TECHNICAL ANNEX with country details

Transcription

1 WG ECOSTAT report on common understanding of using mitigation s for reaching Good Ecological Potential for heavily modified water bodies Part 1: Impacted by water storage TECHNICAL ANNEX with country details 1

2 Prepared by: ELEFTHERIA KAMPA 1, SEBASTIAN DÖBBELT-GRÜNE 2, JO HALVARD HALLERAKER 3, VERONIKA KOLLER- KREIMEL 4 1 Ecologic Institute, Germany, 2 Planungsbüro Koenzen in order of the German LAWA, Germany, 3 Norwegian Environment Agency, Norway, 4 Federal Ministry for Agriculture, Forestry, Environment and Water Management, Austria 2

3 Contents 1 Introduction Mitigation for interrupted continuity for fish Mitigation for flow alteration Mitigation for sediment alteration Mitigation of ponded rivers (impoundments) Mitigation of lake level alteration Mitigation for physico-chemical alteration Tables with country information

4 List of Tables December 217 Table 1. Upstream continuity: Measure hierarchy (ranking) Table 2. Downstream continuity: Measure hierarchy (ranking) Table 3. Upstream continuity: Ecological effectiveness of s... 5 Table 4. Downstream continuity: Ecological effectiveness of s Table 5. Upstream continuity: Practical effectiveness of s Table 6. Downstream continuity: Practical effectiveness of s Table 7. Upstream continuity: Relative effect on water use of s Table 8. Downstream continuity: Relative effect on water use of s Table 9. Continuity: Frequency of use of s Table 1. Continuity: Frequency of reasons for ruling out s Table 11. Flow: Cases where mitigation is normally required Table 12. Flow: Period of year flow-based mitigation applied Table 13. Flow: Typical magnitude of mitigation low flow in period as a percentile exceedance of natural flow Table 14. Flow: Range of variation from typical magnitude of the mitigation flow across sites Table 15. Site-specific factors taken into account in determining the magnitude of the mitigation flow... 6 Table 16. Flow: Period(s) of time during which mitigation flow is applicable... 6 Table 17. Flow: Period(s) of time during which fish mitigation flow is applicable Table 18. Flow: River types apllied for setting variable flows Table 19. Flow: Typical method of delivering variable flows; Matching of flow variability to the upstream flows; Dimension of variable flows mitigation in comparison to low flows Table 2. Flow alteration: Measure hierarchy (ranking) for flow mitigation s Table 21. Flow alteration: Ecological effectiveness of flow mitigation s Table 22. Flow alteration: Practical effectiveness of flow mitigation s Table 23. Flow alteration: Relative effect on water use of flow mitigation s Table 24. Flow alteration: Frequency of use of s Table 25. Flow alteration: Frequency of reasons for ruling out s Table 26. Sediment alteration: Measure hierarchy (ranking) for sediment alteration Table 27. Sediment alteration: Ecological effectiveness of sediment alteration s Table 28. Sediment alteration: Practical effectiveness of sediment alteration s Table 29. Sediment alteration: Relative effect on water use of sediment alteration s Table 3. Sediment alteration: Frequency of use of s Table 31. Sediment alteration: Frequency of reasons for ruling out s Table 32. Ponded rivers: Measure hierarchy (ranking) for ponded rivers

5 Table 33. Ponded rivers: Ecological effectiveness of s for ponded rivers Table 34. Ponded rivers: Practical effectiveness of s for ponded rivers Table 35. Ponded rivers: Relative effect on water use of s for ponded rivers Table 36. Ponded rivers: Frequency of use of s Table 37. Ponded rivers: Frequency of reasons for ruling out s Table 38. Lake level alteration: Measure hierarchy (ranking) for lake level alteration... 8 Table 39. Lake level alteration: Ecological effectiveness of lake level alteration s Table 4. Lake level alteration: Practical effectiveness of lake level alteration s Table 41. Lake level alteration: Relative effect on water use of lake level alteration s Table 42. Lake level alteration: Frequency of use of s Table 43. Lake level alteration: Frequency of reasons for ruling out Table 44. Physico-chemical alteration: Measure hierarchy (ranking) for physico-chemical alteration 86 Table 45. Physico-chemical alteration: Ecological effectiveness of physico-chemical alteration s Table 46. Physico-chemical alteration: Practical effectiveness of physico-chemical alteration s Table 47. Physico-chemical alteration: Relative effect on water use of s Table 48. Physico-chemical alteration: Frequency of use of s Table 49. Physico-chemical alteration: Frequency of reasons for ruling out s Table 5. Country responses on question Do you consider this to be one of the s necessary as a minimum to ensure a functioning aquatic ecosystem?... 9 Table 51. Overview of frequency of reasons for outruling s

