As we discussed in the previous article in this series, when the crop area is located at a higher elevation than the elevation of the water source, lift irrigation is used to lift the water to a suitable point and distribute it from there. Normally, lift irrigation system is installed on a perennial or seasonal water source.
In this second part, we will have a look at what are various requirements and various crucial components of a typical lift irrigation system.
Requirements of a lift irrigation system:
Any lift irrigation system, consists of a large number of components. Apart from these components, there are some basic requirements which need to be in place for setting up an irrigation system. These requirements are:
Access to a water source: In order to lift the water, one needs access to a water source. This water source can either be perennial or seasonal. Also, if a natural water source like a lake or a river is not available, it can be created in form of a dam or a canal from a nearby source.
Lifting Medium: A prime mover like a pump is absolutely essential to actually lift the water from the source to the point of collection. Based on the elevation and rate of pumping required, one can select a suitable type and capacity of the pump.
Conveying Medium: Any irrigation system will heavily depend upon a conveying medium like a pipe through which the water will be lifted. The pipes can either be of metal or concrete.
Components of a Lift Irrigation System:
The different components of lift irrigation system are as follows-
Jack well :Though the irrigation system will get water from a water source, as a best practice, the water is first collected in a structure, called jack well and then lifted from there. The jack well is usually sized as per the quantity of water to be lifted.
Pump House : The pump house serves as a central and safe place where pump and the power unit are housed. Since the pump and power unit might get damaged due to water ingress, pump house is designed in such a way, that even during flooding and other extreme conditions, the internals remain isolated.
Sump Well : A sump well serves similar purpose at command area, which a jack well serves at the source. Water which is lifted from the jack well, is stored in the sump well and distributed to the command area from there. Sump well has to be located at an elevation higher than the area under consideration for water distribution.
Rising Main : The rising main is the prime carrier through which the water is pumped from the jack well to the sump well. The size of the rising main depends on the quantity of water which needs to be pumped and its diameter varies from 0.2 m to 5 m.
Sub-Mains : Water which is lifted into the sump well, needs to be distributed to the crop area, often referred to as command area. Sub-Mains serve this purpose. Normally, sub-mains are made up of PVC or other non-metallic material. Since multiple lines are used, size of each sub main is comparatively smaller and ranges from 30 to 240 mm.
Electric Pumps : Electric pump are without doubt the heart of the lift irrigation system. Normally, heavy capacity pumps, ranging from 30 HP to 500 HP are used so as to cater to the full expanse of the command area. At locations where electricity is not available or electric supply is unreliable, diesel operated pumps are deployed. Now-a-days, even Solar Pumps are trending.
Limitations and constraints :
A lift irrigation systems have some disadvantages and constraints and might pose following challenges:
Cost of the system : Installing a lift irrigation system calls for investments and has a cost factor associated with it. Considering the tight budgets on which farming in India runs, cost is a prime hindering factor. Through government support and co-operative efforts, this constraint is generally overcome.
Running costs : Lift irrigation systems primarily run on electricity and lead to higher electricity bills and hence increased operating costs.
Over irrigation : If not done properly and moderately, irrigation can damage the crop and soil. Over irrigation can also rise up the water table to the root level which is detrimental for the crop as well as the soil.
Dependence on electricity : If electric supply fails, irrigation system is of no use unless it has a diesel backup, which usually increases the cost of the system.
Maintenance and Leakages : Irrigation systems call for periodic maintenance. If not maintained, leakages might form and lead to water loss and higher operating costs.
Benefits of Lift Irrigation:-
In spite of the disadvantages listed above, lift irrigation systems have proven to be highly beneficial for farmers as well as the economy. Here are some very obvious and direct benefits of irrigation systems:
Higher production and increase in income levels.
Enhanced availability of drinking water and farming water in drought prone areas.
Surety and stability to farming activities and income out of it.
Less dependence on the human labor.
Land acquisition issues are at minimum.
Did You Know?
World's largest lift irrigation project is located in India.The Kaleshwaram Lift Irrigation Project (KLIP) is situated on the Godavari River, Kaleshwaram, Bhoopalpally in Telangana. The project targeted at irrigating around 45 lakh acres. This Project involves three barrages, 20 lifts, 19 pump houses, 19 reservoirs with a total capacity of 145 TMCs, where 43 machines of the capacity of 40MW each pumping the water through 203 Km of tunnels and 1,531 Km of canals. The cost of the project is near about Rs.80,000 crore!
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