Assessment of river response to water abstractions in the Weyib Watershed, Ethiopia

ABSTRACT

This study aimed to examine the impact of water abstractions on runoff and streamflow using the MIKE 11 NAM model. A field survey of water abstraction was conducted to ascertain the actual withdrawal from the Weyib watershed. The baseline period from 1986–2000 was considered based on low human interventions of water abstractions to simulate existing from 2013 to 2022, short-term from 2026 to 2035, and 2036 to 2045 for long-term developments. The annual water withdrawals for those development periods were 10.22, 31.25, and 77.42 Mm³, respectively. The mean annual streamflow in the baseline period was 15.16 m³/s, whereas for existing, short-term, and long-term developments depicted as 10.81, 9.55, and 8.42 m³/s, respectively. The mean annual runoff for the natural baseline was 132.53 mm, and it dropped down by 37.64, 48.70 and 58.54 mm for existing, short-term and long-term developments, respectively. In comparison to the baseline period (7177.93 Mm³), the cumulative volume streamflow of the river was decreased by 2038.01, 2637.12, and 3169.84 Mm³ owing to the development periods, respectively. The streamflow and surface runoff dropped significantly due to increasing water abstraction. The beneficiaries required to follow efficient irrigation water application and extraction practices for sustainable water resources development. To cope up with the challenges of water abstraction, the long-term development plan needs to be revised, and Ethiopia’s proposed irrigation water charges policy need to be implemented.

ARTICLE HIGHLIGHTS

• MIKE 11 NAM model sensitive parameters identified and performance evaluated for future studies in data-scare regions.

• Estimation of water balance for Weyib watershed.

• Impacts of water abstractions on the runoff and streamflow were assessed.

KEYWORDS:

• Existing development
• Irrigation
• Long-term development
• MIKE 11 NAM
• Short-term development
• Streamflow
• Water abstraction

Acknowledgements

The authors are grateful to the Ethiopian, National Meteorology Agency, the Ministry of Agriculture, the Oromia Water and Energy Bureau, and the Ministry of Water and Energy for providing the relevant data free of charge. The researchers also acknowledge the Bale Zone: Agricultural Offices, and Water and Energy Offices for assistance during field survey data collection. The authors also acknowledge MIKE Powered by DHI Group for providing student licenses of MIKE Zero Software to undertake the research. The authors express gratitude to Arba Minch University for financial support.

Disclosure statement

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

Data availability statement

The raw data was received from the National Meteorology Agency (http://www.ethiomet.gov.et/) for each climate station, documents and streamflow from the Ministry of Water and Energy (https://mowe.gov.et/), Ethiopia. The corresponding author will provide the processed datasets during this study depending on a reasonable request.