In this study, a GIS-based integration of multi-criteria analysis and the Height Above Nearest Drainage (HAND) terrain model was adopted to delineate potential flood hazard zones and vulnerability of the Ogun River Basin, Nigeria. Flood causative factors were used as input for multi-criteria analysis using an analytical hierarchy process (AHP) and weighted overlay ArcGIS 10.5 to generate potential flood hazard zones. The flood hazard map was overlaid with demographic population data to identify areas where vulnerable people and assets are located. The results show the varying degree of people’s susceptibility to flood hazards. Flood hazard zones were classified into Very High, High, Moderate, Low and Very Low, with area coverage of 1269.40, 14139.50, 7188.40, 17.41 and 0.85 km², respectively (occupied by 466 290, 355 542, 69 554, 231 and 54 people, respectively). This study serves as a preliminary guide for early warning and policy decision-making for flood disaster risk reduction.

Cation exchange capacity (CEC) is a good indicator of soil productivity and is useful for making recommendations of phosphorus, potassium, and magnesium for soils of different textures. Soil water holding capacity (SWHC) defines the ability of a soil to hold water at a particular time of the season. This research predicted CEC and SWHC of soils using pedotransfer models developed (using Minitab 17 statistical software) from basic soil properties (Sand(S), Clay(C), soil pH, soil organic carbon (SOC)) and verify the model by comparing the relationship between measured and estimated (obtained by PTFs) CEC and SWHC in the Forest Vegetative Zone of Nigeria. For this study, a total of 105 sampling points in 35 different locations were sampled in the study areas. Three sampling points were randomly selected per location and three undisturbed samples were collected at each sampling point. The results showed success in predicting CEC and SWHC from basic soil properties. In this study, five linear regression models for predicting soil CEC and seven linear regression models for predicting SWHC from some soil physical and chemical properties were suggested. Model 5 [CEC = -13.93+2.645 pH +0.0446 C (%)+2.267 SOC (%)] was best for predicting CEC while model 12 [SWHC (%)=36.0- 0.215 S (%)+0.113 C (%)+10.36 SOC (%)] is the most acceptable model for predicting SWHC.

Proper utilization of land is essential to soil quality maintenance and sustainable agricultural development. This study was conducted to evaluate effects of land use management on physico-chemical characteristics of soils in Ekiti State, Southwestern Nigeria. In this study, a total of 105 sampling points in 35 locations comprising of the 3 land uses were sampled. Random sampling pattern of 3 sampling points per location were carried out and undisturbed soil samples were collected at depths up to 30 cm. Soil physical properties (bulk density (BD), water holding capacity (WHC), and particle size distribution) and chemical properties (organic matter content (SOM), cation exchange capacity (CEC), phosphorus (P) and organic nitrogen (SON)), were determined and evaluated. Results showed that natural forest on the overall accumulated more nutrients than plantations and cropland. The highest SOM value of 4.07 % was recorded in the natural forests, while the lowest value of 1.52 % was found in the croplands. Organic matter accumulation showed a decreasing trend in the order: forest > plantation > cropland. Natural forest soils had significantly higher volumetric moisture content (VMC) than plantations and croplands. C orrelation analysis of the 11 physico-chemical properties for the study area, showed a significant correlation among 70 of the 190 soil attribute pairs. Land use system reveals a significant decline of soil quality under cropland. Management systems by which soil could be improved towards the development of suitable agricultural management systems must be incorporated during land cultivation. In order to have sustainable land use systems, land use development must not be only economically sustainable but also socially acceptable and environmentally sound. Therefore, strategies to improve agricultural productivity have to seek a sustainable solution that better addresses soil fertility management.