The Gamka River

THE GAMKA RIVER – WESTERN CAPE



Contents

1. Overview
2. Tributaries
3. Geophysical

a. Topography
b. Geology
c. Soils
4. Hydrology
5. Ecology
6. Climate
7. Land use
8. Populated places
9. Water Infrastructure
a. Dams

Overview

The name 'Gamka’ is derived from the
Gamka River, which crosses through the
bottom of the valley; while the name 'Gamka'
means 'Lion' and was probably named this
by the San (Bushmen).

The Gamka River flows from the North East
of the Gamka Dam and the Dwyka from the
North West. Both rivers flow into the Gamka
Dam from there the Gamka river flows south
and becomes the Gourits River at Calitzdorp

The Gamka River rises in the mountains of

Figure 1: Gamka River the Great Karoo to the north of Beaufort

West and is joined by the Leeu and

Koekemoers Rivers at Leeu Gamka, flowing southwards as the Gamka River into Gamkapoort

Dam. Downstream of Gamkapoort Dam the Gamka River flows through the Klein Swartberg to its

confluence with the Olifants River in the Little Karoo south of Calitzdorp.

Figure 2: Gamka River bridge

Tributaries

Bloukopleegte
Dalajalon River
Gedenksteen se leegte
Groot River
Kat River
Kweekleegte
Koekemoers River
Leeuw River
Perdevlei River
Veldmans River
Waterkloof River

Geophysical

Topography

The Gamka River rises in the mountains of the Great Karoo to the north of Beaufort West and is joined
by the Leeu and Koekemoers Rivers at Leeu Gamka, flowing southwards as the Gamka River into
Gamkapoort Dam. Downstream of Gamkapoort Dam the Gamka River flows through the Klein
Swartberg to its confluence with the Olifants River in the Little Karoo south of Calitzdorp.

Geology

The Karoo Supergroup of Permian age consists
of the Dwyka Formation, Ecca Group and
Beaufort Group. The Beaufort group overlies the
Ecca group and consists of alternating mudstone
(red in places) and sandstone. It sub-divides into
the lower Abrahamskraal Formation (1500-
2000m thick) and an upper Teekloof formation
(±1400m thick) with the boumdary arbitrarily at
the base of the so-called “Poortjie Sandstone”.

This formation consists of mudstone (red in
places), sandstone and thin greenish cherty beds. The sandstones represent river channel deposits and
the mudstones, floodplain deposits. The cherty beds were originally ashfall tuffs, although the presence
micro-cross-lamination suggests subsequent transportation by water onto the floodplains. Jurassic-age
dolerite extensively intrudes the Beaufort Group as dykes and sheets. Inclined sheets form
crescentshaped or concentric intrusions that are clearly visible on the Middle- and Upper Plateau.

The sills range from a few metres to over 100 m in thickness. The dolerite causes a metamorphosis
effect on the adjacent host rocks. Mudstone altered to hornfells and the sandstones develop a quartzitic
appearance. Deposits of Quaternary age include river terrace gravel, calcrete, alluvium and debris.
Terrace gravel consists of fairly well-rounded cobbles and boulders composed largely of dolerite. The
terrace gravel shows clearly along the banks of the Gamka River where sharp profiles occur.

These gravels are partly calcrete cemented and occur on terrace remnants that now lie from a few

metres to a maximum of 30 m above the general land surface. Calcrete occurs directly on bedrock and

has also formed extensive deposits

within some larger areas of

alluvium, attaining a

maximum thickness of a few

metres.

These gravels are partly calcrete

cemented and occur on terrace

remnants that now lie from a few

metres to a maximum of 30 m

above the general land

surface. Calcrete occurs directly on

bedrock and has also formed extensive deposits within some larger areas of alluvium, attaining a

maximum thickness of a few metres.

Soil

The dominant soil-forming processes have been rock weathering, the formation of orthic topsoil
horizons and, commonly, clay alleviation, giving rise typically to lithucutanic horizons. Soil forms that

are typical of these processes are Glenrosa
and Mispah. Any other soil form can however
also be found in these land types. Oakleaf soil
forms, deep or shallow, developed by rock
weathering also occur in upland sites.

Surface rock with underlying soil or rock
covers sixty to eighty percent of these areas.
The parent material of the slopes consists of
mudstone, siltstone and sandstone with some
dolerite intrusions, and typically Mispah or
Glenrosa soil forms. Dolerite covers most of the middle plateau, with an influence of mudstone, siltstone
and sandstone closer to the upper slopes.

Fertile soils occur on this flat plateau with little erosion save where the deep red soils gradually erode
from a natural basin.

