Weeding out water wastage in irrigation canals

Abstract

Irrigation The largest consumer of water in South Africa, agriculture uses approximately 62% of the total national water supply to irrigate crops. At present, a million hectares from a potential 1,4 million hectares is under irrigation. South Africa has thousands of kilometres of canals criss-crossing the countryside from which the majority of the irrigation schemes receive their water supply. These canals are both lined and earthen structures. Many of these water conveyance structures are plagued by aquatic weeds, such as filamentous algae and aquatic macrophytes. Following the winter months, the increasing day length and consequent rise in ambient temperatures result in increased water temperature and light penetration into water bodies. Optimum environmental conditions, and the presence of sufficient plant nutrients (phosphates and nitrates) – usually the result of pollution – lead to an increase in aquatic weed biomass of affected irrigation canals.

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