Evaluate the Impacts of Land Use/Land Cover Dynamics on Stream Flow of Gelda Watershed, Upper Blue Nile Basin, Ethiopia
14 Pages Posted: 3 Jul 2019
Date Written: June 30, 2019
This study evaluates the impact of land use/land cover change dynamics on Gelda stream using SWAT and SWAT-CUP models in Gelda watershed. Environment for visualizing images (ENVI) and Arc GIS were used to generate land use land cover maps from Landsat TM, ETM+, and OLI/TIRS developed in 1984, 2000, and 2016, respectively. The land cover maps were generated using the Maximum Likelihood Algorithm of Supervised Classification. Change detection was done by using ENVI 5.1 software. During this study, most parts of the grazing land and vegetative covers were changed to agricultural land (14.32%). An increase of agricultural land by 32.23 % from 1984- 2016 resulted in a change of stream flow. In the change detection analysis from this study between 1984 and 2016, the sum of forest, bush, and grazing lands were significantly changed to agricultural land by 32.77% whereas the sum of the forest, bush, and grazing lands were changed to built-up area by 1.14 %. The Model calibration and validation for stream flow were done for 20 (1987-2006) and 10 (2007-2016) years without warm up period respectively. The monthly calibration and validation results showed that a very good agreement between measured and simulated flow with R2 of 0.86, NSE of 0.81 and PBIAS of 0.08 for calibration, and R2 of 0.88, NSE of 0.78, and PBIAS of 0.11 for validation. The analysis indicated that, the stream flow during the wet months has increased, while the flow during the dry months has decreased. The surface runoff increased, while groundwater flow decreased from the year 1984-2016.The model results showed that the stream flow characteristics was changed due to the land use land cover change during the study periods from1984-2016.
Keywords: CFSR data, SWAT, SWAT-CUP, LULCC, Calibration, and validation
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