Dr. Jitendra Sinha

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Sprinkler Irrigation System:
Inventory of Resources & Conditions, Sprinkler Selection &
Spacing
Speaker
Dr. Jitendra Sinha
Associate Professor
Department of Soil and Water Engineering,
SVCAETRS, FAE, IGKV, Raipur
jsvenusmars@gmail.com
7000633581

2. Inventory
• a complete list of items such as property, goods in stock, or the
contents of a building.
• make a complete list of
• Inventory is an accounting term that refers to goods that are in
various stages of being made ready for sale, including: Finished
goods (that are available to be sold) Work-in-progress (meaning in
the process of being made) Raw materials (to be used to produce
more finished goods)
• There are four types, or stages, that are commonly referred to
when talking about inventory: 1) Raw Materials, 2) Unfinished
Products, 3) In-Transit Inventory, and 4) Cycle Inventory
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3. • Why is inventory so important?
• Inventory is a business asset because it has value. ... It also has value
because you can use it as collateral to get a business loan to buy
more inventory or pay your bills. The cost of selling your inventory (called
cost of goods sold) is an important cost for your business.
• What is the role of inventory?
• The primary role of an inventory system is to track your products and
supplies. An effective system keeps records of when you
purchased inventory, when you sold it and how much you have on hand. ...
For example, a supply of rubber may pass through production, go to
shipping and end up in a warehouse in a remote location.
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What is inventory and example?
Inventory refers to all the items, goods, merchandise, and materials held
by a business for selling in the market to earn a profit. Example: If a
newspaper vendor uses a vehicle to deliver newspapers to the
customers, only the newspaper will be considered inventory. The vehicle
will be treated as an asset.
What is the purpose of inventory?
The primary function of inventory is to use marketing and production to
increase profitability, to get the maximum amount for the business'
investment. The other functions of inventory, such as balancing supply
and demand, improving efficiency, establishing a safety stock and
geographical specialization

5. Design of sprinkler irrigation system
• A site specific sprinkler irrigation system needs to be designed
which can economically provide higher efficiencies.
• The first step in this endeavours is :
Inventory of resources and conditions :
• Map of the area
• Water supply
• Climatic conditions
• Depth of irrigation
• Irrigation interval
• Water application rate
• Sprinkler spacing
• Power source
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6. Map of the area
• Map of the area concern is prepared and drawn to scale with sufficient
accuracy to show all dimensions so that length of the main and laterals
can be scaled their form.
• It should be a contour map or at least should show all relevant
elevations with respect to water source, pump location and critical
elevations in the field to be irrigated.
• The elevation differences together with friction losses in the mains and
laterals and the pressure requirements of the sprinklers determine the
pressure that must be developed by the pump
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8. Water supply - source availability and dependability
• It is important that an irrigation system of sufficient size is available to
meet the maximum demand of crops. The quantity available should also
meet the seasonal and annual requirements of the crops in the area to
be irrigated. The water should be chemically suitable for irrigating the
crops and soils of the area. It should not have any corrosive effects on
the equipment. The water should be relatively clean and free of
suspended impurities so that the sprinkler lines and nozzles are not
clogged.
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9. SOURCES OF IRRIGATION WATER
• Sources of irrigation water can be groundwater extracted from springs or
by using wells, surface water withdrawn from rivers, lakes or reservoirs or
non-conventional sources like treated wastewater, desalinated water or
drainage water. A special form of irrigation using surface water is spate
irrigation, also called floodwater harvesting. In case of a flood (spate)
water is diverted to normally dry river beds using a network of dams,
gates and channels and spread over large areas.
• The moisture stored in the soil will be used thereafter to grow crops.
Spate irrigation areas are in particular located in semi-arid or arid,
mountainous regions. While floodwater harvesting belongs to the
accepted irrigation methods, rainwater harvesting is usually not
considered as a form of irrigation.
• Rainwater harvesting is the collection of runoff water from roofs or
unused land and the concentration of this water on cultivated land.
Therefore this method is considered as a water concentration method.

