Wetland park bridges the gap
The new Bhangazi Berm Bridge was officially opened.
GOOD news for regular visitors to iSimangaliso Wetland Park is that one of the Eastern Shores section’s most beautiful and rewarding game drive loops has been reopened.
The 18km Grassland Loop was closed to traffic after the Bhangazi Bridge was washed away a couple of years ago. The new Bhangazi Berm Bridge was officially opened last week and the popular tourist route is back in operation.The rebuilt bridge has been carefully designed and constructed to enable visitors to watch one of the incredible spectacles of this wetland eco-system, the occasional migration of African catfish or barbel (Clarias gariepinus) between the fresh water Lake Bhangazi and the Mfabeni Swamp.
The original bridge consisted of two round concrete pipes. Repairs to the existing structure were not possible and the proposed ‘free span’ bridge would have cost several million rand, far exceeding the available budget.
Explaining the ecological consideration during the rebuild, iSimangaliso chief executive Andrew Zaloumis said that rather than just replace what was there and knowing there was no budget available the authorities did a temporary repair on the pipes and undertook technical engineering and ecological work with Janice Tooley of ACER, the late Roddy Ward and engineer Freek Serton.
“I had previously noticed that barbel were trying to move from Lake Bhangazi to the Mfabeni Swamp and saw that a very large number of the fish had moved out of the lake, up the channel to the pipes under the road. Here they could go no further as the flows were low and all the water was passing to the side and underneath the pipes. The migration of the fish had been prevented by the failure of the pipes under the road. The result was that an estimated 50 000 to 100 000 barbel – all around 50 to 60 cm in length – or 10 to 20 tonnes of fish were trapped in the narrow channel. My concern was that the urge to move upstream in flowing water meant that many of these barbel could die there if we experienced hot and dry weather and they were trapped in a drying channel,” he said.
It was therefore imperative that the new design mitigated against this.
“We put our heads together with our consulting engineers MBB, and constructed a fit-for-purpose ‘portal culvert’ that meets the requisite environmental requirements including unrestricted flow of water between Lake Bhangazi and the Mfabeni Swamp when either is fuller and the free movement of fish. This is a very special system as there is a tilting water gradient and the water is pure due to all of the catchment into lake and swamp originating within the park, ” said Mr Zaloumis.As an added bonus, the new solution only cost 40 percent of what the free span would have cost the park.
