(introduction...)

* Components of Farm Irrigation Systems
* Canal Design, Construction, and Maintenance
* Control Structures: Cheeks, Diversions, and Drops
* Pipe System Design, Construction, and Maintenance
* Land Leveling or Smoothing
* Surface Irrigation Systems
* Surface Irrigation Systems: Border Systems
* Surface Irrigation Systems: Furrow Systems
* Sprinkler Systems
* Localized Systems
* Exam: Section 6 (Designing System Requirements)

Session Topic: Components of Farm Irrigation Systems

Session Goal: Trainees will be able to describe the components of an irrigation system and explain their function.

Objectives:

(1) Trainees will visit several different irrigation projects and identify the components that make up an irrigation system.

(2) Trainees will describe the function of the components in an irrigation system and describe how this information is important in planning projects.

Overview: To familiarize Trainees in cultural practices of irrigation, they should see the components to understand fully how and why the system operates. Trainees should visit several different types of irrigation projects and discuss how each component is an integral part of the system.

Session Activities:
Time
2-3 Hr.	Trainer leads Trainees on walking tour of irrigation projects in the training area. Trainees are told to describe and record the various components of the irrigation systems they are observing (e.g., water supply source, water conveyance methods used, quality of water in the conveyances, farm water application practices, crops being grown, field drainage practices) and to try to develop some assumptions about the reasons for the system designs. Trainees should begin their system review at the water source and end at a farm drainage canal.
60 Min.	Trainees gather at a convenient point and use their observations to label specific components of farm water systems and establish clear descriptions of the features and factors included in each component.

Materials:

* transport

References

Chapter 5, Irrigation Reference Manual: Components of Farm Irrigation Systems

International Irrigation Center Modules #21, #22, #23, #24, #25, #26, and #27

Session Topic: Canal Design, Construction, and Maintenance

Session Goal: Trainees will be able to design and construct simple distribution canals and perform general canal maintenance practices.

Objectives:

(1) Trainees will demonstrate the ability to complete canal design requirements.

(2) Trainees will be able to use the Manning equation to properly design trapezoidal canals and use nomographs to assist in the calculations.

(3) Trainees will design and construct a small canal for a water distribution system.

(4) Trainees will tour an existing water distribution system and identify practices necessary to maintain an efficient system.

(5) Trainees will perform maintenance practices in a canal.

Overview: Canal conveyance systems are a main component in getting water from the source to the field. Trainees will be taught how to properly size a canal to carry a given flow rate and learn construction techniques. This session also enables Trainees to apply many of the concepts they learned in the earlier hydrology and developing water resources session.

Session Activities:
Time
90 Min.	Trainer presents a profile drawing of an irrigation canal. Trainer asks Trainees to identify the factors that must be taken into account when designing this canal. Trainer uses Trainee information to present brief lecture on canal design criteria and requirements. Included in the lecture should be an explanation of the Manning equation, using diagrams to describe the origin of each factor in the equation. Lecture should also include sample problems showing how the Manning equation is used and how to use nomographs. Present and discuss the continuity equation and its use in canal design.
30 Min.	Trainer provides Trainees with some hypothetical data and instructs them to perform independently the calculations necessary to size a canal.
90 Min.	Trainer leads Trainees to the field, where they are instructed to collect the data necessary to design and construct a small canal. Trainer indicates approximate location of canal and requests to review the completed canal design with 90 Min. Trainees are left on their own to determine roles and responsibilities.
2-5 Hr.	Trainees clear brush, stake out route at desired slope, dig the canal, and install a sediment trap. Again, Trainees are left on their own to determine roles and responsibilities in completing this construction work.
45 Min.	Trainees divert and run water into the canal, checking the side slope stability and water velocity. Trainer reviews Trainee work and facilitates discussion of problems and important learning that occurred.
2-4 Hr.	Trainer leads Trainees to tour an existing canal distribution system and asks them to comment on condition of the canal and recommend necessary maintenance practices. Trainees should measure the flow rate in the canal and then perform the necessary tasks to complete a canal maintenance exercise. After completing the canal maintenance, Trainees should again measure the flow rate and evaluate improvements made by canal maintenance.