10. Climatic conditions
• The consumptive use of a crop depends upon the climatic parameters
such as temperature, radiation intensity, humidity and wind velocity.
• Details to obtain consumptive use information is to be well in hand before taking
up the design of sprinkler irrigation system.
• Sprinkler system is designed for the daily peak rate of consumptive use of the crops
irrigated by it.
• Guidelines for determining the approximate peak rates of consumption use on the
basis of different climatic conditions are to be in hand while designing the sprinkler
irrigation system.
• A peak demand in the range of 2 to 10 mm depth per day is equivalent to a
continuous flow of 0.23 to 1.16 litre per second per hectare.
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11. Depth of irrigation
• Depth of irrigation is calculated on the basis of available moisture
holding capacity of the soil in its different layers and the soil
moisture extraction pattern of the crop in its root zone.
• Detailed explanation and the procedure to work out the irrigation
requirement has to be in hand while designing sprinkler irrigation
system.
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14. Irrigation interval
• From the point of view of sprinkler design the
irrigation interval is the length of time allowable
between successive irrigations during the peak
consumptive use of the crop.
• It is interesting to note that the irrigation interval can
also be varied by altering the hours of set for
instance a system designed to supply 100 mm with
20 hours sets at 20 days interval can also supply 50
mm with 10 hour set at 10 days interval such
practices are common during the early stages of crop
growth when the root system has not been fully
developed
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16. Water application rate
• The rate of water application by sprinklers is
limited by the infiltration capacity of the soil.
• Application at rates in excess of the infiltration
capacity of the soil results in runoff, with
accompanying poor distribution of water, loss of
water and soil erosion.
• The suggested values of maximum rates of
water application for various soil conditions are
given in the table and these values may be used
where reliable local information is not available.
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18. Sprinkler spacing: To achieve uniform sprinkling of water it is
necessary to overlap the area of influence of the sprinklers. The
overlap increases with the increase in wind velocity
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19. Ideal Pressure and No Wind
How Much Water in the Cans?
Even in all cans
More in cans closer to the sprinkler
More in cans further from the sprinkler
Uniformity of Water Caught in Cans
around a Single Sprinkler

20. Sprinkler Overlap For Uniformity
Distance between Sprinklers
=
Radius of Throw
Head-to-Head Spacing:
1. Good Uniformity
2. Good Economics

21. Rules for Spacing Sprinklers.
1. Pick a sprinkler with a wetted radius that is as large as possible and does not
greatly exceed the shortest distance across the area.
2. Place part-circle sprinklers at all corners
3. Place part-circle sprinklers at an even spacing on the edges between corners
using head-to-head spacing as a guide.
4. Place full-circle sprinklers in the interior area using the same head-to-head
spacing used on the edge sprinklers.
5. Perfect head-to-head spacing is impossible in most cases. It is O.K. to stretch
and/or crowd the spacing by 10%.
6. Adjust the sprinklers to even out the spacing over the entire area and don’t
leave a big gap in one area to make the rest of the area even.
Are most landscape areas simple
squares and rectangles?

22. Sprinkler irrigation: Spray pattern

23. Sprinkler irrigation: Spray pattern

24. Sprinkler irrigation: Spray pattern:
Variation in pressure

25. Sprinkler irrigation: Solid set system

26. Sprinkler irrigation: Hand move laterals

27. Sprinkler irrigation: Centre pivot system

28. Sprinkler irrigation: Centre pivot system

29. Power source: The source of power to operate the pump is to be
known in advance. Electric power is most convenient when the
pump is stationary. Electric pumping sets are cheaper in initial
cost and maintenance cost. Portable diesel pumping sets are the
most suitable and practical for fully portable sprinkler systems.
What’s the power source here???
Portable system?
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30. Sprinkler selection and spacing
• The actual selection of the sprinkler is based largely
upon design information furnished by the
manufacturer.
• The choice depends mainly on the diameter of
coverage required, pressure available and sprinkler
discharge.
• The tables presented before may be taken as guidelines
during selection.
• The best combination of an individual sprinkler spacing
and lateral moves, suiting the application rate for the
soil and wind condition should be selected.
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39. Application Uniformity
• Distribution uniformity (DU)
– dLQ = average low-quarter depth of water received
– dz = average depth applied
• Popular parameter for surface irrigation
systems in particular







zd
d
DU
LQ
100

40. Application Uniformity Cont’d…
• Christiansen’s Coefficient of Uniformity (CU)
– n = number of observations (each representing the same
size area)
– dz = average depth for all observations
– di = depth for observation i
• Popular parameter for sprinkler and microirrigation
systems in particular
• For relatively high uniformities (CU > 70%),
Eq. 5.4 and 5.5 relate CU to DU





 
 
n
i z
iz
nd
dd
CU
1
1100

41. Efficiencies and Uniformities
• Application efficiency (Ea)
– dn = net irrigation depth
– dg = gross irrigation depth
– fraction or percentage
• Water losses
– Evaporation
– Drift
– Runoff
– Deep percolation
E
d
d
a
n
g


44. Reference
• Irrigation : Theory and Practice by A. M. Michael
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