Assessment of land use/land cover change impact on streamflow: a case study over upper Guder Catchment, Ethiopia

The dynamic nature of land use/land cover modifies the basin's hydrology and, therefore, evaluation of its impact on hydrological elements is of great importance. This research aims to quantify the impact of land use/land cover change on the streamflow of Upper Guder River Catchment, Ethiopia. In this study, a semi-distributed Soil Water Assessment Tool (SWAT) model was used to see the static impact of LU/LC change on streamflow for 30 years (1989-2018). Landsat images were classified using a maximum likelihood classifier to generate LU/LC maps for the years 1989, 2002, and 2018. The LU/LC results show that, during the study period, forest/shrubland and grassland decreased by 6.48% and 4.23%, respectively, while Agricultural and Built-up areas increased by 8.04% and 2.69%, respectively. In this study, the SWAT model was calibrated for ten years (1995-2004) and then validated for five years (2005-2009) using daily discharge and LU/LC for the year 2002. During calibration, the R-2 and NSE were 0.84 and 0.74, while during validation 0.83 and 0.72, respectively. The calibrated and validated model parameters then were transferred to run the SWAT model with LU/LC data from 1989, and 2018. The simulated results show that due to modified LU/LC streamflow has increased in the wet season and short rainy season by 10.04% and 5.25%, respectively, while it has decreased by 6.60% in the dry season. The decrease in the streamflow during the dry season is mainly due to changing LU/LC, which has brought an alarming situation at downstream sites. Thus, to cope-up with it an effective integrated participatory approach for catchment management is required in the basin and surrounding neighborhood.