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Issue Date: Feb 2000

First private irrigation system developed with Aquanet

1 February 2001

When 140 farmers in the lowveld put their heads together to improve their yield, the solution was clearly irrigation, but how to afford it? After doing a detailed 'needs investigation', designing of comprehensive water network and preparing a convincing motivation including return on investment, this became the first private community water development in South Africa. The project is in no way comparable to former state subsidised projects. It is a private venture which is totally being financed by the farmers through a R105 million loan obtained from Rand Merchant Bank.
The project, based in the Lower Blyde, is a distribution system which is to provide irrigation water to approximately 140 farmers in the irrigation area under control of the Blyde River Irrigation Board. The project originates at the Blyde-rivierspoort Dam in Mpumalanga and serves as an area approximately 30 km long by 15 km wide in the Northern Province. The system will annually deliver approximately 70 million cubic metres of irrigation water on a seasonal crop demand basis. During peak summer demand the system will abstract 4,5 cumec from the Blyde Dam.
The planning was done on AllyCAD and the analysis and design of the network was carried out on Aquanet, by Jaco Swart, of Jaco Swart Consulting Engineers in Hoedspruit. Aquanet, a comprehensive water network analysis package from Allyson Lawless allowed demand patterns to be defined, taking seasonal variations into account. This has the net result that an optimum solution was achieved with size, types of pipes and fittings being selected for maximum supply, ease of construction and minimum maintenance.
The final closed pipe network consists of approximately 120 km of pipeline, ranging in size from 150 to 1500 mm. There are approximately 11 km of steel pipes; 95 km of asbestos cement pipes and the rest of the length is made up of µPVC piping. There are approximately 600 isolating valves, ranging in size from 100 mm RSVs and water butterfly valves to a 1400 mm butterfly valve. Sixty-two of these valves are electric actuator driven with some controlled through a telemetry system. There are also approximately 150 control valves and more than 200 air valves.
The entire system will eventually be telemetry controlled from a central control station, and Allymap, the GIS from Allyson Lawless will be used for management and maintenance of the system. The value of this system to the community it serves is enormous.
The efficiency of the new system will result in 10% or 8 100 000 m3 becoming available for new purposes. Much of the agricultural production is for export. In addition, current informal trading in the area is predominantly local produce purchased by 'hawkers' for distribution and sale within a 100 km radius of Hoedspruit. It is estimated that this could double in five years and would equate a retail trade of R60 million a year. In terms of the mature irrigation area it is expected that 9300 workers, with earnings in excess of R32 550 000 and supporting 64 000 dependants, would eventually be required.
Allyson Lawless
(011) 476 4100


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