Lecture 13
Center Pivot Nozzling
I. Center Pivot Nozzling
The wetted width of the application package can be reduced closer to the
pivot point because the towers are moving at a slower speed at inner points;
therefore, the application intensity (AR) is le
Lecture 23
Manifold Hydraulic Design
I. Introduction
Manifolds in trickle irrigation systems often have multiple pipe sizes to:
1. reduce pipe costs
2. reduce pressure variations
In small irrigation systems the reduction in pipe cost may not be significan
Lecture 22
Numerical Solution for Manifold Location
I. Introduction
In the previous lecture it was seen how the optimal manifold location can be
determined semi-graphically using a set of non-dimensional curves for the
uphill and downhill laterals
This lo
Lecture 24
Hydraulic Design of Mainline & Supply Line
I. 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 int
Lecture 21
Pipe Specifications & Trickle Lateral Design
I. Plastic Pipe Specifications
Trickle and sprinkle irrigation systems are
commonly built with plastic pipe, of which there
are various types and specifications
It is important to understand how the
Lecture 12
Center Pivot Design & Operation
I. Introduction and General Comments
Center pivots are used on about half of the sprinkler-irrigated land in the USA
Center pivots are also found in many other countries
Typical lateral length is 1,320 ft (400 m)
Lecture 19
Water Requirements in Trickle Irrigation
I. Trickle Irrigation Requirements
1. Daily Use Rate
The daily transpiration rate under a trickle system is based on Ud and the
percent area shaded (covered) by the plant leaves. Eq. 19.9:
Td = 0.1 Ud Pd
Lecture 20
Emitter Selection & Design
I. Introduction
There are hundreds of models, sizes and types of emitters, sprayers,
bubblers, and others, available from dozens of manufacturers
Prices of emitters can change frequently
Some emitters have longer life
Lecture 18
Trickle Irrigation Planning Factors
I. Soil Wetted Area
Trickle irrigation systems typically apply small amounts of water on a
frequent basis, maintaining soil water near field capacity
But, usually not all of the soil surface is wetted, and mu
Lecture 17
Filtration for Trickle Irrigation Systems
I. Introduction
Water for trickle irrigation systems can
come from open reservoirs, canals, rivers,
groundwater, municipal systems, and other
sources
Solid contaminants can include both organic
and inor
Lecture 14
Center Pivot Uniformity Evaluation
I. Introduction
The calculation of an application uniformity term must take into account the
irrigated area represented by each catch container
It is more important to have better application uniformity furthe
Lecture 15
Maximizing Linear Move Field Length
I. The Procedure
The following procedure for maximizing field length is from Allen, 1983, Univ.
Idaho and Allen, 1990 (Irrig. Symp. Paper), and is used in the USUPIVOT
computer program
The basic strategy is t
Lecture 16
Trickle Irrigation System Components & Layout
I. Introduction and Descriptions
Trickle and drip are terms used to describe what can be generally called
micro-irrigation systems, in which water is applied in relatively precise
quantities and pre
Lecture 11
Pumps & System Curves
I. Pump Efficiency and Power
Pump efficiency, Epump
Epump =
water horsepower W HP
=
brake horsepower BHP
(221)
where brake horsepower refers to the input power needed at the pump shaft
(not necessarily in horsepower; could
Lecture 10
Minor Losses & Pressure Requirements
I. Minor Losses
Minor (or fitting, or local) hydraulic losses along pipes can often be
estimated as a function of the velocity head of the water within the particular
pipe section:
hml
V2
= Kr
2g
(208)
where
Lecture 9
Mainline Pipe Design
I. Split-Line Laterals
Laterals are usually distributed evenly along a mainline because:
More equal pump load at different lateral positions
Reduced mainline cost
Dont need to dead-head back when finished (cross over to othe
Lecture 8
Set Sprinkler Lateral Design
I. Dual Pipe Size Laterals
Sometimes it is useful to design a lateral pipe with two different diameters to
accomplish either of the following:
1. a reduction in hf
2. an increase in hf
In either case, the basic objec
Lecture 7
Set Sprinkler Lateral Design
I. Basic Design Criterion
The basic design criterion is to size lateral pipes so that pressure variation
along the length of the lateral does not exceed 20% of the nominal design
pressure for the sprinklers
This crit
Lecture 3
Sprinkler Characteristics
I. Hardware Design Process
1.
2.
3.
4.
5.
Sprinkler selection
Design of the system layout
Design of the laterals
Design of the mainline
Pump and power unit selection
II. Classification of Sprinklers and Applicability
(s
Lecture 2
Types of Sprinkler Systems
I. Sprinkler System Categories
Two broad categories: set and continuous-move
Set systems can be further divided into: fixed and periodic-move
II. Set Systems:
Hand-Move
very common type of sprinkler system
costs about
Lecture 6
Economic Pipe Selection Method
I. Introduction
The economic pipe selection method (Chapter 8 of the textbook) is used to
balance fixed (initial) costs for pipe with annual energy costs for pumping
With larger pipe sizes the average flow velocity
Lecture 4
Set Sprinkler Uniformity & Efficiency
I. Sprinkler Irrigation Efficiency
1. Application uniformity
2. Losses (deep percolation, evaporation, runoff, wind drift, etc.)
It is not enough to have uniform application if the average depth is not
enoug
Lecture 5
Layout of Laterals for Set Sprinklers
I. Selecting Sprinkler Discharge, Spacing, and Pressure
In Chapter 6 of the textbook there are several tables that provide guidelines
for nozzle sizes for different:
Wind conditions
Application rates
Sprinkl