Faculty Publications
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Item Trend and variability of hydrometeorological variables of Tikur Wuha watershed in Ethiopia(Springer, 2020) Ketema, A.; Dwarakish, G.S.The study assessed monthly, seasonal, and annual variability and trend of hydrometeorological variables for 1978–2017 of Tikur Wuha watershed in Ethiopia. The Mann-Kendall trend test and Sen’s slope estimator were employed for the trend and size of the trend, respectively. Besides, the coefficient of variation has been computed for variability analysis. The areal average annual rainfall exhibited an insignificant declining trend with a magnitude of 20.8 mm/decade at a watershed scale. The watershed has been suffering from irregular and erratic rainfall during the dry season. Temperature exhibited a statistically significant rising trend with minimum temperature rises faster than that of the maximum temperature. The streamflow of the Tikur Wuha River was found to be increasing at the rate of 21.16 MCM/decade. The increasing trend of streamflow without the corresponding increase of rainfall in the watershed needs further investigation. © 2020, Saudi Society for Geosciences.Item Prioritization of sub-watersheds for conservation measures based on soil loss rate in Tikur Wuha watershed, Ethiopia(Springer Science and Business Media Deutschland GmbH info@springer-sbm.com, 2020) Ketema, A.; Dwarakish, G.S.Soil erosion is unquestionably the trickiest land degradation that adversely agricultural productivity. Since resources are scarce, in developing countries like Ethiopia, implementing soil and water conservation practice at a time on the entire watershed is not feasible. Therefore, recognizing erosion-prone areas (the priority watersheds) based on the magnitude of soil loss rate is indispensable. The purpose of this study is to delineate priority sub-watersheds of the Tikur Wuha watershed in Ethiopia based upon the soil loss rate. A universal soil loss equation under the geographic information system environment was employed to estimate the soil loss rate. The result revealed that the average soil loss rate from the watershed is 14.13. It is resulting in a gross soil loss of 962,083 from the entire watershed. A small portion of the watershed (9.22%) is suffering from severe and very severe soil loss rate (> 25). A total of 14.41% of the watershed have soil loss rates above the maximum soil loss tolerance of the area (> 12). Among the seven sub-watersheds in the watershed, four sub-watersheds (SW_3, SW_1, SW_2, and SW_4) are falling under the top priority zone. Soil and water conservation measures should be executed rapidly in the Tikur Wuha watershed, consistent with the rank of the priority watersheds. © 2020, Saudi Society for Geosciences.Item Hydro-meteorological impact assessment of climate change on Tikur Wuha watershed in Ethiopia(Springer Science and Business Media Deutschland GmbH, 2021) Ketema, A.; Dwarakish, G.S.This study focused on examining the potential effects of climate change on hydro-meteorological variables at the Tikur Wuha watershed (TWW). The weighted average of the validated Coordinated Regional Climate Downscaling Experiment (CORDEX) data of the five Regional Climate Models (RCMs) from multiple General Circulation Models (GCMs) was used to simulate the potential impacts of climate change on streamflow using Soil and Water Assessment Tools (SWAT) model in TWW. The result revealed that the Bega, Kiremt, and annual rainfall increased in both mid and end century for all scenarios. In contrast, the Belg rainfall decreased for all cases except for RCP8.5 at the end century. The rainfall increased more in the end century than mid-century. The increase in rainfall is higher in the Bega compared to Belg and Kiremt season. No significant change in variability of precipitation is observed in the study area. Both the average minimum and maximum temperature increased for all scenarios and time horizons. The annual average streamflow in TWW increased in all cases except a slight reduction in the RCP4.5 scenario in mid-century. Climate change affects the streamflow in the study watershed by increasing the wet season flow and reducing the dry season flow. © 2021, The Author(s), under exclusive licence to Springer Nature Switzerland AG.Item Hydrological responses to land use/land cover change in Tikur Wuha Watershed in Southern Ethiopia(Springer Science and Business Media Deutschland GmbH, 2022) Ketema, A.; Dwarakish, G.S.; Makhdumi, W.Due to its diverse environmental impacts, change in land use/ land cover (LU/LC) has become a global concern. LU/LC change is a critical factor that directly impacts watershed hydrology. The study intends to assess the LU/LC dynamics and their impacts on the streamflow of the Tikur Wuha watershed (TWW) in Ethiopia. LU/LC change was assessed using Landsat images. Each image is classified using a maximum likelihood algorithm of the supervised classification method. The Soil and Water Assessment Tools (SWAT) model were used to examine the impact of LU/LC change on streamflow. The overall accuracy of the LU/LC maps ranged from 77.50 to 87.33%. The findings demonstrated an increase in built-up and cultivated areas and a decrease in shrubland, grassland, swampy areas, and water bodies. The calibration and validation results showed a reasonable performance rate of the SWAT model. The LU/LC changes, which occurred between 1978 and 2017, had increased the average annual streamflow by 8.12%, 9.78%, and 14.77% between 1978 and1988, 1978 and 1998, 1978 and 2017. The Kiremt season flow increased by 9.80% during the first half of the study period (1978–1998) and by 5.41% in the second half (1998–2017). It is risen by 15.74% in 2017 compared to in 1978. The observed changes in the streamflow have resulted from LU/LC changes in the TWW. The study suggests that quick action is required to manage the LU/LC shift and execute land use planning to ensure water availability in the watershed. © 2022, The Author(s), under exclusive licence to Springer Nature Switzerland AG.