Gully erosion in Auchi has become a serious environmental disaster to the town and its neigbouring villages. It has threatened and even destroyed many of the urban infrastructure, properties, and lives as well as retarding the social and economic growth and development of the town. The research work therefore assesses the impact of gully erosion on Auchi town with the aid of data derived from satellite imageries, Global Positioning System (GPS), base map, as well as direct field observation. The approach involve digitizing the imageries along the gully path on the Arcmap to establish the extent of loss of land due to gully erosion as well as creating contour map, Digital Terrain Model (DTM), slope profile of the study area using the Digital Elevation Model (DEM) of the study on ArcGIS 10.1, Surfer10 and Global mapper softwares. Results obtained from the analysis of the imageries revealed that a total area of 37913m2 was lost to gully erosion between year 2006 and 2012, and that the gully is expanding at an alarming rate of 6318.8m2 per annum. By the year 2015, a total area of 15,9407m2 is expected to be claimed by the disaster if no effective measure is taken to ameliorate the devastating effect. The research therefore, recommends channelling of runoff water to less risk areas, planting of trees and other vegetal cover, and public awareness campaign to enlighten the inhabitants on the need to control gully erosion.
Key words: Environmental disaster, impact of gully erosion, runoff water, urban infrastructure.