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MDLOTI ESTUARY: Catchment Characteristics |
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Main Rivers and tributaries |
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Mdloti River |
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Gudwini |
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Kwazini |
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Dams |
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The Hazelmere dam is situated 20 km above the lagoon and has a total capacity of 24x108m3 |
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River run-off |
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Information on the mean annual
run-off ranged from 97x106 m3 to 134x108m3.
Records show that during the season 1963/1964 to 1968/1969 run-off was
the lowest on record. |
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The Mdloti river flows
perennially. The mean annual average flow is given as 2 m3/sec
(Ref.1). Prior to 1978, the maximum flows recorded were 5 m3/s
on 14 December 1964 (Ref.1). |
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Geomorphology |
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Geology |
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The river traverses Archaean Granite (Gneiss), Table Mountain Sandstone, Dwyka conglomerates (tillites), Ecca shale and recent deposits in its drainage basin. Borehole data reveals bedrock at 31 m to be Ecca sandstone. (Ref.1) |
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Nature of bottom materials |
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Orme (Ref.2) describes these as
“typical estuarine deposits, representing deposition in a tranquil
lagoon”, and points out that there is a distinct lack of any
appreciable scour. The first 2 m of the Mdloti deposits are made up of
fine sand. Below these is coarse fluvial sand and lenses of mud and clay
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The
sandbar characteristics according to Ref.1. in 1978: The Mdloti sandbar is 600 m long and south extending.
400 m of the bar is well stabilized by Scaevola.
If permitted to do so,
the mouth opens across rocks in the extreme south of the system,
although (Ref.2) suggests the mouth position changes considerably.
The crest of these rocks is at such a level that the lagoon, when open
in a southerly position, never empties itself completely. |
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Breaching of the mouth as descibed in 1978 (Ref.1): The bar is breached artificially at various times of the year by sugar farmers, when water levels in the lagoon rise too high. Most of the lagoon is above mean sea level which means it empties almost completely. When the bar is breached the stench of organic materials that have been decomposing on the bottom (typical of a sugar cane influenced system) becomes almost overpowering, as such materials are disgorged into the sea. |
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