Four charts showing optimal habitats in the floodplain for different stream insects.
The discharge (Q) at each point in the floodplain that produces the optimum suitable habitat for stream insects at that point. The figure illustrates how zones of suitable habitat move downstream more rapidly than bottom-dwelling larval insects can migrate downstream. Credit: Gabbud et al. [2019], Figure 5
Source: Water Resources Research

Hydropower plants extract water from streams at an intake structure. The decrease in flow at this structure causes sediment deposition that, if not removed, can limit the ability to extract water. Consequently, sediment is periodically flushed from the intakes using a rapid, abrupt pulse of water, a process known as intake flushing.

Gabbud et al. [2019] use field observations and numerical modeling to address the ecological impacts of intake flushing in Alpine hydropower systems. Although these types of hydropower installations and associated flushing are widespread in the Alps, the ecological impacts have received almost no attention and legislation designed to protect stream ecosystems has ignored intake flushing.

This paper combines hydrological, geomorphic, and ecological investigation to demonstrate the impacts of flushing on benthic macroinvertebrates. A primary effect is that the portion of the stream within which habitat is suitable for aquatic insects migrates downstream more rapidly than the insects can move. This finding suggests that current management emphases on simply maintaining minimum flows within the stream below a hydropower plant is not sufficient to sustain river ecosystems.

Citation: Gabbud, C., Bakker, M., Clémençon, M., & Lane, S. N. [2019]. Hydropower flushing events cause severe loss of macrozoobenthos in Alpine streams. Water Resources Research, 55.

—Ellen Wohl, Editor, Water Resources Research

Text © 2019. The authors. CC BY-NC-ND 3.0
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