(introduction...)

* Diversion Dams
* Designing Spring Boxes
* Selecting Pumps
* Design and Use of Pump a
* Installing, Operating, and Developing Maintenance Plans for Pumps
* Wells: Hand Dug and Drilled
* Storage Pond Design, Construction, and Management
* Exam: Section 4 (Water Supply Estimates and Designs)

Session Topic: Diversion Dams

Session Goal: Trainees will be able to design and construct small diversion structures.

Session Objectives:

(1) Trainees will be able to select appropriate sites for diversion structures in small stream beds.

(2) Trainees will be able to design small diversion dams using locally available materials.

(3) Trainees will construct a small diversion dam.

Overview: In this session, Trainees will design and construct small diversion dams. All of the building materials will be obtained locally, and the construction will be done in a small stream bed. The purpose of the dam is to raise the water level or create a small reservoir for irrigation. This session should follow introductory sessions on hydrology and tool use.

Session Activities:
Time
30 Min.	Trainer asks Trainees to describe factors that need to be considered in designing and constructing dams to divert water for irrigation projects. Discussion should cover types of diversion structures that can be built, dam stability and minimum side slopes, spillway features, sediment control, and appropriate materials that can be used in construction. Trainer informs Trainees that they will now go to the field and construct a diversion. They should identify the tools and materials they will need to complete this job and then assess if these materials are available in the tool supply area. If any tools or materials are lacking, Trainees should get resourceful and determine what local materials can serve as a substitute.
180 Min.	Trainer leads Trainees to the field adjacent to a very small stream. Trainer has Trainees define the criteria they would use to select a site for a diversion structure and then use these criteria for selecting a site in the nearby stream. Trainees divide into groups of four; each group selects a site, assigns work roles, and proceeds to construct a diversion dam in the stream. Trainer concludes session by asking Trainees what could have improved the design or final product. Trainer also asks Trainees how they might have done things differently (or not) if the diversion had been for a larger stream.

Trainer Notes: Ideally, the diversion dam (s) constructed will be able to serve some practical purpose for a local community. If not, then the dam(s) should be removed immediately after the completion of the session.

Materials Required:

* digging bar, hoes, picks, and shovels
* sheets of plastic
* swim suits

References:

Chapter 3, Irrigation Reference Manual International Irrigation Center Module #21

Session Topic: Designing Spring Boxes

Session Goal: Trainees will be able to describe the hydrologic processes that result in springs and design a structure to capture the flow at a spring site.

Session Objectives:

(1) Trainees will be able to describe the tasks involved in spring development.

(2) Trainees will prepare an illustrative spring box design.

Overview: Springs can often represent an important water supply source for irrigation projects. In this session Trainees will learn methods to develop springs, and practice these methods in the field. They will visit completed spring boxes and observe spring hydrology in the field. This session should refer back to basic concepts covered in the watershed hydrology session.

Session Activities:
Time
60 Min.	Trainer brings Trainees to two spring sites in the field: the first should be an undeveloped spring that is flowing; the second should be a developed spring with completed, functioning spring box. At the undeveloped spring site, trainer should have Trainees describe the basic ground water hydrology that resulted in this spring source. Trainees should perform a simple flow measurement of the spring and identify any difficulties in determining the total flow, especially if the spring does not flow uniformly from a single outlet point. Trainees should describe the process they would follow to develop this source.
45 Min.	Trainer then leads group to developed spring site and has Trainees determine what steps were apparently followed in completing the spring development. Trainees should compare the process followed at the developed site with the process they described at the undeveloped site. Trainer distributes copies of diagrams that demonstrate procedures for constructing spring boxes, and Trainees compare diagrams with actual construction at the developed site.
45 Min.	Trainees return to undeveloped spring site and are instructed to collect data necessary to prepare a complete spring box design at the site. (If the distance between the undeveloped and developed site is great, then this data collection exercise should be done prior to leaving the undeveloped site.) Trainer divides the Trainees into groups of three and instructs each group to complete a spring box design as a homework assignment with 4-day due date. The design should include a complete materials list for the type and quantity of materials to be used in building the spring box. Trainee groups should work independently on this exercise.
30 Min.	After Trainee groups turn in their spring box designs, trainer facilitates session in which they compare the designs produced and resolve any outstanding questions or concerns about completing the actual construction of the design in the field.

Trainer Notes: If time permits, it is recommended that Trainees actually proceed to build their spring box. Building a spring box, however, is a time consuming effort, which unfortunately could detract from other essential sessions in the irrigation training. It may be necessary to limit the effort to this simple theoretical exercise.

