Spatial and seasonal water level dynamics in dryland grabens along the Rift Valley of northern Ethiopia

ABSTRACT

We investigated water levels in semi-closed grabens of northern Ethiopia. Springs (n = 79), streamflows (n = 48), wetlands (n = 3), endorheic lakes (n = 3), hand-dug wells (n = 48) and boreholes in unconfined aquifers (n = 25) were monitored (2015–2017). Spring discharge fluctuates between wet (2.75 ± 1.5 L/s) and dry seasons (0.87 ± 0.21 L/s) (n = 68, p < .0001). Spring discharge and streamflow were larger at the foot of the escarpment than at the horst (p < .001). The water level of wells varied between horsts and escarpments in the grabens (p < .02). A water level depletion of up to 2.23 m/year occurred in response to withdrawals in the irrigated plains. Importantly, water level fluctuation was faster in streams, springs and hand-dug wells than in boreholes. Striking water level variations in the grabens were linked to rainfall deficit and management scarcity. An integration of surface water and groundwater management responses will bring the water table nearer to the surface; this could mitigate water storage in the fertile and productive grabens.

KEYWORDS:

• graben
• natural spring
• streamflow
• dry season
• escarpment
• Ethiopia

Editor S. Archfield Associate Editor G. Jeelani

Editor S. Archfield Associate Editor G. Jeelani

Acknowledgements

The first author is grateful to the Short Research Stay project (Global Minds) coordinated by Ghent University (VLIR-UOS, Belgium) for its financial support. Appreciation also goes to Mekelle University (Ethiopia) for permitting research leave to Belgium from March to May 2020. The Graben Team Project (VLIR) and its staff are acknowledged for their contribution to this work. Finally, we thank the Aba’ala, Ofla, Raya Azebo, Raya Alamata and Raya Kobo Woreda Agricultural Offices for their support of this study.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Global Minds + VLIR-UOS.