Types of Sprinklers
There are different types of sprinklers available in the suited for various terrains and crops. Portable impact sprinklers are best suited for small orchards and vegetable fields. Stationary impact sprinklers remain fixed in the field and cover circular areas. Spinner or radial arm sprinklers provide even water distribution over rectangular areas. For large tracts of land, several sprinklers are interconnected through a pipeline network and are automatically controlled through timers and valves. Gun or boom irrigation systems use a pumping unit connected to long water hoses or pipes fitted with nozzles. These guns travel long distances sprinkling water as they move on wheels. Center pivot irrigation systems are large self-propelled structures that rotate around a central pivot applying water through sprinklers.
Importance of Water Pumps
Irrespective of the Irrigation Machinery technique used, water pumping forms an integral part of any irrigation system. Surface water sources like canals, ponds and lakes need to be lifted to field levels for pressurized distribution. For extracting groundwater, powerful pumps are required to draw water from considerable depths. Monsoon rains replenish groundwater but water tables deplete rapidly during summer seasons necessitating heavy duty water pumps. Petrol or diesel engines were traditionally used to power irrigation pumps but these are being replaced by electric motors which are more efficient, require less maintenance and avoid air and noise pollution.
Various Types of Water Pumps
Centrifugal pumps that work on the centrifugal force principle are most commonly used for irrigation. Submersible pumps are ideal for lifting water from borewells or open wells as the motor unit is installed below water level inside the well. Monoblock pumps have the motor mounted above the well on a common structure with the pump. For higher discharge rates and pressures, turbine pumps that use propeller thrust in place of centrifugal action are preferred. Wastewater from farm ponds can also be recycled for irrigation by installing shallow well jet pumps incorporating the Venturi effect. Self-priming pumps find application where the suction lift is more than the static suction lift limit of centrifugal pumps.