ABSTRACT      

An assessment of geological and geotechnical parameters of selected gully sites in Sangere Loko Area of northeastern Nigeria is presented. Field geological study revealed that the area is underlain by basement rocks consisting of granites and granite gneiss which has been intruded by the Tertiary basaltic rocks. The soils in the area are product of insitu weathering of the underlying basement rocks giving rise to clays, silts, laterites and sand deposites occurring more than 3 meters in depth. Results of sieve analysis indicate that soils at the gully sites have sorting values ranging from 0.204 to 1.434 showing well to poorly sorted soils. Furthermore the mean hydraulic conductivity values of 4.89 x 10-3 cm/s and mean transmissivity value of 1.24 x 10-4 cm2/s indicate relatively moderately permeability, seepage fluxes and pore pressures which will likely reduce the shear strength of the soils. The plastic limits of the soils vary from 13.15% to 21.90 % whereas the plasticity index varies from 12 % to 21.30 % revealing soils of low to moderate plasticity as well as friable, poorly cohesive soils that are susceptible to gully erosion. The compaction test display maximum dry density values of 1.78 kg/m3 to 2.21 kg/m3 with an optimum moisture content values of 6.10 % to 10.20 % revealing generally loose soils that are susceptible to gully erosion. The results of the study were used to infer the surface and subsurface processes that contribute to the formation and expansion of gullies as well as recommendations on how to control the menace of gully erosion in the area were made.