Wetlands

Wetlands



Contents

Definition of Wetlands
Importance of Wetlands
South African RAMSAR sites
Featured wetlands: Verlorenvlei

Definition of Wetlands

Definitions according to:

UWC Enviro Facts:

"Wetlands are difficult to define because of their great variation in size and location. The most
important features of wetlands are: Waterlogged soils or soils covered with a shallow layer of
water (permanently or seasonally), unique types of soil, and distinctive plants adapted to water-
saturated soils. Marshes, bogs, swamps, vleis and sponges are examples of wetlands.“

Rennies Wetland Project:

"A wetland is wet land (i.e. land which is wet) ! But not all wet land results in a wetland. Why is
this so? A wetland is found where the land is wet enough (i.e. saturated or flooded) for long
enough to be unfavourable to most plants but are favourable to plants adapted to anaerobic soil
conditions. As soil becomes increasingly wet, the water starts to, fill the space; between the soil
particles. When all the spaces are filled with water the soil is said to be saturated. In areas which
are not wetlands, water drains away quickly and the soil does not remain saturated. However, in
wetlands the water persists or drains away very slowly and the soil remains saturated or flooded
for long periods. Soil in these conditions is said to be waterlogged. Depending on factors such as
temperature, it usually takes a week or so for the plant roots and other living organisms in the
soil to use up the oxygen, causing anaerobic conditions to develop in the waterlogged soil.“

Endangered Wildlife Trust:

"Wetlands are ecosystems or habitats for specific plants and animals that are saturated with
water. The presence or absence of water determines their formation, processes and
characteristics.

Wetlands are characterised by specific vegetation, particular soils and the presence of water at
least for a period of time in the year. A wetland may have all of these characteristics or only one
or two of them.

Floodplains, marshes, bogs, deltas, swamps, peatlands, estuaries, river catchments and lakes are
all types of wetland.

Wetlands occur in areas ranging from higher altitude mountain ranges (seeps), through to mid-
catchment areas (marshes), through to estuaries at the coast.

Some wetlands are constantly wet but others temporarily dry up.
The type of wetland present depends on the soils, the rainfall, climate and the topography."

Importance of Wetlands

"Wetlands play an essential part in the regulation of river flow, they filter pollutants and fertilizers,
they are spawning zones for some species of fish (pike in particular). They also provide a habitat for
plants, insects, batrachians and birds… "
"The expanse of groundwater in these deposits when they are well developed can constitute a large
reserve which absorbs the variations of water flow. Alluvial deposits act rather like sponges which
absorb surplus water before releasing it later. In these alluvial areas part of the water follows the
course of the river: this drainage can represent a large volume. This water has been filtered, has a
more constant temperature and constitutes a reserve of good quality water.“

REF: NATURAL RESOURCES PROTECTIVE ASSOCIATION

"For many years people thought of wetlands as yucky, soggy, useless land. It would be much better
if this land was drained so crops could be grown, or filled so people could build on it. It even seemed
a great spot to use as a garbage dump because then you could both dump and fill.
Now people are trying to save and protect wetlands because we understand why they are
important."

Many animals depend on wetlands for some part of their life cycle, like fish, frogs and
mosquitoes.

Wetland plants are very productive and support a rich web of life, from simple molds to
mammals.

Wetlands provide shelter and food for fish.
Wetlands provide flood control by soaking up the water that falls as rain. Wetlands also
slow the spring snow-melt run-off.
Wetlands make the water clearer and filter out things that make the water impure, like
chemical pollution.
Wetlands are a wonderful place to visit, look, and listen, learn and experience life.

