Tempo-spatial land use/cover change in Zeway, Ketar and Bulbula sub-basins, Central Rift Valley of Ethiopia

摘要

Understanding tempo-spatialdynamics of land-use/cover (LULC) and its drivers is instrumentalin synthesizing knowledge for informed natural resource managementplanning and associated decisions. The present study investigates tempo-spatialLULCchanges, their drivers and the associated impacts in three sub-basins(Zeway, Ketarand Bulbula) in the Central Rift Valley (CRV) of Ethiopia. Satellite imageries of differentperiods in ArcGIS, field observations, focus group discussions (FGDs) and secondarydata were used to analyse the LULC dynamics, their drivers and associated impactsfrom 1973 to 2014. The overall accuracy of 1973, 2003 and 2014 classification mapswas 88.7%, 88.9% and 91.6%, respectively. The analysis results revealed a continuousincrease of farmland and town built-upareas at the expense of grasslands, shrub-bushland and woodlands. It further indicated area of open irrigated agriculture, increasingfrom none to 2.61% of the total area. The FGDs demonstrated agricultural land expansion,resettlement and wood extraction were proximate causes of the observed LULCchanges. Population increases, changes in land tenure system and decreased farmlandproductivity were determined to be the underlying causes of the changes. The FGDsfurther indicated these changes have negatively affected the natural resources. Thepresent study findings indicate the need to reconsider land-usedecision tradeoffsbetween economic, social and environmental demands, and their implications forother similar areas in Ethiopia and beyond. Quantitative analysis and periodic evaluationof the drivers of such change and the impacts of existing and emerging land-usesin the face of changing climate is recommended to facilitate sustainable use of thefragile ecosystems in the Ethiopian CRV.