Engineering geology, mining and environment aspects: a case study from tropical Sudan

There are several factors which influence the properties of rocks, soils and the environment degradation in tropical Sudan. The parent rock geology, the climate and the geomorphology all appear to have affected the type, degree and pattern of rock weathering as well as the development of soil masses and materials in the area. The engineering index properties of rocks deteriorate with the increase in weathering grade. The durability and weatherability of these rocks need to be tested before their use as construction materials is decided. In addition to the weathering, rock masses stability in slopes and mines have been affected by discontinuity surfaces and both surface and groundwater conditions. Moreover, residual soils dominate and show progressive change from submature brown soil at hill tops and slopes to brown mixed soil at lower slopes, to mature black soil in the flat plain. These soils show variation in texture, clay mineral composition and engineering index properties. Compared with the brown soil the black soil proved to be highly plastic, expansive and needs stabilization. Environmental degradation occur due to natural and manmade causes. Examples are land surface discription and change, deforestation, soil erosion and high sedimentation yields in reservoirs.