GEOLOGICAL AND GEOTECHNICAL CONTROL OF GULLY EROSION, UNGOGO, KANO, NORTH WESTERN NIGERIA

Abstract

Gully erosion is an environmental hazard that is ravaging the landscape of Ungogo area. This study was carried out to investigate the geological and geotechnical control of gully erosion in the study area. Geological field mapping was carried out to assess the causes and extent of erosion. Soil samples were collected from four (4) gully sites at depth between 0 -5m, 0.5 - 1m and 1 - 1.5m for geotechnical analyses. Four (4) index properties of soil were determined: Specific gravity, sieve analysis, Atterberg test and compaction test both in accordance with British standard code: BS-1377-2, 1990. Specific gravity values were used to determine the probable risk of erosion. The grading index recorded from the sieve analysis showed that coefficient of uniformity ranged between 17.2 - 1.13 and coefficient of curvature ranged between 6.01 - 0.85. The coefficient of permeability falls between coarse sand and silt. The plasticity index of the soil samples were found to be 4%, 5%, 9%, 2%, 7%, 6% 2%, 20%, 9%, 11%, 3%, and 3% and all the soil samples from gully sites have their plot clustered within clay of low plasticity and silt of low plasticity indicating cohessionles properties thus the potential for the control of gully erosion formation in the area. The optimum moisture content and the maximum dry density of the soil indicated that soils are majorly loose sand and this could pave way for erosion susceptibility. Mitigation measures such as Landfilling, construction of check dam, geo-textile, fencing and stabilization are recommended for the control of gully erosion in the area.