Draft concept note on pilot case study inter-comparison of water bodies impacted by water storage

Transcription

1 Draft concept note on pilot case study inter-comparison of water bodies impacted by water storage Draft Please check: Annex I: Cover note to participants of the Workshop on GEP inter-comparison case studies on water storage, February 2017, Vienna Annex II: Brief description of four generic typical cases related to hydropower use

2 Table of Contents 1 Introduction Generic typical cases related to hydropower use (rivers/ponded rivers and lakes/reservoirs) Questionnaire to be filled in for each generic case study (after the workshop) Overview of case study inter-comparison process Next steps (February July 2017) ANNEX I: Cover Note for Workshop Participants ANNEX II: Brief descriptions of four generic typical case studies related to hydropower use Case Study 1 (CS1). Low head run-of-river HPP with water abstraction and ponding effect Case Study 2 (CS2). Low head run-of-river in-stream HPP with ponding (impoundment) Case Study 3 (CS3). Large scale HPP with storage in lake reservoir with discharge into river Case Study 4 (CS4). High head HPP with storage in (artificial) lake reservoir in high altitude area 26 2

3 1 Introduction The recommendation for the next step towards intercalibration is the intercomparison of the methods for definition of GEP for heavily modified water bodies (HMWBs), via case studies representing typical hydromorphological (hymo) alterations. This exercise is led by the GEP core group under the CIS WG ECOSTAT and it was one of the key conclusions and recommendations of this core group in the recent ECOSTAT report on common understanding of using mitigation measures for reaching Good Ecological Potential for heavily modified water bodies Impacted by water storage : 1 "It is recommended that the Common Implementation Strategy agrees to an exercise to compare the outcomes produced by countries national methods by applying them to a comparable set of heavily modified water bodies. Consideration should then be given to incorporating the results of both exercises into a good practice guide. There is probably a need to supplement CIS Guidance no. 4 on HMWB with an appendix based on this exercise, to ensure common environmental requirements in HMWBs". Furthermore, the ECOSTAT report on mitigation measures for GEP (cited above) highlighted critical issues which need further clarification as they seem not to be sufficiently covered in existing WFD guidance. The report recommended information exchange to improve understanding of the following as part of a follow up exercise: how countries select relevant mitigation measures which are needed to improve the ecological situation significantly; how countries determine the level of significance of adverse effects of measures on use (e.g. hydropower, water supply) and, hence, at which further mitigation is ruled out; how countries distinguish between ruling out measures required for GEP and setting less stringent objectives (e.g. moderate or worse potential); the typical scales of ecological impact (including in spatial terms) resulting from hydromorphological alterations beyond which countries require measures to be considered to achieve GEP; how countries assess the (minimum) conditions that would be expected for GEP using each country s method, including ruling out of relevant measures; the use of disproportionate cost for measures in connection to the ruling out of mitigation measures in the GEP setting versus the decision-making process for exemptions in HMWBs; the need to develop and agree on a generalised framework for deciding on the mitigation required for GEP (flow-chart describing the relevant considerations to be used in this decisionmaking process). Although the intercomparison exercise focuses on the definition of GEP for HMWBs, one of the aims is also knowledge sharing and better understanding of the conditions and reasons which may lead to designation of HMWB, e.g. in the case of river stretches affected by water abstraction without any significant ponding or storage. 1 Available at: 3

