Environmental degradations caused by erosion and landslide within an area in the South-eastern part of Nigeria were assessed, and also an attempt to characterize the underlying soils based on their degree of susceptibility to erosion and landslide. Factors affecting soil erodibility such as physical and chemical properties of soil, as well as vegetation density and slope gradient was determined in 20 different areas. Simple linear regression and principal component analysis were employed to relate the factors controlling erosion and landslide to the erosion and slide densities, and to determine the pattern that exists in the data and as well express the data in such a way as to highlight their similarities and differences. Four vertical horizons and two horizontal zones of soil were distinguished based on their degree of weathering as well as their chemical and mineralogical composition; hence the soils were classified into six different types based on their degree of susceptibility to erosion and landslide. Variations in their degree of susceptibility to erosion and landslide were majorly controlled by its chemical and mineralogical composition rather than its particle size distribution.

This work assessed the impact of environmental pollution on soils susceptibility to water erosion within South-eastern Nigeria. Sources of pollutants which could possibly affect the chemical composition of runoff; hence its pH, were first determined by remote sensing and field observations. Rain and runoff water samples collected within the study area were analysed for its physicochemical compositions. Soil samples were also collected and analysed for their geotechnical properties, and chemical composition of their fine fractions. An empirical method was then employed to determine the effect of change in chemical composition of runoff on the susceptibility of the studied soil to water erosion. This was achieved by conducting soil aggregate slaking, dispersion and dissolution tests on aqueous solutions of varying pH. Results from the experiment shows that the fine particle fractions of the soils are chiefly composed of sesquioxides. The slaking of these sesquioxide-cemented soils is not affected by the variations in pH of the solutions, but rather by the plasticity index of the soils. However, dispersion and dissolution of the soil samples where dependent on variations in the pH of the solutions. It was therefore concluded that environmental pollution has the potential of increasing runoff erosivity.

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Gully erosion studies are usually complex and expensive due to the multiple nature of the causative factors, heterogeneity of the underlying geologic materials, and the high volume of point source data required within a given area. For this reason, thorough gully erosion studies are rarely carried out especially in developing countries with little resources allocated to environmental studies. Thus, it becomes di cult in solving problems arising from such geologic hazard in those areas. However, the availability of data emanating from remotely sensed operations can be utilized in solving complex gully erosional problems using modern geospatial analytical tools. Consequently, gully erosion studies within the study area were carried out by integration of geomorphologic and environmental data which were acquired remotely, and geotechnical information derived from eld and laboratory investigations of the underlying geologic materials. The integrated geomorphologic, environmental, and geotechnical data was analysed with analytical tools such as ArcGIS, Google Earth, and Microsoft Excel, following the frequency ratio method. Results from the study revealed that slope angle, soil plasticity, angle of internal friction, cohesion, and population density contributed about 20%, 23%, 20%, 18%, and 9%, respectively to soil's susceptibility to gullying. Slope angle and population density were positively correlated with the frequency of gully erosion, whereas plasticity, cohesion, and angle of internal friction were negatively correlated with frequency of gully erosion. The spatial distribution of the data revealed areas that are susceptible to gullying in their various degrees; thus providing affordable information for proper environmental planning and development.

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