Some of the principles of the Turn System were retained such as the zones and stream sizes, which factors had to be accepted as the canal system was constructed for this system and therefore no additional costs would be incurred.
1.Generally the Irrigator would request the volume of water (hours) he would require as the stream flow rate is fixed, and as an indication as to when he would require the water in the following week.
2.The staff would then organise and sort these requests using the requested hours and stream sizes that apply.
2.1Currently this information is grouped, i.e. the farmer’s request is tabulated under the zones and once this is obtained the zones are linked as the full week of 104 hours, or whatever is applicable in utilized.
3.An in-house developed computer program, which contains all the relevant data of all the registered properties, is used. The requirements are input into the program, which then calculates the volumes required at the various control and monitoring points.
4.A provisional leading chart is sent out to the Irrigators, indicating the time water delivery can be expected.
5.Once the required readings and the time that it must occur at the control and monitoring points including the release from Darlington Dam is determined it is provided to the staff who must ensure that the flows in the canals at these points are as per the calculated values at a given time. The readings to the points that have been automated are then fed into the computer.
6.Notice of delivery to the Irrigator is in the form of a final leading chart followed by a water note, which indicates the volumes to be delivered and the times this will occur.
7.The volumes of the water notes are input into the computer and then utilization and losses can be determined for the canal system and any irregularities can be attended to and efficiency of the system determined as well as control of the Irrigators volumes of abstraction.
Advantages of the request system
1. No restriction on types of crops.
2. Not necessary for a large dam to be constructed.
3. Awareness of water is created, as the Irrigator must assess his needs on a weekly basis.
4. Flexibility of supply to the Irrigator. Requests of Irrigators can be more easily satisfied.
5. System losses can be determined and controlled.
6. Water that is not required is retained at the head of the system.
Disadvantages of the request system
1. Additional effort by Staff with regards to the administrative control of the water supply.
2. Maintenance periods have to be determined and work programmed and executed effectively.
Benefits of the request system
1. This system is adaptable to virtually all circumstances.
2. Water is utilized beneficially and economically.
3. Water losses limited to absolute minimum.
4. Investment on the part of the Irrigator largely reduced to the minimum.