REF: ATHENA CURRICULUM EARTH

"Wetlands associated with streams and rivers slow floodwaters by acting as giant, shallow
bowls. Water flowing into these bowls loses speed and spreads out. Plants in the wetland play
an important role in holding back the water. The wetland acts as a sponge as much of the
flood water is then stored in the wetland and is slowly released to downstream areas, instead
of it all rushing to the sea within a few days. This greatly reduces flood damage, particularly
erosion, and ensures a more steady supply of water throughout the year."
"Wetlands improve water quality as they are very good natural filters, trapping sediments,
nutrients (e.g. nitrogen and phosphorus), and even pathogenic (disease-causing) bacteria. In
addition, pollutants such as heavy metals (e.g. mercury, lead) and pesticides may be trapped
by chemical and biological processes. In other words, the water leaving the wetland is cleaner
than the water entering it."
"Wetlands are filters where sediments and nutrients accumulate so many plants grow there,
e.g. bulrushes, grasses, reeds, waterlilies, sedges and trees. The plants, in turn, provide food
and a place for attachment and shelter for many creatures. There is more life, hectare for
hectare, in a healthy wetland than in almost any other habitat. These productive places
support huge numbers of insects, fish, birds and other animals. Some animals are completely
dependent on wetlands, whilst others use wetlands for only part of their lives. The wattled
crane, for example, is dependent on wetlands for breeding. The rich diversity of water birds in
southern Africa (totaling 130 species) is possible because of the many wetlands spread across
the sub-continent. The wetlands of southern Africa are of international importance as they are
the southern destination for many migratory wading birds."
"Wetlands have been used for centuries as grazing for domestic stock, and as a source of
reeds used for thatching, hut construction and basket weaving. They are provide fishing,
hunting and the opportunity to observe wildlife, especially birds. Wetlands are appreciated
for their beauty as open spaces and also for their educational value."

REF: UWC ENVIRO FACTS

South African RAMSAR sites

What is a RAMSAR site?

The Convention on Wetlands, signed in Ramsar, Iran, in 1971, is an intergovernmental
treaty which provides the framework for national action and international cooperation for
the conservation and wise use of wetlands and their resources. There are presently 155
Contracting Parties to the Convention, with 1674 wetland sites, totaling 150 million
hectares, designated for inclusion in the Ramsar List of Wetlands of International
Importance.

Barberspan
Blesbokspruit
De Hoop Vlei
De Mond
Kosi Bay
Lake Sibaya
Langebaan
Natal Drakensberg Park
Ndumo Game Reserve
Nylsvley Nature Reserve
Orange River Mouth
Seekoeivlei Nature Reserve
St. Lucia System
Turtle Beaches/Coral Reefs of Tongaland
Verlorenvlei
Verloren Vallei Nature Reserve
Wilderness Lakes



General Information

Velorenvlei is situated on the west coast of South Africa, about 25km from the small coastal town of
Lamberts Bay, in an area where the cold Atlantic Ocean contrasts beautifully with the dry and rocky
interior. Verlorenvlei is located in the Western Cape (32º24’S 018º26’E). With and area of 1 500 ha, it is
one of the largest lakes and one of the country’s few coastal freshwater lakes. The catchment of the
lake is about 1 890 km2 in extent (Ref. 5). A small estuary connects the lake to the sea and marshlands
are present along the main river which enters the lake (Ref. 1). The Verlorenvlei stretches between the
West Coast villages of Elandsbaai and Redelinghuys. The Verlorenvlei wetland has been classified as
comprising both fresh oligotrophic lake (Type 19) and marshland and reedswamp (Type 26).

Figure 1: Verlorenvlei ~ Bryan Dyason

Land Uses

Natural: It is proclaimed a Ramsar site (No. 525). The Lake itself is owned by the state.
Agricultural: The surrounding area is privately owned and farm boundaries extend to the 50 year
flood line. Fields have been established along part of the lake margins and extend below high
water marks in places. Extensive ploughing has occurred in the surrounding area particularly on
the hills south of Verlorenvlei. The greater part of the Verlorenvlei wetlands is used as natural
veld grazing for sheep and cattle and water is pumped for irrigation purposes and the marshland
is used for cattle grazing.
Industrial: Important fishing grounds are found along the coast and four small fish processing
factories have been built along the coast at Baboon Point. These factories are mostly concerned
with the crayfish industry although a small amount of fish processing does occur.
Urban: A small village, Eland's Bay, lies along the coast near the mouth of the estuary.

