Impact of Climate Change on the Hydrology of the Upper Awash River Basin, Ethiopia

Abstract

This study investigated the impacts of climate change on the hydrology of the Upper Awash Basin, Ethiopia. A soil and water assessment tool (SWAT) model was calibrated and validated against observed streamflow using SWAT CUP. The Mann–Kendall trend test (MK) was used to assess climate trends. Meteorological drought (SPEI) and hydrological drought (SDI) were also investigated. Based on the ensemble mean of five global climate models (GCMs), projected increases in mean annual maximum temperature over the period 2015–2100 (compared with a 1983–2014 baseline) range from 1.16 to 1.73 °C, while increases in minimum temperature range between 0.79 and 2.53 °C. Increases in mean annual precipitation range from 1.8% at Addis Ababa to 45.5% over the Hombole area. High streamflow (Q5) declines at all stations except Ginchi. Low flows (Q90) also decline with Q90 equaling 0 m3s−1 (i.e., 100% reduction) at some gauging stations (Akaki and Hombole) for individual GCMs. The SPEI confirmed a significant drought trend in the past, while the frequency and severity of drought will increase in the future. The basin experienced conditions that varied from modest dry periods to a very severe hydrological drought between 1986 and 2005. The projected SDI ranges from modestly dry to modestly wet conditions. Climate change in the basin would enhance seasonal variations in hydrological conditions. Both precipitation and streamflow will decline in the wet seasons and increase in the dry seasons. These changes are likely to have an impact on agricultural activities and other human demands for water resources throughout the basin and will require the implementation of appropriate mitigation measures.

Trends in climatic and hydrological parameters in the Ajora-Woybo watershed, Omo-Gibe River basin, Ethiopia

“…Hydro-meteorological characteristics have considerably improved the most common forms of natural disasters in Sub-Saharan Africa, particularly in drought and humidity [2,3]. Climate change's impact on river basins is a serious problem for Ethiopia in terms of the sustainability of water supplies and agricultural productivity [4]. The country is also sensitive to climate variability, which increases the frequency and magnitude of disasters at the local and national levels [5].…”

“…As a result, understanding climate variability and change, as well as their relationship to local water resources, is critical for economic growth and the creation of adaptation strategies [7]. Surface water resources are impacted by climate change due to changes in spatial-temporal distribution and magnitude [4], which will therefore affect the water balance in the area and the ecological environment [4,8]. Climate can fluctuate cyclically, monthly, seasonally, annually, and over decades, due to time-based variance (upward or downward trend) [9].…”

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

“…Hydro-meteorological characteristics have considerably improved the most common forms of natural disasters in Sub-Saharan Africa, particularly in drought and humidity (Serdeczny et al, 2017;Teshome & Zhang, 2019). Climate change's impact on river basins is a serious problem for Ethiopia in terms of the sustainability of water supplies and agricultural productivity (Emiru et al, 2021). The country is also sensitive to climate variability, which increases the frequency and magnitude of disasters at the local and national levels (Getahun et al, 2021).…”

“…Surface water resources are impacted by climate change due to changes in spatial-temporal distribution and magnitude (Emiru et al, 2021), which will therefore affect the water balance in the area and the ecological environment (Emiru et al, 2021;Thoma et al, 2020). Climate can uctuate cyclically, monthly, seasonally, annually, and over decades, due to time-based variance (upward or downward trend) (Mahmood et al, 2019).…”

Selection of CMIP6 Climate Models Using Statistical and Data Mining Approaches, Case of Upper Awash Sub-Basin (UASB), Ethiopia

“…Similarly, an ensemble of two GCMs [34] and three selected GCMs [35] from the CMIP5 archive was used to characterize the river flow in the first case and to estimate river nutrient load in the second one. Ensemble mean of five randomly selected GCMs from the CMIP5 archive was used in characterizing the hydro-meteorological situation in the Upper-Awash Basin by [36]. Most recently similar research which was published also suggests a group of four climate models which come from different ensembles of the CMIP6 climate model as an output [37].…”