4 The objective of the workshop in Vienna (13-14 February 2017) is to serve as a preparatory workshop for the GEP case study inter-comparison exercise. This first workshop is considered as the start of a process for comparing approaches between countries and sharing information and experience on the definition of GEP for the most relevant water uses based on mitigation measures. The objectives of the Vienna workshop are explained in more detail in Annex I of this note. How to ensure comparability/inter-comparison between physically altered water bodies across water use, river types and national measure methodologies? To test out how comparable the environmental standards in HMWBs/AWB are, the criteria for the identification of HMWBs and the methods for implementation of mitigation/restoration measures are essential. To ensure a relevant comparison and bring further clarity on crucial issues, the following aspects are relevant for ensuring inter-comparability of the practice of managing regulated water bodies (impacted by water storage): 1. Type of water body a) size, river/lake/reservoirs, b) reference conditions e.g. habitat, gradient of river c) biogeographical conditions such as inside/outside the natural fish zone with migrating fish (long/medium/short distance migrators) 2. Type and extent of alterations a) Type of water use (water storage, flood, drainage etc) and drivers like hydropower, water supply, irrigation etc. b) Single or multiple stressors (various hymo alterations and/or pollution/others) 3. Type and significance of ecological impact from water use 4. Identification of relevance of measures (mitigation/restoration measures) a) All relevant measure applied or b) Design and combinations of measures (including the level of ambition) 5. Selection or ruling out of measures for defining good ecological potential a) Documentation of effect vs. significant adverse effect on use from measures, b) Effect on wider environment 6. Experience sharing and clarification of costs, benefits and disproportionality 7. Common understanding and definition of key terms (if not already given in the GEP storage report) 8. Ways to monitor the achievement of the objective of GEP and the effectiveness of implemented mitigation measures (e.g. use of existing or adapted assessment methods for relevant BQE) 2 Generic typical cases related to hydropower use (rivers/ponded rivers and lakes/reservoirs) The GEP core group started to develop and test out a questionnaire on a limited number of river schemes impacted by water storage (in specific, by hydropower in the first stage). Other types of 4

5 pressures are excluded from these case studies (as long as they are not connected to the water storage use). The water bodies will be illustrated in a water storage scheme (map), followed by basic information about physical characteristics and ecological monitoring data in a comparable way. The description of these generic typical cases addresses the pre-mitigated state, i.e. it is assumed that no mitigation measures have been applied yet. The GEP core group will also propose scenarios related to effects on use/environment and costs and benefits of relevant mitigation measures. For the purpose of the Workshop on GEP inter-comparison case studies on water storage in Vienna (13-14 February 2017), several generic typical cases have been prepared as first starting point for discussion. These typical cases (parts of catchments) are: Case Study 1 (CS1). Low head run-of-river HPP with water abstraction and ponding effect Case Study 2 (CS2). Low head run-of-river in-stream HPP with ponding (impoundment) Case Study 3 (CS3). Large scale HPP with storage in lake reservoir with discharge into river Case Study 4 (CS4). High head HPP with storage in (artificial) lake reservoir in high altitude mountains You find brief descriptions on these four case studies in Annex II of this note. A possible additional case (CS+) may deal with low or high head run-of-river HPP with water abstraction without any ponding effect or storage. An overview of the key hydropower schemes and hymo alterations addressed by the cases is given in the following tables. Table 1 matches the case studies with the typical situations ( types ) of lakes and river stretches affected by significant hymo alterations. Table 2 indicates the combination of alterations which are covered in the case studies. The workshop in Vienna aims to get people familiarised with the first generic case studies developed by the GEP core group. It should be noted that the first case studies are not fixed : participants may propose modifications, additions, simplifications if needs be, and are also invited to propose additional cases. Ideas for case studies related to water storage will be collected at the workshop and developed later in the process. Ultimately, the compilation of case studies should provide examples on the 10 main mitigation measure groups (see ECOSTAT report on mitigation measures for water bodies impacted by water storage) and cover most of the relevant river types. 5

6 Table 1 Relation between case studies and typical situations ( types ) of lakes and river stretches with significant hymo alterations (mainly related to large scale hydropower plants [HPP]), to be prepared by the GEP core group prior to the first workshop in Vienna. Main typical L. Lake R. River situations ( types ) of lakes and river stretches with significant hymo alterations L1. Artificial L2. Natural R1. Stretch with flow depletion (reduced quantity / dynamics ) R2. Stretch with rapidly changing flow R3. Stretch with ponding effect CS1. Low head run- x x of-river HPP with water abstraction and ponding effect CS2. Low head run- x of-river in-stream HPP with ponding (impoundment) CS3. Large scale HPP with storage in lake reservoir with discharge into river CS4. High head HPP with storage in (artificial) lake reservoir in high altitude mountains x x x x x x CS+. Low or high head run-of-river HPP with water abstraction without any ponding effect or storage x x 6

