GEOTECHNICAL INVESTIGATION OF GULLY EROSION SITES IN

ANKPA METROPOLIS, KOGI STATE, CENTRAL NIGERIA.

*Omali, A.O. ^*Imasuen, O.I and **Musa, K

*Department of Earth Sciences, Kogi State University, Anyigba

**Department 0f Mineral Resources, Kogi State Polytechnic, Lokoja

E-mail: isaacokpes@yahoo.com

ABSTRACT

The study area covers Ankpa metropolis in Ankpa Local Government Area of Kogi State. It is underlain by rocks of Anambra Sedimentary basin consisting of Ajali Formation and Mamu Formation. Geotechnical investigations of soils from gully sites on the basis of Atterberg limit, particle size and compaction tests were carried out to assess the geopedologic and hydrologic causes of the gully erosion in the area and proffer solutions to the menace. Plasticity index of the soils ranges from 1.2% to 5.2% which shows that the soils are non-cohesive and non plastic. Sieve analysis revealed that the soils from the gully sites are within the medium to coarse grain range with low percentage of silt/clay, hence an indication that the soil is non-plastic. The compaction test shows that the optimum moisture content ranges from 13.50% to 15.20% while the maximum dry density ranges from 1.75mg/m³ to 1.98mg/m³. The maximum dry density values are generally low which indicates that the soil is not compact but loose. A proper and concrete drainage should be constructed along highways and areas suffering the menace of gully erosion. Concrete terracing of gully affected areas is recommended to reduce the impact or the force of rain-drop. This will reduce widening of incipient gullies. A holistic development program of monitoring the pedosphere is recommended to ensure a safe environment.