Seven Benefits of Converting Canals to Pipelines
By Gary Vert, PE, CFM – Completing canal to pipeline conversion projects can be challenging for irrigation districts throughout the western United States. Many districts are looking for ways to conserve water, improve efficiency, and modernize their water delivery system. While irrigation districts may be able to address these needs by lining their canals, it may be more beneficial to convert your canal into a pipeline instead. From our experience, there are seven major advantages to this solution.
The truth is that many irrigation systems are old, with deteriorating infrastructure that needs to be repaired or more often, replaced. Because of this, the focus tends to be on structures, with less attention given to the conveyance systems such as canals or laterals.
In the western United States, many irrigation projects were created in the 1930s, 1940s, and 1950s when federal funding for large-scale irrigation projects became available. Many of those same irrigation projects still operate throughout the West—often with their original 60-year-old-plus infrastructure. Those irrigation projects primarily used open channels such as canals and laterals to convey surface water to users.
Today, these open channels can present some issues for irrigation districts, including:
- seepage losses
- evapotranspiration losses
- embankment breaches and washouts
- capacity issues
- water quality/erosion
- level management due to interception of storm water runoff
- vegetative growth impeding flow and turnouts
- poor on-farm efficiency
- additional operation and maintenance (O&M)
To address these issues, irrigation districts typically explore one of the two following solutions:
Lining the Canal
Due to low material costs, liners tend to be the cheaper option when compared to pipeline systems. For irrigation districts in the West, this can be the deciding factor when choosing between liners and pipelines. While lining a canal provides many benefits to irrigation districts such as cost effectiveness, conservation of water or improved capacity of the canal, liners typically have a shorter design life, require more operation and maintenance than pipeline systems and present more safety hazards. Liners can also be difficult to install, especially if there are several structures within the canal.
Converting to a Pipeline
Converting earthen canals to pipelines can have many benefits for users and the irrigation district. Irrigation districts that convert unlined irrigation channels to pipelines are realizing significant reduction of seepage losses and reduced O&M. There are several benefits to this approach such as:
- Eliminating seepage losses. In general, conveyance efficiency for earthen canals is 70% or less depending on the soil type. Pipelines eliminate water losses associated with seepage and can increase conveyance efficiency up to 95 to 100%.
- Eliminating evapotranspiration losses. Open channel flow exposes water to losses associated with evaporation from the canal surface and transpiration from vegetation along the canal bottom or banks. Converting to a pipeline will eliminate evapotranspiration losses.
- Conserving water. By eliminating water losses and increasing delivery efficiency, pipelines will help the irrigation district conserve water. Water conserved can be stored in reservoirs, left in rivers or streams to increase in-stream flows and habitat, used for irrigation of additional acres, or used to increase the length of the irrigation season.
- Improving water quality. Converting from open channel to pipeline will help reduce erosion that is common within earthen canal systems. Erosion within water delivery systems can lead to sediment transport, eventually returning sediment-laden water to downstream surface waters through wasteway or drain systems. Erosion and sedimentation can also result in deposits at structures within the irrigation delivery system that cause significant O&M. By eliminating erosion, pipeline systems help improve water quality at downstream receiving waters and reduce O&M throughout the irrigation district.
- Reducing operation and maintenance (O&M). Earthen or lined canals often require significant O&M work to keep them operational. Earthen canals can have severe erosion that leads to sedimentation, water quality issues, and increased work to help keep the canal free of sediment buildup or in some instances, even repair canal washouts. Additionally, earthen canals can oftentimes become overgrown with vegetation that causes water loss, reduces capacity, limits the hydraulic function of the canal, and requires a significant amount of O&M work. Lined canals can also result in increased O&M. Liners can puncture or tear, resulting in repairs that are time-consuming and require specialized equipment. Ballast material, used to keep liners in place and prevent floatation, will oftentimes require replacement. Pipelines have a long design life and require less O&M compared to its open channel counterparts. O&M tasks may include clearing of debris at pipeline inlets, regular cleanouts at sag locations, and dewatering for the irrigation offseason. Having a reliable product in place can help irrigation districts save time and money typically spent on O&M tasks.
- Improving on-farm efficiency, increasing crop yields and agricultural revenue, and conserving energy. In some situations, pipelines can provide more head at downstream turnouts compared to open channel flow due to pressurized flow. This allows individual users to save money/energy associated with pumping operations. Increased head at downstream turnouts will help increase crop yields and agricultural revenue. On-farm water application will be much quicker when diverting water from a piped system, therefore distributing water to the crop more quickly and more efficiently. This can lead to longer watering sets, more crop cuttings throughout the irrigation season, and increased agricultural revenue generated for the individual user.
- Providing reliable water delivery. Converting from open channel to pipeline will eliminate the potential for canal washouts, which could leave users without irrigation water for a significant period while repairs are made. Pipeline systems eliminate the threat of canal washouts and provide a reliable delivery method for irrigation districts.
There are several reasons why canal to pipeline conversions may be the best solution for your irrigation system. However, there are several considerations you should take into account prior to making any final decision. In my next article, I will outline the top five considerations for canal to pipeline conversions. In the meantime, please reach out with any questions or concerns you may have.
Gary Vert, PE, CFM is a water resources engineer and certified floodplain manager who works in Morrison-Maierle’s Helena office. He has ten years’ experience and specializes in hydrologic and hydraulic analysis, irrigation design, grant writing, permitting, and on-farm design. When not at work, Gary enjoys mountain biking, fishing, traveling, and supporting his favorite soccer team, Liverpool FC.
Technical review of this article provided by Ken Salo, PE.