6 List of Figures December 217 Figure 1 a and b. Continuity: Measure hierarchy ranking of upstream continuity s (upper), and downstream continuity s (lower) Figure 2. Continuity: Ecological effectiveness - upstream continuity s (upper), and downstream continuity s (lower) Figure 3. Continuity: Practical effectiveness - upstream continuity s (upper), and downstream continuity s (lower) Figure 4. Continuity: Relative effect on water use - upstream continuity s (upper), and downstream continuity s (lower) Figure 5. Continuity: Frequency of use - upstream continuity s (upper), and downstream continuity s (lower) Figure 6. Continuity: Frequency of reasons for ruling out - upstream continuity s (upper), and downstream continuity s (lower) Figure 7. Flow: Evaluation of European mitigation relevance with regard to the key types of flow mitigation s Figure 8. Flow alteration: Hierarchy of mitigation s with regard to mitigation for low flows, fish flows and variable flows; 3 ranking options: 1 st, 2 nd, 3 rd and lower Figure 9. Flow: Ecological effectiveness of flow mitigation s (low flow, fish flow, variable flows) Figure 1. Flow: Ecological effectiveness of mitigation s for rapidly changing flows Figure 11. Flow: Practical effectiveness of flow mitigation s (low flows, fish flows, variable flows) Figure 12. Flow: Practical effectiveness of mitigation s for rapidly changing flows Figure 13. Flow: Relative effect on water use of flow mitigation s (low flows, fish flows, variable flows) Figure 14. Flow: Relative effect on water use of mitigation s for rapidly changing flows Figure 15. Flow: Expected frequency of flow mitigation s (low flows, fish flows, variable flows)... 3 Figure 16. Flow: Expected frequency of mitigation s for rapidly changing flows Figure 17. Flow: Reasons for ruling out flow mitigation s (low flows, fish flows, variable flows) Figure 18. Flow: Reasons for ruling out mitigation s for rapidly changing flows Figure 19. Sediment alteration: Hierarchy of mitigation s for sediment alteration Figure 2. Sediment alteration: Ecological effectiveness of mitigation s for sediment alteration Figure 21. Sediment alteration: Practical effectiveness of mitigation s for sediment alteration Figure 22. Sediment alteration: Relative effect on water use of mitigation s for sediment alteration Figure 23. Sediment alteration: Expected frequency of mitigation s for sediment alteration 36 6

7 Figure 24. Sediment alteration: Reasons for ruling out mitigation s for sediment alteration 37 Figure 25. Ponded rivers: Ecological effectiveness ponded rivers (impoundments) Figure 26. Ponded rivers: Practical effectiveness ponded rivers (impoundments) Figure 27. Ponded rivers: Relative effect on water use ponded rivers (impoundments)... 4 Figure 28. Ponded rivers: Frequency of use ponded rivers (impoundments) Figure 29. Lake level alteration: Ecological effectiveness lake level alteration Figure 3. Lake level alteration: Practical effectiveness lake level alteration Figure 31. Lake level alteration: Relative effect on water use lake level alteration Figure 32. Lake level alteration: Frequency of use lake level alteration Figure 33. Physico-chemical alteration: Ecological effectiveness temperature mitigation s Figure 34. Physico-chemical alteration: Practical effectiveness Figure 35. Physico-chemical alteration: Relative effect on water use from mitigation s Figure 36. Physico-chemical alteration: Frequency of use - s to mitigate temperature alteration Figure 37. Physico-chemical alteration: Frequency of reasons for ruling out - s to mitigate temperature alteration

8 1 Introduction December 217 This technical annex accompanies the main report of the Working Group ECOSTAT on common understanding of using mitigation s for reaching Good Ecological Potential for heavily modified water bodies Part 1: Impacted by water storage. This annex provides the detailed analysis of the Mitigation Measures Templates for heavily modified water bodies impacted by water storage, as completed and returned by 23 countries. A general introduction and description of the key types of mitigation addressed are given in the respective chapters of the main report. This annex includes, for every key type of mitigation, information on the following: - Relevance of this type of mitigation at European level - Ranking and the effectiveness of the mitigation s - Relative effect of mitigation s on water storage - Frequency of using the different types of s and the main reasons for ruling out s. The diagrams and tables summarising the country data are based on responses to the Mitigation Measures Template from 23 countries and additional data/information submitted by countries as part of different consultation rounds with ECOSTAT within 216. For more background information on the structure of the Mitigation Measures Template and the objectives of the country information exchange on mitigation s for Good Ecological Potential, please refer to the main report which is available at: 8

9 2 Mitigation for interrupted continuity for fish 2.1 Relevance in Europe Conclusions: Relevance: Continuity for fish is important for all countries, and mitigation of interrupted fish migration is normally expected for GEP (9 % of countries). Impact on fish continuity from water storage is the most widespread impact to be mitigated, via s to ensure upstream continuity in particular. Several countries are lacking mitigation s for downstream continuity, and will probably benefit by knowledge exchange or transfer of experience from others. When relevant (in the fish zone), fish passes are among the most frequently used s considered as minimum requirements for GEP in many countries. The following key findings regarding key s for mitigating interrupted fish continuity, are based on information from 23 responding countries: 21 out of 23 countries have recognised the impacts for upstream migration, and all of them have included at least one mitigation in their national libraries. 21 out of 23 countries have recognised the impacts for downstream migration, and 18 of them have included at least one mitigation in their national libraries. However, three countries have recognised the impact but are presently lacking s to mitigate downstream continuity. Please refer to the main report for full country details on the inclusion of s in national lists of mitigation s as well as Table 1-2 and 5-51 in Chapter 8 (Annexes) for more country details. Compared to other key s these are among the most widely recognised impacts from water storage used, and most countries have mitigation s in their libraries. However, this is the case more for upstream than for downstream continuity. In fish regions, fish passes (particularly to ensure upstream migration) are among the most frequently used s considered as minimum requirements for GEP, for those countries having criteria for ensuring functioning aquatic ecosystems in HMWBs. 2.2 Ranking and effectiveness Ranking and effectiveness: By-pass channels and other fish passes (like fish ladders) have the highest priority in most countries. By-pass channels are considered to have relative high both ecological and practical effectiveness for upstream migration in most countries, and also for downstream continuity in many countries Fish friendly turbines are also considered to have high practical effectiveness for downstream migration in many countries. Catch, transport and release or fish stocking have lower priority in all responding countries, and also generally lower effectiveness (both ecological and practical). Ranking of alternatives (hierarchy of mitigation s): Upstream: Only 11 out of 21 countries have ranked at least one of their s for upstream continuity. Of the 11 with ranking; 7 have 1 st rank for by-pass channel and fish pass, while 3 have ranked ramp first. No country has ranked catch, transport and release or stocking from hatchery (stocking) first, while 3 countries have catch, transport and release as their 2 nd options, while using stocking have a lower ranking in all countries (see Table 1 for full country details). 9

