Impact of Climate Change on Streamflow Hydrology in Headwater Catchments of the Upper Blue Nile Basin, Ethiopia

Worqlul, Abeyou W.; Taddele, Y. D.; Ayana, Essayas K.; Jeong, Jaehak; Adem, Anwar A.; Gerik, T. J.

doi:10.3390/w10020120

Cited by 100 publications

(48 citation statements)

References 55 publications

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“…These changes imply negative consequences for agriculture and water resource availability. The findings are inconsistent with previous studies where warming and wetting were reported for the upper Blue Nile basin Worqlul et al 2018). The discrepancies, particularly in rainfall simulation results, are due to the differences in the spatial and timescales of the studies, types of the model used and climate scenario considered.…”

Section: Spatiotemporal Climate Trendscontrasting

confidence: 99%

Spatiotemporal climate and vegetation greenness changes and their nexus for Dhidhessa River Basin, Ethiopia

et al. 2019

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Background: Understanding spatiotemporal climate and vegetation changes and their nexus is key for designing climate change adaptation strategies at a local scale. However, such a study is lacking in many basins of Ethiopia. The objectives of this study were (i) to analyze temperature, rainfall and vegetation greenness trends and (ii) determine the spatial relationship of climate variables and vegetation greenness, characterized using Normalized Difference in Vegetation Index (NDVI), for the Dhidhessa River Basin (DRB). Quality checked high spatial resolution satellite datasets were used for the study. Mann-Kendall test and Sen's slope method were used for the trend analysis. The spatial relationship between climate change and NDVI was analyzed using geographically weighted regression (GWR) technique. Results: According to the study, past and future climate trend analysis generally showed wetting and warming for the DRB where the degree of trends varies for the different time and spatial scales. A seasonal shift in rainfall was also observed for the basin. These findings informed that there will be a negative impact on rain-fed agriculture and water availability in the basin. Besides, NDVI trends analysis generally showed greening for most climatic zones for the annual and main rainy season timescales. However, no NDVI trends were observed in all timescales for cool subhumid, tepid humid and warm humid climatic zones. The increasing NDVI trends could be attributed to agroforestry practices but do not necessarily indicate improved forest coverage for the basin. The change in NDVI was positively correlated to rainfall (r 2 = 0.62) and negatively correlated to the minimum (r 2 = 0.58) and maximum (r 2 = 0.45) temperature. The study revealed a strong interaction between the climate variables and vegetation greenness for the basin that further influences the biophysical processes of the land surface like the hydrologic responses of a basin. Conclusion: The study concluded that the trend in climate and vegetation greenness varies spatiotemporally for the DRB. Besides, the climate change and its strong relationship with vegetation greenness observed in this study will further affect the biophysical and environmental processes in the study area; mostly negatively on agricultural and water resource sectors. Thus, this study provides helpful information to device climate change adaptation strategies at a local scale.

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Section: Spatiotemporal Climate Trendscontrasting

confidence: 99%

Spatiotemporal climate and vegetation greenness changes and their nexus for Dhidhessa River Basin, Ethiopia

et al. 2019

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“…The simulated mean annual rainfall under RCP4.5 and RCP8.5 is larger than the baseline period. The result showed that the RCP4.5 rainfall simulation increased rates were greater in spring than other seasons, which is in agreement with Worqlul et al (2018) findings in the Upper Blue Nile basin.…”

Section: Discussionsupporting

confidence: 89%

“…The increase in streamflow due to rainfall increment was also discussed by Pandey et al (2017); they revealed that a 28% increase in annual rainfall may result in streamflow increased by approximately 49% from their study in the Armur watershed in Godavari river basin, India. The decrease in streamflow during the rainy season associated with the rainfall reduction corresponds with the findings of Worqlul et al (2018) in the Upper Blue Nile Basin, Ethiopia.…”

Section: Discussionsupporting

confidence: 82%

Modeling the Impact of Climate Change on Hydrological Responses in the Lake Tana Basin, Ethiopia