7 Table 2 Combination of alterations (and relevant mitigation measures to consider) which are covered in the case studies. Key alterations Upstream Downstream Low Fish Variable Rapidly Sediment Ponded Lake level Physico- continuity continuity flow flow flow changing alteration rivers alteration chemical flow alteration CS1. Low head run-ofriver HPP with water abstraction and ponding effect X (X) X (X) X X X (X) CS2. Low head run-ofriver in-stream HPP with ponding (impoundment) X X X X CS3. Large scale HPP with storage in lake reservoir with discharge into river X X X X (X) (X) X CS4. High head HPP with storage in (artificial) lake reservoir in high altitude mountains X (X) X X X (X) X (X) CS+. Low or high head run-of-river HPP with water abstraction without any ponding effect or storage X X X X X (X) 7

8 3 Questionnaire to be filled in for each generic case study (after the workshop) A questionnaire is being prepared by the GEP core group to collect information on how different national methods are applied for selecting or ruling out mitigation measures for the case studies developed in relation to hydropower use. This draft questionnaire will be discussed at the workshop and further developed and optimized after the workshop taking into account the workshop discussions. 4 Overview of case study inter-comparison process As mentioned above, the Vienna workshop on GEP inter-comparison case studies on water storage will be the first workshop to initiate country exchange and discussions on the advanced GEP intercomparison exercise based on these case studies. The process of preparing the generic typical case studies of water storage schemes (related to hydropower use and later to other water uses) and filling in the relevant questionnaires is illustrated in the flow-chart on the next page. 8

9 GEP CORE GROUP ALL WFD IMPLEMENTING COUNTRIES Generic typical cases (1 st round of cases on hydropower use) Brief descriptions and illustrations (premitigated state) Feb 2017 Draft Questionnaire for selecting and out ruling mitigation measures 1 st Workshop (Vienna) Discuss cases and draft questionnaires Revise Draft Questionnaire for selecting and out ruling mitigation measures Generic typical cases (1 st round of cases on hydropower use) Full case descriptions Feb - March 2017 Develop further generic typical cases Brief descriptions and illustrations (premitigated state) to be presented at ECOSTAT (April) meeting 4-6 April 2017 ECOSTAT (Berlin) Discuss set of generic typical cases and revised questionnaire April 2017 May July 2017 After July 2017 Compilation of case studies for European report Develop generic cases Full case descriptions further typical Apply national methods to available generic typical cases MS select cases relevant to their regional context Fill in questionnaire for selecting and out ruling mitigation measure 9

10 5 Next steps (February July 2017) - The outcomes of the workshop in Vienna will be used to improve the descriptions of the 1st set of generic typical case studies on water storage and revise the draft questionnaire on the selection of mitigation measures. The aim is to agree on the case studies and questionnaire at the ECOSTAT meeting on 4-6 April 2017, in Berlin. - Furthermore, additional case studies may be proposed in the Vienna workshop. For these additional case studies, brief descriptions and illustrations should be prepared for further discussion at the ECOSTAT meeting in April. - After the ECOSTAT meeting in April 2017, all case studies which have been agreed to be used in the inter-comparison exercise should be described in sufficient detail. - The final case study descriptions and the final questionnaire on the selection and ruling out of mitigation measures will be circulated to all WFD implementing countries in May Countries will be requested to fill-in the questionnaire for mitigation measures applicable to each case study by early July According to the WFD, this is an exercise requiring the participation of all countries to ensure comparability in the definition of GEP. 10