Materials

* bucket
* calculators
* hoes, rakes, shovels, picks, machetes
* leveling device
* measuring tape
* stakes
* stopwatch
* surveying rod

References:

Chapter 5, Irrigation Reference Manual: Control Structures

Session Topic: Control Structures, Checks, Diversions, and Drops

Session Goal: Trainees will identify the factors involved in selecting and applying the use of control structures in a canal system, design simple checks, diversions, and drops, and be able to construct and install them.

Objectives:

(1) Trainees will list different types of control structures and describe their function in a canal system.

(2) Trainees will be able to design, construct, and install simple control structures in a canal system.

(3) Trainees will be able to demonstrate the use of a canvas and pole as a check structure in a canal.

Overview: Often earthen canal systems are inefficient because water is not controlled properly in the canal. This results in erosion and washouts. Control structures limit flow velocities to permissible rates so that this does not occur. This session builds on canal design and construction and will give Trainees more flexibility in routing canals through irregular and sloped topography and make water distribution easier and more efficient from the conveyance canal to the field.

Session Activities:
Time
60 Min.	Trainer asks Trainees to describe simple structures they can build to control flow in a canal. Trainer uses this list to diagram types of structures available and their functions. Diagrams should indicate design criteria.
90 Min.	Trainees go to the field where they collect the necessary data and prepare to construct a wooden or concrete control structure in a canal. Preparation should include gathering materials and bringing them to the construction site.
2-3 Hr.	Wooden or concrete control structure should be constructed and installed. Trainer will critique the installation.
60 Min.	After several days, Trainees should return and remove the forms for the structure, and send water through the canal. The operation of all control structures should be checked to determine if there are any washouts or rocks at the downstream side of the drop (energy dissipaters). The water velocities in the canal should be measured. Trainer can conclude exercise with discussion of the importance and applications of control structures.
60 Min.	Have Trainees construct a canvas check dam and install it in a farm irrigation ditch to adjust the water in the canal to a level that will permit distribution onto a field.

Materials:

* 1.5 m poles
* buckets
* canvas or sheets of plastic
* cement
* gravel
* hammers, saws
* hoes, machetes, picks, shovels
* rails
* sacks (haul gravel/sand)
* sand
* stopwatch
* tape measure
* wood planks/lumber

References:

Chapter 5, Irrigation Reference Manual: Control Structures International Irrigation Center Module #21

Session Topic: Pipe System Design, Construction, and Maintenance

Session Goal: Trainees will be able to size tubing correctly for pressurized systems, describe basic hydraulic phenomena that commonly occur in pipelines, and list the criteria for pipeline installation.

Session Objectives:

(1) Trainees will be able to describe the term "pressure head" in units commonly used in irrigation, e.g., psi, kg/cm², feet, and meters.

(2) Trainees will be able to calculate frictional losses in a pressurized pipeline and determine proper pipe sizing for a given pressure head.

(3) Trainees will be able to describe certain hydraulic principles in pressurized pipe systems (i.e. water hammer, air relief, pressure relief) and ways in which they can be controlled or reduced.

(4) Trainees will be able to list different types of piping material and describe their use and specifications.

(5) Trainees will be able to describe pipeline installation criteria.

Overview: This session is the basis for the design of pressurized irrigation systems. Proper main line design and installation will assure an adequate operating pressure at the sprinkler nozzles or drippers. Trainees will learn methods to calculate frictional loss in pipelines and installation practices to assure adequate and trouble-free operation.

