Παρασκευή 5 Ιανουαρίου 2018

CONSTRUCTION OF KARIBA DAM ZIMBABWE



CONSTRUCTION OF KARIBA DAM ZIMBABWE

The Kariba hydroelectric project was built by IMPRESIT (later renamed IMPREGILO) between 1956-1960. Employer, the Central African Federation, consisting of South Rhodesia (Zimbabwe), North Rhodesia (Zambia) and Nyasaland (Malawi), then governed by Great Britain. Funding of the project by the World Bank. The dam was built at Kariba  gorge, located halfway  on the course  of Zambezi  river  originating  in Zambia and flowing into the Indian Ocean in Mozambique. The course of the river at Kariba marks the border between Zambia and Zimbabwe. With a length of   2754 km,  the Zambezi River is the fourth longest in Africa after rivers  Nile, Congo and Niger.The project consists of a double-curvature   concrete dam, length at the crest  620 meters, height 128 meters, thickness at the base 24 m. at the top 14 m. Total volume of  concrete cast on dam wall  975,000 cubic meters. Underground excavations on the right bank for    power plant, penstocks, water outlets, etc. 600,000 cubic meters and 150,000 cubic meters of concrete.  Generating capacity  installed 700 MW. Additional  generating  capacity of 615 MW was installed by the construction of a power station  on the left bank of the river in Zambia. The spillway comprise  six hydraulic gates located 30 meters below  maximum water level of the reservoir  with  discharge  capacity of up to 9600 cubic meters of water per second. The dam formed the largest  man made  lake on earth, contains 185 billion cubic meters of water and covers an area of ​​5400 square km. It stretches over 220 km and has a width of up to 40 km. Kariba lake took 5 years to fill (1958-1963) to its maximum level. In  OPERATION NOAH  many species of wild life  trapped on islands were saved from  drowning as the lake water level grew,  by transporting  them  to the shores  of the lake. The dam was completed in June 1959 and the power plant started operating on January 1, 1960. The project was inaugurated by Queen Elizabeth, mother of today's Queen of England.

CLICK  PHOTO TO WATCH VIDEO OF KARIBA DAM 



During  design and construction of  Kariba dam,   problems arose due to lack of long-term statistics on the seasonal flow of the Zambezi river. The maximum flow of the river during raining  season at the catchment area could   reach 18600 cubic meters  per second, while during low season flow is reduced to 920 cubic meters per second. Delays and damages occurred, caused  by  exceptional flooding of the Zambezi River during 1957/58, the time of starting implemention of  phase four of construction, i.e. laying the foundation of the dam inside the central  cofferdam. The  cofferdam was  overflowed and flooded,  thereby delaying  foundation work of the dam.The video  that I post, shows the flooded cofferdam and the dramatic increase in river flow. Fortunately, the concrete blocks already cast on the river bed towards the left bank,  resisted the  enormous pressure of the flooded river. Subsequently, the  successful implementation of an accelerated working program during the years  that followed, resulted  not only in overcoming delays,  but in  completing  the project  six months ahead of schedule.  A large number of technical and administrative staff, mostly Italians, were employed on the project as well as a great number of  indigenous workers. A workforce  of 5,000 Italians were employed  on KARIBA , including those who  resisted only  a short  while  and then returned to Italy. The bed of the Zambezi river  in Kariba  lies at an altitude of only a few meters above sea level and for this  reason climate at  Kariba was very warm  throughout  the  year.  For me, it was the beginning of a marvelous "journey"  that started at KARIBA and  carried on   with the same firm, building  4 dams including the largest  rock fill dam in the world, Tarbela, built on the Indus River in Pakistan between 1968 and 1974. Outstanding  achievements in various countries of the world, in collaboration with  the wonderful people of IMPREGILO, still world leader in construction of  hydroelectric plants around the globe and other major projects such as ports, roadworks, airports, widening of the Panama Canal, etc. The same company has just completed the imposing CULTURAL CENTER OF ATHENS (National Library and Opera) at the PHALIRON DELTA,  at a cost of over half billion dollars, donated  to the people of Greece by  Stavros Niarchos Foundation. 

 British  Pathe’ newsreel concerning flooding of the Zambezi river in 1958 affecting construction of KARIBA DAM.












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