11 6 ANNEX I: Cover Note for Workshop Participants Dear participant, In the context of the CIS WG ECOSTAT activities on Good Ecological Potential, the workshop on February 2017 in Vienna aims to serve as a preparatory workshop for the GEP case study intercomparison exercise, focusing on water bodies impacted by water storage. The objectives of the workshop are to: Present and discuss the concept of the case study inter-comparison regarding water bodies impacted by water storage. Present and discuss the first generic typical case studies of the inter-comparison relevant to hydropower use. Share knowledge on the application of specific types of mitigation measures relevant to hydropower use. Discuss how different national methods can be applied to select or rule out mitigation measures for these case studies (including discussion of a draft questionnaire being developed to collect information for this purpose). Discuss and agree on the next steps of the case study inter-comparison exercise. Day 1 of the workshop starts in plenary to set the stage of the inter-comparison exercise, including presentations on current CIS activities on hydromorphology, a reminder on the key outcomes of the ECOSTAT report on mitigation measures for GEP of water bodies impacted by storage, and an introduction to the concept of the inter-comparison exercise. The 1st set of case studies prepared by the GEP core group will be presented and illustrated. In the afternoon of Day 1 and the morning of Day 2, two parallel break-out sessions are organised to foster more concrete discussions on how countries currently select and rule out mitigation measures for stretches impacted by water storage, as illustrated in the case studies which have been prepared for the discussion. Please refer to the following material in order to prepare for the workshop: - Draft concept note on the pilot case study inter-comparison of water bodies impacted by water storage. - Draft descriptions of the first generic typical case studies on hydropower use (see Annex II) - Draft questionnaire on selecting and ruling out mitigation measures (see separate Excel spreadsheet). Organisation of break-out sessions at the workshop in Vienna At the registration desk, you will be asked to indicate preference for one of the following break-out groups, each of which will deal with a different set of the case studies: 11

12 Group A Case study 1. Low head run-of-river hydro-peaking with water abstraction and ponding effect Case study 4. High head hydro-peaking with storage in (artificial) lake reservoir in high altitude mountains Group B Case study 2. Low head run-of-river in-stream HPP with ponding (impoundment) Case study 3. Large scale HPP with storage in lake reservoir with discharge into river In the break-out groups, the case studies presented in plenary will be used to foster discussions on how different countries select and rule out mitigation measures in stretches impacted by water storage. To facilitate these discussions, the organisers would like to invite delegates to consider the following questions proposed for discussion with specific reference to the case studies: - Which mitigation measures (technically feasible) would you take into account to significantly improve the situation in a situation similar to the generic typical case? - Would the mitigation measures be relevant in all cases or be dependent on scale and other physical factors? - Which mitigation measures would you rule out (e.g. due to significant adverse effects on use or wider environment) and why? - What kind of information do you need to be able to explain the reasons for ruling out specific measures? What might be the scenarios which are relevant? - What are the criteria that you would use to assess the level of significance of adverse effects on use or the wider environment? - How do you choose between mitigation measures targeting the same impact, which do not have a significant adverse effect on the use or the wider environment? How do you consider issues related to cost and effectiveness, environmental benefits and sustainability of measures when taking such decisions? - What amendments are needed to the draft questionnaire to cover all possible reasons for selecting and ruling out mitigation measures? - What other outstanding information on the description of the case studies would you need in order to be able to fill in the questionnaire on selecting / ruling out measures for each specific case? - Do you have any cases affected by small hydropower in your country, where water bodies are being designated as heavily modified? We hope you will find this information useful in preparing for the workshop discussions. Looking forward to meeting you in Vienna, The workshop organisers 12

