This document discusses the implementation of a multicriteria analysis (MCA) approach to determine optimal minimum instream flows while planning for mitigation measures. The MCA approach was used on a pilot case study river section in Slovenia to evaluate different residual flow levels and assess their impacts on ecology, hydropower potential, and other criteria. The MCA involved habitat modeling, expert analysis, and software to evaluate flows, simplify the decision tree, calculate hydropower potential, and analyze tradeoffs between criteria. The results showed that additional mitigation measures could allow for lower residual flows while achieving the same ecological outcomes. The approach provides a framework to balance ecological and energy objectives in a transparent and efficient manner.

1. Implementation of
MCA approach for optimal
Minimum Instream Flow determination
with mitigation measures planning
mag. Sašo Šantl, Saša Erlih, Tina Mazi, dr. Nataša Žvanut Smolar
Institute
for Water of
the Republic
of Slovenia
Aosta –5/30/2012 2012
24th May

2. page 2
Backgrounds
• Hydropower is most important RES in Alpine regions
• RES Directive <-> Water Framework Directive,
Habitat Directive
• Needs for clear and efficient tools to:
• Support decision making based on multicriteria approach
• Evaluate impact on environment
• Evaluate HP potential,
• Evaluate mitigation measures
Aosta – 24th May 2012

3. page 3
Pilot case area
Possible water intake location.
Possible water release location.
Section of analysis
Existing SHPP intakes.
At the analysed saction there are 4 impasable weirs
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4. page 4
MCA – decision tree
Objective of this MCA is to
determine Residual flow
(acceptable for all stakeholders).
Alternatives are defined with
different values of residual flow.
Higher number of indicators
means more expert research
and work.
To make MCA more efficient
simplification of MCA tree can be
proceeded.
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5. page 5
MCA – decision tree
Example of criteria/indicators reduction according to the main conflict of interests,
indicator causal trends and their similarity.
Determination of trends of indicators (rising falling and neutral)
Indicator score
Residual flow
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6. page 6
MCA – decision tree
Habitat modelling (hydraulic model,
substrate, fuzzy sets and rules) -> suitabilty
(CASIMIR software)
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7. page 7
MCA – decision tree
Expert determination (Institute for water of RS)
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8. page 8
MCA – decision tree
Software for HP potential evaluation and
determination - VapIdroAste
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9. HP potential calculation –
page 9
VapIdroAste - results
Aosta – 24th May 2012

10. HP potential calculation –
page 10
VapIdroAste - results
Technical potential of upper Kokra river according to the length of derivation
10000
1000 m 2000 m 5000 m
Nature value Ecological important area A < 10 km^2 or Qlow < 80l/s
Reference section
1000
Insalable power [kW]
100
10
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Downstream Progresive [km] Upstream
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11. HP potential calculation –
page 11
VapIdroAste - results
Feasible potential:
~ 5200 kW
~ 30.000 MWh/year
Environment:
- additional costs for mitigation
measures
- exclusion of prohibit areas by
law (reference sections by River
Basin Manag. Plan)
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12. page 12
MCA model
Model establishment and analysis – SESAMO software
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13. page 13
MCA model
Criteria and indicator weighting
Nature 3/8 Phytobenthos 30
Ecology value
preservation
Fish 30
2/3 3/4 9/16 Temperature 20
Good water 3/8 Lateral connectivity 10
status Longitudinal connectivity 10
Increase of
1/6
RES objective
RES
1/4 1/4 7/16
Efficient energy 1/6
use
Weights Weights Ann. Electr. Production 100
WECOLOGY = 9/16 ÷ 3/4 = 0.5625 + 0.1875 * (Lnatura/Lwater body)
WRES = 1/4 ÷ 7/16 = 0.4375 - 0.1875 * (Lnatura/Lwater body)
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14. page 14
Results
Results for case without additional measures (fish pass planned only on intake weir)
No score for indicator
„longitudinal continuum“
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15. page 15
Results
Results for case with additional measures (fish pass planned for 4 barriers in derivation section)
Score for indicator
„longitudinal continuum“ not
calculated only in case
without SHP scheme
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16. page 16
Results
With implementation of additional
measure (assuring longitudinal
continuum along all derivation river
section) same result is assured with
app. 140 l/s less of Qres then
optimum value of Qres in the case
without additional measure.
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17. page 17
Conclusions
• Reduction of number of indicators is efficient
• less indicators means less research work and expert
subjectivity
• addition work: focus on the main conflict (water), indicator
trend analysis, searching for delegate indicators
• In the MCA the weighting is the most political phase
• Further MCA decision tree prunning (inclusion of
anthropogenic influences into final representative
indicators)
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18. page 18
Conclusions
Example of inclusion of anthropogenic influences into representative indicator „Fish fauna“
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Aosta – 24th May 2012

19. Implementation of
MCA approach for optimal
Minimum Instream Flow determination
with mitigation measures planning
Thank you for your attention.
mag. Sašo Šantl, Saša Erlih, Tina Mazi, dr. Nataša Žvanut Smolar
Institute
for Water of
the Republic
of Slovenia
Aosta –5/30/2012 2012
24th May