1. Applying Irrigation Water in Circles (vs. squares)
Why
(briefly)
Economical
Low O & M
High Reliability
Central Delivery Point
Intro page

2. Applying Irrigation Water in Circles (vs. squares)
Why it’s a little trickier?
In a circular system the area
increases as the radius increases
Hence, each sprinkler applies
water to a differently sized Area (A)
In a rectangular system each
sprinkler applies water to an
Identically sized Area (A)
Explain how area considerations affect nozzle sizing, spacing and possibly throw diameter 1 2 3 4 1 2 3 4
A1 = A2 = A3 = A4
A1 < A2 < A3 < A4

3. How Does this Weigh up on a Typical System?
(System Capacity = 6 gpm / acre)
Circle Area Computations
Sprinklers are sized appropriately
along length of pivot to maintain
uniform applications along linear
length of the center pivot machine
Area = π R2
Radius
(ft.)
Total Area (acres)
Spoke Area
(acres)
Flow Required
(gpm)
130
1.2
7.2
260
4.9
3.7
22.2
390
11.0
6.1
36.6
520
19.5
8.5
51.0
650
30.5
66.0
780
43.9
13.4
80.4
910
59.7
15.8
94.8
1040
78.0
18.3
109.8
1170
98.7
20.7
124.2
1300
121.8
23.1
138.6
Area calculations and how they relate to necessary flow to maintain uniform coverage

4. How Does this Weigh up on a Typical System?
High Pressure
Potential sprinkler coverage on high pressure system

5. How Does this Weigh up on a Typical System?
Medium Pressure
Potential sprinkler coverage on medium pressure system

6. How Does this Weigh up on a Typical System?
Low Pressure
Sprinkler coverage on low pressure system – indicate how this affects potential erosion

7. Soil / Water Intake Curves
0.2
0.3
0.4
0.5
0.1
Time (hrs)
0.0
1.0
2.0
3.0
4.0
Intake Rate (in / hr)
Soil / Water Intake Curves
1.0 Family
0.5 Family
0.3 Family
Example intake curves for different families

8. Sprinkler Pressure vs. Intake Characteristics
Timed Rain Gauge Analysis Thunderstorm Intensity
Illustrate how pivot moving over a point in the field applies water and what this means with respect to the soil intake characteristics of the soil

9. Sprinkler Pressure vs. Intake Characteristics
Timed Rain Gauge Analysis Thunderstorm Intensity
Low
Medium
High
Representation of low, medium and high application pressure and where they potentially fit with respect to soil intake rates
Low
Medium
High

10. CPNozzle Program Windows Version Similar Inputs Better Visualization
New Version
Windows Version
Similar Inputs
Better Visualization
Residue Component
Estimates Surface Storage and Runoff

11. CPNOZZLE Important Variables Application Rate Soil Family
Field Position of Soil Family
Residue Amount
Slope
Sprinkler Radius of Throw
Hyperlink to CPNOZZLE program
RUN CPNOZZLE

12. GIS – Toolkit Applications
CPNOZZLE divides field into 10 concentric circles and indicates the potential for runoff in each one. Toolkit can be used to find the percentage of each family of soil within each circle to spatially analyze the potential affects of erosion on an entire field .

13. Example Composite Worksheet
CPNOZZLE
Example Composite Worksheet
Worksheet to combine CPNOZZLE and toolkit information and summarize on for potential runoff on entire field

14. Irrigation System Design (Some Basic Concepts) Don’t Over - Complicate
Up Here
We Want To Get This
FIELD
WATER
Begin design concept presentation

15. Irrigation System Design (Some Basic Concepts) Don’t Over - Complicate
Up Here
We Want To Get This
FIELD
WATER

16. Irrigation System Design (Some Basic Concepts)
2 Important Parameters
Flow (most commonly given in gpm)
Bucket–Fulls
Per Unit Time
Flow and pressure concepts
2)Pressure or Head (given in psi or ft. of water)
Squirting
Distance

17. FLOW DETERMINATION
Crop / Soil Requirements
a) effective root zone
b) soil texture
2) Field Size
3) Water Source Limitations
a) physical
b) by permit
c) other

18. Crop Requirements (gpm / acre) General Rule = 6 gpm / acre
From NDSU: “Selecting a Sprinkler Irrigation System”
ND values from North Dakota State University
General Rule = 6 gpm / acre

19. (Crop Requirement) x (Field Size) = Flow Requirement
EXAMPLE
(6 gpm / acre) x (125 acres) =
750 gpm
(Not Written in Stone but good guidelines
to follow)
May also be physical or permit demanded constraints on pumping rate which dictate

20. PRESSURE or HEAD 4 Main Considerations
1) To offset Elevation difference between
source and delivery point
2) To compensate for Friction losses in
the mainline delivery system
3) System Operational Requirements
4) Other Minor losses
Pressure requirements for system operation