10 Fishfriendly turbines Fish screens By-pass channel Trap, transport & release Fish pass ranking no ranking no answer % of ranked no. of MS Ramp Fish pass By-pass channel Catch, transport & release Stock from hatchery ranking no ranking no answer % of ranked no. of MS December 217 Downstream: Only 11 out of 18 countries have ranked at least one of their s for downstream continuity. Of the 11 with ranking, 7 have 1 st rank for by-pass channel, 6 have ranked fish pass first, 5 have ranked fish-friendly turbines first, while 5 have ranked fish screens first. No country has ranked catch, transport and release first; 1 country has ranked catch, transport and release as their 2 nd option, while 4 countries have a lower ranking of this (see Table 2 for full country details) st 2nd 3rd and lower st 2nd 3rd and lower 54, Figure 1 a and b. Continuity: Measure hierarchy ranking of upstream continuity s (upper), and downstream continuity s (lower). Ecological effectiveness of alternatives: Upstream: All 21 countries with mitigation s on upstream continuity have estimated the (relative) ecological effectiveness of at least one of their s. Of these; 1 of 17 have high and 5 of 17 have medium ecological effectiveness for by-pass channel, while 3 of 19 have high and 14 of 19 have medium ecological effectiveness for fish pass. 6 of 1 have high and 3 of 1 have medium ecological effectiveness for ramps. No country has high ecological effectiveness for catch, transport and release but 3 of 5 with medium effectiveness for this. For fish stocking; 1 country has high and 1 of 5 has medium ecological effectiveness (see Table 3 for full country details). Downstream: 1

11 Fishfriendly turbines Fish screens By-pass channel Trap, transport & release Fish pass mm relevant mm not relevant no answer % of relevant no. of MS Ramp Fish pass By-pass channel Catch, transport & release Stock from hatchery mm relevant mm not relevant no answer % of relevant no. of MS December 217 All 18 countries with mitigation s on downstream continuity have estimated the (relative) ecological effectiveness of at least one of their s. Of these; 7 of 15 have high and 8 of 15 have medium ecological effectiveness for by-pass channel, while 1 of 13 have high and 1 of 13 have medium ecological effectiveness for fish pass. For fish-friendly turbines; 3 countries have indicated high and 5 of 12 countries medium ecological effectiveness. For fish screens; 2 have indicated high and 5 of 1 countries medium ecological effectiveness. No country has high ecological effectiveness for trap, transport and release but 2 of 5 have indicated medium effectiveness (see Table 4 for full country details) High Med Low High Med Low 47, Figure 2. Continuity: Ecological effectiveness - upstream continuity s (upper), and downstream continuity s (lower). Practical effectiveness of alternatives: Upstream: All 21 countries with mitigation s for upstream continuity have estimated the (relative) practical effectiveness of at least one of their s. Of these; 7 of 16 have high and 6 of 16 have medium practical effectiveness for by-pass channel, while 3 of 18 have high and 9 of 18 have medium practical effectiveness for fish pass. For ramps, 5 countries indicated high and 3 of 1 countries medium practical effectiveness. 11

12 Fish-friendly turbines Fish screens By-pass channel Trap, transport & release Fish pass % of relevant Ramp Fish pass By-pass channel Catch, transport & release Stock from hatchery % of relevant December 217 No country has high practical effectiveness for catch, transport and release or stocking, but 1 of 6 has indicated medium effectiveness for this. For stocking; all 5 countries have indicated low practical effectiveness (see Table 5 for full country details). Downstream: All 18 countries with mitigation s on downstream continuity have estimated the (relative) practical effectiveness of at least one of their s. Of these, 5 of 14 have high and 6 of 14 have medium practical effectiveness for by-pass channel, while 2 of 13 have high and 5 of 13 have medium practical effectiveness for fish pass. For fish-friendly turbines, 5 countries indicated high and 1 of 8 countries medium practical effectiveness. For fish screens, 8 countries indicated high and 1 of 11 countries indicated medium practical effectiveness. For trap, transport and release, all 5 countries have indicated low practical effectiveness (see Table 6 for full country details) High Med Low High Med Low 2 1 Figure 3. Continuity: Practical effectiveness - upstream continuity s (upper), and downstream continuity s (lower). 2.3 Relative effect on water use Effect on water use 12

