Faculty Publications
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Item Hydrological effects of land use /land cover changes on stream flow at Gilgel Abay River Basin, Upper Blue Nile, Ethiopia(CAFET INNOVA Technical Society 1-2-18/103, Mohini Mansion, Gagan Mahal Road, Domalguda, Hyderabad 500029, 2016) Mulu, A.; Dwarakish, G.S.Water is the most important resource for the survival of living things and it is the most essential resource associated with land use/ land cover (LU/LC) changes. Therefore, it is very important to make evaluations of the expected impact on the hydrology and water resources due to expected changes. The main objective of this study is to assess the hydrological effect of land use/ land cover changes on stream flow at GilgelAbay river basin using Precipitation Runoff Modeling System (PRMS) model. System inputs are daily time-series values of precipitation, minimum and maximum air temperature, and parameter files which are generated from GIS Weasel. To identify effect of changes in LU/LC, vegetation type and vegetation density on stream flow, LU/LC, vegetation type and vegetation density data from 1990-2000 and 2001-2010 years were considered. This different period LU/LC, vegetation type and vegetation density with soil data and DEM were given to GIS Weasel to generate different parameters for PRMS model. These generated parameters together with time series data (daily minimum and maximum air temperature, daily precipitation and daily stream flow) feed to PRMS model to simulate stream flow for the years 1993-2000 and 2001-2008. From the time series data, climate changes (daily maximum and minimum temperature and daily precipitations) were kept the same as baseline period (1993-2000). The stream flow of 2001-2008 compared with baseline period (1993-2000) and the effect of LU/LC, vegetation type and vegetation density was identified using calibrated and simulated PRMS model. Hence, as LU/LC, vegetation type and vegetation density changed from 1993-2000 period to 2001-2010 period, stream flow increased from 7.8% (128.4 Mm3) to 25.3% (432 Mm3) and ET decreased from 4.2% (75 Mm3) to 20% (524 Mm3) from baseline period. For the whole simulation periods (2001-2008) stream flow increased by 10.9% (784 Mm3), but ET decreased 6.7% (43 Mm3) related to baseline periods. © 2016 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.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 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.Item INFLUENCE OF LAND USE LAND COVER CHANGE ON RUNOFF CHARACTERISTICS OF NETRAVATHI RIVER CATCHMENT, KARNATAKA, INDIA(Zibeline International Publishing Sdn. Bhd., 2024) Dwarakish, G.S.; Pai, J.B.; Jubina, C.K.The effect of LU/LC on the streamflow characteristics of the Netravathi river basin, Karnataka, India, is studied using Soil and Water Assessment Tool (SWAT) model. Landsat images, soil map from FAO, ASTER DEM (30m grid) and streamflow data, forms the database for the present work. The most significant changes from 1981 to 2015, in the LU/LC includes agricultural land (31.86%), built-up area (67.9%), forest cover (-20.01%), coconut plantation (55.12%), other vegetation (-18.55%) and others (-11.82%). The verification of performance of model was carried out by the coefficient of determination values (R2 > 0.8) and N S E (NSE > 0.78) were obtained and hence proved that SWAT model performance in estimating streamflow.. The average streamflow is increased by 13.74% from 1981 to 2015, which is mainly due to dynamic changes in LU/LC. Hence, it can be concluded that changes in LU/LC have a direct impact on streamflow in the study area. © 2024, Zibeline International Publishing Sdn. Bhd.. All rights reserved.