Ecohydrological processes on the intake structure of the Plave hydropower plant, Slovenia
- Authors: Mitja BRILLY, Luka ŠTRAVS, Gregor PETKOVŠEK, Mihael J. TOMAN
- Citation: Acta hydrotechnica, vol. 21, no. 35, pp. 77-85, 2003.
- Abstract: The intake structure of the Plave power plant has a 6800 m long tunnel, with a longitudinal slope of 0.315 ‰ and a diameter of 7.80 m. In the tunnel the subcritical free surface flow is controlled by a sluice gate. In summer, the power production has decreased in the past few years up to 10 percent. An in-house investigation was carried out, however failing to show the underlying causes of the power decrease. At the end of August 2001, velocity measurements were launched on the intake structure. For three days, the current meter with an internal memory measured the velocity. After that velocities were measured with ultrasonic current meter for three months, until the end of November 2001. When dismantling the current meter it was discovered that the instrument was covered with unidentified organisms. The sample of biogenesis from the current meter and three samples for biological analysis scraped off of the wall of the tunnel were investigated in the laboratory of the Biological Department of the University of Ljubljana. It was established that the current meter was completely covered with dipteran larvae (f. Simulidae). The three scraped samples were identified as periphyton community with relatively low diversity. Cyanobacteria and diatoms prevailed. The roughness of the tunnel changed seasonally, which was analyzed from the monitoring data of power plant production for a three-year period. Water levels on the intake and outlet and discharge were correlated for steady state conditions. Changes in roughness were also analyzed with hydraulic modelling.
- Keywords: hydropower plant, velocity measurements of water, roughness, larvae Simulidae
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