Micro Irrigation has gained attention during recent years because of its potential to increase yields and decrease water , fertilizer and labour requirements if managed properly.
Principal characteristics distinguishing the micro Irrigation with other pressurized technologies are:
- Low flow rate
- Localized , partial wetting of the soil volume
- Frequent water application due to the limited wetted volume
- Low operating pressure ,compared to sprinkler irrigation
Drip Irrigation involves technology for irrigating plants at the root zone through emitters fitted on a network of pipes( mains ,sub-mains and laterals). The emitting devices could be drippers ,micro sprinklers, mini sprinklers ,micro jets, misters ,fan jets, micro sprayers, foggers and emitting pipes, which are designed upon specific requirements , which may vary from crop to crop . Water requirement, age of plant spacing ,soil type , water quality and availability are some of the factors which would decide the choice of the emitting system .
In cases where the water sources is an open well or tubewell / borewell , then for assessment of water availability and pumping power requirement it is necessary to compute the following:
- Depth of the water table
- Discharge of the well
- Total pumping level
- The depth of water level below the ground level, before pumping begins ,is the depth of the water table . It can be measure by a simple procedure using a rope with a stone tied at one end .
- The discharge of the well / tubewell is measured after running the pump for a period of 30 minutes to 1 hour . It can be measure by adopting volumetric measure.Under this method , the discharge is emptied into a ditch of container of know dimensions for a certain length of time . the rate of discharge is calculated by dividing the total volume of water discharged by the time taken. This method works for low discharge say upto 5 litres per second. For higher discharges volumetric measurement may be difficult and therefore standard devices like water meter/c.notch/flume may be used.
- Total pumping level includes the depth of the water level, drawdown and height of the outlet above the ground level. To measure the drawdown the pump installed over the well/tubewell is run for a period of 30 minutes to one hour so that constant water level is attained in the well/tubewell. The new depth of the water level is measured. The difference between the depth and level above the ground level is also to be measured . Once the total pumping level is determined , the horsepower .
HP= Q*H/75*n
where Q = Discharge ,Ips
H=Total head ,m
n = Efficiency of the pump and motor
Depending up on the water availability and water requirement of the crop (as given in the table ) for the entire area in calculated .Then the piping network and number of sections will be decided accordingly.
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