21. between water source and point of distribution
Elevation Difference
between water source and point of distribution
Vertical distance between pumping water surface
and the field delivery point
(for center pivots use the highest point in the irrigated
field for conservative calculations)
Example 50 feet
Surface Water
Ground Water

22. Friction Losses
Most friction losses in irrigation systems are developed in
the system mainline (transmission pipeline)
(Significant friction loss also occurs in the pivot itself but
Is usually calculated and included as part of the
operational pressure requirements)
Transmission Pipeline
Most often PVC but may also
be aluminum, steel or PE

23. Friction Losses
Important factors in the calculation pipe friction loss are:
Pipe Inside Diameter (id)
Pipe Material
Pipe Length
Fluid Velocity or Flow Rate
Friction loss is typically calculated using one of several common
equations:
(Hazen Williams equation or Darcy equation)

24. Hazen Williams Equation
Friction Losses
Hazen Williams Equation
H = 10.44LQ1.85
C1.85d4.87
Where:
H = head loss from friction (ft.)
L = length of pipe (ft.)
Q = flow (gpm)
C = friction factor (140 – 150 for PVC pipe
higher number means smoother pipe)
d = inside diameter of pipe (in.)
Also note Darcy equation used in CPED

25. Friction Losses Example 12.3 feet
Hazen Williams Equation
H = 10.44LQ1.85
C1.85d4.87
Example
If 750 gpm is flowing through 1500 feet of new 8 inch ID PVC pipe
the friction loss will be
{10.44 x (1500) x (750)1.85 } / {(150)1.85 x (8)4.87} =
12.3 feet

26. Operational Pressure Requirements
At the Center Pivot Consist of:
1) Pressure necessary to operate sprinklers and regulators
satisfactorily (5 psi or greater above rated pressure of regulator) ) Friction losses incurred in span pipe
Calculation is usually combined together with sprinkler package
spreadsheet
Requirements are commonly given at pivot point location
Elevation differences along pivot may also be included
Example pivot point requirement:
gpm

27. Minor Losses
The majority of minor losses which will increase the overall
head requirement can be caused by:
1) Small friction losses which occur due to fittings and deviations
in pipeline alignment
2) Extra losses through pump and suction pipe
3) Friction loss incurred in well tubing
4) Other
In large pipeline networks minor losses can be a substantial
portion of the total head requirement
Typically in irrigation systems minor losses are not a large
part of the total head requirement – Often times it is good enough to
simply add 5 to 10 feet to the final head calculation as an adjustment
for any minor losses which may occur in the system

28. Example Pressure Totals
1) Elevation Head = 50 ft.
2) Friction losses in the mainline
delivery system = 12.3 ft.
3) System Operational Requirements
= 45 psi or 104 ft. (2.3 ft. of water = 1 psi)
Minor losses estimate = 10 ft.
Total Dynamic Head = 176 ft.

29. Total Dynamic Head (ft.)
PUMP SELECTION
225
Full Impellor
10% Trim
85%
20% Trim
82%
30% Trim
176
Total Dynamic Head (ft.)
79%
Illustrate for this example how pump would be selected.
750
1250
Flow (gpm)

30. Total Dynamic Head (ft.)
PUMP SELECTION
225
85%
20% Trim
82%
Total Dynamic Head (ft.)
79%
Illustrate different operating points on pump curve. Go over how pump my operate with wear and changes in system.
1250
Flow (gpm)

31. PUMP STUFF 1) Pumps DO NOT make pressure (only flow)
The system to which the pump is attached creates resistance to flow (pressure)
2) Pump speed is proportional to output (flow) but the head that a pump can resist is proportional to the square of speed. (which means changing speed changes pump flow reasonably but changes head characteristics a whole bunch) (pump affinity laws)
3) Typically slower running pumps are used for low head - high volume applications.
4) Common speeds for irrigation pumps: RPM (flood pumps), 1800 RPM (sprinklers with moderate head requirements), 3600 RPM (sprinklers with high head requirements).

32. POWER REQUIREMENTS
Horsepower Required
= TDH x Q
3954 x n
Where n = wire to water efficiency
(pump efficiency minus a little good first guess is .75)
EXAMPLE
{(176 ft.) x (750 gpm)} / {3954 x .75} =
44.3 hp

33. CPED PROGRAM Rewritten for use by NRCS in EQIP program
Evaluates sprinkler package coefficient of uniformity (must be at least 85% according to NRCS sprinkler standard)
Uses pump input parameters to give an entire system evaluation
Sprinkler inputs set up similar to OUTLETS program
Hyperlink to CPED program
RUN CPED

34. IRRIGATION WATER MANAGEMENT By the Checkbook Method
Treats soil profile as a checkbook
Water is the $
Inputs and outputs are measured or estimated and the balance is tracked throughout the growing season
Can be tracked by hand, in a spreadsheet or with other software