13 Few countries are considering s to mitigate up or downstream migration of fish to have a high relative effect on the water use for water storage. Low to no effect on water storage is dominating for these migration mitigation s. Mitigation of fish migration is rarely considered to have significant effect on water storage. Relative effect on water use: Upstream: High effect on use is expected for 1 of 16 countries for by-pass channel, for 2 of 1 for ramps, and none for the other alternative s. Medium effect on use has been estimated for 1 of 1 countries for ramps, for 4 of 18 for fish pass, for 6 of 16 for by-pass channel and for 1 of 6 for catch, transport and release. Most countries have estimated low or no effect on use to be dominating for s related to mitigation of upstream migration. Low effect on use has been estimated for 6 of 1 countries for ramps, 12 of 18 for fish passes, 9 of 16 for by-pass channel and 2 of 6 for catch, transport and release. No effect on use has been estimated for 1 of 1 countries for ramps, 2 of 18 for fish pass, none of 16 for by-pass channel, 3 of 6 for catch, transport and release and 5 out of 5 for stocking (see Table 7 for full country details). Downstream: High effect of mitigation s for downstream continuity on use is only expected for 1 of 13 countries for fish pass and 2 of 11 countries for fish-friendly turbines. Medium effect on use has been estimated for 2 of 11 countries for fish-friendly turbines, 1 of 9 for fish screens, 5 of 13 for fish pass, 8 of 15 for by-pass channel, and 1 of 5 for catch, transport and release. Low effect on use has been estimated for 7 of 11 countries for "fish friendly turbines", 7 of 13 for fish pass, 7 of 15 for by-pass channel, 5 of 9 for fish screens and 1 of 5 for "trap, transport and release". No effect on use has been estimated for 3 of 9 countries for fish screens and 3 of 5 countries for trap, transport and release. Most countries have estimated low or no effect on use to be dominating for s related to mitigation of downstream migration, except for by-pass channels (8 medium vs. 7 low out of 15). (see Table 8 for full country details). 13

14 Fish-friendly turbines Fish screens By-pass channel Trap, transport & release Fish pass % of relevant Ramp Fish pass By-pass channel Catch, transport & release Stock from hatchery % of relevant December High Med Low no effect High Med Low 2 no effect 1 Figure 4. Continuity: Relative effect on water use - upstream continuity s (upper), and downstream continuity s (lower). 2.4 Frequency of use or reasons for ruling out Frequency of use Mitigation s for fish migration, and especially fish passes, ramps or by-pass channels for upstream migration are considered to be implemented from nearly always to more common than not in many of the countries. Mitigation for interrupted downstream migration seems to be implemented to a less extent in HMWBs. Reasons for ruling out: Technical solutions not possible or disproportionate costs seem to be the dominating reasons for ruling out relevant s. Mitigation not required at sites due to natural conditions like natural fish barriers or, lack of relevant habitats upstream/downstream or uncertainties on the ecological effect from s on non/short distance migratory fish is also common reason for outruling in some countries. Significant effect on wider environment or water storage do not seem to be reasons for ruling out migration s in Europe. 14

15 Frequency of use: General: Mitigation of upstream continuity is more common than for downstream. More than 1 countries have estimated mitigation s for upstream migration such as fish pass, ramp or bypass channels (at least one of these options) to be implemented from nearly always (6 countries) to more commonly than not. When relevant, fish passes are among the most frequently used s considered as minimum requirements for GEP in many countries, particularly to ensure upstream migration. Upstream: 18 countries have estimated the expected frequency of in use in water bodies to mitigate interrupted upstream fish continuity due to water storage, either already implemented s or s needed in the coming RMBPs to reach GEP. Estimated as common s for GEP (nearly always to more common than not) are ramps in 5 out of 15 countries, fish pass in 12 of 18 countries, by-pass channels in 6 of 17 countries, catch, transport and release in 1 of 14 countries and fish stocking in 3 of 14 countries. More rarely/uncommon s are estimated to be ramps in 7 of 15 countries, fish pass in 5 of 18 countries, by-pass channels in 8 of 17 countries, catch, transport and release in 6 of 14 countries and stocking in 3 of 14 countries. Too early to say (will then possibly be implemented in coming planning cycles), are answered by single countries for fish pass, by-pass channel and catch, transport and release. Several countries have not included the following s in their libraries: 3 for ramp, 1 for fish pass, 2 for by-pass channel, as many as 7 (5 %) for "catch, transport and release" and 8 countries (more than 5 %) for stocking. Downstream: 15 countries have estimated the expected frequency of s in use in water bodies to mitigate interrupted downstream fish continuity due to water storage, either already implemented s or s needed in the coming RMBPs to reach GEP. Estimated as common s for GEP (nearly always to more common than not) are fish-friendly turbines in 1 of 15 countries, fish screens in 3 of 13, by-pass channels in 3 of 12 countries, and fish pass in 5 of 14 countries. More rarely/uncommon s are estimated to be fish-friendly turbines in 7 of 15 countries, fish screens in 6 of 13, by-pass channels in 7 of 12, catch, transport and release in 6 of 13 and fish passes in 7 of 14 countries. Too early to say (will then possibly be implemented in coming planning cycles) are answered by 3 of 15 countries for fish friendly turbines, and by single countries for fish screens, by-pass channel and trap, transport & release. Several countries have not included the following s in their libraries: 4 for fish friendly turbines, 3 for fish screens, 2 for by-pass channel, 2 for fish pass and as many as 6 (46 %) for "trap, transport & release". See Table 9 for full country details. 15

