Kruger’s river connectivity a work in progress
SKUKUZA - The Kruger National Park’s (KNP) process of removing man-made structures started as early as the late 1990s.
The most recent removal involved the demolition of the Mingerhout Dam.
As a way of explaining its ongoing river rehabilitation process, the KNP recently invited the media to the sites of the former Mingerhout Dam and still-functioning Engelhardt Dam respectively, both located along the Letaba River.
Comparisons were made that explained why the Engelhardt Dam remained while Mingerhout was done away with.
Standing at Engelhardt, Dr Eddie Riddell, KNP water resource manager, explained its significance.
The dam was built around the 1950s and it was in the previous management era of the KNP where the aim was, among others, to establish new water points to assist wildlife. “What we have realised in recent times is that this kind of structure is actually bad for the river ecosystem - it breaks up what we call river connectivity. So fish and so forth cannot move up- and downstream.”
What still makes this dam sustainable is the fish ladder built into it.
This helps fish move up- and downstream where a normal dam wall prohibits this movement.
Aside from this feature, the Department of Water and Sanitation also uses it to measure cross-border flow into Mozambique and as a flood forecasting system.
Robin Petersen, a freshwater ecologist, elaborated on the term “river connectivity”. A big dam creates a barrier in the system, which especially becomes a problem when the flow of water declines. “Fish need to be able to fulfil their life cycle. They need to spawn somewhere, they need to feed somewhere.
“Luckily within SANParks, probably in the 50s and 60s while they were building all these dam structures, the then park warden made it mandatory that all structures like this must have fish ladders to maintain river connectivity.” As stated, this dam still serves a purpose and thus remains.
This was not the case, however, for the Mingerhout Dam, and it was demolished in February (during Eloise, over the course of two or three weeks) by the South African National Defence Force (SANDF).
SANParks has been working with the SANDF for the last two decades on projects like these. The defence force uses these opportunities as training exercises, which is beneficial to the park because of the costs that would have been incurred were they to handle the task themselves.
The rubble that comes from demolitions like these gets repurposed for areas with erosion or where structures need support.