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This study is mainly focusing on the application of HEC-HMS model for evaluating the impacts of land cover changes on the stream flow through satellite Remote Sensing and Geographic Information System integrated with the HEC-HMS model. Hence such modeling and evaluating practice have not been practiced in this particular catchment. ArcMap10.2 used to generate land use and cover maps from Landsat ETM, ETM+ and OLI where used to detect land use change for the years of 1999, 2003 and 2015 respectively through Supervised Classification. The model calibration was carried out using observed stream flow data from 1999 to 2002 and a validation period from 2003 to 2005. Using the two generated land cover maps (1999 and 2003) HEC-HMS models set up were run to evaluate the impacts of the land use and cover changes on the stream flow of the catchment. The accuracy of the classified maps was assessed using error Matrices and the process produced high accuracy LULC maps for the years of 1999, 2003 and 2015 with an overall accuracy of 84.4%, 86.3% and 88.5% respectively. The land use evaluation results showed that the urban area and agricultural land increased by 1975% and 12.8% between 1999 and 2015 and slightly decrease in forest, grassland and water by 65.4%, 42.8% and 11.3% respectively. Both the calibration and validation results showed good match between measured and simulated stream flow data with the coefficient of determination (R2) of 0.74 and Nash-Sutcliffe efficiency (ENS) of 0.67 for the calibration, and R2 of 0.65 and ENS of 0.51 of the validation period. Generally the analysis indicated that significant increases in peak discharge of the catchment by 3.51% and the base flow dimensioned by 33.56% from 1999 to 2003 due to the increment of urban and cultivated lands. |
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