The Midmar potable water transfer line employed innovative design and state-of-the-art construction techniques to provide the region with water well into the next century. The potable water transfer element of the Midmar Project, winner of a Pietermaritzburg Branch Award for Excellence in Civil Engineering and nominated for last year's SAICE National Award, is an aqueduct that conveys treated water from the new Midmar Waterworks, via a system of pipelines and the Midmar Tunnel, to a point near the D V Harris Waterworks. From this point, the water will enter Umgeni Water's Inland System, initially through a tie-in to the existing 61 pipeline to the new Worlds View reservoir. The new aqueduct ties in to the existing 251 pipeline in the vicinity of the tunnel inlet.
In South Africa's first plant of its type, flash mixing, floculation and float layer removal are performed hydraulically. The 20-year-old waterworks at Klipdrift, situated at Hammanskraal north of Pretoria, consisted of seven 'package' plants, with a total capacity of 12 Mt/d. Each package plant consisted of a sedimentation clarifier followed by sand filters, a process eminently suited to most surface waters in which silt forms the major undesirable particulate matter. Klipdrift, however, receives its water from the Roodeplaat Dam, situated on the Pienaar's River to the north of Pretoria, via a 30 km long open irrigation canal. Urbanisation and the influence of effluents from wastewater treatment works have increased the nutrient content of this water to the stage where algal growths occur both in the dam and in the open irrigation canal.
The impact of HIV/AIDS on the planning environment of the water sector as well as the financial planning, human resources and human resource costs of enterprises operating in this sector are considered. South Africa is moving beyond the HIV epidemic to the critical phases of AIDS sickness and deaths. The 1996 national prevalence of 11 per cent of the adult population (or one in every nine adults) is well beyond epidemic levels, and continues to increase rapidly. The national prevalence is expected to peak at 25 per cent of the adult population by the year 2006. The increased morbidity and mortality arising from this deadly virus will have profound demographic and economic consequences.
The use of carefully sited, low-powered, short-range, inexpensive radars provides a useful tool for management purposes. Precipitation measuring, or weather radar as it is more generally known, is potentially a powerful tool for use by meteorologists and hydrologists for the remote sensing, forecasting and measurement of precipitation. Hydrological and hydraulic models are now routinely in use in, for example, the planning and design of urban drainage systems (UDSs). Moreover, there is a growing realisation of the potential for the real-time control of these systems and a recognition of the potential for weather radar data to provide a timely input to these models for this purpose. This paper descriptionbes the use of low-powered, short-range, inexpensive, C-band weather radars and the data they provide to meet identified user needs in urban areas.
A new way to bring water and sanitation to communities through partnership between the public and private sectors. Build, operate, train and transfer - these are the elements of a new concept that will break through existing backlogs to make clean, safe water and healthy sanitation available to millions of South Africans. At the moment, between 12 and 18 million people in this country are thought to be without safe and adequate water services and between 17 and 21 million lack basic sanitation. Eighty per cent of these people are in the four most rural and disadvantaged provinces - the Eastern Cape, KwaZulu-Natal, Mpumalanga and Northern Province.