16 Fish-friendly turbines Fish screens By-pass channel Trap, transport & release Fish pass % of relevant Ramp Fish pass By-pass channel Catch, transport & release Stock from hatchery % of relevant December Nearly always More commonly Uncommonly / very rarely Too early to say No answer Nearly always More commonly Uncommonly / very rarely Too early to say No answer 2 1 Figure 5. Continuity: Frequency of use - upstream continuity s (upper), and downstream continuity s (lower). Frequency of reasons for ruling out: As shown in Figure 6 and Table 1, the most frequently used reasons for ruling out continuity s (both upstream and downstream) seem to be (no of country replies): - For ramps, technical solution not possible in some sites. - For fish pass or by pass channels, technical solutions (7, 8) or disproportionate costs (3, 5) respectively. - For catch and transport, not the first choice mitigation - normally another mitigation likely to be used or too early to say. - For stocking not the first choice. 16

17 Ramp Fish pass By-pass channel Catch, transport & release Stock from hatchery % of relevant December 217 The most widely reasons for ruling out downstream continuity s seem to be; for fish friendly turbines and for fish screens technical solutions (5 and 5 respectively). No countries have indicated significant effect on wider environment as reason for ruling out (up or downstream) mitigation s. For downstream s, no countries have indicated significant effect on water use as reason for ruling out s. For upstream s, only one country has indicated significant effect on water storage as reason for ruling out ramps, one country for fish passes and two countries for by-pass channels. In general: Significant effect on wider environment or water storage do not seem to be frequent reasons for ruling out necessary s for mitigating interrupted fish migration in Europe. Other explanations for not implementing up or downstream mitigation s: Natural barriers to fish before dam or intake structure; originally no fish passing e.g. water fall. No fish habitats; very steep rivers or in regions with no fish or no natural migration Reasons particularly for downstream continuity: Uncertainty about impact on non-migratory fish Lack of experience with found to be efficient in some countries (R&D need) See Table 1 for full country information Technically not possible Significant impact (use / wider environment) Disproportionately costly Impact not present Not the first choice Too early to say No answer

18 Fish-friendly turbines Fish screens By-pass channel Trap, transport & release Fish pass % of relevant December Technically not possible Significant impact (use / wider environment) Disproportionately costly Impact not present Not the first choice Too early to say No answer Figure 6. Continuity: Frequency of reasons for ruling out - upstream continuity s (upper), and downstream continuity s (lower). 3 Mitigation for flow alteration 3.1 Relevance in Europe Conclusions Flow mitigation is definitely considered ecologically important in many countries (21 out of 23 responding countries) Relevant aspects are mitigation for low flows, fish flows, variable flows and rapidly changing flows (key types) for which 11 main s in total were identified. Most of the countries included flow mitigation s in their mitigation s libraries but not always for all of the 11 s. Low flow mitigation is more common than setting s to ensure fish flows and flow variability or mitigating rapidly changing flows Measures to mitigate rapidly changing flows are mainly addressed in countries with large hydropower schemes 23 European countries returned the template filled with information on mitigation of flow alterations. However, not all of them provided information for all questions asked in the mitigation s templates. Some countries provided in some cases information split for specific river basins or types of water bodies. In this case the most representative or most detailed answers were used as the evaluation was done on country level. The following key findings regarding key s for flow mitigation can be extracted from the Mitigation Measures Templates: Impacts of extended/ missing low flows were identified by 18 out of 23 countries, fish flows by 14 countries, variable flows by 18 and rapidly changing flows by 15 countries. Mitigation of these identified flow alterations seems to be common but there are differences with regard to the 4 main flow pressure types. Most of the countries which have identified the impacts of flow alterations have included at least 1 mitigation in their national mitigation 18

19 mm relevant mm not relevant no answer mm relevant mm not relevant no answer mm relevant mm not relevant no answer mm relevant mm not relevant no answer no. of MS no. of MS no. of MS no. of MS December 217 libraries. 17 out of 18 countries have done this for low flow mitigation, 13 out of 14 for fish flow, 15 out of 18 for variable flow and 12 out of 15 countries for rapidly changing flows. It therefore can be concluded that low flow mitigation is more common than setting s to ensure fish flows and flow variability or mitigating rapidly changing flows. Up to 9 countries reported that they do not see a need to include flow mitigation s in their mitigation s library at all but the number also varies according to the flow pressure type: 5 countries do not see a need for mitigation s regarding low flows, 5 for variable flows, 8 countries for rapidly changing flows and 8 mitigation for fish flows. 2 countries out of the 9 which do not see a need for mitigating of at least one of the 4 flow pressure types, do not identify a need for all of the 4 types of flow alterations at all. Please refer to the main report for full country details on the inclusion of s in national lists of mitigation s. Low flow Fish flows Variable flows Rapidly changing flows Figure 7. Flow: Evaluation of European mitigation relevance with regard to the key types of flow mitigation s. In some cases the reason for no need for a specific type of mitigation was explained: AT for example indicated that long distance migrating fish species are missing on national territory and therefore fish flows to trigger migration are not relevant. However, in most cases it is not clear what the reason for not identifying the need to include s in the mitigation library is. There are several options: No significance of impact: o pressures altering the relevant flow components are absent at all on national territory (for example rapid flow fluctuations seem to be more typical for countries where the geomorphological condition of high slopes is used for hydropower generation with hydropeaking) o pressures are existing but impacts is considered to be not significant 19

