Abstract
There is an increasing need globally to establish relationships among flow, ecology, and livelihoods to make informed decisions about environmental flows. This paper aimed to establish the ecological foundation for a holistic environmental flow assessment method in the Gumara River that flows into Lake Tana in Ethiopia and the Blue Nile River. First, the ecological conditions (fish, macro-invertebrate, riparian vegetation, and physicochemical) of the river system were characterized, followed by determining the hydrological condition and finally linking the ecological and hydrological components. The ecological data were collected at 30 sites along the Gumara River on March 2016 and 2020. River hydrology was estimated using the SWAT model and showed that the low flow decreased over time. Both physico-chemical and macroinvertebrate scores showed that water quality was moderate in most locations. The highest fish diversity index was in the lower reach at Wanzaye. Macroinvertebrate diversity was observed to decrease downstream. Both the fish and macroinvertebrate diversity indices were less than the expected maximum, being 3.29 and 4.5, respectively. The normalized difference vegetation index (NDVI) for 30 m and 60 m buffer distances from the river decreased during the dry season (March–May). Hence, flow conditions, water quality, and land-use change substantially influenced the abundance and diversity of fish, vegetation, and macroinvertebrate species. The pressure on the ecology is expected to increase because the construction of the proposed dam is expected to alter the flow regime. Thus, as demand for human water consumption grows, measures are needed, including quantification of environmental flow requirements and regulating river water uses to conserve the ecological status of the Gumara River and Lake Tana sub-basin.
Highlights
Knowledge about environmental flows is essential in conserving vigorous, prolific, and resilient aquatic ecosystems that benefit flora, fauna, and human beings [1]
The Gumara River drains a basin of 1376 km2
In March 2016, when the first sampling was performed, flow in 93% of the reaches was extremely low when compared to the 80% exceedance probability flow (Q80), whereas in 2020, all sites were at moderate/high flow conditions compared to Q80
Summary
Knowledge about environmental flows is essential in conserving vigorous, prolific, and resilient aquatic ecosystems that benefit flora, fauna, and human beings [1]. For determining environmental flows in rivers, there is a need to establish relationships among flow, ecology, and livelihoods. The concept of environmental flows is broad and includes the quantity, quality, and timing of freshwater flows in rivers and levels necessary to sustain aquatic ecosystems supporting human cultures, economies, sustainable livelihoods, and well-being [2]. The knowledge and skill of establishing relationships between ecological processes and hydrological characteristics in rivers and floodplains are important in estimating environmental water requirements of water bodies to maintain ecological health impacting human livelihoods [3]. McClain et al [5] inferred flow–ecology relationships by examining the ecology and annual flow regime of the Mara river in Kenya and Tanzania. Other studies on environmental flow assessment in Africa include the Great
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