Session Activities:
Time
90 Min.	Trainer demonstrates concept of pressure head by elevating a five-gallon bucket filled with water to a height of two meters, and siphoning from the bucket. Check the head in the tube at lengths of 5 and 10 meters and the outflow from the hose. Now elevate the bucket to a height of five meters and do the same thing. Trainer uses this demonstration to lead into lecture on basic principles of hydraulics, emphasizing the concepts of pressure head, friction, and energy.
60 Min.	Trainer presents brief overview of equations used to calculate friction losses in pipes and the cost per unit length of various sizes and types of pipe, demonstrating how this information is used to select pipe sizes. Trainees are provided with sample data and instructed to select proper pipe sizes for a hypothetical system. The design should emphasize selection of pipeline components and materials to avoid unacceptable pressure losses and ensure adequate flow while accounting for economic considerations. Trainer concludes exercise with overview of the concept of water hammer and techniques for identifying potential water hammer problems in the field.
60 Min.	Trainer reviews techniques used to control pipe pressures and describes mechanisms for siting relief valves. Trainer brings out sample pipe materials to describe the varieties of pipe types and pressure ranges available and to demonstrate installation procedures and criteria.

Trainer Notes: This session can appear to be very complicated to Trainees with limited or no background in hydraulics. Trainers should be prepared to use diagrams and drawings wherever possible to relate the concepts to real situations and to use pipe materials to show how these concepts are applied.

Materials Required:

* 2 1/2" diameter tees
* 5-gallon bucket
* bucket
* rope
* 30 meters of 1/2" diameter polyethylene tube (one 20-meter length and two 5-meter lengths)
* calculator
* stopwatch

References:

Chapter 5, Irrigation Reference Manual: Pipeline Hydraulics and Design

Session Topic: Land Leveling or Smoothing

Session Goal: Trainees will be able to identify and analyze land leveling needs and perform a land smoothing exercise with a low-input implement to move soil.

Session Objectives:

(1) Trainees will be able to identify land leveling needs.

(2) Trainees will be able to describe construction criteria and constraints in land leveling.

(3) Trainees will describe low-input implements used in land smoothing.

(4) Trainees will perform a land survey and smoothing exercise.

(5) Trainees will construct a land smoothing implement (wooden buck scraper).

Overview: Land leveling is an important practice to establish a level land grade so that surface water advances and is distributed uniformly. Often this is not practical in small-scale operations because of the large investment to move soil. Therefore, land smoothing is preferable for small farmers. This session builds on previous sessions on surveying and soils and will allow Trainees the opportunity to work with implements powered by animal traction. This session will also be useful in the following session on border irrigation practice.

Session Activities:
Time
60 Min.	Trainer shows Trainees drawings or slides of fields that have not been well leveled and asks Trainees to identify techniques that can be used to improve water distribution in the field. Trainer uses this information to define the concept of land leveling and its application in surface irrigation. Descriptions of land leveling limitations and practical techniques are included.
120 Min.	Trainees use trainer diagram to construct a land smoothing implement (buck scraper is recommended). Trainees should be allowed to determine work roles and responsibilities in completing this task.
60 Min.	Trainees should observe the spread of water over a field and determine the variation in depth of water due to unevenness of the field. This exercise will help them see the extent of leveling required. A plow and buck scraper can be used to move soil from high to low areas when the field dries out, thus making the soil surface more even.
60 Min.	If time permits, Trainees may construct a graded border with no cross slope as follows. Trainees complete a survey of a field and lay out the contour lines at a very slight slope (0.5-1 percent). The spacing of the contour lines will depend on the depth of soil and the desired width of the border. Generally, border width will vary from 3 meters to 10 meters, depending on the convenience of operating machinery in the border and avoiding excessive topsoil removal.
120 Min.	Trainees should plow between their guide markers and then use their land smoothing implement to smooth and level between contour lines.
30 Min.	Trainer can conclude by asking Trainees to describe time management skills they will need to develop in order to factor in all of the varied activities necessary in developing a farm irrigation system.

Trainer Notes: If Trainees have very little experience in working with farm animals, it may be advisable to have a local farmer help them with this exercise.

