Sprinkle & Trickle Irrigation Lectures Page 275 Merkley & Allen Lecture 24Hydraulic Design of Mainline & Supply LineI. Introduction •Chapter 24 of the textbook contains a good summary and discussion of the design process for trickle irrigation systems •Keller & Bliesner divide the trickle irrigation design process into three phases: 1. Phase 1: Planning factors, gross application depth, preliminary system capacity, filtration requirements, etc. 2. Phase 2: Hydraulic design of laterals, manifolds, and subunit layout. 3. Phase 3: Hydraulic design of main and supply lines, control head, and pumping plant. II. Factors Affecting the EU •Solomon (1985) studied the various factors affecting emission uniformity and ranked them according to importance using model studies and field surveys. This is his ranking: 1. Plugging of emitters and other system components 2. Number of emitters per plant, NBpB3. Emitter coefficient of variation, ν4. Emitter exponent, x 5. Emitter discharge variation with temperature 6. Pressure head variations in subunits 7. Coefficient of variation on pressure regulators 8. Friction loss from manifolds to laterals 9. Number of pipe sizes in manifolds •In general, plugging (or the lack thereof) has the greatest influence on EU, except in cases where the system design is very poor •Plugging cannot be prevented by design only -- it is up to the management to continuously maintain the system as necessary •The above ranking implies that a poorly designed system might perform better (in terms of application uniformity) than a well designed system, provided that the system operation and maintenance is given due attention and effort
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