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Tesfaneh Getaw
Evaluation of the Impact of Land Use/Land Cover Changes on Streamflow of Bogena Watershed, Upper Abbay basin, Ethiopia
Abstract
Hydrologic modeling and water resources administration studies are intimately linked to the spatial methods of the hydrologic cycle. This succession is overelaborated by various factors such as Land Use/Land Cover (LU/LC) and climate alteration. Deforestation is a day-to-day action of the individuals in the Bogena watershed; the area is facing soaring soil loss due to forceful rainfall that intensifies the land cover change of the watershed. Hence, this study focused to estimate the effect of land use/land cover changes on the stream flow of Bogena watershed by using GIS, and Soil and Water Assessment Tool (SWAT). Input facts were climate data, land use/land cover, DEM, and soil. The land cover map was created by means of the Extreme Possibility Classifier of Supervised Classification. After identifying the necessary data for simulation of the model, sensitive factors were identified using sensitivity analysis. Hence, Sensitivity analysis showed that CN2, SOL_BD, SOL_K, SFTMP, SOL_Z, GW_DELAY, GWQMN, EVLAI, SURLAG, and REVAPMN were the most sensitive parameters. The model was calibrated using stream flow data from 1991 to1997 years and validated using 1998 to 2003 years. The R2 and NSE value was essential to estimate the feat of the model. The outcome indicated that 0.997 and 0.988 are R2values and 0.86 and 0.79 are NSE values during regulation and confirmation correspondingly. Hence, the results of the study indicated that the land use/land cover changes had substantial impact on infiltration rate, runoff, sediment loading, water yield, and evapotranspiration as well as water holding capacity of the soil. The analysis also specified that the stream flow through the rainy months was greater than during the dry months. The surface runoff (SURQ) increased, but groundwater flow (GWQ) decreased from 1990-2015 periods due to the development of agricultural land, legal/illegal taking out of groundwater for small-scale irrigation, and other purposes. In general, the stream flow features altered due to the LU/LC changes from 1990-2015 periods.
Keywords: Bogena watershed, GIS, LU/LCC, SWAT-CUP, SWAT model
