Papers by Wondimu Hailesilassie
International Journal of Global Warming, 2023
This study aims to project potential evapotranspiration (PET) in
Ethiopia’s Lake Ziway Watershed... more This study aims to project potential evapotranspiration (PET) in
Ethiopia’s Lake Ziway Watershed using the ensemble means of five CMIP5
GCMs for the 2050s under the RCP4.5 and RCP8.5 scenarios using the
LARS-WG model. LARS-WG’s calibration and validation results show that the
model can generate future climatic data. PET’s future projection was based on
the LARS-WG model’s forecast of future temperatures. The results revealed
that the increment in PET under the scenario of RCP8.5 is higher than RCP4.5.
Monthly PET is expected to rise from 5.70% to 18.09%, with the smallest in
October, and the largest in May. Its increment is most noticeable in the spring.
PET is projected to rise by up to 15.70% as the annual mean temperature rises
to 2.04°C. Future climate change projections could have a significant impact on
PET, which influences the water cycle and could pose a drought risk in the
research area.
Hydrology Research
Droughts are defined by a prolonged absence of moisture. For making drought assessments, a drough... more Droughts are defined by a prolonged absence of moisture. For making drought assessments, a drought index is a crucial tool. This study aims to compare drought characteristics across the Central Main Ethiopian Rift using three drought indices – the Standardized Precipitation Index (SPI), the Reconnaissance Drought Index (RDI), and the Standardized Precipitation Evapotranspiration Index (SPEI) – from 1980 to 2017 at six climate sites in spring, summer, and a 6-month period (March - August). With 1% and 5% significance levels, Modified Mann-Kendall and Sen's Slope Estimators were used to determine trend and magnitude, respectively. The temporal fluctuations of the three drought indices revealed that droughts are frequent, unpredictable, and random. Furthermore, they behaved similarly and had significant links. At most places, the drought indices found no significant trends. However, in the spring season, Butajira (by the three indices) and Wulbareg (by the SPI) showed significantly...
Environmental and Earth Sciences Research Journal, 2019
The Ethiopian Rift Valley Lakes Basin consists of chain of lakes, many feeder streams and wetland... more The Ethiopian Rift Valley Lakes Basin consists of chain of lakes, many feeder streams and wetlands with unique hydrological and ecological characteristics having regional and global environmental importance. With growing population and consequent various human activities and degradation of watersheds aggravated by climatic change, the water quality of rivers and lakes and feeder rivers are deteriorating fast. The purpose of this study is to assess physicochemical water quality parameters in two of relatively fresh water lakes (Ziway and Hawassa) which are occupying in the Central Main Ethiopian Rift floor. These parameters are pH, dissolved oxygen (DO), total dissolved solids (TDS), turbidity (NTU), Electrical conductivity (EC), and fluoride ion concentration(F-). The mean values of those physico-chemical parameters were compared with maximum permissible limit (MPL) for drinking water as standardized by the Ethiopian Ministry of Health (MoH) and the World Health Organization (WHO). The result revealed that most of the parameters show clear deterioration over the last few decades. The likely factors are rapid urbanization, sedimentation, excessive use of fertilizers and industrialization in towns established along their shorelines. Hence, these trends demand immediate intervention to avert the grave environmental consequences.
Journal of Water and Climate Change
The purpose of this study is to predict future changes in precipitation in the Central Ethiopian ... more The purpose of this study is to predict future changes in precipitation in the Central Ethiopian Main Rift, which is vulnerable to climate change. The Long Ashton Research Station Weather Generator (LARS-WG) model was applied to project precipitation based on five global climate models (GCMs) (EC-EARTH, MIROC-ESM, HadGEM2-ES, INM-CM4, and CCSM4) from Coupled Model Intercomparison Project phase 5 (CMIP5) under two representative concentration pathways (RCP4.5 and RCP8.5) in the periods of 2041–2060 compared to the baseline period of 1976–2005. The model's calibration and validation results showed that it could predict future precipitation. According to the analysis, the mean rainfall is expected to increase in January (up to 14.2%) and December (up to 27.8%) under the RCP 4.5 and RCP 8.5 scenarios, respectively. However, a drop is anticipated in June (up to 8.2%) and May (up to 7%) under the RCP 4.5 and RCP 8.5 scenarios, respectively. In both scenarios, summer precipitation (usu...
