Water History KOUGA DAM – Serving the fertile Gamtoos valley In one of the most fertile valleys of the of 1 500 m above sea level, the Kouga eastern boundary of the Cape settle- Eastern Cape lies the Kouga Dam, which River flows through the Langkloof ment. This remained so until 1804 Valley, lying between the Tsitsi- when the area became part of the for more than 50 years has played a kamma, Kouga and Winterhoek newly proclaimed Uitenhage district. pivotal role in water supply and flood mountains. After joining up with its Between 1816 and 1818 the first control in the region. Lani van Vuuren tributary, the Baviaanskloof River, farms of around 1 713 ha each were it flows through a narrow gorge, the officially handed over to European traces the history of the dam. Kougapoort, to its confluence with farmers. the Groot River. After the conflu- ituated between winter and ence, the name of the river changes THE START OF summer rainfall areas the to Gamtoos. IRRIGATION Gamtoos valley is known for The valley was originally popu- itsS rich, fertile soils, its fresh water, lated by Khoisan communities. Trek- rrigation in the valley started in and its subsequent agricultural boers first settled in the Gamtoos Ithe 1840s and gained momen- bounty. The main river running valley with their livestock in the era tum after the introduction of through the valley is the Kouga of Dutch occupation, and by 1770 lucerne to bolster the production of River. Rising at Avontuur at a height the Gamtoos River was declared the ostrich feathers. Storage weirs and 20 The Water Wheel January/February 2011 Water History distribution canals were constructed the river itself, from which the water “Prisoners had a ten- by several farmers in the district might be brought on the land either dency to deliberately who wanted a share of one of South by gravitation or by pumping.” injure themselves on Africa’s most lucrative export prod- These unorganised and primitive ucts at the time. Where weirs were methods of extracting water led to site so as to avoid the impractical steam and oil pumps numerous requests by community hard, physical work.” were used to bring water from the leaders and the farmers themselves river to the field. for intervention by the State through 1916 and included a weir, 29 km- Following a visit to the valley the development of proper irrigation long canal and a tunnel of 163 m to agricultural assistant to the Cape schemes. In 1910, the Cape Director irrigate 1 285 ha of land. government wrote in 1904: “Some of Irrigation, FE Kanthack, visited Periodical floods were the enemy help is needed to simplify the present the valley. He called it “the most of irrigation farmers in the Gamtoos complicated system of distribution... favourable part of the Union.” Fol- valley. In May 1916, such an extreme The present system of using the lowing the promulgation of the Irri- event led to the death of 24 people. water is wasteful to extreme. The gation and Conservation of Waters The Gamtoos River destroyed every- temporary dams are inefficient and Act of 1912 several Irrigation Boards thing in its path, including the newly constantly being broken by floods. were established in the Gamtoos constructed irrigation infrastructure The water leading canals are small valley, including the Kougapoort, as well as 514 ha of scheduled irriga- and long, badly laid out and far too Reenen and Rademeyer Irrigation tion land. Many of the farmers also numerous, owing to a lack of com- Boards. By the 1950s, there were lost their crops. bination among the proprietors and some 4 798 ha of land under irriga- More loans had to be made to it only requires organisation and tion in the valley. The main crops rebuild the works. Extreme measures a readier outlet for the produce to under irrigation at that time were were taken to protect the structures bring great prosperity. citrus, tobacco, vegetables, potatoes, from further flood damage, includ- “Should the government under- wheat, maize and lucerne, with Port ing surrounding them with thorny take the work of regulating and Elizabeth proving a convenient branches and gabions of rock and conserving the water supply of market. steel. These were often simply the Gamtoos valley the scheme The boards immediately set to washed away when the river came that would meet the most general work improving irrigation infra- down. In long stretches of the river, approval on the part of the inhabit- structure with significant loans no large rocks could later be found. ants would be one for the construc- from the government. One of these Another notable flood hit the tion of a series of dams in the bed of schemes, Reenen, was completed in region in 1932, this time destroying