13 7 ANNEX II: Brief descriptions of four generic typical case studies related to hydropower use 7.1 Case Study 1 (CS1). Low head run-of-river HPP with water abstraction and ponding effect Geographical context and frame conditions Main typical situations of lakes and river stretches with significant hymo alterations L1. Lake artificial L2. Lake natural R1. River stretch with flow depletion R1 run of river hydropower plant diversion type (large hydro) R2. River stretch with rapidly changing flow R3. River stretch with ponding effect Other typical situation Type (reference condition) Medium size alpine river (MQ > m 3 ), altitude ( m), catchment km 2 ; gradient: 2,5 % o Stream order 7 (Horton Strahler), distance from source 230 km; moderated nival regime; Bioregion: Central Alps/Mountains; Subtype Austrian large alpine river Mur (width about m) Fish: hyporhithral community; biomass >> 50 kg/ha No of typespecific species: 18; 4 typespecific dominant species Grayling/Äsche (Thymallus thymallus) Danube Salmon/Huchen (Hucho hucho)* Freshwater lamprey/neunauge (Lampetra fluviatilis)* Souffia/Strömer (Telestes souffia)* 9 typespecific subdominant species Burbot (Lota lota) Chub (Leuciscus cephalus) Brown trout (Salmon trutta morpha fario) Stone loach (Barbatula barbatula) Barbel (Barbus barbus) Minnow (Phoxinus phoxinus) Gudgeon (Gobio gobio) Bullhead (Cottus gobio)* Nase (Chondrostoma nasus) 5 typespecific rare species Pike (Esox lucius) Common bleak (Alburnus alburnus) Roach (Rutilus rutilus) Bleak (Alburnoides bipunctatus) 13

14 Fish zone Fish migration (diadromous or potamodromous species) Vulnerable or endangered freshwater related species Other important information on environmental values, e.g. protected habitats/species, Natura 2000, ecosystem services etc Steingressling (Romanogobio uranoscopus)* Benthic invertebrates: hyporhithral community natural saprobic condition: oligo-ßmesosaprob (SI 1,75) Phytobentos: natural trophic condition: meso(eu-) throphic Phytoplankton: No authochtonous due to high natural flow velocitity Natural/Hyporhithral (Grayling zone) Potadromous; medium distance migrators 5 FFH fish species: Danube Salmon (Hucho hucho)* Freshwater lamprey (Lampetra fluviatilis)* Souffia (Telestes souffia)* Bullhead (Cottus gobio)* Steingressling (Romanogobio uranoscopus)* Other case-specific frame conditions Main road very close to the right bank side and railway close to the left side of the river, Hydropower scheme/station Type of plant(s) (e.g. run-of-river) Head (m) Installed capacity (MW) Several run of river plants upstream and downstream of the case site; many run of river plants in the catchment Low head run of river plant diversion type 16 m range 10 to 50 MW Annual production (GWh) range 40 to 200 GWh Environmental information Key hydromorphological pressures Hydromorphological alterations and impacts Dam (12m height) run-of-river structure (water abstraction), ponding effect upstream of dam bank reinforcement Key observations and conclusions: Continuity iinterruption - stretch 1: ponding over a length of 5 km (reduced flow velocity upstream of dam, change of riverine character to more lake type, bank fixation; altered sediment composition; reduced sediment transport/dynamics, reduced widt/depth variation;) - stretch 2: flow depletion over a length of 3 km (extended low flows, missing flow dynamics resulting in pool character, sediment 14

15 Biological and physico-chemical elements colmation, reduced sediment transport/dynamics Key observations and conclusions on environmental impacts - Disruption of fish migration Stretch 2 (flow depletion) - Fish: moderate status - typespecific dominant and subdominant species significantly reduced in number and biomass, (reduced population structure); indifferent (euryök) species are replacing typespecific dominant species; No selfsustaining populations of rare species, high deficits of FFH-species - Benthic invertebrates: moderate status - Typespecific sensitive taxa significantly reduced; reduction of rhithral and increase of epipotamal/litoral species composition; reduced biodiversity Other relevant case-specific information Stretch 1 (ponded) - Fish: poor status decreased composition like in reduced flow stretch and very low biomass - Benthic invertebrates: bad status (loss of riverine character/rheophilic composition more lake type/litoral species) Up to 3 C temperature increase in summer 15

