A method to assess impacts from hydropeaking

Transcription

1 A method to assess impacts from hydropeaking Atle Harby, Torbjørn Forseth, Ola Ugedal, Tor Haakon Bakken, Julian Sauterleute, Julie Charmasson Centre for Environmental Design of Renewable Energy (CEDREN) Environmental design of regulated rivers Adapting downstream flow Constructing habitats Increasing both salmon and power production Increasing power production 1

2 Hydropower supporting other renewables Hydro New role for hydropower - still need for environmental design! Hydropower in Norway Resource base Water, high head Large natural reservoirs 2

3 Norwegian hydropower Currently: 32 GW 130 TWh/year Hundreds of large reservoirs 20 reservoirs with more than 100 Mm 3 20 GW of extra capacity possible ~15 TWh always availble storage CEDREN Case study 2030 A MW possible 3

4 Folie 6 A2 Author;

5 Hydropeaking Rapid changes in power production by hydropower plants as a consequence of varying electricity generation and demand on the electricity market. Hydropeaking 1. How big? 2. When? 3. How often? 4. What impact? Flow [m3/s] day 4

6 What is hydropeaking? frequency Ratio Focus on downstream impacts Rate of change Duration Frequency Photo: UNI Research 5

7 Photo: UNI Research Photo: UNI Research 6

8 Photo: Michael Puffer Photo: UNI Research 7

9 Photo: UNI Research Photo: UNI Research 8

10 Substrate conditions Armouring? Fine materials washed out? Increased erosion? Depending on flow variations Ice conditions Less surface ice Increased frazil ice production 9

11 Assessment and characterization Effect factors: Effect factors Rate of change Dewatered area Magnitude of flow changes Frequency Distribution Timing Indicator Water level change ratio Change in watercovered area Flow ratio Annual frequency Flow reductions in critical periods Valued into different classes according to given criteria: Small Moderate Large Very large effect Combine effect and score for total effect score Effect factors: SINTEF Energy Research Factor Indicator Criteria Very large Large Medium Small E1: Rate of change E2: Magnitude of flow variation E3: Dewatered area E4: Frequency E5: Timing Variation in water level [cm/h] > < 5 Flow ratio > < 1.5 Change in wetted area from Qmax Qmin [%] Flow reduction in critical periods 4 > < 5 Daily and seasonal irregular In daylight at winter 3 Irregular in one season After dark at winter 2 Diurnal variation several periods Spring and early summer 1 Diurnal variations in one period Summer and autumn 20 10

12 Effect factors: Scoring SINTEF Energy Research A value from 1 to 4 is assigned for each factor E1 (rate of change) and E2 (dewatered area) multiplied, the rest of the factors added Total score [ E1 E2 E3 E4 E5 E6 If the first rate of change is slow after a period without hydropeaking total score reduced with the value of 1 Score between 4 and 32 Combined effect Score Very large Large Moderate Small 4 9 ] Assessment and characterization Vulnerability factors: Vulnerability factors Effective population size Degree of limitations in recruitment Low flow periods as bottlenecks Habitat degradation Reduced water temperature Other factors Percentage of impacted river length compared to total length Indicator Number of females last 5 years Amount and distribution of spawning grounds Change in lowest annual weekly flow in winter and summer combined Change in magnitude and frequency of flood events Reduction in summer water temperature Proportion of river reach with peaking operations compared to total length [%] Valued into different classes according to given criteria: Low Moderate High vulnerability Combine vulnerability for total score 11

13 Vulnerability factors: Factor V1: Effective population size V2: Limitation in recruitment V3: Low flow periods V4: Habitat degradation V5: Reduced water temperature V6: Other factors V7: % of impacted river length vs total Indicator Avg # of females last 5 years Amount and distr. of spawning grounds Change in lowest annual weekly flow Change in magnitude and frequency of flood events Reduction in summer water temperature Acidification, water quality, habitats % of river with peaking vs total SINTEF Energy Research Criteria High Moderate Low < > 250 Low Moderate Much Strong bottleneck High and documented probability Moderate bottleneck Moderate probability No or weak bottleneck Low probability > 3 C 1 3 C < 1 C Strongly reduced stock Moderately red. stock No or small red. stok > 40 % % < 10 % 23 Vulnerability factors scoring A value from 1 to 3 for each factor (by criteria or professional judgement) All values are added Reduced if positive effects of regulation: Annual weekly low flow both summer and winter increase > 50% Annual weekly low flow only in winter increase > 50% Annual weekly low flow only in summer increase > 50% 3 points reduced score 2 points reduced score 1 point reduced score 12

14 Combinations of hydropeaking effects and vulnerability for total impact assessment Hydropeaking effects Very large Large Moderate Small 4-9 High Vulnerability Moderate Low pages book available (in Norwegian) Always someone benefiting.. So long, and thank you for the fish! 13

15 27 Contact: Hydropeaking rapid flow change in downstream river 14