35. Checkbook Account Transfers Deep Percolation (Withdrawal)
Evapotranspiration
(Withdrawal)
Irrigation
(Deposit)
Rain
(Deposit)
Checkbook concept illustration
(Account Balance)
Soil Profile
Deep Percolation (Withdrawal)

36. IRRIGATION SCHEDULING by the CHECKBOOK METHOD
NDSU software
Baled Lotus spreadsheet which tracks soil depletion throughout growing season
Estimates crop water use based on daily high temperature input and days past emergence of particular crop
Soil available water inputs are entered at setup
Contains historical weather record for several sites in ND and MN.
Actual soil water measurements can be entered to keep record closer to actual
Run NDSU checkbook program
RUN IRRIGATION

37. Irrigation Water Management Plan
EQIP
Irrigation Water Management Plan
Worksheet
Example

38. 1) Plan Purpose / General Details
General statements outlining where the producer is currently at and how he plans to improve his water management through the use of an irrigation scheduling and or crop water monitoring plan.
Open with regards to the producers beginning and ending points.
Producer must implement the use of checkbook type irrigation scheduling by the end of the three year contract as a minimum.

39. Daily Application Rates at ____ efficiency
2) System Capacity / Field Information
Flow(gpm)
Total Area(acres)
System Efficiency(%) 75
Daily Application Rates at ____ efficiency
Daily application rate at 100% efficiency (in / day) = (0.053) x Flow(gpm) / Area(acres)
100%
90%
80%
70%

41. Cumulative Available Water to depth (in.)
3) Soils Information
Soil Name
Farland
Grail
Stady
Bryant
Field Acreage 46 44 38 2
Field Percentage
35.4
33.9
29.2
1.5
Irrigation Group 8c
10c 6i
Cumulative Available Water to depth (in.)
Top 1 foot
2.5
Top 2 feet
4.5
Top 3 feet
6.5
5.5
Top 4 feet
8.5
6.0
Top 5 feet 10
10.5
10.0

42. 4) Crop Data 2006 2007 2008 Corn Potato Wheat 4.0 2.0 3.5 50 40 25.9
Year
2006
2007
2008
Crop
Corn
Potato
Wheat
Full Rooting Depth (ft.)
4.0
2.0
3.5
Suggested MAD (%)* 50 40
Avg. Annual Water Use
25.9
23.2
18.8
Est. annual no. days crop water use exceeds system capacity 25 23 18

43. Data taken from North Dakota Ag. Weather Network
Data taken from North Dakota Ag. Weather Network. 5 year averages illustrate on average how much producer will need to rely on soil water storage or natural rainfall to meet water requirements of crop

44. 5) Water Management Plan
Year
2006
2007
2008
Crop
Corn
Potato
Wheat
Managed Soil
Farland
Stady
Managed Crop Rooting Depth (ft.)
4.0
2.0
3.0
Managed Available Water Total (in.)
8.5
4.5
6.5
MAD (in.)
4.25
1.8
3.25
Deficit for Rainfall (in.)
0.50
0.1
Managed Soil Water (in.)
3.75
1.7
2.75
Minimum Soil Available Water
(in., %)
4.25,50
2.70,60
3.25,50
Producer needs to analyze field soil percentages and select which one to use for the water management of each crop or divide management spatially dependant upon soil location in field

45. CSP Irrigation Water Management
Evaluation Sheet
Evaluates an irrigation system and management scheme for placement/eligibility in the CSP program
RUN CSP program
CSP worksheet hyperlink

46. Irrigation Handbook Modifications Located in Section II of EFOTG
Chapter 1: Definitions of useful terminiology
Chapter 2: Irrigation group classification designations and descriptions (These have changed with this version of the guide)
Individual County Soils Classification (in soils section)
ND EFOTG information

47. Cnty Soils
Link

48. CH 1
link
CH 2
link

49. Electrical Center Pivot Operation
3 Phase Electric Power so that motors can be easily reversed and consequently the machine will reverse directions
Motor power is 480 V 3Ph, Control power is 120 V 1Ph
Main power supply is delivered to main control panel at pivot point. Control and motor power is delivered to each tower via a 10 or 11 conductor cable mounted on top of span
Timer circuit controls last tower, it runs when timer is activated. The rest of the towers play catch up through the use of micro-switches
General pivot operation info

50. Electrical Center Pivot Operation
Tower map

51. Electrical Center Pivot Operation
Last Tower Controlled
By Percent Timer
Percent timer controls how often last tower moves - allows application rate (in. / acre) to be varied.

52. Electrical Center Pivot Operation
Next Tower Follows
When Micro-switch
Triggers
Micro switch keys following towers to “catch up” with last tower

53. Electrical Center Pivot Operation
All Other Towers
Follow Similarly

54. Center Pivot 10 Conductor Span Cable
Timer
Forward
End Gun
Reverse
Safety
Neutral
Ground
Discuss basics on how each circuit works. How they can potentially be modified if necessary.
Power
Power
Power

55. THE END