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18 7.2 Case Study 2 (CS2). Low head run-of-river in-stream HPP with ponding (impoundment) Geographical context and frame conditions Main typical situations of lakes and river stretches with significant hymo alterations R3. River stretch with ponding effect Several (chain of impoundments) Type (reference condition) Fish zone Fish migration (diadromous or potamodromous species) Gravel dominated very large river, sinuous to meandering river with side channels in steep floodplain (> 0,5 ) Barbel zone (epipotamal) diadromous: Sturgeons (e.g. Acipenser ruthenus) potamodromous: e.g. Hucho hucho, Barbus barbus, Chondrostoma nasus, Lota lota Vulnerable/ endangered freshwater-related species e.g. different fish species (Hucho hucho, Gymnocephalus schraetser, Zingel zingel) Other important information on environmental values (e.g. protected habitats/species, Natura 2000, ecosystem services etc.) Several FFH-species Other case-specific frame conditions Main land uses: dikes, floodplain forests, roads/ railways, industry Hydropower scheme/station Type of plant(s) (e.g. run-of-river) Run-of-river Head (m) 7.5 Installed capacity (MW) Annual production (GWh) Indicated range: 10 to 50 MW Indicated range: 40 to 200 GWh 18

19 Environmental information Key hydromorphological pressures Dam (height: 7.5 m), impoundment, dikes, bank reinforcement Hydromorphological alterations and impacts Impoundment, disrupted continuity and changed substrate size (sediments) reduced flow velocity altered cross section/ instream habitats altered flooding regime/ ground water level, altered/ disconnected floodplain habitats Biological and physico-chemical elements Altered species composition/ communities: reduced abundance/ loss of rheophilic species increased abundance of insensitive species presence/ increased abundance of stagnant species disrupted continuity (biota) Reduced abundance/ loss of floodplain related species/ communities Other relevant case-specific information 19

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23 7.3 Case Study 3 (CS3). Large scale HPP with storage in lake reservoir with discharge into river Geographical context and frame conditions Main typical situations of lakes and river stretches with significant hymo alterations L1. Lake artificial Lake reservoir at 400 masl. Water level increased by L2. Lake natural 50 meter due to water storage for hydropower production. Large areas of mainly peat land, become water covered due to water storage. R1. River stretch with flow depletion Stretch 2, 3, 5 Riffle-pool, gravel river in bottom of valley Stretch 4; Steep river, without access for long distance migratory fish R2. River stretch with rapidly changing flow R3. River stretch with ponding effect Other typical situation Type (reference condition) Fish zone Fish migration Vulnerable or endangered freshwater related species Other important information on environmental values, e.g. protected habitats/species, Natura 2000, ecosystem services etc Other case-specific frame conditions Stretch 6 Riffle-pool, gravel river in bottom of valley with tailrace from HPP with storage in (artificial) lake reservoir in medium altitude area (400m) Stretch 1: Side tributary with no direct impact from water storage, except reduced fish migration from/to sea Catchment area; >1000 km2, altitude masl Reservoirs in medium altitude (400 masl), with intakes transferred from several small catchment. River stretch 4 (an alpine small catchments, upstream stretch 1 and 2); Steep cascade river above anadromous fish zone. River stretch 1-3, 5-6: Riffle-pool, gravel river in bottom of valley. Several smaller side tributaries (normally steeper brooks) River stretch 7: Pool-glide meandering deeper river Reservoir area: fish zone (trout; short distance migrators) Stretch 4 - no natural fish migration Stretch 1-3, 5-7, natural fish zone Stretch 1-3, 5-7, anadromous (dominated by Atlantic salmon and seatrout) and catadromous (eel) fish with access to sea. River estuary into sea, with oxbows and wetland Important river for Atlantic salmon, with large historical catches therefore sport fishing and recreational services relevant Hydropower scheme/station Type of plant(s) (e.g. run-of-river) Large scale HPP storage plant with tailrace in river valley 23

