Agriculture Reference
In-Depth Information
understanding of how irrigation-water management can be improved, thereby build-
ing human capacity, allowing targeted investments to be made with fewer social and
environ- mental costs. Using the lessons learnt during the WRC project, best prac-
tices and technologies were identifi ed and then illustrated.
It is recommended that the research output, that is, the guidelines for management
advice on improved effi ciency of irrigation-water use, should be further developed
into a user-friendly package with supporting training material, targeting farmers, ser-
vice providers and policy advisors. This will contribute to better understanding of
the realities and potential for effi cient irrigation water use across all levels of water
management, and encourage the adoption of the water-balance approach.
4.9 SUMMARY
The purpose of an irrigation system is to apply the desired amount of water, at the
correct application rate and uniformly to the whole field, at the right time, with the
least amount of nonbeneficial water consumption (losses), and as economically as
possible. We know that irrigated agriculture plays a major role in the livelihoods of
nations all over the world and South Africa is no exception. With the agricultural
water-use sector being the largest of all water-use sectors in South Africa, there have
been increased expectations that the sector should increase efficiency and reduce con-
sumption in order to increase the amount of water available for other uses.
Studies and research over 40 years, on the techniques of fl ood-, mobile- and mi-
cro irrigation have contributed to the knowledge base of applying irrigation meth-
ods correctly. In a recent study on irrigation effi ciency, the approach is that irriga-
tion effi ciency should be assessed by applying a water balance to a specifi c situation
rather than by calculating various performance indicators. The fraction of the water
abstracted from the source that is used by the plant is called the benefi cial water-use
component, and optimized irrigation water supply is therefore aimed at maximizing
this component. It implies that water must be delivered from the source to the fi eld
both effi ciently and effectively. Optimizing water use at farm level requires careful
consideration of the implications of decisions made during both development (plan-
ning and design), and management (operation and maintenance), taking into account
technical, economic and environmental issues. An exciting, newly developed South
African Framework for Improved Effi ciency of Irrigation Water Use covers four lev-
els of water-management infrastructure: the water source, bulk conveyance system,
the irrigation scheme and the irrigation farm. The water-balance approach can be
applied at any level, within defi ned boundaries, or across all levels to assess perfor-
mance within the entire water management area.
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