Abstract
M.Sc.
This dissertation establishes the present – day condition of the Hennops River in terms of its water quality and hydrological status. The Hennops River is situated between Johannesburg and Pretoria within the provincial boundaries of Gauteng. The province has a high population density and is regarded as the economic powerhouse of South Africa. As such, rivers flowing through Gauteng have become polluted by the different land uses and activities present in the province. The Hennops River itself has lost most of its aesthetic appeal and has become less useful for recreational and agricultural uses. Furthermore, the Hennops River has become a liability and concern in suburbs south of Pretoria and, more importantly, has become less suitable for sustaining aquatic ecosystems in some of its sections. The Hennops River, therefore, has an effect not only on the environment itself, but also in terms of social and economic aspects.
Because of these concerns it was deemed necessary to determine the actual water quality conditions and associated problems prevailing in the Hennops River. Being fed by tributaries, these problems could not be overlooked and were also included in this study. In order to achieve the aim of the study a literature review concerning the concept of water quality and the different physical and chemical constituents affecting aquatic ecosystems needed to be conducted. Added to this, attention had to be given to the study area’s physical features and land uses having an effect on the catchment’s water quality and associated problems. A literature review on existing knowledge of the Hennops River and its principal tributaries was also conducted so that it could be determined whether these rivers have deteriorated over the past three decades. The most recent water quality data was not only compared against existing knowledge, but also in terms of the Target Water Quality Range for Aquatic Ecosystems as stipulated by the Department of Water Affairs and Forestry.
This study showed that deterioration of the Hennops River has occurred since rapid urbanisation within its catchment started during the 1970’s. Most of the River’s water quality and associated problems can be ascribed to problems occurring further upstream in the form of the Kaalspruit and Olifantspruit flowing through formal and informal settlements, industrial areas and agricultural land. The water quality of these rivers and the upper Hennops River is the least suitable of the whole study area for aquatic ecosystem well-being. Not only is this a concern but additional hydrological problems occur as well. These include problems such as erosional activity of riverbeds and riverbanks and the silting-up of Centurion Lake.
An urgent need exists for holistic catchment management and rehabilitative measures to be implemented to improve the ecological state of these rivers. Rehabilitative measures were proposed and are aimed at improving the water quality and associated problems of the Hennops River and its affected tributaries. It is concluded, therefore, that the status of the Hennops River is not going to improve without the implementation of rehabilitative measures that should form part of an environmental management plan.