Land cover classification and change detection as a basis for hydrological runoff modelling in the Main Ethiopian Rift Valley

This study examines the land cover changes that occurred in the catchment of Awassa between 1986 and 2006 in order to evaluate the importance of urban growth and deforestation in the context of lake level rise and increasing discharge values. The study is based on a LANDSAT scene acquired on January 21, 1986 and a ASTER scene acquired on January 27, 2006. By doing so, two independent maximum likelihood classifications were performed. Consequently, a difference map was calculated and spectral changes were evaluated using the IR_MAD transformation. Results show that urban growth and deforestation occurred but there is no proof that these processes took place on a large scale and that they are significantly influencing the discharge patterns. Nevertheless, the change detection map created on the basis of IR-MAD indicates that the difference map based on the individual classifications does not account for the deforestation processes that occurred in the eastern part of the catchment in a sufficient amount.