Materials Required:

* leveling device (e.g. water level)
* lumber
* nails
* nuts and bolts
* plow implement
* saws, hammers
* shovels, hoes
* stakes
* steel chain
* team of oxen

References:

Chapter 5, Irrigation Reference Manual: Land Leveling

Session Topic: Surface Irrigation Systems

Session Goal: Trainees will be familiar with the different types of surface irrigation methods and be able to describe basic criteria for their selection and design.

Session Objectives:

(1) Trainees will be able to list the different types of irrigation methods and give a brief explanation of each.

(2) Trainees will be able to describe the appropriateness and adaptability of each irrigation method in relation to specific land and crop conditions.

(3) Trainees will be able to list the advantages and disadvantages of each method in relation to local conditions.

(4) Trainees will be able to describe basic design criteria for surface systems.

Overview: This session is used to introduce and discuss different types of surface irrigation and their adaptability to agricultural conditions. Specific terms will be defined and basic design criteria for systems should be presented.

Session Activities:
Time
45 Min.	Trainer asks Trainees to describe the types of methods that can be used to divert water from a canal and irrigate a field. Trainer should use this information to establish different surface practices (e.g. flood, furrow). Trainees are asked to describe the advantages and disadvantages of each system and identify criteria that must be used in designing each system.
30 Min.	Trainees are divided into groups of three with each group assigned a particular surface irrigation method. Trainer provides each group with basic data and the group is instructed to complete a simple system design.

Trainer Notes: This session can be supplemented through use of slides or videos.

Materials Required: none

References:

Chapter 5, Irrigation Reference Manual: Surface Irrigation Systems

International Irrigation Center Modules #22, #23, #24, and #27

Session Topic: Surface Irrigation Systems: Border Systems

Session Goal: Trainees will be able to design, install, and operate a border irrigation system.

Session Objectives:

(1) Trainees will demonstrate skills to design a small border irrigation system.

(2) Trainees will demonstrate skills to lay out and construct a border irrigation system.

(3) Trainees will demonstrate skills to operate border irrigation system.

Overview: In this session, Trainees will develop a border irrigation system from design to operation. It will give them confidence to complete future projects. The session builds on canal design, conveyance systems, and land leveling sessions. It is recommended that the field for the irrigation system be the same field where the land leveling session took place.

Session Activities:
Time
60 Min.	Trainer reviews data requirements, design criteria, and construction techniques for a border irrigation system. Trainees are instructed to collect the necessary data and construct a border system in a designated field.
90 Min.	Trainees collect necessary data on topography, soils, and crops, and complete system design.
4-6 Hr.	Trainees construct a conveyance system to bring water to the field, lay out and construct the borders, and construct the tail water ditch.
2-3 Hr.	Trainees will plant crops in the borders, irrigate the field, and check the borders for stability.

Trainer Notes: This exercise can be done with a local farmer to make the end result very practical.

Materials Required:

* crop ready to be planted
* leveling device, survey rod, stakes
* sheet of plastic
* shovels, picks, hoes
* soil auger
* tape measure
* two poles 1.5 m

References:

Chapter 5, Irrigation Reference Manual: Surface Irrigation Systems

International Irrigation Center Module #24

Session Topic: Surface Irrigation Systems: Furrow Systems

Session Goal: Trainees will be able to design, install, and operate a furrow irrigation system.

Session Objectives:

(1) Trainees will demonstrate skills to design a furrow irrigation system.

(2) Trainees will demonstrate skills to lay out and install a furrow irrigation system.

(3) Trainees will demonstrate skills to operate and manage a furrow irrigation system.

Overview: In this session, Trainees will develop a furrow irrigation system from design to operation. It will give them confidence to complete and be involved in future projects. This session builds upon canal design and conveyance systems and if possible, these prior sessions should be incorporated into this larger irrigation project.

