Gully erosion sites are becoming more and more of a danger to environmental sustainability, posing serious environmental risks. The geotechnical and environmental risk assessment of two gully erosion sites in Nkwoegwu, Abia state, is the subject of this study. Four (4) soil samples were taken at various depths between 21.4 and 20.3 metres. The soil samples' geotechnical qualities were investigated. Soils at Site A were formed of (Clay and Silt – 29.48 percent, Sand – 69.01 percent, Gravel – 1.51 percent), whereas soils in Site B were composed of (Clay and Silt – 41.71 percent, Sand – 57.54 percent, Gravel – 0.75 percent), indicating that they are nonplastic. The liquid limit values for site A and site B are 26 and 19 percent, respectively, whereas the plasticity index values for site A and site B are 7.0 and 6.0 percent, suggesting that they were noncohesive. The maximum dry density (MDD) values for site A and site B are 1.99 mg/m3 and 2.02 mg/m, respectively, indicating their loose character. The optimal moisture content (OMC) values are 12.1 percent and 13.3 percent, respectively, with CBR values of 32 percent and 4%. The erosive soil samples had moisture content of 8.5 percent and 11.2 percent, respectively. The bulk density values for site A and site B are 1.38 g/cm3 and 1.28 g/cm3, respectively, whereas the shear strength values, which include cohesion, C, and angle of internal friction, are 1.38 g/cm3 and 1.28 g/cm3, respectively. , resulting in a C of 34 N/m2 for both sites A and B, as well as a 14° (site A) and 16° (site B) temperature difference. This demonstrated that the soils are unable to withstand runoff. The soils were predominantly loosed sands with a high porosity and low proportion of silt/clay fractions. The noncohesive qualities of soil components render them susceptible to erosion agents such as rainfall, land-surface slope, and human activities. The topographical survey revealed that gully sites are the lowest spots in the area, with drainage flowing in the same direction. The research area's total surface runoff is predicted to be 384000 m3/day. Hazards to the environment, such as the loss of arable land and the threat to life and property, were also recognised. Terraces are suggested as a means of preventing the two gullies from expanding further. Surface runoff will be reduced as a result.
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