Materials Required:

* bucket, cup, funnel
* tape measure
* stopwatch
* spring box design procedures handouts

References:

Chapter 3, Irrigation Reference Manual: Structures for Springs and Seeps

Session Topic: Selecting Pumps

Session Goal: Trainees will be able to describe different kinds of pumps available and the factors that influence pump selection.

Session Objectives:

(1) Trainees will be able to describe the different types of pumps available - human, animal, mechanical - and their applicability.

(2) The Trainees will demonstrate an understanding of basic hydraulics that affect the selection and design of pumps.

(3) Trainees will identify the types of pumps suitable for local conditions.

Overview: A familiarity with pumps and their applicability is required for the Volunteer to design systems that lift or pressurize water. This session will strengthen some of the material covered briefly in the session on wells and will supplement material to be presented in sessions on farm water delivery systems.

Session Activities:
Time
45 Min.	Trainer will present and describe various types of pumps that are used locally or regionally in well development or irrigation projects. Include in this discussion a description of the concepts of pressure, lift, flow rate, pumping conditions encountered (rivers, wells, reservoirs, canals), typical purchase costs, and how these factors influence decisions about pump selection. If time permits, trainer can have Trainees disassemble and reassemble one or more of the pumps, making certain that they record the procedures that they followed.
30 Min.	Trainees will list criteria that must be considered for pump selection, and trainer will provide basic data to enable Trainees to calculate total dynamic head and flow rates and perform pump selections. Trainees will identify factors that could constrain a quantitative selection of pumps. Trainees will determine those pumps that are most appropriate for local conditions.
45 Min.	Trainees will visit pumping plants in the field and describe the components in detail.

Trainer Notes: Trainees should have an opportunity to identify and work with a variety of pumping plants in the field. Providing Trainees with an opportunity to inspect or actually disassemble a pump would add a great deal to the value of this session. If time does permit disassembly and reassembly of a pump, it is recommended that trainers limit the number of tools available to do this job in order to simulate typical site conditions.

Materials Required:

* centrifugal pump, hand pump, suction pump
* tools for disassembly
* transport to field

References:

Chapter 3, Irrigation Reference Manual: Pumps and Water Lifting Devices

Session Topic: Design and Use of Pumps

Session Goal: Trainees will be able to develop the specifications for small irrigation pumps required by the pump supplier and installer.

Session Objectives:

(1) The Trainees will be able to develop the specifications for a mechanically driven centrifugal pump - total dynamic head, flow rate, horsepower requirements, transmission devices, prime movers (electric or internal combustion), and intake structures.

Overview: Pumps powered by small engines or electric motors are commonly used by small-scale farmers to obtain water from streams and wells. The irrigation technician, pump supplier, and installer must be familiar with the concepts of pump design and use if the correct pump specifications are to be developed. This session is intended to follow an earlier session on pump selection.

Session Activities:
Time
45 Min.	Trainer will briefly review the material discussed in the Pump Selection section and then ask Trainees to identify factors that specify the characteristics of a pumping station, e.g., flow rate, horsepower, pressure, lift, total dynamic head, and cavitation. Trainer will then work out a sample problem to demonstrate to Trainees how these factors are calculated and accounted for. Trainer provides sample problems for the Trainees to solve.
90 Min.	Trainees will interview a local pump supplier to determine the types of pumps available and the technical information that exists or is lacking to support pump design and selection procedures.
45 Min.	Trainees will travel to the field where they will collect the data necessary to determine the appropriate pump for a specific location. They will then use these data to design the specifications for a pump station.
90 Min.	Trainees will then travel to another nearby field site where a pump is to be installed. They should apply the basic skills learned to determine whether the location, intake structures, and general conditions are appropriate for the pump selected. If possible, Trainees should participate in or conduct the pump installation.

Trainer Notes: Trainer should locate an installed pump that can be visually observed during operation by the Trainees, a pump supplier representative of typical Volunteer site accessibility, and a site where a pump is planned for installation.

Materials Required:

* Abney level
* pressure gauge
* surveying rod
* tape measure

References:

Chapter 3, Irrigation Reference Manual: Pumps and Water Lifting Devices; Wells

Session Topic: Installing, Operating, and Developing Maintenance Plans for Pumps

Session Goal: Trainees will be able to properly install, operate, and perform maintenance procedures on a pumping plant.

Session Objectives:

(1) The Trainees will participate in exercises that enable them to evaluate the installation, operation, and maintenance of a pumping plant.

Overview: Proper installation, operation, and maintenance procedures are essential to ensure that a pump maintains its capacity to perform efficiently over time. This session should immediately follow the two previous sessions in pump selection and design.

