Özet:

This study assessed the effects of land use/land cover change on surface runoff in Abelti watershed located at upper Omo river basin, Ethiopia using Soil and Water Assessment Tool and satellite land use maps of 2000, 2010 and 2017 which were processed using Earth Resources Development Assessment System, Imagine 2015 and ArcGIS10.1 software by the method of supervised classification. There was significant change surface runoff in the watershed due to spatial and temporal change of land use/land cover change. Surface runoff was very high during wet seasons and very low during dry seasons at different parts of the watershed during the study periods. Accuracy assessment of land use classification using confusion matrix and kappa coefficient for 2000, 2010 and 2017 maps indicated an overall accuracy of 86.04%, 90.75% and 89.71% and kappa index of 0.82, 0.88 and 0.86 respectively and image classification accuracy was almost in strong agreement. The model performance was found very well according to the three objective functions of R2, Nash, Sutcliffe Efficiency and Percent Bias with values of 0.79, 0.78 and 6.3% for calibration and 0.92, 0.85 and 4.1% for validation periods respectively. Land cover types contribute minimum and maximum surface runoff based on the interception capacity of each land cover types in the watershed. Along with land use/land cover changes, considerable consequences were obtained in the surface runoff of the watershed which was increased from 2000 to 2010 by 19.963% but decreased from 2010 to 2017 by 3.898% due to change of land use/land cover in the watershed. Therefore, surface runoff was highly affected by land cover types and increased when the interception was less because of the forest cover decreased, surface runoff decreased when the forest cover become increased.

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