Unveiling the dynamic future of Ethiopian lakes: A call for conservation

By Dr Wuletawu Abera and Yonas Getaneh

Ethiopian lakes, vital to both local ecosystems and communities, face multiple threats from human activities and natural factors, including climate change. Yet, the long-term dynamics of water surface area in many of these lakes have remained a mystery. New research, carried out under the CGIAR Initiative on NEXUS Gains, sheds light on this crucial issue, presenting the first comprehensive account of the long-term water surface area changes in major Ethiopian lakes. This study provides essential insights for prioritizing lake conservation strategies.

Key findings: Common and distinct trends

The research revealed both common and distinct trends in the long-term water surface area dynamics of Ethiopian lakes. Many lakes commonly exhibited synchronized temporal patterns, with similar recession and expansion cycles. Abrupt change points common to many lakes also existed. However, inter-annual variability intensified after 2000, resulting in a transition from a 14-year cycle to more frequent sub-decadal fluctuations. Despite these commonalities, the lakes also displayed unique behaviors:

• Declining trends: Lakes Abiyata, Langano, Shalla, Chamo, and Hayq have experienced long-term declines in water surface area.
• Expansion trends: Lakes Ziway, Hawassa, and Abaya have shown a trend of expansion.
• Non-homogeneous (mixed) trends: Lakes Tana and Hardibo exhibited no clear long-term trend, highlighting the complex interplay between regional climate phenomena and lake-specific factors.

The implications for conservation

Dr Wuletawu Abera, a Senior Scientist at the Alliance of Bioversity International and CIAT and co-author of the paper, explained, “You can’t manage what you can’t measure. This was our motivation for improving monitoring of lake area changes, as it is a critical component of water storage indicators.”

The research findings suggested that, despite being situated in different geographical locations, the common periodicities in the water area dynamics of the lakes likely reflect the influence of regional climate factors governing expansion and recession cycles. Conversely, divergent trends suggest the impact of local factors specific to each lake, influencing the magnitude of these periodic changes.

Lakes experiencing significant historical water loss and persistent declines face a high risk of water storage degradation. The researchers prioritize conservation efforts for these critical lakes, including Abiyata, Chamo, Shalla, Langano, Hayq, and Hardibo. These lakes have undergone drastic fluctuations in water level, highlighting the need to address unsustainable water resource use and other contributing factors.

The study recommends bathymetric surveys, particularly for Abaya and Hawassa, which show continuous expansion despite potential water degradation. These surveys will help differentiate between siltation impacts and actual water storage changes.

Dr Wuletawu Abera is a Senior Scientist at the Alliance of Bioversity International and CIAT; Yonas Getaneh is Research Fellow at the Alliance of Bioversity International and CIAT.

This work was carried out under the CGIAR Initiative on NEXUS Gains, which is grateful for the support of CGIAR Trust Fund contributors: www.cgiar.org/funders

Header image: Lake Langano, Ethiopia. Photo by Matthew McCartney/IWMI.