Figure 2: Verlorenvlei

Ecology

Algae

Large masses of filamentous green algae, including Chaetmorpha and Cladophora, are
common in the channel, particularly between the railway bridge and the lower causeway,
where the water is often stagnant and hyper saline.

Aquatic Vegetation

Extensive beds of emergent aquatic macrophytes occur along the margins of the lake with
Phragmites australis, Typha latifolia and sedges as dominants. Downstream of Redelinghuys
there are fairly wide and open wetlands with patches of mixed sedges and reed communities
along the course of the Verlorenvlei River over a distance of 11km. Dense reedbeds are
present in the upper part of the lake. Myriophyllum spicatum, a submerged macrophyte,
dominates large areas of the lake where the water is about 2m deep. The water lily,
(Nymphaea capensis), a species which is becoming rare in South Africa due to destruction of
wetlands, occurs in small numbers.

Terrestrial Vegetation:

The Verlorenvlei wetland is of significant botanical importance, because of its position at the
transition between the karroid and fynbos vegetation types. The region therefore, has a high
diversity typical of an ecotone area.
The different types are:

Strandveld:
Seaward dune strandveld
Shrubby strandveld

Restoid strandveld
Saltpan vegetation
Lowland fynbos
Dry mountain fynbos
Mountain fynbos
Karroid scrubland
Marsh vegetation
The site also supports notable rare plant species, such as Ferraria foliosa, F. densepunctulata,
Cerycium venom (presumed extinct) and Cullumia floccose.

Birds:

In 1976, 934 and 1 371 waders were recorded respectively during two surveys in the lower
reaches of Verlorenvlei. Of these numbers, 95% were migrants. In a later survey (1983) of
the whole Verlorenvlei, 3 655 waders were reported, of which 2 928 were migrants and
727 residents. This same survey yielded a total of 6 829 birds of 60 species in the environs
of Verlorenvlei. The vlei also provides feeding, nesting and roosting sites for 200 species
of birds in the surrounding area. It is an important moulting area for Egyptian geese
(Alopochen aegyptiaccus) and other waterfowl.
Waterbirds seen at Verlorenvlei include herons, egrets, ibises, spoonbills and flamingos.
The presence of glossy ibises and African spoonbills is important, since these species are
uncommon in the south-western Cape (Ref. 8). Flamingos appear at Verlorenvlei when
other vleis, such as Rocher Pan (35km south) and Wadrifsoutpan (13km north) dry up.
Flamingos are listed in the South African Red Data Book as requiring conservation (Brooke
1984.

Figure : Flamingo

Figure 5: Heron

Figure : African Spoonbill

Other Red Data Book species include the little bittern and the Caspian tern. The area is possibly
also an important moulting ground and summer refuge for ducks, with 600 Cape shoveller and
1 200 yellow-billed duck being observed in May 1979 (Ref. 1). In addition, Verlorenvlei is a type
locality for several species of birds, including the white-backed duck (Thalassomis leuconotus).
Up to 150 great white pelicans were counted by the Fitz Patrick Institute in 1976, representing
26% of the total south-western Cape population (Ref. 8). On 23 March 1982, 212 pelicans were
counted. The great white pelican is rated as rare in South Africa, and therefore in need of special
protection.
The vlei is also an important feeding area for the rare white pelican (Peleanus onocrotalus).

Figure 6: Pelican

Mammals

Little information exists on mammal populations at Verlorenvlei. Archaeological and historical
evidence suggest that larger mammals were present in abundance in the past, whereas they are
non-existent today. A survey by Stuart (1981) indicates the presence of the 12 carnivore species
and 11 other mammal species in the vicinity.

Topography and Geology
Topography

Verlorenvlei Wetlands is between 1 and 5 m above mean sea level. The catchment is about 87km
long in a north-west/south-east direction and up to 43km wide. Its surface area is estimated (Ref.
5) to be 1 890km2, or 198 000 ha.

