Great Fish River

The Great Fish River Nature Reserve at Double Drift

The Great Fish River ( Afrikaans Groot- Visrivier, dt Great Fish River, formerly known as Great Salt River ) is a river in South Africa's Eastern Cape Province. It has a length of about 730 kilometers and has a catchment area of ​​30 366 square kilometers. The river drains along with the nearby Sundays River west of it, the eastern parts of the semi-arid Karoo. Important tributaries are the Kariega River, Kat River, Little Fish River, Koonaprivier and the Tarka River.

Course

The headwaters of its upper tributaries are located in the northwestern section of the Eastern Cape Province, in the wider community of the city of Middelburg. The sources are located in the northern part of the Bamboesberg massif and the eastern part of the massif Sneeuberg ( Snow Mountains ). The river stretches south of Middelburg through the small town Visrivier to Cradock and on to the area east of Somerset East, from where his right tributary of Little Fish River approaches and in the countryside between Sheldon and Carlisle Bridge in the Great Fish River flows. From about this point, his turns are clearly increasing and the valley cuts deeply into the landscape. Further downstream, he takes the Koonaprivier on with its tributaries from the winter mountains area and the Kat River, which gradually brings its water from the Katberg and Elandsberg area.

In the lower reaches the river bed meandering very strong and cuts deep into the hills of the region around Grahamstown one. His mouth is in Waterloo Bay east of Port Alfred at Fort D ' Acre on the coast of the Indian Ocean. There, its valley widens and the estuary is characterized by a powerful sandbar. The regional road R 72 crosses here the valley by a bridge.

Geological situation

Its headwaters and the main tributaries are in the range of the eastern Great Karoo, the geological structure of sandstones and other sedimentary rocks of the Beaufort Group is determined. In the area of the Great Fish River Nature Reserve, there are mainly sandstones of the Middleton Formation ( Beaufort Group), which characterize the geological structure of the riparian zones. Further downstream traverses its course north of Grahamstown the narrow sandstone zone of the Ecca Group and has been with tillites of the Dwyka Group Contact, before he penetrates further south in older layers of rock. Now the Great Fish River reaches the folding zone of the Cape Supergroup. There are mainly rocks ( shale ) of the Witteberg Group (Devon). His mouth region is in the range of folding zone.

From its headwaters in Middelburg to the north of Grahamstown the Great Fish River flows through a basin -like landscape. This area is called the Great Fish River Basin (Fish River Basin ). It is a flat to gently undulating landscape with an area of ​​about 25,000 square kilometers. The basin is characterized by low annual rainfall ( 350-450 mm). Swellable clay minerals in the soil, such as montmorillonite, take a considerable part of the surface water to bind it for a long time and give it successively in the form of water vapor back into the atmosphere. This process favors the semi-arid climate in the Great Fish River basin, since only small amounts of water in the aquifer ( here mostly sandstones ) is recorded. This process is referred to as evapotranspiration.

Typical alluvial deposits on the wavy relief of the Fish River basin are clayey loam soils.

History

Between 1779 and 1853 the banks of the Great Fish River were the scene of border wars between European settlers and African natives. Then as now, was the distribution of scarce water resources central conflict. Currently responsible for the water distribution of the Administration of the Water User 's Association and its 17 regional Water Control Officers.

Water reservoirs in the catchment area

In the catchment area of ​​the Great Fish River, there are five large water reservoirs that are used for water supply in their regions.

• Grass Ridge Dam ( at Groot Brak )
• Kat River Dam (at the Kat River)
• Kommandodrif Dam ( on the Tarka River)
• Lake Arthur ( on the Tarka River)
• Ncora Dam (at the Tsomo River)

Nature reserves on the Great Fish River

A portion of the river has been declared because of its scenic and ecological characteristics and its biodiversity to reserve Great Fish River Reserve.

This conservation area with an area of ​​45,000 hectares consists of three individual reserve areas. These are:

• Double Drift Nature Reserve
• Andries Vosloo Kudu Reserve
• Sam Knott Nature Reserve

This nature reserve is crossed by the regional road R 345 and can be reached from the towns of Alice in the north and in the south Peddie. The regional road R 67 leads past its western edge.

Use patterns in the catchment area

The largest part of its catchment area, 94 percent are natural areas that were subject to low or no anthropogenic change and use. It involves dry steppe and scrubland of the Great Karoo with a predominantly very small urban use. As agricultural land only 3 percent of the area to be used and an equal proportion is considered degraded landscape that is affected by erosion. Built-up areas hold a stake of less than 1 percent of the catchment area, although to them the towns of Adelaide, Bedford, Cradock, Fort Beaufort, Middleburg and Somerset East belong. The reason for this pattern of use is in the specific geological and climatic conditions of the Karoo region.

The development of economic activities is difficult due to these conditions and in view of the sensitive ecological conditions also limited possible and desirable everywhere. Historically, it is traditional farmland that only limited use is but for this purpose. Today, efforts are made by public and private activities to sustainable tourism in the often semi -desert landscape.

The Great Fish River Museum in Cradock showing objects from the history of European settlement in the upper reaches of the Great Fish River.