Geotechnical Assessment Of Gully Erosion Site In Umuagor Urualla, Imo State South Eastern Nigeria

ABSTRACT 

Erosion is one of the major environmental hazards currently ravaging the southeastern part of Nigeria, especially Imo-state. This present study was conducted to assess the impact of Umuagor-Urualla gully erosion site. Analysis of undisturbed soil samples collected at three distinct positions (surface, subsurface and base of the gully) showed that the liquid limit and plastic limit for sample 1 was NP (non-plastic), with Plasticity Index of 0%, while the Plasticity Index for samples 2 & 3 were 12% and 18% respectively, average shear strength was 177.8 KN/m2, average bulk density was 1.8mg/m3 and dry unit weight was 1.6mg/m3. Advanced Geosciences inc. ID software was used to process the vertical electric sounding (VES) result which showed  that the resistivity of the underlying material ranged  from 671ohm-m to 3684ohm-m; with an average depth of 7.5m. These results showed that the incidence of gully erosion in Umuagor-Urualla is predominantly controlled by the nature of the underlying material (shale and silt stone). Thus adequate drainage channelization from the advancing gully head into Orashi River is recommended. 

Key words: erosion, vertical electrical sounding, hazards, plasticity index.