Geomorphic considerations in the deterioration of rural roads : the case of Inkandla, Indwedwe and Ga-Modjadji.
The condition of the rural road network in South Africa is in a severe state of deterioration and remains a matter of concern for inhabitants of rural areas. Apart from heavy use, the main problem is that road development is often neglected and the main focus is placed on the geomorphic environment. The objective of this study is to identify the nature of the geomorphic constraints of vehicular access on unarmoured roads in the rural areas of KwaZulu Natal and the Limpopo Province of South Africa, and to gain a better understanding of how these function. It is hoped that some of the insights gained can then be used to inform policy decisions regarding the location and design of rural roads in the future. In this study, a number of unarmoured roads were studied in detail to identify the possible environmental constraints on vehicular access. A number of soil physical and chemical properties were used to examine the state of road degradation. These properties included particle size analysis, soil strength, Cation Exchangeable Capacity and Exchangeable Sodium Percentage. The results of the investigation of soil properties have shown that they play a significant role in road degradation. The major geomorphic factors involved in road deterioration include soil type, soil erosion and precipitation characteristics, mass movements, slope conditions and human activity. The physical characteristics, especially the soil and slope conditions, make the access roads in all study areas susceptible to soil loss. Factors such as geology, drainage and friable soils vulnerable to mass movements have been identified as seriously constraining vehicular access. Soil erosion problems in the study area are largely the result of physical and chemical properties of soils combined with steep gradients and have been identified as the primary cause of road degradation. It was further found that the socio-economic conditions, together with the anthropogenic influences such as the construction of rural access roads on vulnerable slopes, population density and the removal of vegetation cover in all the study areas have significantly enhanced road deterioration.