The catchment is bounded by the Swartberg and Olifantsrivierberge in the east and by the
Piketberg in the south, and includes the Eendekuil basin, a low-lying area lying between the
Olifantsrivierberge and the Piketberg. The Verlorenvlei River and its tributaries drain the entire
Eendekuil basin, the Table Mountain Group mountains around Paleisheuwel, the northern outliers
of Piketberg, the extensive flats of Tertiary to Recent sands between Het Kruis and Redelinghuys
and the 5km strip of low Table Mountain Group hills and sand flats on either side of the lake which
contribute seepage.
Average depth of open water area of the lake is between 2 and 3 metres with maximum depth of
5 metres.

Geology

The Malmesbury Group (Proterozoic) has been subdivided on purely lithological grounds into
three groups, calcareous, quartzose and phyllite with greywacke. The calcareous group comprises
pure limestone, dolomitic limestone and dolomite. Carbonaceous patches and calcareous rocks
grade into quartz-rich varieties.
Sediments showing a high degree of lithological similarity to the Klipheuwel beds of the type area
are found in small occurrences along Verlorenvlei. No angular inconformity is visible between
them and the Table Mountain Group but their regional relationships clearly show the presence of
an inconformity. Rogers named these rocks Ibiqua Beds, which implies a correlation with the
Nama System, for which there is no proof available yet.
The Klipheuwel Formation (Proterozoic) comprises the following: purple to red-dish brown sandy
micaceous shale which is mostly poorly-bedded and grades into mudstone; alternating beds of
sandstone, shaly sandstone and sandy shale with colours ranging from buff to purple and red;
white and brightly coloured sandstone and grit with minor conglomerate and shale layers. The
arencaeous strata are commonly cross-bedded, quite often feldspathic, and much softer than the
Table Mountain Group sandstone. The maximum thickness exposed on the eastern boundary of
this area amounts to about 375m.

White to slightly-reddish sandy soil originated mainly from the underlying unconsolidated to
partly-consolidated sand and clay, and to a lesser extent from the Table Mountain Group, the
coastal dunes, and fluviatile deposits of past and present drainage systems.
The phenomenon of 'heuweltjies' occurs on the Verlorenvlei area, and is easily detectable both on
the ground and in aerial photographs. Different theories have been propounded as to their origins.
They include calcareous layers and higher clay content in the soil deriving from old termitaria. The
activity of mole rats may also contribute to the formation of 'heuweltjies'.

Soils

Von Harmse (Ref. 3), in his Schematic Soil Map of Southern Africa (1978), classifies the Verlorenvlei
area as a zone of littoral sands which are arenosols, or of aeolian origin. He points out that the
salient feature of such soils is their low reserve of weatherable minerals, and the low silt/clay ratio.
Taylor (1987) describes these coastal lowlands as consisting of sands and conglomerates of
Tertiary to Recent origins. He comments on their low water-retaining capacity, being either acid
and relatively infertile or, nearer the coast, alkaline with a distinct horizon of lime accumulation.
The 'heuweltjies' or hillocks have higher clay content than the surrounding soils.
The general Verlorenvlei area is characterized by type a fine sandy soil, in which the dominant
types are Fernwood and Mkambathi; the sub-dominant Hopefield; and the rare Langebaan,
Sandveld and Sonneblom. On the southern bank, extending from Elandsbaai to Redelinghuys, are
isolated sections classified as rock and undifferentiated lithosols.

The stratigraphy is:

Elandsfontyn Formation beneath, being peaty clay and sand;
the controversial Saldanha Formation;
the Varswater Formation, being conglomeratic phosphorite;
the Bredasdorp Formation (on top), with three aeolianite phases, the third being unconsolidated.

Rubble and debris are found in numerous places at the foot of cliffs and along small streams that
flow down hillsides after heavy downpours. The river is flanked by strips of alluvium, part of it being
black and rich in plant material. Several patches of drift sand and bare dunes away from the coast
originated mostly from mismanagement of the veld. A large dune field occurs to the north of the
river mouth and the town of Elandsbaai.

