This document discusses downstream flow regimes for hydropower projects. It notes that planning for reservoir filling and power plant operation must consider ecological, social, and economic factors. There is often a lack of scientific data and regulation to guide discussions on downstream flows. The document presents two case studies where downstream flow levels were negotiated: the Salto Caxias project, where ecological and community concerns over reduced flows to Iguazu Falls led to an agreed minimum flow of 155 cm/s; and a smaller project where community concerns over reduced scenic waterfall flows resulted in an agreed minimum flow of 6 cm/s, versus the regulatory minimum of 2.2 cm/s. The document concludes that downstream flow discussions must be case-specific,

1. Brookfield Energia Renovável
IHA WORLD CONGRESS – Advancing Sustainable Hydropower
June 2011 – Foz do Iguaçu
ANTONIO FONSECA DOS SANTOS
Environment and Sustainability Director

2. DOWNSTREAM FLOW REGIMES – Session 8b

3. DOWNSTREAM FLOW REGIMES
Planning and negotiations for the definition of the flow regime have to be done
considering two moments
Filling of the reservoir Operation of the power plant
Several factors should be addressed during these discussions as:
Ecological factor – fish species and habitats, aquatic ecosystems, water quality
Social factors – water uses and necessities downstream (irrigation, drinking water,
leisure and recreation, tourism, etc)
Economic factors – do not impact energy production of the power plant
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4. DOWNSTREAM FLOW REGIMES
TRIPLE BOTTOM LINE
Ecological factors
Social factors Economic factors
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5. DOWNSTREAM FLOW REGIMES
All these issues must be discussed during the planning of the project, but this
discussion, are neglected most of the time (Kept in offices)
There is a lack of scientific results to show the best solution from a biological point
of view, mainly because it can be specific for each location
There is a lack of regulation in Brazil to at least present initial criteria to fundament
such a discussion:
DNAEE - National Department of Water end Energy - Resolution number 125
“...downstream a dam.....at least 80 % of the minimum monthly average flow...” (up
to early 80’s)
CONAMA-Environment National Council - Resolution number 20 “.. to maintain
the level of dissolved oxygen ... minimum flow for a drought of 7 days of duration
and 10 years of return period”. (late 80’s to 2000’s)
Some of the state´s environmental authorities in Brazil are now defining as a
percentage of the flow for the 95% value of the flow frequency curve for the power
plant specific location. (now a days)
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6. DOWNSTREAM FLOW REGIMES
ECOLOGICAL
?
Project owner/developer
Regulatory authority
Environmental authority
Research Institutions
Local community
SOCIAL ECONOMIC
EQUILIBRIUM
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7. DOWNSTREAM FLOW REGIMES
FLOW REDUCTION IGUAÇU RIVER VALLEY
Some concerns of the IAP - Paraná State Environmental Institute - (State of Paraná
Environmental Authority), mainly during the filling of the Salto Caxias power plant
reservoir period ( 1250MW located 200 Km upstream the Iguaçu Falls).
Economic impacts to the city of Foz do Iguaçu, due to the decrease of visitors
caused by the reduction of flow over the Iguaçu Falls, one of Brazilian’s main
tourist attraction.
Same impact in Puerto Iguazu – Argentina leading to an International Issue
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8. DOWNSTREAM FLOW REGIMES
FLOW REDUCTION IGUAÇU RIVER VALLEY
Legislation Thresholds at that time
DNAEE -Resolution
Salto Caxias Site 112 cm/s
Iguaçu Falls Site 150 cm/s
CONAMA - Resolution
Salto Caxias Site 152 cm/s
Community of Foz do Iguaçu demand
“Nothing less than the minimum ever registered or nothing
worse than the nature had already done”
Iguaçu Falls registered data - from 1901 to 1995
Minimum monthly average flow registered - 150 cm/s
Ecological sluice gate with capacity of 155 cm/s
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9. DOWNSTREAM FLOW REGIMES
SCENIC FLOW
Small power plant in North Brazil – 12 MW
Discussion with the community about tourism activities downstream the
water falls (used only in the summer)
CONAMA-Environment National Council - Resolution number 20 “.. to
maintain the level of dissolved oxygen ... minimum flow for a drought of 7
days of duration and 10 years of return period” – 2,2 cm/s
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10. DOWNSTREAM FLOW REGIMES
SCENIC FLOW
The project owner built a model (CEHPAR in Curitiba) to try to help the visualization of the
impact
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11. DOWNSTREAM FLOW REGIMES
SCENIC FLOW
Downstream flow with 2,2 cm/s
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12. DOWNSTREAM FLOW REGIMES
SCENIC FLOW
Downstream flow with 3 cm/s
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13. DOWNSTREAM FLOW REGIMES
SCENIC FLOW
Downstream flow with 6 cm/s – The solution accepted by the community
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14. DOWNSTREAM FLOW REGIMES
SOME LESSONS TO TAKE AWAY
ALL STAKEHOLDERS HAVE TO BE CONSULTATE DURING THE
PLANNING STAGES
ENVIRONMENTAL AND REGULATORY AUTHORITIES SHALL
SET THE INITIAL CRITERIA FOR THE DISCUSSIONS BASED IN
RELIABLE TECHNICAL DATA
THE DISCUSSION MUST BE DONE IN A CLEAR AND
TRANSPARENT MANNER, AND THE LOCAL COMMUNITIES
SHALL BE LISTEN AND THEIR OPINIONS MUST BE TAKEN
INTO ACCOUNT
THE DISCUSSIONS HAVE TO BE IN A CASE BY CASE
SCENARIO
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RESEARCH (MAINLY BIOLOGICAL) HAVE TO BE DONE
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TO ENHANCE THE CRITERIA FOR THE DISCUSSIONS