Hydro-Meteorological Trends in the Upper Omo-Ghibe River Basin, Ethiopia

Abstract

This study aimed to assess trends of hydro-meteorological variables in the Upper Omo-Ghibe river basin, Ethiopia. Data records from eleven rainfall, eight air temperature, and five streamflow stations between 1981 to 2008 were investigated. The trends and change points were evaluated for different periods of time depending on data availability. Mann-Kendall and Pettit tests were used to identify trends and change points at a 5% significance level. The tests were applied to mean annual, monthly and seasonal time scales. Rainfall exhibited statistically decreasing trends at a mean annual time scale, while seasonal rainfall depicted heterogeneous results in both directions. For the majority of the stations, air temperature showed statistically significant increasing trends. The magnitude of change in temperature for mean annual, wet and dry season has increased about 0.48, 0.46, and 0.61 °C per decade for Jimma station. The Pettit test revealed that the late 1980s and 1990s were the change points. There is generally a decreasing trend in streamflow. The decline in annual rainfall and rise in temperature affected the streamflow negatively. Overall, the results indicate that trend sand change point times varied considerably across the stations and catchments. The identified significant trends can help to support planning decisions for water management.

Trend Analysis of Climatic and Hydrological Parameters in Ajora-Woybo Watershed, Omo-Gibe River Basin, Ethiopia

“…As indicated below (figure 5) in mean annual rainfall trend, the rainfall is generally homogenous and decreasing but it was insignificant rate. This result agreed with the work done by Jaweso et al (2019) 2019) also showed that the decline in precipitation in the southern part of the country is large enough to produce trends on the national level. CV was used to classify the degree of variability of rainfall events.…”

“…Asfaw et al (2018), showed intra-and inter-annual variability of rainfall in northern Ethiopia of Woleka sub basin. Jaweso et al (2019), in Upper Omo-Gibe River revealed rainfall exhibited statistically decreasing trends at a mean annual time scale, while seasonal rainfall depicted heterogeneous results in both directions. For the majority of the stations, air temperature showed statistically significant increasing trends.…”

“…In addition, many researchers also applied Pettit test in climatic and hydrological time series (e.g. Asfawu et al, 2018;Belihu et al, 2018;Jaweso et al, 2019;Bodian et al, 2020).…”

Three decades of pastoralist settlement dynamics in the Ethiopian Omo Delta based on remote sensing data

“…Overall, the region is semi-arid with high seasonal rainfall from February to September and frequent prolonged drought (GoE and EEPC 2009;Jaweso et al 2019). By the end of the rainy season, parts of the Delta area are flooded by the Omo River (Hathaway 2009), the principal stream of the hydrologically closed Turkana basin, supplying more than 80 % of the inflow to Lake Turkana (Velpuri and Senay 2012).…”

Assess the impacts of climate change on the patterns of rainfall, temperature, and streamflow in the Abelti Watershed of Southwestern Ethiopia

“…The response of a catchment is primarily in uenced by physical characteristics and climatic elements. For instance, cascade hydropower schemes, modernized and traditional agricultural practice to meet their needs despite the future effect of CC on hydro-climatic variables and trends will exacerbate already existing challenges in the catchment (Jaweso, 2019). Moreover, the changing patterns of rf, stf, and temperature amounts will affect the generation of hydroelectric power, the management, and the operation of the dam.…”