Abstract:
Hydrologic modeling and water resources management studies are closely related to the spatial
processes of the hydrologic cycle. This cycle is affected by several factors like climate and land
use / land cover changes. Deforestation is a day to day activity of the people living in the Muga
watershed, the watershed in this study facing high erosion by the effects of intense rainfall of the
watershed which aggravates the land cover change of the watershed. Population pressure, lake
of awareness and weak management are considered the major cause for the deforestation and
degradation of natural resources .This study is mainly focusing on the assessment of the impacts
of the land use / land cover changes on the stream flow of Muga watershed, by Gis interface soil
and water assessment tool (SWAT). For this study SWAT Simulation is used in identifying the
most vulnerable sub basins to the stream flow and sediment load changes of Muga watershed.
The model was calibrated and validated using the observed Stream flow of Muga River at a
gauging station near Dejen. Sensitivity analysis shows curve number CN, GW_DELAY and
SOL_AWC are the top three sensitive parameters. The model was calibrated using stream flow
data from 1993 to1998, validated from 1999 to 2002 and from 1990-1992 used for warm up
period. The R2
and NSE values were used to examine model performance and the result indicates
0.88 and 0.90 to R2
and 0.86 and 0.89 to NSE during calibration and validation respectively.
The result of land use /land cover change showed that the land use / land cover changes have
significant effects on infiltration rates, runoff production, water yield, sediment loading, and
evapotranspiration and water retention capacity of the soil. The result of this analysis indicated
that the mean monthly stream flow for wet months had increased by 17.75 m3
/s while the dry
season decreased by 12.76m3
/s during the 1995-2013 period due to the land use and land cover
change. The highest annual surface runoff was attributed by sub basin 5 whereas sub basin 6
contributes the highest ground water respectively for 1995, 2003 and 2013 land cover maps. In
terms of sediment yield, sub basin 1 contributes a maximum load for the study periods.