Session Activities:
Time
45 Min.	Trainees are divided into three groups. One group is assigned the task of describing the procedures necessary to correctly install a pump, a second group describes the procedures to operate pumps, and the third group describes pump maintenance. Groups reconvene after 10-15 minutes and make a presentation of their ideas to the full group. Trainer works with this information to instruct Trainees in common techniques for evaluating pump performance (pressure and flow rate). Trainees describe how this information can be integrated with the information from the previous pumping sessions and applied in a comprehensive process as part of an overall irrigation system design.
75 Min.	Trainees travel to the field where they evaluate a pump for flow rate, pressure, general condition, transmission devices, and motors or engines. As a group, Trainees develop recommendations on how to improve operation and maintenance for this pumping plant.

Trainer Notes: Pumps often do not perform as they should due to poor selection, installation, or maintenance. Thus, it is important for Trainees to evaluate a pumping plant that is not necessarily perfect and in which recommendations for improvement will be valid.

Materials Required:

* flow measuring device
* pressure gauge and fittings to install on pump discharge
* tape measure

References:

Chapter 3, Irrigation Reference Manual: Pumps and Water Lifting Devices; Wells

Session Topic: Wells: Hand Dug and Drilled

Session Goal: Trainees will be able to select a suitable well site, rehabilitate a well, and facilitate well development.

Session Objectives:

(1) Trainees will identify factors that determine a suitable well site according to the type of well being considered.

(2) Trainees will describe the construction steps necessary for a shallow hand dug well and a drilled well.

(3) Trainees will describe practices used to protect wells.

(4) Trainees will rehabilitate a well in the field.

Overview: Wells can represent an important water supply source for irrigation. As Volunteers, Trainees may have access to both drilling facilities or labor to dig shallow wells. This session provides Trainees with sufficient background information to plan and guide well development. This session should be done after Trainees have had some exposure to basic hydrology concepts.

Session Activities:
Time
90 Min.	Trainer presents a diagram of the hydrologic cycle, with some delineation of geologic formations. Trainees are asked to indicate suitable locations for wells that could tap the water stored in these formations. Trainer should use this exercise to explain the types of wells available and the general steps followed in constructing a simple hand dug well and a drilled rotary well. It will be important to use many graphical depiction's of the steps followed in well development. Trainees are asked to list the kinds of problems they might anticipate in digging or drilling a well and maintaining the well after it is in operation. Trainer concludes with a description of the procedures used to disinfect wells and protect wells from contamination if they are for household use as well as irrigation purposes.
90 Min.	Trainees travel to the site of a well that is no longer in use or simply in need of repair. Trainees will interview owner(s) of the well and learn the history of the well's development and maintenance. Trainees describe the steps that were apparently followed to design and construct the well and indicate measures that might have improved the process. Trainees will inspect the well and determine the need for well rehabilitation: improved well protection, well disinfection, pump repair, or repair of lining.
2-4 Hr.	Trainees rehabilitate the well, completing all of the tasks they identified as necessary in their well inspection.
45 Min.	Trainees meet with well owner(s) and provide them with information to guide their future use and management of the well.
3-4 Hrs.	Trainees visit the site of a drilled well in the drilling stage. Trainees observe the drilling process, describe the steps that were apparently followed in developing the well, and interview the drillers.

Trainer Notes: It is advisable to select a well for rehabilitation that does not require a great deal of effort. Simple hand pump repair and disinfection of the well may be enough to fill out this exercise. If pump repair will be a part of the session activities, then this session should follow the sessions on pumps in the Developing Water Sources section of this manual. While it would be ideal for Trainees to actually construct their own hand dug well, this would consume from 3-5 days in the training and may demand too much time. Trainers need to identify some well projects under construction for the Trainees to visit during this session.

Materials Required:

* chlorine
* rope
* transport
* wrenches, pliers, vice grips, and screwdrivers

References:

Chapter 3, Irrigation Reference Manual: Pumps and Water Lifting Devices; Wells

Brush, R.E. 1982. Wells Construction: Hand Dug and Hand Drilled. Peace Corps Information Collection and Exchange Manual M-9. 282p.

Peace Corps. 1984. Rural Water/Sanitation Projects: Water for the World. Peace Corps Information Collection and Exchange. pp. 107-142.

Session Topic: Storage Pond Design, Construction, and Management

Session Goal: Trainees will be able to list site criteria for pond construction and design and construct a small storage pond.

Session Objectives:

(1) Trainees will identify the appropriate type of storage pond for specific water sources and topographical conditions.

(2) Trainees will conduct a rapid site survey to determine basic pond construction requirements.

(3) Trainees will design earth embankments.

