Image Database Export Citations


Analysis of Virtual Water Flows Associated With the Trade of Maize in the SADC Region: Importance of Scale

Show simple item record

dc.contributor.author Dabrowski, J. M.
dc.contributor.author Masekoameng, E.
dc.contributor.author Ashton, P. J.
dc.date.accessioned 2011-01-25T20:53:47Z
dc.date.available 2011-01-25T20:53:47Z
dc.date.issued 2009 en_US
dc.identifier.uri https://hdl.handle.net/10535/6897
dc.description.abstract "The concept of virtual water encourages a country to view agricultural crops in terms of the amount of water required to produce those crops, with a view to implementing trading policies that promote the saving of scarce water resources. Recently, increased attention has focussed on partitioning the virtual water content of crops into green and blue water (derived from rainfall and irrigation, respectively) as the latter has higher opportunity costs associated with its use and therefore impacts directly on scarcity. Maize is the most important crop traded within the SADC region. South Africa is the largest producer and exporter of maize, with the majority of its exports destined for other SADC countries. In comparison to other SADC countries, South Africa produces maize relatively efficiently, with a low virtual water content and a high green (868 m3 t−1 ) to blue (117 m3 t−1 ) water ratio. The blue water content is however higher than for maize produced in all other SADC countries, with the exception of Namibia (211 m3 t−1 ). Current trade patterns therefore result in a net expenditure of blue water (66×106 m3 ), almost all of which is exported by South Africa (65×106 m3 ). South Africa is one of the most water scarce countries in the region and analysis of virtual water flows indicates that current SADC maize trading patterns are influenced by national productivity as opposed to water scarcity. The virtual water content of maize was estimated for each of South Africa’s nineteen Water Management Area’s (WMA) and used as a proxy to represent water use efficiency for maize production. The virtual water content varied widely across all of the WMAs, ranging from 360 m3 t−1 in the Ustutu Mhlatuze to 1000 m3 t−1 in the Limpopo. A comparison of the virtual water content and production of maize (expressed as a percentage of the total national production) identified those WMAs where maize production is highly water inefficient(e.g. Lower Orange and Limpopo WMAs). Results suggest that, while a national estimate of the virtual water content of a crop may indicate a relatively efficient use of water, an analysis of the virtual water content at smaller scales can reveal inefficient use of water for the same crop. Therefore, analysis of the virtual water content of crops and trading of agricultural products at different spatial scales (i.e. regional, national and WMA) could be an important consideration within the context of water allocation, water use efficiency and alleviation of water scarcity." en_US
dc.language English en_US
dc.subject agriculture en_US
dc.subject irrigation en_US
dc.subject maize en_US
dc.subject water supply en_US
dc.title Analysis of Virtual Water Flows Associated With the Trade of Maize in the SADC Region: Importance of Scale en_US
dc.type Journal Article en_US
dc.type.published published en_US
dc.type.methodology Case Study en_US
dc.subject.sector Water Resource & Irrigation en_US
dc.identifier.citationjournal Hydrology and Earth System Sciences en_US
dc.identifier.citationvolume 13 en_US
dc.identifier.citationpages 1967–1977 en_US

Files in this item

Files Size Format View
Analysis of vir ... ith the trade of maize.pdf 388.8Kb PDF View/Open

This item appears in the following document type(s)

Show simple item record