Global Advanced Research Journal of Agricultural Science (GARJAS) ISSN: 2315-5094
January 2016 Vol. 5(1): pp. 014-027
Copyright © 2016 Global Advanced Research Journals

Full Length Research Paper

An Assessment of Gully Erosion in Kano Metropolis, Nigeria

¹Mallam I, ²Iguisi E.O., and ³Tasi’u .Y.R

¹Department of Environmental Management and Toxicology, Federal University, Dutse, Nigeria.

²Department of Geography, Ahmadu Bello University Zaria, Nigeria

³Department of Geography, Sa’adatu Rimi College of Education, Kano

Email: kutamasak@yahoo.com

Accepted 15 January, 2016

Abstract

The study was carried out to determine the effect of gully erosion in parts of Kano metropolis, fifteen gully heads were purposively selected from the study area for determining the magnitude, mechanism of gully development and head ward retreat. The development of gullies is one of the ruthless environmental problems in Kano metropolis. It has threatens urban infrastructure, properties and lives. Linear retreat of the gully heads was monitored by pegging technique. Field measurements and laboratory analysis were used in data generation. Results from the field measurements showed that gully variables (length, depth and widths) have significantly increased in the last 10 years. Laboratory analysis of soil particle size revealed that sand proportion was 73.2%, silt 14.3% and clay 11.4%. Soil chemical properties also showed that the soils are moderately acidic and contained low organic matter. The study shows that, gully heads retreated at different rates ranging from 13 cm to 121 cm depending on instability factors. Gully heads are few times steeper than angle of internal friction that introduces instability. Near vertical and overhanging slope of considerable height develop tension cracks leading to mass failure and gully head retreat.  The mean area occupied by gullies from the study area stood at 42,915m², the advancement rate of gully heads ranged from 3m to 7m per year and the mean total volume of material removed as soil loss was 130,776.1m³ for the period of study. Factor analysis revealed that rainfall energy and slope steepness has the greatest influence for the occurrence of erosion in this study area. The effect of the five factors can be rated as E>F>S>L>i in accordance with their relative importance for the occurrence of erosion. This study recommend the need for scaling of gullies banks should be undertaken, in which barrages should be constructed along the principal gullies to stabilise them and stop their expansion. 

Keywords: Gully erosion, Gully head retreat, soil properties, rainfall, and Kano metropolis.