The dominant soil-forming processes have been rock weathering, the formation of orthic topsoil
horizons and, commonly, clay alleviation, giving rise typically to lithucutanic horizons. Soil forms that
are typical of these processes are Glenrosa and Mispah. Any other soil form can however also be found
in these land types. Oakleaf soil forms, deep or shallow, developed by rock weathering also occur in
upland sites. . Surface rock with underlying soil or rock covers sixty to eighty percent of these areas. The
parent material of the slopes consists of mudstone, siltstone and sandstone with some dolerite
intrusions, and typically Mispah or Glenrosa soil forms. Dolerite covers most of the middle plateau, with
an influence of mudstone, siltstone and sandstone closer to the upper slopes. Fertile soils occur on this
flat plateau with little erosion save where the deep red soils gradually erode from a natural basin.
Dolerite rocks cover most of the Puttersvlei section of land type Ib, with the underlying sandstone
appearing in terraces, descending in a northerly direction.

Hydrology

A number of important rivers have their
source in the park, namely the Sak, Leeu
and Gamka rivers. The Leeu river flows
through the park towards the west, and
is joined by the Paalhuis river,
Klipplaatsfontein river, Boesmanskop
river, Doringhoek river and Sand river,
all of which have their sources within
the park. In the north east, the Gamka
river has part of its source partly in the
Park and then flows through the park
toward the south. The Stolshoek river
originates in the park and joins the
Gamka river further downstream. Also in the north east the Puttersvlei area drains from a gentle slope
towards the north and forms the source of the Sak river. All of these streams and rivers are seasonal
and dependent on rainfall to flow. However, some of these such as the Klipplaatsfontein and
Doringhoek rivers can retain water in pools for long periods after rain.

Ecology

Terrestrial Animals

Mammals likely to be seen include klipspringer, grey rhebuck, kudu, baboon and dassie, and on the
flatter areas at Gamkapoort, springbok. Leopard and caracal also occur in the area, but are seldom seen.
More than 130 bird species have been recorded here, notably black, fish and martial eagle, Cape
sugarbird and pied kingfisher.

Vegetation

The vegetation is remarkably diverse, featuring renosterveld, mountain fynbos, Karoo-veld, spekboom
veld, and numerous geophyte species. Some
species will be in bloom virtually throughout the
year. Most plants flower in spring, but early
autumn is the time that many protea species
flower, attracting large numbers of sugarbirds
and sunbirds. During mid-summer (December -
February) many of the interesting plants on the
higher Swartberg peaks are in flower, including
the rare Protea venusta.

Climate

Temperature

This is an area of climatic extremes, with very cold winters, often with snow on the mountains and
temperatures well below zero, while summers can be uncomfortably hot with temperatures reaching
40°C and more!

Rainfall

Rain occurs throughout the year, peaking in early winter and spring, and with thundershowers in the
summer months.

Land Use

Agricultural

Lucerne and pasture is the dominant crop type upstream of Gamkapoort Dam whilst stone fruit and
vineyards are the main crops downstream of the dam, reflecting differences in assurance of supply.

Sheep, cattle and goat farming can also be found in the area.

Nature Conservation, Reserves and Tourism

Fishing is allowed in the Gamka River and the Gamkapoort Dam, with possession of a fresh-water
angling license. Canoeing and windsurfing are permitted on the Gamkapoort Dam and the Gamka River.

The remote and isolated Gamkaskloof valley is about 90 km from Oudtshoorn and 60 km from Prince
Albert and is only accessible via the Otto du Plessis road, which turns off from the Swartberg Pass.

The valley is of ecological, archaeological and cultural-historical importance and is now managed as
part of the Swartberg Nature Reserve.

Visitors to the kloof may stay in two restored houses or camp. Attractions and activities include
picnicking, a Norwegian mill, angling in the Gamka River, and sightseeing and relaxing in this natural
paradise as well as a 6 km interpretation hiking trail (3 hours).

Populated places

Beaufort West
Calitzdorp
Leeu Gamka
Prince Albert

Figure 3: LeeuGamka

Water Infrastructure

Dams

Gamka Dam
Gamkapoort Dam
Leeugamka Dam

Figure 5: Gamkapoort Dam



References

I. Department of Water Affairs and Forestry, South Africa. 2004. Gouritz Water Management Area:
Internal Strategic Perspective. Prepared by Ninham Shand (Pty) Ltd in association with Jakoet &
Associates and Umvoto Africa, on behalf of the Directorate: National Water Resource Planning.
DWAF Report No P WMA16/000/00/0304.

II. South African National Parks
III. Karoo National Parks
IV. Swartberg - A strenous hike over the Swartberg Mountains
V. Swartberg Nature Reserve

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