Final Interventions Report - DWA Home Page

Water Reconciliation Strategy Study for the Large Bulk Water Supply Systems: Greater Bloemfontein Area 36
Water stored in the Kalkfontein Dam (Riet River) is released in the Kalkfontein canal for the irrigation
farmers. No river releases are made.
The Orange-Riet WUA pump water out of the main canal from the Vanderkloof Dam. This water is
transferred and used along the Orange-Riet canal and the Riet River settlement near Jacobsdal. Water is
also released out of the canal system in the Riet River and for irrigation in the lower Modder River up to the
confluence with the Vaal River. These releases and flow in the Orange-Riet canal are managed with
regular flow measurement and telemetry.
The Lower Modder River and Krugersdrift WUA and the Kalkveld WUA selected to become one WUA. This
report will therefore deal with them as one WUA. The Modderrivier and Kalkveld WUA manage the
catchment area of the Modder River from the N1 west to about Kimberley. One sub-area is for farmers with
irrigation out of groundwater. The second sub-area is for irrigation farmers next to the Modder River
downstream of the Krugersdrift Dam. Water releases out of the Krugersdrift Dam are made for irrigation
farmers downstream on request of the farmers. Weirs in the river store the water between releases. The
third sub-area is for the farmers who irrigate with surface water upstream of the Krugersdrift Dam.
Vanderkloof WUA manage the irrigation farmers next to the Orange River from the Vanderkloof Dam
downstream close to the confluence with the Vaal River near Douglas. Water is released in the Main canal
(same as Orange-Riet WUA) and then to the Ramah canal. This water is managed according to the water
application of the farmers next to the canal. The water released in the Orange River is from the
hydroelectric plant managed by Eskom. The DWA and Eskom manage these water releases. The
irrigation farmers next to the river abstract the water directly out of the Orange River for irrigation.
3. IRRIGATION PRACTICES
In all the WUAs the on-farm losses occur between the point of abstraction and the field edge. Actual
irrigation technologies are, for the most part, modern and sophisticated and do not leave much room for
improvement. It is recognised that many farmers have installed efficient on-farm irrigation methods such as
pivots, drip, and micro jet. Many farmers are also using the latest technology for irrigation scheduling in
order to use water efficiently. Water saved by efficient water use is utilised by extending the irrigation area,
as farmers pay for the full quota.
4. IRRIGATION CANAL LOSSES
The following WUAs use canals to convey the water: Orange-Riet, Kalkfontein, and Vanderkloof. The
Orange-Riet WUA uses the latest technology to monitor (flow meter and telemetry) and manage the flow in
the canals and the river. The Kalkfontein WUA uses data loggers in the main canal and branch canals to
monitor the flows. Their overall losses in the canals are calculated to be less than 30 %.
Whilst little can be done to reduce evaporation losses, proper maintenance and upgrading of ageing water
distribution infrastructure serving the WUAs, can reduce conveyance losses. The building of a balancing
dam in the Kalkfontein WUA can help to reduce the distribution losses.
5. FARM DAM LOSSES
The Kalkfontein WUA contains a number of private farm dams. It is likely though that the costs associated
with lining of farm dams will be prohibitively expensive.
Interventions Report June 2012