Analysis of the Mkuze link canal.

The possibility of an interbasin transfer from the Pongola to the Mkuze has been raised. (Apparently such transfers have happened accidentally in the past.)

It is beyond the scope of this report to fully analyse the effects and operation of such a scheme, but some simplistic results are presented here to show the direction of future studies.

  
Figure 34: The effect of timing releases on the salinity of the Tewate Bay.

Figure 34 shows the effects on the salinity in Tewate Bay of timed releases of water from Pongolapoort dam. The ``constant'' trace shows the effect of added a constant amount of to the Mkuze.

The ``timed release'' trace shows the effect of releasing water into the Mkuze, at when :-

1. Water is flowing from lake to sea.
2. There is not a major flood.
3. The concentration in Catalina Bay is above

The average flow in the Mkuze for the period shown is .

The points I wish to make from this graph are the following...

• To significantly effect the salinity of the lake, a quantity of water of the same order as the volume of the lake () needs to be released.
• The effect of the releases may be maximised by timing the releases to flush out salt when it is ...
  • at a high concentration.
  • The natural rainfall has brought the lake to a point where salt is being pushed out to sea.

  The graph shows the effect of a timed release to be roughly twice that of a constant release. I cheated in timing my releases in that I knew when a major flood would occur. Therefore I do not expect any operational system to do any better than I have here.

• The ability to create timed releases may be limited by the size of the link canal from the Pongola and the amount of water required to have an effect.