Agricultural Irrigation Part 2: Pumping Different Water Sources

Agricultural Irrigation Part 2: Pumping Different Water Sources

Commercial Agricultural Irrigation Pump

Irrigation solutions for agricultural farmers rely on a variety of factors forcing growers to have in-depth knowledge in many areas, including soil properties, climatology, botany, and the quality and quantity of water sources. An understanding of engineering and hydraulics is also necessary to choose the right type of pump system, to match the irrigation system that works best with the characteristics of the water source.

Pump performance in agricultural irrigation relies heavily on a thorough analysis and evaluation of the water source to select the proper equipment.

Water Availability and the Water Cycle

Water is available from a variety of sources, such as groundwater, surface water (lakes, rivers, streams), water storage, or rain harvesting. Water is a valuable resource that must be correctly managed. The total availability of water on Earth consists of:

  • 30% available from groundwater and surface water (lakes, rivers, streams)
  • 70% held in ice caps
  • 3% fresh water with 1% available for use

Some farmers can easily access multiple water resources, while other growers have difficulty obtaining a sufficient supply of water from just one source. The location of crops, the type of crops being grown, and the irrigation method used all affect the amount of water required. A successful growing season is completely dependent upon growers correctly managing their water source.

Groundwater Pumping for Agricultural Irrigation

Managing groundwater properly is critical as it is the most reliable source of water on the planet and must be available for future use. Measuring groundwater can be complex since the water flow is actually hidden. If not carefully monitoring groundwater availability, problems can occur such as supply limitations, clogging, over-pumping, and excessive wear placed on pumps. Over-pumping occurs when more water is pumped out of the well than it can supply, which requires replenishment of the groundwater.

This will cause damage to the pump when it runs dry, and if it continues to run, the pump could pull in sand, which will cause more damage. Using a sand separator in the well before the pump unit can remove unwanted sand. Analyzing the water supply the well can provide, however, is the best way for growers to manage their water supply and prevent damage to pumps and agricultural irrigation equipment.

Water Characteristics Are Critical for Pump Selection

The characteristics of groundwater use for irrigation are important factors when selecting the right type of pump for irrigation. Water characteristics such as temperature, pH, salinity, and minerals in the water are important considerations. Additional considerations include the total run time of the pump and the length of the irrigation period to make sure there is time for service or repairs or if additional irrigation time is required during high temperatures.

It is important to select the pump size that will provide water delivery during off-peak operating times when electrical use rates are based on pump operating time. Different irrigation systems will have different operating pressures that must be taken into account when selecting a pump. Different systems require different pressure, such as a sprinkler system versus a drip irrigation system. An incorrect pump selection can cause an adequate water pressure and/or supply.

The quality of the water source is another important consideration, as increased wear on pump components and the impellers could result from water with excess minerals or sediments. Water availability from a well could also continually change, in which case a variable frequency drive (VFD) should be used. VFDs are designed to safeguard the pump from dry running by reacting to unsteady water flow to maintain the flow and pressure required of the irrigation system. It is important to select the irrigation pump and motor for the maximum drawdown level to maintain the correct pressure and water requirement.

In the case of pumping from a well that will not supply enough water, a reservoir can be used to store water so that the system can pull from this surface water when required. This can help provide a sufficient water supply for farmers. Storage of well water must be treated as surface water and requires water treatment to prevent algae and organic material buildup.

Surface Water Pumping for Agricultural Irrigation

The second most common source of freshwater is surface water which is available in many forms such as lakes, rivers, streams, springs, ditches, etc. Important factors must be considered when pumping from a surface water system, such as whether or not it is a public surface water source if the source is prone to flooding, and the quality of the surface water.

Farmers must be aware that many users will be pumping from public surface water sources which can significantly affect water availability, which can cause pump dry running. Creating a water storage facility can prevent dry running and ensure an adequate supply of water.

Submersible pumps should be used in cases where the water source is prone to flooding, as dry motor pumps could be damaged beyond repair if they become submerged. Dry motor pumps should be protected with a fence or protective structure to prevent vandalism and theft.

Water quality is an important consideration when pumping surface water which can include a substantial amount of sand, silt, mud, and other particles, especially during rainy seasons or when snow is melting. Constructing a settling canal prior to the pump suction will prevent these particles from entering and damaging the pump system. The canal should be no less than 20 feet long with a flow velocity of no more than .05 feet per second during water pumping.
As particles settle in the canal, they should be removed at the beginning of each irrigation season to ensure efficient performance and system functionality. The canal should also be covered to prevent organic growth from sunlight and should be treated and/or incorporate the use of self-cleaning screens at the pump intake to prevent organic materials from entering the pump.

Harvesting Rainwater for Agricultural Irrigation

With limited or no availability of groundwater or surface water, two different types of artificial reservoirs can be created to supply agricultural irrigation. Harvesting rainwater and water storage systems can provide additional water sources. In dry climates, collecting sufficient rainwater may not be practical, although it can provide an additional water source to supplement groundwater or surface water supplies.

Storage tanks can collect rainwater on roofs or in paved areas with consideration given to the size of tanks required in the average amount of rainfall. Water treatment in storage tanks is required, and water quality should be a consideration.

Water storage systems can be created aboveground, underground, or in an open-air basin. Water storage systems supply added irrigation during times of peak demand when the main water source cannot meet watering requirements. Aboveground systems can be less expensive to construct, although they can lead to salt buildup, are prone to algae and organic growth, experience evaporation, and take up productive space. Aboveground open-air basins also pose a drowning risk. Underground tanks eliminate these risk exposures, although they are more costly to construct.

Parallel operating boosters should be used for this water distribution pumping design in both types of water storage systems. Boosters provide many benefits, such as starting amp reduction, smaller motor sizes, and water hammer reduction.

Agricultural Irrigation Pump Supplier

Illinois Process Equipment, IPE, offers turnkey irrigation solutions as your single source for fluid handling pumps and process equipment. We differ from other pump suppliers with our technical expertise and on-staff engineers well-versed in many niche market applications. IPE offers a complete irrigation process system design considering all pertinent factors, including water supply, quantity, and quality of water sources.

IPE is a leading pump and process equipment supplier offering high-quality pumps from leading manufacturers, including Grundfos, Paco, and others with centrifugal pumps, submersible pumps, gear pumps, and more. We offer complete system design with integrated pumping solutions, pump monitoring, boosters, and features such as variable frequency drives (VFDs). Contact us with any questions on improving your agricultural irrigation process with reliable pumping solutions.