Drip Irrigation Design basics

Hi everyone,
As we know Drip irrigation is the only best available option for the farmers to save water and get higher production. Here i am trying to explain how to select the proper drip irrigation system for the field.
There are few steps in the selection of the proper drip irrigation design and material for your field, which are,
1. Survey of the field
2. Emitter/ dripper selection
3. Input- Output matching
4. Lateral Selection
5. Sub main line selection
6. Main line selection
7. Filter selection
8. Pump selection / check

Now i am going to explain the aspects above.
1. Field Survey:
In this step, one has to measure the whole field, either manually or with the help of GPS or any other method. After measuring draw a rough diagram or map of the field on a blank paper with all the measurements. Also don't forget to mention the "North" Direction. (You can find it simply by, facing towards the sun at this time your left hand side is NORTH).
After completing the diagram fill out the following details, as we are going to need it in the next steps, viz,
For Online drip

• Crop:
• No. of Emitters per plant:
• Discharge of each emitter:

For Inline drip

• Crop
• Lateral Spacing (mtr)
• Emitter Spacing (mtr)
• Discharge of each emitter

2. Emitter/ Dripper Selection
It is different from country to country, for INDIA inline drippers are used for close spacing crops like Cotton, Castor, Potato, Vegetables etc. and online drippers are used widely for Plantation, horticultural crops like, Mango, Sapota, and Custard Apple etc.
3. Input- Output matching
This is the main part of any drip irrigation system design here one can need to calculate some data.
No. of sections / Valves = Input (Total water requirement of the field)
                                    ---------------------------------------------------
                                       Output (water available at the pump set)
For ONLINE drippers,
INPUT = No. of Plants X No. of Emitters per plant X Discharge of each emitter in LPH
For Inline drippers,
INPUT (LPH) = No. of emitters X Discharge of each emitter (LPH)
Where,
Lateral length (mtr) =  Area (Square meter)
                             ----------------------------------
                                  Row Spacing (mtr)

No. of emitters =  Lateral length
                       ----------------------------
                           Emitter spacing

Now with all this data you can find out how many sections you will need in your field to irrigate the whole field with the drip irrigation system.
4. Lateral selection
5. Sub main line selection
6. Main line selection
all above aspects are depend on the water flow available for your system, for sub main and main lines the selection of pipes will depend on the flow listed below,
Water holding capacity of PVC pipe:

• 63 mm (2") - 0 to 18 m3/hr.
• 75 mm (2.5") - 0 to 25 m3/hr.
• 90 mm (3") - 0 to 32 m3/hr.
• 110 mm (4") - 0 to 40 m3/hr.

Note: Above details are approximate figures.

7. Filter Selection

In this section one should have to select the appropriate filter for the drip irrigation system. Selection of filter is depending on the water source. One can select the filter with the help of the following,

Open Well - Sand filter with backup, Screen filter/ Disc filter

Open Tank - Sand filter with backup, Screen filter/ Disc filter

Stream - Sand filter with backup, Screen filter/ Disc filter

Bore well with silt - Screen / Disc filter

Bore well with river sand - Hydro cyclone filter with Back up Mesh/ Screen filter

8. Pump selection / Check
You have to check the total head and discharge of the pump set.
For well-designed drip irrigation system the discharge of the pump set should be equal to the discharge of the each section in the field.
Total Head (mtr) = Suction
Elevation
System operating pressure
Friction Loss in Head unit / filter
Friction loss in main line
Friction loss in sub main line
Friction loss in lateral line
Friction loss in Fittings
Others
Where,
System Operating Pressure = Minimum pressure required at emitting point of the emitter.
Selection of pump:
Pump Horse Power (H.P.) =      Q X H X 100
                                         ----------------------
                                              75 X n (%)
Where,
Q = Maximum Sectional Discharge (lps)
H = Total Dynamic Head (mtr)
n = Efficiency of the pump
Efficiency of the pump:
For Mono-block pump set 65 to 70 %
For Coupled pump set 60 to 65 %
For Submersible pump set 50 to 55%
This is the most common aspects to choose a proper drip irrigation system in the field, i hope you all find useful information from this article.

You can find more information in details in the topics below,

1. Technical aspects of drip irrigation
2. Drip Irrigation component Installations
3. Head Loss & Velocity in irrigation pipes
4. Video tutorial on drip irrigation design
5. Water carrying capacity of irrigation pipes

or scan a QR code here,

I am a professional trainer in MIS system designs, for cost and other details please mail me on the below address,

Cheers!

Hardip Gajjar
(hrdpgajjar@hotmail.com)