Gamtoos Irrigation Board Irrigation Gamtoos Above: Kouga Dam is located near the downstream end of the Gamtoos valley in a narrow gorge. Right: The Kouga Dam wall during construction. Cocopans were used to bring concrete to the top of the wall. Here the rail can clearly be seen. Gamtoos Irrigation Board Irrigation Gamtoos The Water Wheel January/February 2011 21 Water History BEERVLEI DAM n 1946, the Union government Irather unexpectedly decided to first construct a flood control dam at Beervlei on the Groot River near Willowmore, before making a final decision on a dam in the Gamtoos valley. The site, situated about 5 km below the confluence of the Groot River with the South and Kariega rivers, was first identified in the early 1920s. Considered one of the best stor- age basins in the country, irrigators along the Groot River agitated for this dam for many years. However, because of the extremely irregular flow, high mineral content and silt load of the rivers, the government was at first reluctant until it was decided to use Beervlei mainly for DWA/eWISA flood control instead. Only around 2 190 ha of irrigated area would be regulated from this dam. The Beervlei Dam 932 ha of land and washing away topographical surveys were made Construction of the multiple arch during construction. weirs and canals. Thankfully the of alternative sites near Guerna, a The distinctive multiple dam started in 1953. At that time arrival of a telephone service years short distance below the infall of arch structure comprises it was government policy to make 15 cylindrical arches earlier meant that people could the Witteklip River in the Kouga, use of black convict labour on large with gravity sections on be forewarned and no loss of life and on the farm Tweerivieren in public works projects and so a large its flanks. occurred. At Hankey, known at Kougapoort. prison labour camp was constructed that time for the quality of its The latter site, located about at the site. Around 400 prisoners apples and other fruit, most of the 5 km above upstream of the Kouga/ eventually worked on the dam. trees were lost. Following the flood Gamtoos confluence, was eventually Excavations for foundations the Irrigation Commission sur- selected, and the dam was initially started in July 1954, and the first veyed the damage in the valley and known as Tweerivieren Dam. Topo- concrete was placed in May, 1955. recommended the construction of graphical surveys were carried out Due to the high mineral content of dams to control these periodical of the Gamtoos valley in 1952/1953. the water, a super sulphated cement floods. In 1956, the Department of Agri- was imported from Belgium and When the farmers were not culture commissioned an investiga- used in the preparation of concrete tormented by floods they had to tion into the suitability of the soil for the dam. The spillway was origi- contend with droughts. Available in the valley for the expansion of nally at two levels, the upper level flow in the Kouga and Gamtoos irrigation. was 1,8 m above the full supply level rivers was insufficient for around a third of the time. Farmers upstream KOUGA DAM ENGINEERING FEATURES were better positioned than their downstream neighbours, especially • Dam type: Double curvature arch dam in times of deficit. • Maximum height above lowest foundation: 94,5 m A number of sites for storage • Crest length: 204 m dams in the Kouga River catchment • Maximum water depth: 53 m had been investigated from time to • Gross storage capacity: 133 million m3 time. As early as 1931 a site on the • Surface area (at full supply level): 555 ha farm Kruisrivier, immediately below • Total quantity of concrete in wall: 268 000 m3 the confluence of the Kouga and • Maximum thickness of wall: 10,2 m Baviaanskloof rivers was surveyed, • Design flood (1:200 year): 4 249 m3/s while in 1947 and 1953 further 22 The Water Wheel January/February 2011 Water History and reached over three of the dam’s 15 cylindrical arches. The project was finally completed in September, 1957. In 1967, the full supply level of the dam was raised to the level of the upper spillway to increase the capacity of the dam from 52 208 million m3 to 92 850 million m3. The dam wall has a height above lowest foundation of 31 m, and a crest length of 348 m. The volume content of the dam is 0,042 million m3 and it has a gross capacity of 100 731 million m3. KOUGA DAM n 1955, Paul Sauer, then Minister Iof Lands, stated that once Beervlei Board Irrigation Gamtoos Dam was completed, a start would be made with a dam on the Kouga River. A White Paper proposing the building of the Kouga Dam was submitted to Parliament in 1957, and not long thereafter a construction team moved onto site.