Hydrology and Geohydrology

The entire channel is very shallow (about 0,5m deep), tending to inhibit free water circulation. A
natural obstruction at the mouth is a rocky sill topped by a sand bar, above the normal reach of
high tides. The sand-topping is formed by a south going longshore current, in combination with
frequent onshore winds.
The two types of wave-induced inshore currents, one north going and the other southward,
appear to keep a hydraulic and sedimentological near-equilibrium at the beach. Consequently,
provided the balance (including source of sand) is not disturbed, a sufficient sand supply from the
beach will always tend to cober the rocky barrier at the mouth, to such an extent that the mouth
has little chance to remain open for any appreciable length of time after breaching.
In order to upgrade the estuary and enhance the estuarine water circulation, it is clear that the
four artificial obstructions in the channel must be removed, or replaced by longspan bridges.

Climate

Verlorenvlei has a mild, Mediterranean climate, with predominantly sunny days throughout the
year.
Precipitation: Verlorenvlei has an average annual rainfall of 275mm of which an average of 70%
falls in the winter half-year (April to September). Single very rare heavy showers can account for
as much as the normal annual precipitation. Hail is seldom reported in this region.
Temperature: The highest average maximum temperature (24, 42 °C) occurs in January and the
lowest average minimum temperature (8, 7 °C) occurs in July.

Threats

Development pressure in the Verlorenvlei area has been concentrated along the coastline, in the
vicinity of Elands Bay. The pressure is beginning to increase in the form of applications for
township extensions (Ref. 10). The coastal environs attract weekend and holiday visitors,
particularly in the summer, causing short term, seasonal increases in the demand for facilities.
The land and its vegetation cover have been degraded, mainly due to grazing and clearing of
land for agriculture and rural settlement. Despite the long history of human use of the area for
grazing and cultivation, the level of degradation is presently low enough to allow for natural
rehabilitation, but the rate of degradation is escalating. For example, agricultural activities have
led to interference with the natural function of the estuarine channel. The culverts in the
causeway near the mouth have been blocked in order to dam fresh water for irrigation of
recently cleared land.
Likely sources of threats in the future include:

Existing and additional obstructions which interfere with natural estuarine and coastal
lake dynamics.

Increases in domestic live stock, particularly goats.
The clearing of natural vegetation for the extension of agriculture.
Increased extraction of underground water for irrigation

REFERENCE

South African Wetlands Conservation Programme: Verlorenvlei. Information sheet for the site
designated to the List of Wetlands of International Importance in terms of the Convention on
Wetlands of International Importance especially as Waterfowl Habitat.
http://www.ngo.grida.no/soesa/nsoer/resource/wetland/verlorenvlei.htm
Rogers, J. (1980). First report on the Cenozoic sediments between Cape Town and Elands Bay.
Pretoria Rep. Geol. Surv. S. Afr. 165:1-64.
Harmse, HJ, Von M. (1978). Schematic soil map of southern Africa south of latitude 16o30'S. In:
Werger, M.J.A. Biogeography and ecology of Southern Africa. Junk, The Hague. pp: 73–75.
Taylor, H.C., (1978): Capensis, in Werger, M.J.A. (ed), Biogeography and Ecology of Southern Africa,
Junk, The Hague, 171-229.
Noble, RG. and Hemens, J. (1978). Inland water ecosystems in South Africa - a review of research
needs. CSIR, Pretoria, South Africa.
Robertson, HN. (1980). An assessment of the utility of Verlorenvlei water. University of Cape Town.
Summers, R. W., Pringle, J. S., and Cooper, J. (1976). The status of coastal waders in the south-western
Cape, South Africa. Western Cape Study Group. 162p.
Cooper, J. (1976). The ornithological importance of Verlorenvlei and its value as a nature reserve.
Unpublished memorandum. University of Cape Town, Percy Fitz-Patrick Institute of African
Ornithology.
Brooke, R.K. (1984). South African Red Data Book - Birds. S. Afr. Nat. Sci. Prog. Report. 97: 1 - 123.
Heinecken, T.J.E. and Badenhorst, P. (1985). Elandsbaai extensions 2 and 3. Unpublished report.
Stellenbosch, National Research Institute for Oceanology, CSIR.

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