20 December 217 o pressures existing with significant impacts, but they are already mitigated so that impact are significantly reduced and GES/e-flow is already achieved (means that there is no HWWB designation due to hydropower, water supply or irrigation) Natural type-specific conditions (i.e. the native, type-specific fish community do not include long distance migrators, which need a triggering flow for migration) Lack of relevant assessment systems: assessment methods applied so far are not sensitive enough to identify the impact Unknown situation There might be another reason for answering no in case a national mitigation s library does not exist Application details Conclusions Flow mitigation is in many countries required for both downstream of an intake structure and downstream of a dam/reservoir including the river upstream of the tailrace Fish is the most relevant BQE taken into account for flow mitigation Most countries apply statistical evaluation of flow value, some wetted area Mitigation of low flow is sometimes adapted to site characteristics (e.g. considering habitat and/or ecological criteria; etc) The maintenance low flow is mainly required all over the year Fish flow mitigation is commonly applied in countries with long distance migrators for both periods of up and downstream migration The required low flow components show a large variation but concentrate in the range Q92 to Q97 With regard to the magnitude, the mitigation flows for variable flows are usually higher than for low flows Many countries also provided more detailed information on the requirements and application of the specific key types of mitigation and s to mitigate flow alterations. Low flow mitigation Up to 16 countries out of 23 delivered detailed information with regard to low flow mitigation moreover the number was even less for specific questions. Low flow mitigation might be required for: Rivers downstream of dam (including river upstream of tailrace) Downstream of tailrace Downstream of intake structures 15 out of 16 responding countries have at least a requirement for low flow mitigation in one of the 3 types of affected parts of the river as mentioned above. One country requires mitigation for all cases. In 1 out of the 16 countries low flow mitigation is normally required in river stretches downstream of an intake structure and downstream of a reservoir dam including the river stretches upstream of tailrace but 1 country of them reported that in case of specific type of ecoregion or specific old licences mitigation is not required in both situations neither downstream of intake nor upstream of tailrace. 2 countries do not require low flow mitigation downstream of intake structures and 2 countries act in the opposite way: no mitigation required upstream of tailrace but downstream of intake structures See Table 11 for full country details. 2

21 Period of year low flow based mitigation required: December countries answered the question with regard to the period of year where low flow mitigation (additional flow provision) is required. In 12 out the 16 countries mitigation is required for all of the year, 2 of them indicated that for specific water body types low flow mitigation may be only required for specific seasons. In 1 country additional flow has to be provided only for a specific season in general. 3 countries indicated that they have no detailed information on this question. See Table 12 for full country details. Typical magnitude of the additional flow: 2 countries informed that low flow mitigation is only done by morphological optimisation but 8 countries delivered information on the typical magnitude of mitigation flow required (expressed as a percentile exceedance of natural flow). The magnitude of additional flow provision concentrates on the range of Q 97 to Q 92 which is the figure provide by 5 countries out of 8. One of these 5 countries additionally reported that there is a diverse magnitude for specific cases. But in general there is a wider range in Europe as 1 country indicated the range of Q99 to Q97 whereas in 2 countries the required low flow is < Q6. See Table 13 for full country details. With regard to the range of variation from typical magnitude of the mitigation flow across the sites 4 countries reported that there is no variation (and if there is one, that it falls within the typical flow range magnitude category identified above) and 6 countries indicated that a variation exists. In 2 countries the variation covers 1 and in one country even 2 magnitude categories whereas in 3 countries there is a site to site variation but which is not able to be quantified. See Table 14 for full country details. 7 countries are using physical characteristics and 9 countries principal ecological elements for a site-specific determination of the magnitude of the mitigation flow. With regard to the provision of additional flow 6 countries indicated wetted area, 4 countries depth and 4 countries velocity as decisive physical factors. In 2 countries there are none as the magnitude is set nationally. See Table 15 for full country details. With regard to the s of morphological optimisation only one country reported the use of physical characteristics and indicated that wetted area as the relevant site specific factor. With regard to principle ecological quality fish seems to be the most relevant ecological QE. For additional flow provision 7 countries focus on fish, 2 on fish & benthic invertebrates and 4 countries indicated to use all QE. Fish is also the relevant ecological factor for the one single country which reported on the morphological optimisation. Fish flows Most of the countries are using specific information to decide on the timing, frequency, magnitude and duration of the fish flow which is needed to trigger up and downstream migration of long distance migrators. From the 12 countries which indicated to have fish flow mitigation s in place 11 countries delivered information on the period of time during which mitigation flow is applicable to ensure an adequate fish flow to trigger migration of long distance migrators. See Table 16 for full country details. In 9 out of the 11 countries both periods of upstream and downstream migration are taken into account, in one country there seems to be a variation depending on the type of the river/ecoregion and in one country mitigation is explicitly only required for the period of upstream migration. With regard to site-specific factors used for deciding timing & frequency of mitigation flow the factor fish community at the site concerned is used by 8 countries followed by observation of fish behaviour (7 countries) whereas catchment rainfall is relevant in 3 countries and water temperature only in one country. 21

