African Wildlife & Environment Issue 81

CONSERVATION

generational inequity that our noble constitution sought to dismantle. A Permanent Solution to a Misdiagnosed Problem The Ugu Municipality is proposing a permanent solution to the temporary saline intrusion at the St Helens Rock Pump Station, in the form of an expensive concrete weir. It is claimed that this weir

because of the loss of freshwater above it, either to evaporation, or from reduced streamflow arising from the over-abstraction upstream. The alteration of the profile of the riverbed, by industrial scale sand mining, has created two new drivers of change. The first is an increase in the volume of the estuary. This means that each tidal pulse is increasingly unable to reach the mouth and discharge fully into the ocean.This leaves a saline plug in the estuary, that is slowly forced upstream by each

will create a separation barrier between fresh and salt water. However, this simplistic solution ignores the complexity of the interaction between the natural flood pulse and the tidal pulse, because once the permanent barrier has been created, the probable outcome will be a permanently hypersaline estuary. We have already learned about hyper-salinity in places like St Lucia, so it is vital that we interrogate the logic underpinning the proposed solution, by applying the best available science, tempered by the precautionary principle entrenched in our environmental law. Forensic evidence has shown that no less than eight berms have already been built across the river, in two different

Satellite image showing the encroachment of the first dredger approaching the pump station on 1 May 2015, but with limited alteration of the bed and bank upstream of the abstraction point

locations. Each berm has failed, and none have ever halted the intrusion of saltwater at the pump station, simply because they have ignored the complexity of the interaction between the natural flood pulse and the tidal pulse. It can be argued, with considerable scientific evidence in support, that there are two major drivers of saline intrusion in the uMzimkhulu estuary – attenuated flood pulse from upstream abstraction in excess of the legal WUL allocations, and the alteration of the bed, bank and flow of the river by industrial scale sand mining. Both can be remedied by means of regulator intervention. That intervention will remove the need to permanently alter the last free-flowing river in South Africa, and will return us to the rule of law that seems to have been abandoned by municipal officials looking to justify big ticket projects, from which they can sustain the patronage networks that keep them in power.

successive tidal pulse. The second is the removal of sandbanks that previously created a natural shallow pooling of water. This is an activity that burdens the next generation to pay for the short-term needs of the current generation Those sand banks accelerated the velocity of flow over them, creating turbulence sufficiently strong to keep the saline wedge away from the St Helens Pump Station. These natural barriers were most effective during the lowest flow of the river, at the exact time when the wedge was the furthest upstream. Nature had provided a brilliant solution, disrespected by Man, and removed by sand mining in the pursuit of profits. In short, this is an activity that burdens the next generation to pay for the short-term needs of the current generation. It is a classic example of the inter-

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