Session Activities:
Time
60 Min.	Trainer reviews data requirements, design criteria and construction techniques for furrow irrigation systems (level, contour, graded, corrugated). Trainees are instructed to collect the necessary data and construct a contour furrow system in a designated field.
90 Min.	Trainees collect necessary data on topography, soils, and crops, and complete system design.
4-6 Hr.	Trainees construct a conveyance system to bring water to the field, lay out and construct the furrows, and construct the tail water drain.
2-3 Hr.	Trainees perform an advance/recession test for a given flow, check water distribution with a soil auger (depth and lateral movement), and check for erosion problems. If necessary, the trainer may need to demonstrate the use of a siphon in order to complete this exercise.

Trainer Notes: This exercise can be done with a local farmer to make the end result very practical.

Materials Required:

* leveling device
* measuring tape
* polyurethane or polyvinyl chloride siphons (1" or 1 1/2")
* sheet of plastic
* shovels, hoes, picks
* soil auger
* stakes
* two poles 1.5 m

References:

Chapter 5, Irrigation Reference Manual: Surface Irrigation Systems

International Irrigation Center Module #23

Session Topic: Sprinkler Systems

Session Goal: Trainees will be able to design, install, operate, and manage a small-scale sprinkler irrigation system.

Session Objectives:

(1) Trainees will collect the field data necessary to design a sprinkler irrigation system.

(2) Trainees will design a small-scale irrigation system that includes at least three to four sprinklers.

(3) Trainees will install a sprinkler irrigation system and prepare a simple operation and maintenance program for the system.

Overview: In this session Trainees develop a small-scale sprinkler irrigation system from the design to operational stage. This completed project can give Trainees confidence in future projects and should provide them with sufficient information to work with sprinklers on a limited scale. This session draws upon the experience obtained in the pipeline design session.

Session Activities:
Time
120 Min.	Trainer introduces session by asking Trainees to list reasons why they might choose a sprinkler system in an irrigation design. Trainer indicates if sprinkler usage is or isn't common in-country but points out that either way, understanding the mechanics of these systems is necessary. Trainees brainstorm the data requirements and design criteria for sprinkler systems. Data requirements should include:
	- shape and area of the field,
	- topography (in reference to water source to field),
	- soil characteristics (infiltration rate, water-holding capacity),
	- crop characteristics (water requirements at peak use, rooting depth), and
	- wind conditions.
	Design criteria should consider:
	- water flow rate (required or available),
	- pressure required or available (for pumping station need pump capacity; for gravity flow need elevational difference from water source to field),
	- distance from water source to field (to determine main pipeline length),
	- diameter and length of conveyance pipe and fitting (frictional loss; pipe diameter availability and cost),
	- sprinkler type and nozzle size (flow and wetted diameter at operating pressure; water application rate to match soil intake rate),
	- sprinkler availability: types, sizes, and pressure required, and
	- sprinkler spacing (to achieve adequate uniformity).
	Trainer uses actual sprinklers to demonstrate what all of these concepts mean in terms of metal and moving parts. Trainer then informs Trainees they will now be designing and constructing a very simple irrigation system. Trainees should appoint a facilitator and then work as a group to prepare a material list for this system and establish management criteria. Management criteria should include water application requirements and rates, estimated time to irrigate, schedules, and schematics. Trainer should allow Trainees to complete this activity on their own but should review the final product and offer advice on additional information that should be considered if the Trainees have left gaps in their lists. Trainees are given field data and instructed to prepare a complete design for a system that will include three to four sprinklers. The pipeline length should be kept relatively short, if possible, as this will reduce the amount of field time required. Trainer informs Trainees they will need to make their own materials purchases and that they should appoint a small group to do this task. Allocate one to two hours of training free time for this Trainee group to complete this exercise.
3-5 Hrs.	Trainees travel to proposed work site. As initial task, the group that purchased sprinkler supplies should describe their experience completing this task. Trainer should facilitate a review of the procedures to be followed in constructing a sprinkler system. Trainees then proceed to carry out the installation of their system design.
60 Min.	Trainer reviews Trainees' experience completing the system construction work. Trainer provides brief explanation of system evaluation procedures. Trainer informs Trainees they will need to conduct an evaluation of the system they constructed, and that they should gather materials and plan to complete this exercise.
1-5 Hr.	Trainees work as a group in the field to complete an evaluation of their sprinkler system. This will not be a continuous activity, as there will be considerable lag time while the Trainees wait for water to be applied. This component of the session can be done while Trainees are performing other activities nearby. In conducting the evaluation Trainees should (a) evaluate water application distribution, (b) check pressure at several points along the main line and lateral lines, and (c) check flow rate at sprinkler.
45 Min.	After Trainees have obtained all of their data they can return to the classroom and complete the evaluation using the distribution uniformity coefficients graph. Trainer should lead discussion to determine how Trainees might change any aspect of the process they used.

