Analysis of land use/land cover changes in the Debre-Mewi watershed at the upper catchment of the Blue Nile Basin, Northwest Ethiopia

Changes in land use/cover at the Debre-Mewi Watershed in northwest Ethiopia were analyzed over a period of 51 years (1957-2008). The changes were measured through interpretation of aerial photos taken in 1957 and 1982, and a Landsat image of 2008, supported by focus group discussions and repeated field visits. Based on the image analysis, four major land use/cover classes (natural forest, shrub, grazing, and cultivated land) were identified for the period 1957 to 1982. In addition to the four land use/cover types, areas covered by Eucalyptus plantation forest and rock outcrop were observed on the 2008 image. In the three consecutive periods, the natural forest cover accounted for 4.48, 1.30 and 0.37%; shrub land cover 6.10, 6.01 and 2.39%; grazing land 18.39, 14.86 and 11.14%; and cultivated land 71.04, 77.83 and 81.51% of the total area (543.82 ha) of the watershed, respectively. Areas under Eucalyptus plantation and rock out crop accounted for 1.28 and 3.30%, respectively, of the total area of the watershed in 2008. Within the last 51 years, the natural forest cover declined by 91.74%, the shrub land by 60.79%, and the grazing land by 39.47%, whereas the cultivated land increased by 14.75%. Between 1957 and 1982, and 1982 and 2008, the largest proportion of the natural forest land (49.21 and 39.63%), shrub land (79.99 and 49.80%), and grazing land (56.83 and 17.04%) were converted to cultivated land use. The implications of these changes suggest that the land use/cover changes have skewed to the rampant conversion of areas once covered with vegetation to cultivation without adequate use of soil and water conservation and rehabilitation practices.