This document outlines the design procedures for drip and sprinkler irrigation systems. It discusses calculating crop water requirements, determining the number of emitters or sprinklers needed based on the wetted area, designing the pipe network with appropriate sizing and spacing to minimize head losses, selecting pumps and reservoirs, and scheduling irrigation based on peak water usage. The key differences between drip and sprinkler design are that drip systems have laterals and consider plant spacing while sprinklers are broadcast systems that mount to hydrants without laterals.

2. Design & Scheduling of High
Efficiency Irrigation Systems
(Drip & Sprinkler)

3. Designing Procedure
ET0 Maximum Evapotranspiration mm/ day From
Table
Blenny Criddle Equation ETo = p (0.46 T mean + 8)
P = Mean daily percentage of annual daytime hours for
different latitudes from Table

4. Evapotranspiration Requirement or
Crop Water
• ET or CWR = Kc * ETo
• ET = Evapotranspiration in mm/day
• ETo =
• Kc = Crop Coefficient (Table)
Reference Evapotranspiration in mm/day
(Table)

5. Peak daily consumptive use per day
PDCU mm/day = CWR * Canopy factor at maturity
Irrigation System Efficiency
Canopy Factor = Canopy Area
(p*p) (R*R)
Total No. of Plants = Area under system m2
(p*p) (R*R)
(p*p) = Plant to plant spacing m
(R*R) Row to Row spacing m

6. Number of Emitters require for each
plant
• This depends on the area of wetting (nearly 40% of total
area) and radius of wetted area of single emitter.
• The Number of emitters = A/R²
• Where
•
•
A = total area to be wetted.
r = radius of wetted area of single emitter

7. Hydrozones
 Area Divide in Equal Hydrozones
 Equal Operating Time
Q = AV where V = 1.5 m/s A = Area of pipe
Importance
Reduce Cost by
1. Smaller Pump
2. Small Diameter Pipes
Block
Hydrozones under one Pump

8. Total no. of Emitters
T.E = No. of plants * no. of emitter per plant
Total flow rate of 1 zone = T.E of 1 zone * Emitter flow
rate (lph)
Application rate = Flow of 1 zone mm/hr/day
1 zone Area
Operating Time hrs = Peak Daily Consumptive Use
Application rate
Should be less than 12 hr per day of all zones

9. Max. depth of irrigation water that can be
applied
Max. Depth mm = Drz * MAD * WHC
100
Drz = Depth of Root zone m
MAD = Management Allowed Deficit %
WHC = Water Holding Capacity mm/m

10. Max. irrigation interval
Max. Irrigation Interval days
= Max. Depth of Application of water mm
Peak Daily Consumptive Use mm/day

11. Total Drip line Length
Total drip line m = Area * No. of Drip lines per Row
Row Spacing
For all zones
No. of Plants = Plants of 1 zone * no. of zones
Drip line of 1 zone * no. of zonesDrip line =
No. of Emitters = Emitters of 1 zone * no. of zones

12. Loop Around the Plant
Irrigation up to whole Canopy

13. Wetting Pattern

14. Storage Reservoir
Total Flow = Flow of 1 zone*Total no. of zones m3/ day
Irrigation Cycle Daily
Warabandi Days
Storage Capacity = Total flow * Warabandi m3
Safe Depth = 1.5 m
Area of Reservoir = Capacity
Depth
Select Length and find out Width of Reservoir

15. Head Loss Calculation
Hazen William Equation
Head Loss m/100m = K ( Q/C)1.85 * (D) - 4.87
K = Hazen William Constant = 1.21 * 1012
C = Pipe Friction constant
Q = Total Flow lps
D = Internal Diameter in mm
Total Head Loss m = Head Loss (m/100m) * Total Length
100
Repeat Procedure for all Lateral , Sub main line and Main Line.

16. Limitations
Lateral Head loss Should be =< 2m
Main line and Sub main Line m /100m =<2m
Velocity Calculation
Main line and Sub-main velocity (m/s) =Q/A
Where Q= Discharge in LPS
A=Area of main and Sub main line sub-main in m2
Main line and Sub Main line Velocities=<1.5m/sec

17. Head loss gradient (Watter & Keller)
Head Loss m/100m = K * (Q)1.75
(D)4.75
K = 7.89 *10 7 (Constant)
Q = Flow in lps
D = Internal Diameter mm
Emitter Operating Pressure is 10 m

18. Fitting Losses
Fitting Losses are taken as 20 % of Pipe Network losses
Lateral Fitting Losses = 20% of Lateral Head Loss
Submain line Fitting Losses = 20% of Submain line Head Loss
Main line Fitting Losses = 20% of Main line Head Loss
Suction and Delivery line Fitting Losses = 20% of Suction and
Delivery line Head Loss

19. Other Losses
Head loss in
Filtration System = 8m
Fertigation System = 2m
Flow Meter = 1m
Field Fitting Losses = 2m
Miscellaneous Losses = 2m
Pumping Lift = At the Spot

20. Total Dynamic Head
(Pipe Network Losses = Lateral Sub main and Main line ) +
(Fitting Loses = 20% of Pipe Networks) + Field fitting losses
Head loss in filter + Head loss in fertigatin system + Pump lift +
Head loss in flow meter + Emitter operating Pressure (1bar) + Misc Head Losses
Total Dynamic Head = Sum of All Head losses

21. Pump hp Requirement
Pump hp = Q (lps) * Head (m)
75 * Ep * Em
Ep = Pump Efficiency
Em = Motor Efficiency

22. Irrigation Scheduling of Drip Irrigation System
Operating Time = Peak Daily Consumptive Use per day
Application Rate
For any month reading of ETo from table and Kc of Crop
Peak use = ETo * Kc & Application rate of Emitter mm /hr/day
Time to Open one zone Valve hrs
in that month
= Peak Daily Use
mm/day Application Rate
mm/hr/day

23. Application rate of each
Emitter
 q = daily water requirement (mm) n = number of
emitters
 t = time of operation (hour per day)
• (E) = q/nt
Where

24. Difference between Drip & Sprinkler Irrigation
Design
There are no Lateral in Sprinkler System
There Canopy factor is 1 because this system
is used in Field or Broadcasted Crops
There is no Plant to plant spacing and no Row to Row
spacing
There are Hydrants on which Sprinkler is Mounted

25. Design Difference
Peak Daily Use = ETo * Kc
Eirrg * (1-Lr )
Where Lr is Leaching Requirements
Lr = ECw
5ECe - ECw
ECw = Quality of Irrigation Water dS/m
ECe = Estimated water quality of root zone
Sprinkler operating pressure is 4 bar = 40m
In Rain gun Sprinkler system no Filter is used

26. Spacing of Hydrants
spacing along lateral = 100% Overlap of Wetted Radius
Hence along lateral they are spaced at Wetted Radial Distance
Across the Lateral = 65% overlap of wetted Radius
Hence Sub main to Sub main line Distance is 65% of
Wetted Diameter

27. Any Question