Trainer Notes: This session involves quite a lot of classroom time, and it may be advisable to break this up over several days in order to maintain Trainee attention spans.

Materials Required:

* bucket
* hoes, machetes, shovels
* leveling device
* plastic cups
* pressure gauge with fittings to insert in line
* screw driver, pliers
* stakes (can be made by Trainees)
* stop watch
* string, measuring tape, plastic or Teflon tape
* sprinkler heads, pipelines, fittings, pressure sources (pump or elevated intake)

References:

Chapter 5, Irrigation Reference Manual: Pipeline Hydraulics and Design; Sprinkler Irrigation Systems International Irrigation Center Module #25

Session Topic: Localized Systems

Session Goal: Trainees will be able to design, install, and operate a low-cost, appropriate technology localized irrigation system.

Session Objectives:

(1) Trainees will describe the basic components that are included in developing a localized irrigation system.

(2) Trainees will design a low-cost localized system.

(3) Trainees will install and operate a localized system.

Overview: This session will introduce localized irrigation to the Trainees. They will be able to design very simple systems, install, and operate them. This session builds on previous sessions that covered pressurized pipeline design and sprinkler irrigation systems.

Session Activities:
Time
60 Min.	Trainer asks Trainees to describe criteria that would warrant the use of a localized irrigation system (e.g., limited available water supplies, emphasis on permanent crops in cropping pattern). Trainer brings out materials used in building a localized system and reviews the functions of each component and considerations that should be considered in planning such a system: types of crops being grown, low system pressure, availability of materials, and costs. Trainer demonstrates how components are assembled and diagrams the process of preparing and completing a simple system design for irrigating a tree crop.
30 Min.	Trainees are divided into two groups and assigned the task of preparing a very simple localized system design, using prepared data obtained from one of the work site areas. Design must include a materials list and budget.
60 Min.	Each Trainee group completes purchasing trip to buy locally available materials for use in their localized system construction.
90 Min.	Trainee groups use the materials purchased to construct their system. After completing the system, each group prepares an operation and maintenance plan and demonstrates their system in operation, discussing problems and possible solutions.

Trainer Notes: If the training group is small (ten or less Trainees), then it may not be necessary or advisable to do this session as two groups. The component activities of this session can be split up and done over several days, if this is more conducive to the overall training design.

Materials Required: Leave this up to the Trainees to decide.

References:

Chapter 5, Irrigation Reference Manual: Localized Irrigation Systems
International Irrigation Center Module #26

Exam: Section 6 - Designing system requirements

1. What are five factors that you should consider in the selection and design of an irrigation system?

Answer:

slope	field geometry
soil type and depth	crop
flow rate	erosion

2. You need to construct a channel to convey irrigation water from a stream diversion to a field. You install a 90° V-notch weir in the stream and measure a head of 11 cm. a) What is the flow rate? You decide that a triangular-shaped canal will be the easiest construction for you and the farmer. With your Abney level, you measure a slope of 1.4% for the canal. b) What will the depth of water be for the triangular channel that will convey the measured flow downstream of the weir once uniform flow has been established? Use a rock-lined canal with a side slope of 1:1 (z = 1); c) What is the velocity of the water?

