Climate and human activities impact on runoff and sediment yield in the central rift valley of Ethiopia

Abstract

This study analyzed the effects of climate variability and human activities on runoff and sediment yield of a watershed in the Central Rift Valley of Ethiopia since the 1980s. In the study, innovative trend analysis, the Pettitt test, and sequential regime shift detector methods were used to analyze trends and abrupt changes during the period 1981–2020. The Soil and Water Assessment Tool model was then integrated to disaggregate the contributions of climate variability, land-use change, and direct human activities on runoff and sediment yield at the watershed scale. The result indicates that the runoff and sediment yield decreased significantly with a sudden change in 2001. The study found that direct human activities played a dominant role, accounting for 57.9%, and 53.4% of annual runoff and sediment yield reduction, respectively. On the contrary, changes in climate and land use have led to a slight increase in runoff and sediment yield after 2001. The greater impacts of human activities can be attributed to the growth rate of water abstraction, and riverbed sand excavation during the past four decades. The findings of the result could be useful in supporting decision-makers in achieving watershed sustainability.

Keywords:

• Central rift valley
• climate change
• human activity
• ITA method
• SWAT model

REVIEWING EDITOR:

• Sanjay Kumar Shukla, Edith Cowan University, Australia

SUBJECTS:

• Agriculture & Environmental Sciences
• Earth Sciences
• Civil, Environmental and Geotechnical Engineering

Acknowledgments

The authors thank the Ethiopian Ministry of Water and Energy, USGS, the editors, and the anonymous reviewers for their invaluable comments and constructive suggestions that improve the quality of this manuscript.

Ethical approval

NA.

Consent to participate

No human or animal participants were involved in this research.

Consent to publish

All authors have read and approved the final manuscript for publication.

Author contributions

The authorship of this work is attributed to the collaborative efforts of the research team. The conceptualization and design of the study were a joint undertaking. The analysis and interpretation of the data were conducted collectively, with each author contributing expertise in their respective areas. The composition of the conclusions and the articulation of their implications were achieved through collaborative deliberation. All authors have reviewed and approved the final version of this manuscript, ensuring its accuracy and scholarly integrity.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

All relevant data are included in the paper.

Additional information

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Notes on contributors

Kokeb Zena

Kokeb Zena is an accomplished instructor actively pursuing his doctoral studies at the Jimma Institute of Technology, where he is under the esteemed guidance of Prof. Dr. Eng. Tamene Adugna and Dr. Eng. Fekadu Fufa. His academic journey has been marked by substantial contributions to the realms of hydraulic and water resources engineering, both in terms of teaching and scholarly endeavors. With an unwavering commitment to the pedagogical landscape, Kokeb Zena has significantly enriched the teaching and learning processes within his field of expertise. Kokeb's multifaceted engagement underscores his profound commitment to the scholarly community and the ongoing evolution of hydraulic and water resources engineering.

Tamene Adugna

Prof. Dr. Eng. Tamene Adugan is a highly regarded scholar and esteemed professor of Hydraulic and Water Resources Engineering at Jimma Institute of Technology, Jimma University in Oromia, Ethiopia. Prof. Tamene’s extensive knowledge and expertise in the fields of environment, water resources, and climate change are reflected in his numerous publications in internationally renowned peer-reviewed journals. His exceptional contributions and research have earned him global recognition as a leading authority in these areas.

Fekadu Fufa

Dr. Eng. Fekadu Fufa is a distinguished scholar and associate professor of Water and Environmental Engineering at Jimma Institute of Technology, Jimma University in Oromia, Ethiopia. With his extensive expertise in the field, Dr. Eng. Fekadu has made a significant impact through his research and contributions to a range of areas including water resources, environmental engineering, and climate change. His exceptional work has been recognized by the international community, with numerous publications featured in prestigious peer-reviewed journals.