TDH) Power of Pump Operating Characteristics of Pump Net Positive Suction Head (NPSH) Selection of Pump Using Manufacturer’s Catalogue Head Losses in Pipe Sections Examining the Sufficiency of Existing Pump in the Field Pumps in Parallel Pumps in Series Selecting a Suitable Diesel Engine for Pump Summary Assessment References and Further Reading Maintenance and Operation of Sprinkler Irrigation Systems Introduction Maintenance Tips for Sprinkler Irrigation System Operation of SIS System Characteristics Matching the Impeller Speed and Diameter for Variable requirements Changing the Speed of Rotation Alone Changing the Diameter of Impeller Alone Time of Sprinkler Operation Soil Moisture Characteristics Field Capacity Permanent Wilting Point Available Water Holding Capacity Management Allowable Depletion (MAD) Irrigation Scheduling Plant Wilt Symptoms Method Evapotranspiration Estimation Methods Irrigation Requirements Irrigation Depth Gross Irrigation Depth Irrigation Interval Capacity of Pump van-Genuchten’s Equation Irrigation Scheduling Under Salinity Summary Assessment References and Further Reading Drip Irrigation Components Introduction Salinity Under Drip Irrigation Classification of Drip Irrigation Systems Point and Line Source Online Drippers Inline Drippers Subsurface Drip Emitters or Drippers Bernoulli’s Law for Flow in Emitter Orifice Emitters Vortex Emitter Long Path Emitters Tortuous Path Emitters Pressure Compensating Dripper Self-flushing Drippers Present-Day Drippers Variation in the Emitters Discharge Due to Manufacturing Filtration Vortex Sand Separators (Hydro Cyclones) Media Filter Disc Filters Screen Filter Filter Selection Hydraulics of Flow Through Filters Chemical Injection Devices Venturi Assembly Pressure Differential Fertilizer Tank Fertilizer Injection Pump Pipes PVC Fittings & Accessories Pump Automation Components Relay Circuit Solenoid Valve Automatic Metering Valve Pressure Management Valves Controllers for Backwashing of Sand and Disc Filters Sensor-Based Irrigation Systems Automated Fertigation Systems Pollution Prevention Accessories in Chemigation Variable Frequency Drive (VFD) Summary Appendix Assessment References and Further Reading Drip Irrigation—Planning Factors Introduction Crop Water Requirement Maximum Area of the Land Irrigated Maximum Area of One Subunit Wetting Pattern of Drippers Empirical Equation for Wetting Pattern Semi-Empirical Equation for Wetting Pattern Ponded Radius Lateral Configurations Emission Point Layouts for Widely Spaced Crops Computing Percentage Wetted Area Case Study Dripper Discharge Rate Spacing Between Drippers Spacing of Lateral Summary Assessment References and Further Reading Hyraulics of Microirrigation Pipes Introduction Friction Loss Through Drip Laterals and Submains Average Friction Loss Ratio of Pressure Head Losses due to Friction Versus Ratio of Lengths Locations of Maximum and Minimum Pressures in Uniform Slopes Coefficient of Variation of Pressure and Discharge Rate in Uniform Slopes Emitter Connection Head Losses Summary Assessment References and Further Reading Drip Subunit Design with Uniform Diameter Pipes in Uniform Slopes Introduction Relative Flow Difference Criterion Maximum Length of a Horizontal Lateral Maximum Length of Lateral/Submain on Slopes Paired Lateral Average Pressure Head Average Pressure Head for Upslope Average Pressure Head for Downslope Average Friction Loss in a Paired Lateral Average Elevation Loss in a Paired Lateral Equal Average Pressure Heads on Both Sides of a Paired Lateral Average Pressure Head for Upslope Average Pressure Head for Downslope Relative Pressure Head Variation in Downslope Slope Profile Type Statistical Variation Criterion Relationship Between CVh and Vh Evaluation of Drip Irrigation Systems with Statistical Criterion Keller and Karmeli Emission Uniformity Criterion Field Evaluation When Using Keller and Karmeli Criterion Summary Assessment References and Further Reading Design with Telescopic Pipes in Uniform and Non-uniform Slopes Introduction Trial-and-Error Method Telescopic Pipe Design Poly-Plot Method Telescopic Pipe with Only Two Sections Computer-Aided Design of Drip Subunits Drip System Simulation Programme (DSSP) Manufacturing Variation Uniformity coefficient Screens of the DSSP Model Problem Design of Lateral Lateral Diameter (ϕ) Design of Submain Design and Evaluation of the Subunit Lateral Data Summary Assessment References and Further Reading Design of Mains Introduction Water Hammer Management Estimation of Surge Pressure Heads Minimal Capital Method Life Cycle Cost Analysis Method Summary Assessment References and Further Reading Fertigation Introduction Nutrient Elements Nitrogen Phosphorous Potassium Calcium, Magnesium and Sulphur Micronutrients Nutrients in Fertilizers Fertilizers and Irrigation Water Concentrations of Fertilizers Solution Water Soluble Solid and Liquid Fertilizers Fertilizer Injection