22 With regard to site-specific factors, which are used for deciding magnitude & duration of mitigation flow, 8 of the 1 responding countries are using it for both periods. Magnitude of competing flows was indicated as relevant decisive factor by 6 out of the 9 countries, length of river to be navigated by 4 countries, instream obstacles (e.g. water falls) by 3 and river gradient by 2 countries. See Table 17 for full country details. Variable flows 3 countries reported that flow variability is not set according to specific river types whereas 7 countries are applying such a differentiation: 3 indicated this for normal river types, 2 for types where flows for particular fish species are important, rivers affected by snow/ice melt or groundwater are the relevant factor in 2 countries each and 1 country indicated to take into account other types of river. See Table 18 for full country details. The typical method for delivering variable flows is the active one which is applied in 11 countries, 4 of them also apply passive delivering. One country indicated that it is using only passive method for flow dynamisation. See Table 19 for full country details. 11 countries answered the question whether the flow variability is matched to variability in the upstream flows or set independently. 5 out of the 11 countries are matching flow dynamics to upstream flows whereas 4 are doing it independently, and 6 countries indicated to use a mixture of both variations. (Overlapping indications have to be clarified in the next intercalibration steps). Information on the comparison of the magnitude of low flow mitigation and variable flow mitigation was given by 9 countries. In 6 countries variable flows are higher than mitigation low flows, in 2 countries it can be higher or lower and in one country the mitigation flow for flow dynamics lies within the mitigation low flow. 3.2 Ranking and effectiveness of s Conclusions All countries which have indicated to have s to mitigate flow alterations in their national libraries have a clear picture on the hierarchical ranking of the options, their (relative) ecological and practical effectiveness and effect on water use, but the estimations were not done for all of the s because not all countries apply all of the identified s on their territory. All s to mitigate flow alterations were qualified to have a high position in ranking as well as concerning ecological and practical effectiveness except fish stocking. Fish stocking is usually only an option if there is no other viable option or is used as additional supporting other s due to its (relative) low ecological and practical effectiveness Diverse experiences seem to exist in case of the 6 s to mitigate rapidly changing flows but for mitigating low flows a clear preference for providing additional flows can be seen due to the high ecological effectiveness compared to morphological optimisation. Only those countries of the responding 23, which have included s mitigating the impact of the different types of flow alterations, provided more detailed information on the s: for low flows 17 countries, for fish flow 13, for variable flows 15 countries and for rapidly changing flows 12 countries. As the numbers of s vary from 1-6 according to the flow pressure type which has to be mitigated the evaluation results are presented for each key type of mitigation separately. 22

23 Provide additional flow River morphology changes Provide fish flow Passive flow variability Active flow variability % of ranked December st 2nd 3rd and lower Low flows Fish flows Variable flows Figure 8. Flow alteration: Hierarchy of mitigation s with regard to mitigation for low flows, fish flows and variable flows; 3 ranking options: 1 st, 2 nd, 3 rd and lower. Hierarchy of mitigation s Information was provided by the countries for all different types of s identified for as key mitigation types for flow alterations, but not all options are applied in all reporting countries and therefore are not ranked by all of these countries. To mitigate extended or missing low flows 16 countries out of 23 have provided information on ranking the two s types providing additional flow and changing river morphology to make best use of existing flow. A clear preference with regard to hierarchy was made with regard to provision of additional flow as this option was ranked 1 st by 7 out of the 16 responding countries (1 country 2 nd rank), one country put morphological optimisation also in the 1 st rank and 7 in 2 nd rank. 8 countries did not do a ranking, 6 of them because morphological optimization is the only mitigation option applied. No specific s were proposed in the Mitigation Measures Template to mitigate inadequate fish flows, as only the provision of additional flow can trigger the migration of long distance migrators. Therefore assessment information with regards s hierarchy is of no relevance for this key type of mitigation. Regarding the s to ensure variable flows to be actively or passively delivered only 2 out of 15 countries who have mitigation s included in their libraries have ranked the 2 options. These 2 countries placed the passively delivered variable flow in 1 st rank, and actively delivered in 2 nd rank. For 3 countries there is no difference in ranking between the 2 options whereas for 7 countries there is only one option. Passively delivering is 1 st ranked by 4 countries but no option for 1 country. To mitigate rapidly changing flows, 6 s were identified and all 12 countries which had reported to have mitigation s included in their national libraries delivered information on the ranking of the different options. All of the 6 s except fish stocking and in channel balance reservoir were 1 st ranked by at least 2 countries (2 s by 3 countries). 4 countries did not rank 23

