Interesting facts about the Knysna Estuary
Yes, Estuary and not lagoon, and here’s why:
There is a significant difference between a lagoon and an estuary regarding their depth. Lagoons are typically shallow, especially the coastal lagoons, whereas estuaries are deeper. As a result, a lagoon could have a huge variation in salinity and temperatures. With estuaries, the water flows faster, and they are strong, whereas in the lagoons they are relatively shallow, and the water flow is sluggish.
DID YOU KNOW? The Knysna Estuary is permanently open, and the volume of influent fresh water relatively small, salinities are stable and near to that of sea water. This stable environment accounts for the remarkable diversity of species recorded here.
DID YOU KNOW? The time it takes for fresh water to exchange with new fresh water in an estuary is known as flushing time.
DID YOU KNOW? The Knysna Estuary covers about 1,827 ha and stretches from the mouth (The Knysna Heads) to the rapids at Charlesford on the Knysna River. It measures about 3 km at its widest
DID YOU KNOW? The reddish-brown colour which stains most of the fresh water in the Southern Cape comes from humic acid, a natural by-product of the process of leaf decay.
DID YOU KNOW? The Heads (‘heads’ – short for headlands) define the Knysna River mouth, which is only about 230 metres wide. The current flows through at speeds of up to 76.2 metres per minute – of 4.572 km per hour (depending on the tide, this translates to a flow of between 1,000 and 2,000 cubic metres of water per second).
DID YOU KNOW? The tidal influence (tidal reach) stretches 17 km upstream from The Heads. The time-lag between tides at The Heads and at Old Drift is about two hours at spring tide.
For interesting research on the Knysna Estuary you can also follow the Knysna Bain Project.