Times Fertigation Scheduling Summary Assessment References and Further Reading Maintenance and Operation of Drip Irrigation Systems Introduction Water Chemical Reactions Bio-chemical Reactions with Water Reaction of Fertilizers With Water Acid Treatment Acid Treatment for Prevention of Carbonate scales Acid Treatment for Clogged Systems Biological Plugging Removal Continuous Treatment Intermittent Treatment Super Chlorination Algae Control in Ponds and Wells Remedy for Iron Regular Maintenance of Accessories Filters Media Filters Flushing Main and Laterals Handling Rats and Squirrel Problems Operation of Drip Irrigation System Minimum Irrigation Duration Maximum Duration of Irrigation Irrigation for Germination Irrigation Scheduling Summary Assessment References and Further Reading Evapotranspiration for Microirrigated Crops Introduction Reference Crop Evapotranspiration Evapotranspiration Estimation by Climatological Data Single Crop Coefficient Approach Single Crop Coefficient Approach Dual Crop Coefficient Approach Summary Assessment References and Further Reading Rhizosphere Modelling Introduction Derivation of Richards Equation Boundary Conditions Unsaturated Hydraulic Conductivity Parameters Parameter Optimization Inverse Modelling with a Double-Ring Infiltrometer Test Soil Water Balance Methods for Estimation of Evapotranspiration Water Balance Models Single Cell–Single Step Model Single Cell–Multiple Step Model Drainage from Root Zone and Capillary Rise to Root Zone Irrigation Depth (it) Average Water Content in Root Zone Results of the Case Study Multiple Cell–Multiple Step Model Derivation of Reactive Transport Solute Transport Equation Diffusion Convection Hydrodynamic Dispersion Adsorption Chemical Reaction Urea Reactions in Soil Continuity Equations for Reactive Solute Transport Boundary Conditions Estimation of Dispersivity Estimation of Urea Reaction Rate Constants Experimental Set-up for Estimation of Urea Reaction Rate Constants Parameter Set Needed for Rhizosphere Modelling Development of Fertigation Schedule by Modelling with Hydrus Summary Appendix I Appendix II Introduction to Finite Difference Methods Truncation Errors and Numerical Dispersion References and Further Reading Water Budgeting and Economic Evaluation Introduction Water Budgeting Rainfall Analysis Water Balancing Basics of Economic Analysis Summary Assessment References and Further Reading Basic Section Pressure, Energy and Power in Water Introduction Units and Terminologies Used Laws of Newton Pressure Pressure Measurement Energy of Water Potential or Gravitational or Datum Energy Kinetic Energy Pressure Energy Total Energy of Water Power of Water Summary Solved Exercises Assessment References and Further Reading Bernoulli’s Law Introduction Bernoulli’s Equation Friction Head Loss Friction Loss Formulae Pressure Change Due to Elevation Flow in Microirrigation Pipes Summary Points to Ponder Solved Exercises Assessment References and Further Reading Soil Texture and Soil Moisture Introduction Soil Types of Soil Water Hygroscopic Water Capillary Water Gravitational Water Soil Moisture Specification Methods Summary Points to Ponder Exercises Solved Exercises Assessment Reference and Further Reading Soil Water Movement Introduction Saturated Flow Unsaturated Flow Energy of Unsaturated Flow Tensiometer Correction of Tensiometer Reading Summary Points to Ponder Solved Exercises Assessment Reference and Further Reading Salinity Introduction Atom Electro-Neutrality Clay Particles Salinity of Soil Leaching Requirement Cation Exchange Capacity (CEC) Exchangeable Sodium Per Cent (ESP) Sodium Adsorption Ratio (SAR) Hydration Summary Assessment Reference and Further Reading Pumps Introduction Basic Physics to Understand Pumps Angular Momentum Torque Rotational Power Centripetal Force and Centrifugal Force Centrifugal Pump Operating Principle Components of Centrifugal Pump Impeller Casing Suction Pipe Foot Valve Strainer Delivery Pipe Delivery Valve Working of Centrifugal Pump Priming Volute Chamber Volute Pump with Vortex Chamber Casing with Stationary Guide Blades Classification of Centrifugal Pumps Radial Flow Mixed Flow Axial Flow Pumps Self-priming Pumps Centrifugal Pump Installation Centrifugal Pump Troubles and Remedies Pump Fails to Start Pumping Pump Working but not Up to Capacity and Pressure Multi-stage Pump Turbine and Submersible Pumps Propeller Pump Jet Pump Airlift Pump Work Done by a Centrifugal Pump Impeller Heads of a Pump Static Head Suction Dynamic Head Delivery Dynamic Head Total Dynamic Head Minimum Speed Needed to Initiate Flow Impeller Diameter Diameter of Suction Pipe and Delivery Pipe Limitation of Suction Lift Loss of Head and Efficiencies Mechanical Losses Leakage Losses Performance of Pumps—Characteristic Curves Specific Speed of a Pump Expression for Specific Speed Specific Speed Versus Operating Characteristics Assessment References and Further Readings