Land use/land cover change investigation of the study area between 1973 and 2002/5 wasrnconducted using remote sensing and geographic information system (GIS) controlled byrnground truthing. The study area is about 560km2 located in the main Ethiopian rift (MER)rnwith in the Orommia Regional Government state and can represent mountain degradation ofrnthe rift valley of EthiopianrnThe research was conducted with the objective of creation of historical and the currentrnLULC maps and LULC change map of 1973-2002/5. The maps were derived utilizingrnstandardized digital remote sensing classification techniques using three multitemporalrnLandsat scenes acquired on Jan 30, 1973(MSS), Jan 21, 1986 (TM), and Feb 30, 2002rn(ETM+). Classification accuracy was determined to be sufficient by means of employingrnstandardized accuracy assessment measures.rnAccording to the statistics calculated from the land use and land cover change data betweenrnthe 1973 and 2002/5, the intensively cultivated and Urban lands have been expanded byrn18710 ha and 555 ha which is 128.43% and 411.11% increase respectively. On the otherrnhand, the wooded cultivated/grass land, the shrub grass land, the wet land and water boMesrnshow decrease by 14779 ha (58.86%), 4478 ha (64.46%), 432 ha (7.98%), 229 ha (6.05%)rnrespectively. The degraded shrub Grass Land also showed an increase by 518 ha (386.57%)rnbetween 1986 and 2002/5.rnThe population growth was certainly the most important factor causing the observed landrncover change because of the increase of demand ofland for cultivation, settlement and treesrnfor fuel and construction purpose. As a result, large areas, which were once under wood andrnshI1lb cover, are now exposed and affected by sheet and rill erosion which in turn resulted inrnformation of big gullies and hence loss of farmlands.rnIf current trends are allowed to continue damage to the natural resource base will continuernand land lost due sheet and gully erosion will increase. The increase in run off and low waterrnretention due to low land cover further intensify the sheet erosion and rill and gullies to widen and deepen which therefore degrade the agricultural land more than the presentrncondition. The sediments removed are channeled to the lakes and cause sedimentation andrnpollution. The increase in the length and depth of the gullies associated with the lUggedrntopography, nature of the soil, low vegetation cover of the area, together with the rainfallrnthat come after a long dry period might cause serious land slide which is observed by soilrnfall occurring in the area.rnIntroducing alternative energy sources such as biogas should be encouraged to reducerndependency on natural vegetation for fuel. On the other hand, Planting of trees individuallyrnor in group in the mountainous areas and in the areas which are degraded so that out of usagernfor agriculture will add to the rehabilitation process and also satisfy need of wood for fuel,rnconstlUction and could compensate for low coverage of woodland and at the same timernreduce erosion currently affecting the environment.rnEducating the society concerning optimum use of natural recourses, conservation systemsrnand their benefits and continuing the current efforts of introducing family planning to makernthe people aware of consequences of population pressure should be carried out intensively.