The president of the Zimbabwe Committee on Large Dams explains how, despite economic problems, some water projects are still progressing
AFTER several years of vigorous progress in the water sector in Zimbabwe, activity has been seriously curtailed due to the economic problems currently besetting the country. Public projects have been suspended or postponed, while private sector development has generally ceased due to uncertainty over the land redistribution exercise. Casualties of the financial crisis include the Mukorsi dam, a 90m high CFRD set to create the largest reservoir in Zimbabwe and intended for expanding irrigated agriculture in the southeast lowveld. Construction commenced early in 1998 but the contract has been in suspension for the last 18 months pending the receipt of arrears payments. Also on hold is the Dande project which was initiated to develop 4000ha of irrigation in the Zambezi Valley. Contracts for the construction of the dam and for drilling a 7km supply tunnel were awarded early in 1999 but, after mobilisation and site establishment, little further work has been achieved as funds have yet to be released from a development bank.
Against this austere background, however, work is continuing on some schemes.
Raising Ruti dam
Ruti dam was built in 1976 and the safe yield is fully committed to existing irrigation. To enable expansion of the irrigated area, the capacity of the dam is to be increased by 25% through the installation of hydroplus fusegates on the 284m spillway cill. Modifications to the masonry cill have been completed, and the 1.5m high fusegates are being cast in concrete at a factory in Zimbabwe from moulds produced in France. The project received soft loan funding from the French Development Bank.
Biri dam is situated on the Manyame river, about 120km northwest of Harare, and is a major private sector development project. It is promoted and funded by a consortium of farmers who will use the water for irrigation on their individual properties. Construction started in September 1999 and the contractors had a race against time to achieve storage and safe passage of flood waters by December 2000.
Biri dam is an earthfill embankment which is 1500m long and 35m high, with a 104m uncontrolled spillway discharging into a tributary channel on the left bank. Total contract cost of the dam is about US$7.3M.
Operation and maintenance of Kariba dam is the responsibility of the Zambezi River Authority, a bi-lateral agency of Zambia and Zimbabwe. It has recently undertaken complete refurbishment and upgrading of the hydro mechanical equipment for operation of the spillway sluice gates and stoplogs, as well as resetting and resurfacing the sealing surfaces on which clearances had diminished due to AAR activity in the dam concrete. The spillway gates were opened early in 2000 to reduce lake levels in anticipation of flood inflows following heavy rainfall in the catchment area; this was the first operational gate opening since 1982.
The Kariba South Bank power station is owned and operated by the Zimbabwe Electricity Supply Authority. An extended exercise is currently under way to rehabilitate and upgrade the six generating sets, which have seen nearly 40 years of service. Each set was originally rated at 100MW but improvements to the alternators have increased the rating to 110MW and new turbine runners will bring the station’s installed capacity to a total of 720MW.