Answer:

a. Q = 0.014 H ^5/2 = 0.014 (11) ^5/2 = 5.6 liters/sec = 0.0056 m³/sec

b. n = 0.032
s = 0.014
z = 1

Q AR^2/3 S^1/2/n (metric)

For a triangular canal,

A = zd²
R = A/wp = zd² /2d(1 + z²)^1/2

For a triangular canal with z = 1,
d = 0.114 m = 11.4 cm c.

Q = velocity x area, or V = Q/area = 0.43 m/sec

3. A field has a slope of 5%. (a) If the channel is to be built in the same direction as the slope, the channel bottom is to have a 1% slope, and drops are 0.5 meters each, how many drop structures per 100 meters of channel would you need? (b) What type of drop structure would you use?

Answer:

The drops will have to compensate for 4% of slope, or 4 m/100 m. Thus, the number of drops is 4 meters/0.5 m = 8 drops per 100 meters.

4. A farmer knows that the water source is above her field, and she wants to irrigate the land. She goes to the market and buys 4 rolls (100 m/roll) of 1/2" ((diameter) polyethylene tubing. She installs the main line and, to her surprise, only a trickle of water comes out of the end of the tube. She calls you and asks for advice. What would you tell her, and how would you explain the problem?

Answer:

friction loss in tube
sizing of tube
elevational difference between water source and field

5. In land leveling, what is the main physical factor that determines if the practice can be done effectively? Explain your answer.

Answer:

topsoil depth
plant growth in minimum depth of 30 cm

6. What recommended flow rate would cover a 10 m x 10 m basin with sandy loam soil?

Answer: (5 L/sec (see Table 5.6, Irrigation Reference Manual)

7. What are the steps in constructing a contour furrow irrigation system?

Answer:

1. survey field
2. lay out guide furrows
3. make furrows between guide furrows

8. For furrows (a) What typical flow rate and length of furrow might you expect on a medium textured soil, down a 2% slope, and with 100 mm of water application? (b) If the furrow were half the typical length, what flow rate might you recommend?

Answer:

a) length = 120 m, Q = 20 L/sec
b) length = 60 m, Q = 10 L/sec

9. Which system generally requires a higher flow rate, borders or furrows?

Answer: borders

10. There is a 30 m elevational drop between the water source and a field that is to be sprinkler irrigated by gravity pressure. A 100 m distance separates them. A farmer wants to irrigate the field, and it will require a flow of 120 L/min. If the minimum operating pressure for the sprinkler system is 30 psi, what size PVC main line would you recommend to the farmer, 1", 1 1/2", or 2"?

Answer:

For the system to work, the elevation head must be greater than the pressure head plus friction losses. For 2" pipe, friction head = 2 m/100 m (Table 5.3, Irrigation Reference Manual), and the operating pressure of 30 psi = 21 m. Thus, elevation head (30 m) > 21 m + 2 m. The 2'' size would allow for up to 7 meters of additional friction losses in fittings, etc., and for slightly higher operating pressure.

11. A farmer comes to you and asks how he can eliminate air from the pressurized pipeline in his gravity flow sprinkler system. You accompany him, inspect the main line, and find all the unions to be watertight. Upon arriving at the stream and finding the farmer has placed the inlet of the main line in a fast-flowing, turbulent section of the stream, what is your recommendation?

Answer:

Construct a small diversion.
Put 50 cm head of water over tube inlet in non-turbulent pounded water.

12. Why do you need debris-free water when operating a localized irrigation system?

Answer: to prevent clogging of emitters

13. Name an appropriate technology localized irrigation system.

Answer: perforated polyethylene tubing, with appropriate sized holes, discharging into small basins around trees