Author(s): Estrella Carrero Carralero; Damian Vericat Querol; Ramon J. Batalla; Antoni Palau Ibars; Chris Gibbins
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Keywords: Hydropeaking flow regime Release pipeline HEP Thermal zones Benthic invertebrate communities
Abstract: Hydropower plants impact the natural flow dynamics of rivers, affecting fluvial processes, physicochemical characteristics, and riverine biota. We characterized the thermal environment and invertebrate communities in a mountain river regulated by a hydroelectric power (HEP) facility that produces a hydropeaking flow regime downstream. Unusually, the facility's turbines are located 5.5 km away from the dam, so hydropeaking water enters the river well downstream - a design common in Spain since the 1990s. Water is released via a pipeline discharging laterally from the left bank, creating a plume with a different temperature than the receiving channel and resulting in three distinct thermal zones with temperature differences of up to 10 °C. Benthic invertebrates differed in density, diversity, and community structure between the upstream zone and the downstream left-bank zone receiving HEP water. The thermally intermediate right-bank zone did not differ from the upstream zone but was consistently different from the left bank. Differences in invertebrate abundance and trait composition corresponded to variations in algae and detrital organic matter on the bed, as well as water temperature differences. Our study shows that very localized differences in invertebrate communities can occur in response to thermal variations, reflecting both direct effects of water temperature and indirect effects related to organic matter accumulation and the feeding habits of the animals.
Year: 2025