24 ranking no ranking no answer ranking no ranking no answer ranking no ranking no answer no. of MS no. of MS no. of MS December 217 the s. Reasons for this (only one option or there is no difference in ranking between the s) have to be clarified in the next step of this exercise. See Table 2 for full country details. From the ranking information it can be derived that reducing the rate of downramping is a general option in 5 countries, morphological modifications in 6, whereas installing an external balancing reservoir as well as fish stocking is explicitly indicated to be an option by only 3 countries each and an internal reservoir and relocation of tailrace by 2 countries each. Comparing the number of 1 st rankings the result for the different options is the following: Installing a balance reservoir external of the river was 1 st ranked by 3 countries. Reducing the rate of ramping down got a 1 st ranking by 3 countries. Relocation of tailrace was 1 st ranked by 2 countries. Modifying river morphology was 1 st ranked by 2 countries as well and 2 nd ranked by 4 countries. Installing a balance reservoir in the river channel got only a 2 nd rank and a 3 rd rank by one country each. Fish stocking is applied in 3 countries but only ranked 3 rd or 4 th category meaning that this is implemented in case that there is no other option or maybe as additional supporting other s. Low flow Fish flows Variable flows Rapidly changing flows No ranking, as there is only one option Ecological effectiveness Ecological effectiveness of flow mitigation s was rated by all those countries, which have indicated to have s to mitigate flow alterations in their national libraries, but the estimation was not done for all of the s because not all countries apply all of the identified s on their territory. See Table 21 for full country details. 24

25 Balancing reservoir(s) (internal) Relocate tailrace Reduce rate Modify river morphology Balancing reservoir(s) (external) Fish stocking % of relevant Provide additional flow River morphology changes Provide fish flow Passive flow variability Active flow variability % of relevant December High Med Low Low flows Fish flows Variable flows Figure 9. Flow: Ecological effectiveness of flow mitigation s (low flow, fish flow, variable flows). There seems no doubt that providing additional flow is of highest ecological effectiveness (14 out of the 17 countries) for mitigating low flows, only 2 countries rated this to be of medium effectiveness. Morphological optimisation however was considered less effective and shows a higher rating variation: it was qualified by 3 countries to be of highest effectiveness, 5 countries indicated medium and 2 countries only low ecological effectiveness. Providing fish flow to trigger migration was considered of high ecological effectiveness by 7 countries and medium by 2 countries. In case of mitigating for variable flows there is a difference between actively and passively delivered flow dynamics. The active method was qualified with highest ecological effectiveness by 8 countries and with medium by 4 countries, while the passive method was estimated to be of highest effectiveness by 3 countries, and a medium rate by 2 countries High Med Low 2 1 Figure 1. Flow: Ecological effectiveness of mitigation s for rapidly changing flows. 25

26 Provide additional flow River morphology changes Provide fish flow Passive flow variability Active flow variability % of relevant December countries delivered information on ecological effectiveness of the 6 s identified for mitigating rapidly changing flows. All s were estimated to be of highest ecological effectiveness by at least 1 (maximum 2) countries, but were mainly rated with medium efficiency (2-7 countries each of the ). The only exception is fish stocking which was not estimated with high effectiveness by any country, but only as medium (1 country) and low eco-effectiveness (4 countries). Practical effectiveness Information on the estimation of the practical effectiveness (i.e. sustainability of the ) was delivered by all countries which indicated to have s for the 4 key mitigation types included in their national library, but the information estimation was not done for all of the s because not all countries apply all of the identified s on their territory. See Table 22 for full country details. With regard to mitigating low flows providing additional flow was estimated to be of high practical effectiveness by 11 out of 17 countries (medium by 3 and even low by 2 countries). In comparison optimisation of river morphology was only rated high by 2 countries (medium by 7 and low by 2 countries High Med Low Low flows Fish flows Variable flows Figure 11. Flow: Practical effectiveness of flow mitigation s (low flows, fish flows, variable flows). Providing fish flows were considered of high practical effectiveness by 3 countries, medium by 3 and low practical effectiveness by 3 countries as well. In case of mitigating for variable flows there is again difference between actively and passively delivered flow dynamics. The active method was qualified with high practical effectiveness by 6 countries (with medium by 4 and low by 2 countries), while the passive method was estimated to be of high effectiveness only by one country (3 medium and 1 low). 26

27 Balancing reservoir(s) (internal) Relocate tailrace Reduce rate Modify river morphology Balancing reservoir(s) (external) Fish stocking % of relevant December High Med Low 2 1 Figure 12. Flow: Practical effectiveness of mitigation s for rapidly changing flows 11 countries delivered information on ecological effectiveness of the 6 s identified for mitigating rapidly changing flows. All s were estimated to be of high practical effectiveness by at least 1 country (river modification 4 countries, reduce rate of ramping down by 3 countries), but there is a high variation in rating from high to low for all s. Only fish stocking was generally only estimated with low practical effectiveness (5 countries, as only these are applying this option). 3.3 Relative effect on water use Conclusions Measures related to the provision of additional flows for low flow fish flow or variable flows and reducing the down ramping rate in case of hydropeaking are usually considered to have a relative high effect on water use compared to other s. Optimising river morphology for low flow mitigation and all other s to mitigate rapidly changing flows except reducing rate of ramping down are mostly considered to have even none or only low relative effect on water use. Information on the relative effect on water use when comparing the different s was again delivered by all those countries, which have indicated to have s to mitigate flow alterations in their national libraries, but the estimation was not done for all of the s because not all countries apply all of the identified s on their territory. See Table 23 for full country details. 27