Teklay

Dile

Asfaw

et al. 2020

Preprint

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BackgroundHydrologic systems have been changing due to the impact of climate change and climate variability. The impacts of climate change are set to increase in the future due to the rise of global warming. Quantifying the impact of climate change on the spatial and temporal hydrological processes is important for integrated water resource management. The Lake Tana basin, which is the source of the Upper Blue Nile, is vulnerable to climate change and variability. This study was carried out in the four major tributary watersheds of the Lake Tana basin: Gilgel Abay, Gumara, Ribb, and Megech. The climate model and hydrological model was used to (i) to evaluate the performance of the Soil and Water Assessment Tool for study watershed, (ii) to assess the future rainfall and temperature variability and change in the study watershed, and (iii) to examine the impact of climate change on future watershed hydrology. The study used dynamically downscaled climate data for the baseline (2010–2015) and future period (2046–2051) under two Representative Concentration Pathways (RCP4.5 and RCP8.5). The climate scenarios were simulated using the Weather Research and Forecasting (WRF) model, with a 4-km horizontal resolution. A linear scaling method was applied to minimize model biases. The SWAT model was used to estimate the baseline and future hydrology using the bias-corrected climate data. ResultsThe performance of the SWAT model was ‘good’ to ‘very good’ for both the calibration and validation periods, with the Nash–Sutcliffe efficiency values between 0.71 to 0.92. The projected changes in rainfall vary with seasons and watershed under both scenarios. On average, annual rainfall may increase by 9.8% and 21.2% under RCP4.5 and RCP8.5 scenarios, respectively. Minimum temperature may rise by 1.68 °C and 2.26 °C while maximum temperature may increase by 1.65 °C and 2.75 °C under RCP4.5 and RCP8.5 scenarios, respectively. The changes in climate may cause an increase in surface runoff by 20.9% and 46.5% under RCP4.5 and RCP8.5 scenarios, respectively, while the evapotranspiration increase by 4.7% and 12.2% under RCP4.5 and RCP8.5, respectively. ConclusionThe findings provide valuable insights to implement appropriate water management strategies to mitigate and adapt to the negative impacts of climate change and variability on the Lake Tana basin, and other regions which have similar agro-ecology.

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“…Beles River originates from the escarpment of south-western of Lake Tana, flows towards southwest, and joins the Blue Nile River just before it crosses the Ethio-Sudanese border ( Figure 1). The nature of rainfall in the study area is unimodal and~70-80% of the total rainfall is received between June and September [44], with annual yearly rainfall totals of about 1490 mm. The highly varied topography of the Beles Basin (577 m to 2735 m), together with the highly variable rainfall and temperature, results in contrasting climatic zones within the basin [45].…”

Section: Study Areamentioning

confidence: 99%

Evaluation and Application of Multi-Source Satellite Rainfall Product CHIRPS to Assess Spatio-Temporal Rainfall Variability on Data-Sparse Western Margins of Ethiopian Highlands

et al. 2019

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The spatio-temporal characteristic of rainfall in the Beles Basin of Ethiopia is poorly understood, mainly due to lack of data. With recent advances in remote sensing, satellite derived rainfall products have become alternative sources of rainfall data for such poorly gauged areas. The objectives of this study were: (i) to evaluate a multi-source rainfall product (Climate Hazards Group Infrared Precipitation with Stations: CHIRPS) for the Beles Basin using gauge measurements and (ii) to assess the spatial and temporal variability of rainfall across the basin using validated CHIRPS data for the period 1981–2017. Categorical and continuous validation statistics were used to evaluate the performance, and time-space variability of rainfall was analyzed using GIS operations and statistical methods. Results showed a slight overestimation of rainfall occurrence by CHIRPS for the lowland region and underestimation for the highland region. CHIRPS underestimated the proportion of light daily rainfall events and overestimated the proportion of high intensity daily rainfall events. CHIRPS rainfall amount estimates were better in highland regions than in lowland regions, and became more accurate as the duration of the integration time increases from days to months. The annual spatio-temporal analysis result using CHIRPS revealed: a mean annual rainfall of the basin is 1490 mm (1050–2090 mm), a 50 mm increase of mean annual rainfall per 100 m elevation rise, periodical and persistent drought occurrence every 8 to 10 years, a significant increasing trend of rainfall (~5 mm year−1), high rainfall variability observed at the lowland and drier parts of the basin and high coefficient of variation of monthly rainfall in March and April (revealing occurrence of bimodal rainfall characteristics). This study shows that the performance of CHIRPS product can vary spatially within a small basin level, and CHIRPS can help for better decision making in poorly gauged areas by giving an option to understand the space-time variability of rainfall characteristics.

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Impact of Climate Change on Streamflow Hydrology in Headwater Catchments of the Upper Blue Nile Basin, Ethiopia

Cited by 100 publications

References 55 publications

Spatiotemporal climate and vegetation greenness changes and their nexus for Dhidhessa River Basin, Ethiopia

Spatiotemporal climate and vegetation greenness changes and their nexus for Dhidhessa River Basin, Ethiopia

Modeling the Impact of Climate Change on Hydrological Responses in the Lake Tana Basin, Ethiopia

Evaluation and Application of Multi-Source Satellite Rainfall Product CHIRPS to Assess Spatio-Temporal Rainfall Variability on Data-Sparse Western Margins of Ethiopian Highlands

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