Silt Issues and related problems in the Southern Sections of Lake ST. Lucia and the Northern sections of the St. Lucia estuary system within the iSimangaliso Wetland Park World Heritage Site in KZN South Africa are serious and need high level government interventions.
Silt from the Umfolozi River has accumulated where the Northern end of the Narrows (estuary) flows into the Southern edge of Lake St. Lucia esturine system.
The silt accumulated at this location because this is the first place where the water gets an opportunity to slow down. This is where the river opens up wide and mixes with the water in the lake. In the past the lake was semi tidal, and salt water (sea water) flowed into the lake system from the ocean as the tide came in and mixed water would flow out as the tide went out.
This was a strange and wondrous procedure that left pockets of diverse salt levels floating around the lake where some pockets of water had super high saline conditions, and others remained close to pure fresh river water.
After the GEF 5 Project was implemented and the Umfolozi River connected directly to the St. Lucia Lake Systems, the silt became a real nasty problem. The estuary management team appointed by the IWPA was either very INCOMPETENT or was instructed to follow a set narrative and do as they were told. I am not sure which is worse, but we now have a true NASTY problem.
The GEF project connected the Umfolozi River directly to the lake system, deliberately and with intention, by passing or side stepping, the natural filter systems of the Umfolozi Flats and flood plains. this ensured that the silt from the Umfolozi River would settle down in the first place that the river flow slowed down for any reason. This location at the top end of the narrows is a perfect fit, coz the river slows down as it opens up into a wide basin that already has water. this very sudden drop in water speed causes a major silt dropout in this basin full of reeds, sedges and grasses.
This repeated every time there was a flood event in the Umfolozi catchment zones. The accumulative impacts of this silt dropouts has been rather serious, but the estuary management team did nothing to mitigate the growing silt dump that eventually settled at its current height above sea level, which is currently unknown, but by my geustemation is about 2.5 meters above high tide levels. This silt plug is currently preventing the water flow between the ocean and the esturine lake systems .
how will we remove this massive silt plug? any ideas ? Your views will be appreciated.
Eave a comment and subscribe to our blog.
The 4u2fish campaign is taking up the issues around situation in the Southern section of thee lake St the northern end of the narrows where the estuary connects to the lake.
ReplyDelete