Abstract
M.Sc. (Environmental Management)
Whether negative or positive, any human land use will have an impact on water quality. Point and non-point sources of contamination occur throughout the study area. Land use type and intensity will determine to what extent the water quality is affected. The aim of this research is to determine which human land use (within the study area) has the most prevalent effect on water quality. The Wilge River is a vitally important source of water for supply to the Gauteng region, and thus its quality is of a high priority, and yet little known or studied. Situated in the Grassland Biome of South Africa, on the Highveld in the Eastern Free State, the Upper Wilge River Catchment area is dominated by agricultural land use and has two human settlements that play an important role in the quality of water in the catchment. The Catchment is subdivided by four tributaries, which allow for smaller regions to be mapped out and studied individually. The various regions that have been mapped contain alternating types of land use including but not limited to cultivation and livestock agriculture; different types of human settlements. The Upper Wilge River also plays a role in the Tugela-Vaal Inter-Basin-Transfer (IBT) Scheme, and so water quality is also affected by this.
South Africa is a water scarce country with highly erratic and unevenly distributed rainfall and thus the appointment of Catchment Management Agencies to monitor and manage water supply has been implemented by Government. By utilising Land use maps, Water Quality data and water quality guidelines, it is possible to identify spatial trends in water quality. There are nine specific water quality indicators that were selected according to the land use types present because various indicators may aid in identifying or representing specific human land use types, and thus highlight how different human land uses have different effects on water quality over a space. The respective water quality data for the nine specific indicators were acquired over the 12 sample points in the study area for a six year period. Data were transformed, analysed and simply visually represented in the form of bar and pie charts. Land use was mapped over the study area using Google Earth and a GIS (MapWindow). Finally data were interpreted in accordance with land use maps, water quality guidelines and thus water quality trends established.
The main objective of this research was to identify, compare and determine which land use present has the most noticeable and detrimental effect on water quality. Essentially water quality depends on land use type and intensity within a catchment, but can also be affected by a variety of other anthropogenic or natural factors. Overall, the way in which the current human population utilises and impacts on the water quality is negative; but quality remains generally acceptable for the intended purpose of this water to downstream users, however this must be carefully monitored and managed, so as to ensure further degradation does not occur.