MAUSAM
Statistical predictive models were developed to investigate how global rainfall predictors relate... more Statistical predictive models were developed to investigate how global rainfall predictors relate to the March-May (MAM) rainfall over Southern Nations, Nationalities and People's Region (SNNPR) of Ethiopia. Data utilized in this study include station rainfall data, oceanic and atmospheric indices. Because of the spatial variations in the interannual variability and the annual cycle of rainfall, an agglomerative hierarchical cluster analyses were used to delineate a network of 20 stations over study area into three homogeneous rainfall regions in order to derive rainfall indices. Time series generated from the delineated regions were later used in the rainfall/teleconnection indices analyses. The methods employed were correlation analysis and multiple linear regressions. The regression modes were based on the training period from 1987-2007 and the models were validated against observation for the independent verification period of 2008-2012. Results obtained from the analysis revealed that sea surface temperature (SST) variations were the main drivers of seasonal rainfall variability. Although SSTs account for the majority of variance in seasonal rainfall, a moderate improvement of rainfall prediction was achieved with the inclusion of atmospheric indices in prediction models. The techniques clearly indicate that the models were reproducing and describing the pattern of the rainfall for the sites of interest. For the forecast to become useful at an operational level, further development of the model will be necessary to improve skill and to determine the error bounds of the forecast.
Environmental and Earth Sciences Research Journal
This study aims to investigate trends and spatiotemporal variability of precipitation during the ... more This study aims to investigate trends and spatiotemporal variability of precipitation during the period of 1980-2015 in the Main Central Ethiopian Rift Valley Lakes Basin. Mann-Kendall (MK) and Sen’s Slope (SS) estimation were used to detect the trends and magnitudes respectively. The Inverse Distance Weighting method was employed for spatial interpolations. The results revealed that the rainfalls had experienced less concentrated and highly variable in the central rift floor. The trend analysis showed that out of 21 stations, 4 stations (Koshe, Bulbula, Kofole and Shashamane) in annual; six stations (Koshe, Bulbula, Tora, Wulberg, Wondogenet, and Shashamane) in spring; and only one station (Shashamane) in summer showed significantly decreasing trends with -4.5 to -15.59 mm/year range. All stations in spring rainfall revealed no positive trends. Conversely, in both annual and summer rainfall statistically significant increasing trends exhibited for Ejersalelle and Adamitulu with 6.4...
Palaeoecology of Africa, 2015
Uploads
Papers by Wondimu Hailesilassie
Ethiopia’s Lake Ziway Watershed using the ensemble means of five CMIP5
GCMs for the 2050s under the RCP4.5 and RCP8.5 scenarios using the
LARS-WG model. LARS-WG’s calibration and validation results show that the
model can generate future climatic data. PET’s future projection was based on
the LARS-WG model’s forecast of future temperatures. The results revealed
that the increment in PET under the scenario of RCP8.5 is higher than RCP4.5.
Monthly PET is expected to rise from 5.70% to 18.09%, with the smallest in
October, and the largest in May. Its increment is most noticeable in the spring.
PET is projected to rise by up to 15.70% as the annual mean temperature rises
to 2.04°C. Future climate change projections could have a significant impact on
PET, which influences the water cycle and could pose a drought risk in the
research area.
Ethiopia’s Lake Ziway Watershed using the ensemble means of five CMIP5
GCMs for the 2050s under the RCP4.5 and RCP8.5 scenarios using the
LARS-WG model. LARS-WG’s calibration and validation results show that the
model can generate future climatic data. PET’s future projection was based on
the LARS-WG model’s forecast of future temperatures. The results revealed
that the increment in PET under the scenario of RCP8.5 is higher than RCP4.5.
Monthly PET is expected to rise from 5.70% to 18.09%, with the smallest in
October, and the largest in May. Its increment is most noticeable in the spring.
PET is projected to rise by up to 15.70% as the annual mean temperature rises
to 2.04°C. Future climate change projections could have a significant impact on
PET, which influences the water cycle and could pose a drought risk in the
research area.