Structural damage to canals due to spilling as a result of overflows caused by aquatic vegetation.
losses were cut by 17 % and the water saved could be made available to new mines in the area, which are expected to inject more than R1-billion into the local economy— something that would have been difficult to achieve without the available water. Even better results were obtained in the Roodeplaat canal system, north of Pretoria, where water losses were cut by 19 % with ad hoc treatments of the canal with MAGNACIDE™ H Herbicide( L8655). It was found that MAGNACIDE™ H Herbicide( L8655) provides excellent control of both vascular-submersed aquatic vegetation and algae, providing more effective results than any other control method. A single application generally restores canal flow capacity within 24 hours after application; nuisance vegetation disintegrates over a five to 10-day period. The product has no effect on civil canal structures and is not corrosive to irrigation equipment. Preventative maintenance plans are now implemented on local irrigation canal systems to control aquatic vegetation to levels where they cannot cause operational problems and canals will not spill as a result of biomass infestations. Integrated Aquatic Vegetation Management Plans( IAVMPs) are developed and implemented for each irrigation scheme with MAGNACIDE™ H Herbicide( L8655) as chemical control component on the
Treatment of a canal to control aquatic vegetation.
flowing canal water, and sterile Chinese grass carp( Ctenopharyngodon idella) as biological control component in balancing dams, irrigation dams, and other semi-stationary impoundments on the irrigation scheme. The introduction of sterile Chinese grass carp to combat aquatic vegetation in dam structures, both in the water conveyance structures and in on-land irrigation dams, is very successful. The combination of the herbicidal control method with the biocontrol agent has made aquatic vegetation problems in irrigation canal systems something of the past. A preventative maintenance programme consists of a series of herbicidal applications to canals with MAGNACIDE™ H Herbicide( L8655) at a scheduled frequency, while sterile grass carp is stocked in dams. With a preventative maintenance IAVMP in place, the irrigation scheme manager can keep the water distribution system in an optimal operational condition with minimal disruption of water delivery and maximum water savings. u
For more information, contact Kobus du Plessis of Envirokonsult Scientific Services at duplessisk @ envirokonsult. co. za. Website: http:// www. envirokonsult. co. za.
About the author
Kobus du Plessis is a professional water scientist with 30 years of experience in the water sector. He is the managing director of Envirokonsult Scientific Services, based in Hartbeespoort, North West Province. He specialises in water resource management, integrated aquatic vegetation management programmes, water loss control, urban lake management, and irrigation canal maintenance programmes. networking contributor innovations industry debate environment infrastructure municipalities
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