Author(s): Maria Joao Costa; Juan Francisco Fuentes-Perez; Isabel Boavida; Jeff A. Tuhtan; Antonio Pinheiro
Linked Author(s): António Pinheiro, Juan Francisco Fuentes Perez
Keywords: No Keywords
Abstract: Hydropeaking designates the artificial flow fluctuations occurring downstream hydropower plants as a response to the rapid changes in hydroelectricity demand. The consequent alterations in the river abiotic processes affect fish communities, with fish responses ranging from sub-organismal adjustments to key life-cycle changes. It is challenging to determine which flow changes trigger a quantifiable response and measure it accordingly, questioning the effectiveness of mitigation solutions. To address these uncertainties, the consequences of a simulated up-ramping hydropeaking event were assessed in relation to two different instream structures (open triangles or solid pyramids) used as potential solutions to mitigate them. The experiments were conducted in an indoor flume, and the movement responses of Iberian barbel (Luciobarbus bocagei) were quantified. To analyze the hydrodynamic signatures of the instream structures from a fish perspective, a lateral line probe (LLP) was used. The results indicate that the movement of I. barbel was affected by the severity of the hydropeaking event, and the presence and type of instream structure. Fish tended to avoid flume areas where the perceived pressure was highly variable and chose to overcome the structures using the low-pressure areas close to the walls. Although under hydropeaking the use of structures as potential refuges was more pronounced, the variables derived from the LLP explained the I. barbel difficulty to use them as refuges. Being able to sense pressure bodyfluid interactions in a distributed way and at a higher sampling rate than commonly used devices, the LLP was decisive for the interpretation of the behaviour of I. barbel according to the flow field and in relation to the instream structures. These results pinpoint the importance of increasing the dimensionality of measurements by considering high sampling rate measurements to advance in the design of measures that effectively mitigate the consequences of hydropeaking.
Year: 2018