24 Head (m) Installed capacity (MW) Annual production (GWh) Environmental information Key hydromorphological pressures Hydromorphological alterations and impacts Biological and physico-chemical elements Other relevant case-specific information Ca 350 m >50 MW >200 GWh regulatory power with peak load Reservoir dam height (< 50 m), Water transfer from many brooks, small river intake at m altitude. Deep water intake in storage reservoir. Key observations and conclusions - Moderate flow depletion in rivers with water transfer to reservoir (stretch 2 and 3) - Sever flow depletion in river downstream of reservoir (upstream of tailrace re-discharge) -stretch 4 and 5 (+ downstream water intake in many brooks) - Redused migration, raring habitats also for adults at low flow, and possibly increased predation of juveniles (stretch 2, 3, 5) - Rapidly changing flows downstream of tailrace discharge river stretch 6 with damping effect into stretch 7 - Reduced floodings - altered sediment transport/dynamics and altered bed dynamics, increased embeddedness (less cover (particularly stretch 5 and 6) - Reduced fish flow in critical migration periods; spawning season (summer, autumn) and smolt migration (spring) - Lake reservoir: Severe annual changes in water covered area due to water level reduction during winter (normally >30-40 meter) Key observations and conclusions on environmental impacts e.g. Biology: - Macroinvertebrate: reduced growth rate/biomass and species diversity in dewatering zone (mainly Stretch 6) - Fish: Stretch 2-6; reduced biomass - Stretch 6-7: reduced growth rate of juveniles (thermopeaking), dewatering of spawning redds and stranding of juveniles (rapid flow change) - Decreased no of spawners passing tailrace from HPP (stretch 3-5). - Reservoir: No macrophytes and species poor macroinvertebrate fauna due to severe eroded stranding zone. Water temperature and fish (stretch 6-7): - Severely altered water temperature due to deep intake in stratified reservoir - Partly lack of ice cover during winter - Increased smolt age and decreased survival of salmon due to temperature alteration (decreased in summer, increased in winter) 24

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26 7.4 Case Study 4 (CS4). High head HPP with storage in (artificial) lake reservoir in high altitude area Geographical context and frame conditions Main typical situations of lakes and river stretches with significant hymo alterations L1. Lake artificial L2. Lake natural R1. River stretch with flow depletion R2. River stretch with rapidly changing flow R 2 High head HPP with storage in (artificial) lake reservoir in high altitude area (2000m) R3. River stretch with ponding effect Other typical situation Type (reference condition) Bioregion glaciated Central Alps Artificial reservoirs (1,2,3) in high altitude m; River stretch 1 and 2: Alpine Rivers very small catchment and high altitude: steep slope, channel pattern straight; oligoprobic and oligotrophic conditions; outside of natural fish zone River stretch 3): Alpine River small catchment and high altitude: steep slope, channel pattern straight; epirhithralic, oligoprobic and oligotrophic conditions; upper brown trout zone River stretch 4: Alpine river medium catchment size, medium/ high altitude: medium slope, channel pattern straight, oligosaprobic and oligotrophic conditions, Metarhithralic conditions; lower brown trout zone River stretch 6: medium/large alpine river; grayling zone, medium distance migrator Fish zone Reservoir area: no natural fish zone Stretch 1, 2 - no natural fish zone, Stretch 3,4,6, natural fish zone Fish migration (diadromous or potamodromous Stretch 3-5: Potadromous species) Vulnerable or endangered freshwater related species Other important information on environmental Stretch 3-6 FFH species values, e.g. protected habitats/species, Natura 2000, ecosystem services etc Other case-specific frame conditions Hydropower scheme/station Type of plant(s) (e.g. run-of-river) (pumped) storage plant Head (m) High head; reservoir altitude m, 26

27 Installed capacity (MW) Annual production (GWh) Environmental information Key hydromorphological pressures Hydromorphological alterations and impacts Biological and physico-chemical elements Other relevant case-specific information tailrace discharge at 800 m range > 50 MW range > 200 GWh regulatory power, peak load production Reservoir dam height ( m), Key observations and conclusions - flow depletion in rivers with water transfer to reservoir (stretch 1 and 2) - Flow depletion in river downstream of reservoir (upstream of tailrace re-discharge) - stretch 3 (7,5 km length) - Rapidly changing flows downstream of tailrace discharge (> 1:5) river stretch 4 and 6 - altered sediment transport/dynamics - altered bed dynamics Key observations and conclusions on environmental impacts e.g. - Macroinvertebrate: river stretch 1, 2, 3 moderately altered type-specific composition (ecological status 3) - Fish: river stretch 3 moderate status, stretch 4 and 6 poor status, very low individuals and biomass 27

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