Spatial and temporal aspects of soil erosion in Mt Ayliff and Mt Frere, Eastern Cape Province, South Africa.
Madikizela, Primrose Nomawethu Thomzana.
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This study is concerned with the physical and human causes of soil. erosion. Some quantitative information on the magnitude of soil erosion for different ecoregions in South Africa is available. However, such quantitative data is available only from a few sites. One objective of this thesis is to add to the existing data. Site specific data is provided for the two study areas in the Eastern Cape Province, namely, Chani area in Mt Frere and Brooks Nek area in Mt Ayliff. A comparison is made between the physical and chemical characteristics of the soils found in both study areas. The spatial and temporal extent of the erosion problem is also given. Another major objective is to evaluate the soil rehabilitation measures used at these two areas. An evaluation of the relevance and efficiency of the erosion control measures is made. (For gully erosion especially, the present study provides an evaluation of the suitability and effectiveness of the gully control mechanisms adopted.) Most importantly, a third objective of this study is to investigate the awareness and attitudes of the members of the communities affected by the erosion problem. Among the many different factors found to be important in the causal nexus that results >f in soil erosion, it has been found that many of the problems originate from social causes, like that of too large a population for the limited available resources. Added to this, factors like poor development programmes, bad agricultural practices, bad road management, have exacerbated the erosion problem. In other words, from research and interviews conducted in the study areas, erosion problems linked to recent political policies; to farming and to other practices were found to be associated, inter alia, with the shortage of land, unemployment, the lack of the necessary farming equipment, overgrazing and so on. To stress the point, the five important factors contributing to erosion were identified as an over exploitation of the land resource for basic needs, bad road management, floods, drought, and concentrated flow on furrows made by both on and off-road vehicles. We noted that another important feature of this thesis is to give an account of the psychological attitudes of individuals living near the areas affected by erosion, Respondents to interviews and to questionnaires generally agree that there has been a lot of change in their natural and man-made environments, especially in terms of gully development and vegetation reduction. However, there is a disturbing level of ignorance concerning the causes and consequences of erosion. When asked to estimate the date of gully initiation in Brooks Nek, for instance, none of the respondents could give even rough estimates or a specific incident leading to the current dominant erosion problem. The general attitude towards the problem in their midst was one of indifference. The general belief is that erosion is caused not by themselves but by natural phenomena. Further, most respondents thought it is someone else's (e.g. government's) responsibility to ameliorate the harmful consequences associated with land deterioration and soil loss. The data for this thesis have been obtained through surveying the landscape directly over a three-year period (1994-6), and by using aerial photographs for 1982 (Mt Frere site) and 1993 (Mt Ayliff site). Detailed analysis was undertaken of chemical and physical characteristics of soil at both sites. In addition, quantitative and qualitative surveys of people in the area were attempted; to ascertain their understanding and contribution to the problem. The implications, as shown from the results of this investigation, are that the soil erosion problem at both study areas are largely independent of soil characteristics. On the contrary, this study will show that human practices are the major initial causes for soil erosion in all the cases investigated. It was found that over the years, the land use practices in both sites have changed significantly. Factors accelerating the development of erosion forms at Brooks Nek, for instance, include the footpaths and stock trails. In contrast, artificial contouring and poor gabion layout are the major causes in Chani. However, it must be mentioned that it is not always easy to separate the effects of human from natural causes. Once the effects of human activities exceed the optimum limits of soil resistance and resilience, erosion starts. Then erosion acceleration will not necessarily be confined to the original cause(s). Natural storms and floods, or even drought will contribute in accelerating the erosion rates.