Rate of Gully Expansion on Major Land Uses, the Case of Huluka Watershed, Central Rift Valley, Ethiopia

Abstract

Gully erosion is among the many phenomenon which has been interweaving the socio economic and environmental issues of Ethiopians. Actions have been taken to address the problem inadequately. This study was thus aimed at determining the distribution and expansion rates of gullies on the major land cover – land uses in Huluka watershed. This was achieved through collecting historic land cover – land use data using  Geographic Information System (GIS) and Remote Sensing (RS) and gully expansions  using gully assessment method called ‘Assessment of Gully Erosion Rate Through Interview and Measurements (AGERTIM)’. Field observations, discussion with elders were also employed to validate results from remotely sensed data. Accordingly, about 58km length of active (unstable) gullies with 4.7m width and 2.6m depth was registered in the study watershed. Out of this majority of the active gullies were found on lands commonly used for grazing purpose followed by on the land used for crop cultivation purpose.  Unlike the frequency, the dimensions of the gullies on crop land were found larger than the gullies on the lands used for grazing purpose. All active gullies in the watershed have showed continuous and progressive expansion in the last 30 years though the tremendous expansions were seen with in latest period 2005 – 2009 indicating exacerbating rate of gully expansion in the study area. Despite the rapid gully expansions, no any protection and treating measure was registered in the watershed.  This study has thus recommended an intervention of concerned bodies to reverse the rapid gully expansions in the study watershed.

Keywords: Major Land use, land cover, critical period, AGERTIM, Gully development