11Landslide is one of the most ravaging natural disaster in the world and recent occurrences in Nat. Hazards Earth Syst. Sci. Discuss., doi:10.5194/nhess-2016Discuss., doi:10.5194/nhess- -297, 2016 Manuscript under review for journal Nat.

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California Bearing Ratio (CBR) is an important parameter used in designing pavement layers in road construction but testing this parameter requires time, labor, and huge cost. The study therefore applies multivariate approach to evaluate CBR based on contrasted geotechnical parameters along Ilorin-Lokoja highway. The results obtained showed that the migmatite-gneiss-derived soils are slightly more fines (< 0.075 mm; 7.4–59.6%), more plastic (PI; 1.6–39%), and have low strength (MDD = 1.8 mg/m3; CBR = 29.0%) than the metasediments (11–57.7%, 2.0–30%, 1.6 mg/m3, 23.6%) and older granite soils (8.2–32.7%, 2.6–13.4%, 1.7 mg/m3, 27.8%), respectively. The principal component analysis (PCA) revealed three major components (eigenvalues >1) which accounted for 83.8% of the total variance at the rate of 33.4, 14.7, and 11.4%. Major contributing variables for the components were fines (R = 0.87), plasticity index (R = 0.7), and coarse sand (R = 0.67%). Spatial distribution of these groups established interplay of sediment-gradation and moisture-connection evident in hierarchical cluster analysis that revealed patterns of homogeneity and soil relationships. Regression analysis established five models from predictor variables such as fines, activity, free swell, liquid and plastic limits, weighted plasticity index, optimum moisture content, and maximum dry density with the coefficient of determination (R2 = 0.33) and root mean square error (RMSE) of 7.80.

The hydraulic characteristics of aquifers in Lokoja and Patti Formations were investigated using combination of vertical electrical sounding (VES), pumping and laboratory tests. A total of 20 VES (10 each in areas underlain by Lokoja and Patti Formations) were carried out at different locations with 5 pumping tests around VES stations in order to determine the geoelectric layers, thickness, depths to water table and groundwater potential of the area. 21 samples extracted fromaquiferous units of surface outcrops were also subjected to laboratory constant head and falling head permeameter tests in order to determine hydraulic conductivity (K) values using the Darcy’s law of liquid flow. The results of VES for areas underlain by Lokoja and Patti Formations revealed 4-5 geo-electrical layers. The depths to water table vary from 5.91-40.8 m. Thickness values are within the range of 7.37-27.3 m for aquiferous units of Lokoja Formation, and 10.8-20.1 m for the Patti Formation. The results of aquifer characteristics using Dar-Zarrouk Parameter gave hydraulic conductivity (K) values between 1.92-91.7 m/day and 2.15-31.8 m/day for aquifers of Lokoja and Patti Formations respectively. Transmissivity (T) values of the aquiferous units of Lokoja Formation fall within 24.97-2117 m2/day, while those of Patti Formation vary from 27.9-456.91 m2/day. There is a strong correlation between the values of measured and calculated hydraulic conductivity and transmissivity between measured and calculated transmissivity for the five wells (R2 = 0.99 and 0.92, respectively). Based on the results obtained and interpretations proffered, aquiferous units in both formations are capable of yielding optimum groundwater for private consumption and partly to small communities, and to some extent can supply water for great regional use. It is suggested that similar study should be carried out in other sedimentary basins where to aid regional planning and management of groundwater resource.

This study aims at determining the state of government provided boreholes, evaluating groundwater potential and quality assessment within the Ayede Ekiti community. 12 Vertical Electrical Soundings (VES) were conducted using Schlumberger array in order to determine geoelectric layers and fracture attributes. Also, 12 water samples were collected from the study area to evaluate physicochemical characteristics of the groundwater. The study revealed average values of total depth of boreholes, static water levels and water column in the boreholes to be 18.77 m, 6.77 m and 11.99 m respectively. 70% of the boreholes are either abandoned, damaged or with evidence of corrosion and encrustation. Geophysical investigation revealed weathered layer thickness ranging from 1.3 to 34.7 m with two regimes of fracture at 40–50 and 75–80 m. The frequency of curve types obtained shows 16.67%, 33.33%, 25%, 8.33%, 8.33% and 8.33% for AK, HA, KH, AA, QH and HK respectively while weathered and fractured basement are identified as the two types of aquifer unit. Results of water analysis unveiled that dominance cations are in order Ca2+ > Na+ > K+ > Mg2+while anions are in the order of HCO3− > Cl− > SO42−. Three types of hydrochemical facies present are CaHCO3 > NaHCO3 > CaCl in 66.67%, 25% and 8.33% respectively. The Wilcox plot suggests the suitability of the groundwater samples for irrigation purposes when compared with the World Health Organization standards. Despite potential for groundwater and good quality of analyzed samples, the problem of water in this community is traceable to inadequacy in exploration, shallow boreholes with consequent seasonal water availability.

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Background radiation involves the measure of the level of ionizing radiation present in the environment at a particular location. This research seek to generate data of the natural background radiation level of some selected Sections at Kabba College of Agriculture, using RadEye G20 survey meter. A total of 15 sections of the College were randomly selected and the background radiation dose rate of the sections were measured. The indoor dose rate ranged from (0.09 – 0.13) 𝜇Sv/yr, while the outdoor dose rate ranged from (0.07 - 0.10) 𝜇Sv/yr. The indoor annual effective  dose were observed to be greater than the outdoor annual effective dose in all the College Sections measured. The lowest total annual effective dose 0.75 𝑚𝑆𝑣/𝑦𝑟 was found at the Academic staff block. The highest total annual effective dose of 1.09 𝑚𝑆𝑣/𝑦𝑟 was found at the livestock building, this might be due to the high-altitude nature of the area and the rocky materials used in the construction of the building. The highest total annual effective dose of the study area was slightly above the recommended limit of 1.0 𝑚𝑆𝑣/𝑦𝑟. The result obtained from this research may not constitute immediate health risk to the staff and student of the college

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