(4) Trainees will construct a small storage pond appropriate to the site conditions.

Overview: Storage ponds are becoming more important in agriculture as competition for use of water sources increases, watershed conditions decline, and seasonal variability of supplies increases. Well designed ponds can supplement plant water needs during periods of low water flow or sporadic rainfall, and they can stabilize or regulate flows. This session provides Trainees with adequate skills to design and construct a small pond.

Session Activities:
Time
60 Min.	Trainer introduces session with brief lecture on the role of ponds in irrigation systems, the types of ponds that can be used (on or off-stream), and the criteria used to select a pond site and estimate pond size. Trainer then presents a graphic example of how earth embankment design is done to stabilize ponds. Trainees are asked as a group how they would organize all of this information to enable them to conduct a rapid field inventory of potential pond sites.
75 Min.	Trainees are divided into groups of three and instructed to go into the field to conduct a rapid survey to locate potential pond sites. After identifying the sites, Trainees should come back together as a group and mutually select the most preferred pond site location. The group process that occurs in this endeavor can be as valuable as the pond construction, and the Trainees should be encouraged to describe the reasoning behind their selection.
6-8 Hr.	Trainees should work as a team to design and construct a small pond. After completing the pond, Trainees should divert water from the stream source and fill the pond. Filling the pond will take some time, and the Trainees can assign a small group to supervise this process. After 1-3 days, the Trainees should return to determine how well the pond is holding up and how much water is being lost through seepage.

Trainer Notes: It is advisable to plan this endeavor with a local community so that they can use the pond after it is completed.

Materials Required:

* hand or Abney level
* large sacks for hauling soil
* manual tampers
* PVC tube (diameter depends on source flow rate)
* sheets of plastic (if soil is very permeable)
* shovels, picks, and hoes
* stakes
* stopwatch
* surveying rod
* tape measure
* wheelbarrow
* 5-gallon bucket

References:

Chapter 3, Irrigation Reference Manual: Ponds for Irrigation Water Storage

Exam: Section 4 - Developing water sources

1. List different types of material that can be used to construct a diversion.

Answer:

earth	sand bags
rocks	gabions
logs	concrete

2. Describe what a gabion is and explain how it can be used in diversion dams.

Answer:

A gabion is a basket made of heavy-duty wire mesh, placed in the stream bed, and filled with rock. It is used as a building block in construction of diversions.

3. Describe the sequential steps in developing a spring source.

Answer:

1. Locate the origin of the flow.
2. Dig large hole.
3. Measure the flow from the spring.
4. Fill in the hole with gravel or rocks to protect spring.
5. Dig diversion ditch above spring.

4. Explain the situations in which you would consider a hand-dug well for irrigation; a commercially drilled well.

Answer:

Hand-dug - Shallow water table, low flow rate required, labor is cheap and available.

Drilled - Deep water tables, hard formations such as rock, larger flow rates required, availability of equipment or commercial well drillers.

5. A farmer comes to you and asks for advice on a secondhand, 5 HP, centrifugal pump that he has just bought. He wants to sprinkler irrigate a 0.5 hectare plot but knows nothing about the pump capacity. What factors must be taken into consideration?

Answers:

1. What flow rate is required?
2. What head is required?
3. Does the pump have adequate flow and head capacity?

6. Describe the equation needed to calculate total dynamic head in a pumping system. (Assume velocity head is negligible.)

Answer:

tdh = h_z + h_p + h_f

h_z = elevation head (vertical distance pump must raise water)
h_p = pressure head (pressure required to operate the sprinkler system, drip system, etc.)
h_f = friction head (pressure losses due to flow through pipe)

7. List the general specifications that you should provide a pump supplier when selecting a pump.

- amount of water to be pumped
- pumping head
- horsepower requirements
- operating efficiency
- type of prime mover and transmission device

8. In a communal system, a farmer is given water 6 hrs/day at a flow rate of 100 L/min. a) If the farmer irrigates every 3 days, how large of a storage pond must he construct to store the water? b) If, at peak use, his crops need 5 cm of water per week, which he will apply through a sprinkler system, how much land can he irrigate with the pond? (No water on Saturdays.)

Answer:

a) Volume = Q x T = 100 L/min x 6 hrs/day x 3 days x 1 m³/1000 L x 60 min/hr = 108 m³. The pond can have an average surface area of 100 m and be 1.1 m in depth. However, a freeboard is generally needed. Thus, add 0.3 meters of required freeboard. Pond should be 10 m x 10 m x
1.4 m.

b) He will apply 2.5 cm, or 0.025 m twice a week. Area = volume/depth = 108 m³/.025 m = 4320 m²