Affected watersheds. Hydropower stations ~700 > 1 MW ~330 > 10 MW, 97% ~ 80 > 100 MW. Blåsjø reservoir Area 84.5 km Volume 3.1 km 3 Energy 7.

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2 Affected watersheds Hydropower stations ~700 > 1 MW ~330 > 10 MW, 97% ~ 80 > 100 MW 3 Blåsjø reservoir Area 84.5 km Volume 3.1 km 3 Energy 7.8 TWh 4

3 Reduce min. flow 75 45m 3 /s No hydropeaking Slow reduction in flow (10cm/s) 5 6

4 Large reservoirs ~70 % of production Average run time ~4200hrs/year Installed effect ~ MW Stable production 7 Little hydropeaking in energydimensioned hydropwer stations 8

5 Effect project Ecological impacts of hydro peaking in rivers : Focus on fish stranding, stress, behaviour, habitat, movement A research collaboration between: 9 The main objective is to assess environmental impacts of hydropeaking and to describe how, when and where hydropeaking may be done with acceptable impacts on the ecosystem. Mitigation strategies will also be addressed. Erosion and sediment transport Temperature and ice Benthos Fish Freshwater mussel Mammals Birds Also including: Model development Catalogue of measures and mitigation Categorizing hydropower plants KMB project

6 Daleelva (5-30 m 3 /s) b a Nidelva (30 - >110 m 3 /s) + experimental stream c Upper Mandalselva (1-25 m 3 /s) Vallaråi (3-25 m 3 /s) 11 12

7 13 Enclosures in Nidelva Stranding experiments ca 90 m 3 /s ca 50 m 3 /s Netbag at low flow ca 30 m 3 /s 14

8 Dewatering in the field Saltveit et al High stranding at low temperatures (in winter) in the day Low stranding during slow drawdown Saltveit et al, Experimental stream Upper figure. Box plot comparison of proportion stranded summer-old (0+) brown trout depending on dewatering speed. The figure shows reduced stranding by reduced dewatering speed, but not total elimination of stranding. Lower figure. Stranding of individual fish (PIT tagged) subject to daily peaking. (Water was put back on to avoid mortality.) The figure shows that 50 fish never stranded. # fish Never stranded Stranded Stranded Stranded Stranded Stranded Stranded once twice 3 times 4 times 5 times 6 times 16

9 Stress response and habituation to daily flow fluctuations (brown trout) Cortisol (ng/ml) 160 *** Control 140 Fluctuation ** Day Flodmark et al Non-stranded brown trout seems to adapt to flow fluctuations within 4 days Flow fluctuations with little increase in dry river banks may be less harmful to fish 17 Behavioural habituation to daily flow fluctuations (brown trout) Flodmark et al, 2006 constant flow fluctuating flow Effects in addition to stranding.. depend on river morphology Steep or gently sloping river banks? 18

10 N/m 2 N/m June surber Zone 1 Zone 2 Zone 3 September surber Zone 1 Zone 2 Zone 3 Hydropeaking and benthic fauna (invertebrates) : before and after one month of hydro peaking before after Chironomidae Oligochaeta Ephemeroptera Plecoptera Trichoptera Hydracarina Tipulidae Others Zone 1: Dry during all peaking Zone 2: Dry at most peaking Zone 3: Always in water 19 20

11 THANK YOU! 21 hydrology/effekt/hydpeak.htm Some references: Vehanen, T., Bjerke, P. L., Heggenes, J., Huusko, A. & Mäki-Petäys, A Effect of fluctuating flow and temperature on cover type selection and behaviour by juvenile brown trout in artificial flumes. Journal of Fish Biology 56: Saltveit, S.J., Halleraker, J.H., Arnekleiv, J.V and Harby, A Field experiments on stranding in juvenile Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) during rapid flow decreases caused by hydropeaking. Regulated Rivers Research and Management, 17: Flodmark, L.E.W., Urke, H.A., Halleraker, J.H., Arnekleiv, J.V., Vøllestad, L.A. & Poléo, A.B.S Cortisol and glucose responses in juvenile brown trout subjected to a fluctuating flow regime in an artificial stream. Journal of Fish Biology 60: Berland, G., T. Nickelsen, Heggenes, J., Økland, F., Thorstad, E. & Halleraker, J Movements of Atlantic salmon parr in relation to peaking flows below a hydro power station. River Research and Applications 20: Flodmark, L.E.W., Forseth, T., L Abbe-Lund, J.H. & Vøllestad, L.A Behaviour and growth of juvenile brown trout exposed to fluctuating flow. Ecology of Freshwater Fish 15: Heggenes, J., Omholt, P.K., Kristiansen, J.R., Økland, F., Dokk, J.G. & Beere, M.C Behavioural movements by wild brown trout in a river: response to habitat contrasts and extreme peaking flows. Fisheries Ecology and Management 14,

12 23 Example: Tonstad (Sira-Kvina) - licenced installed effect 960MW hrs/year, 3 aggregates - annual production 3.6 TWh - reservoir capacity 86% - application for double effect - same water/reservoir Tonstad Hydropeaking Licence Application - lake outlet (15 m depth) 24

13 electro fishing recovery Radio telemetry on salmon to study movements during hydropeaking return to home site anaesthetization, length, weight, etc manual tracking transmitter implant 25 Berland et al

14 Hydropeaking produces specialisation: Some species were only found in permanently wetted areas Some species were only found in the regulated zone Hydropeaking may increase production of water vegetation because of repeated flushing of biomasses There was a relationship between depth and water vegetation No such relationship were found between water velocity and water vegetation 27