Tucurui Reservoir
Experience and Lessons Learned Brief
José Galizia Tundisi*, Instituto Internacional de Ecologia, Sao Carlos, Brazil, jgt.iie@iie.com.br
Marco Aurélio Santos, Cidade Universitaria, Rio de Janeiro, Brazil
Carlos Frederico S. Menezes, Electrobras, Rio de Janeiro, Brazil
* Corresponding author
1. Introduction
2.
Main Problems of Reservoirs in Brazil
In the last 50 years, extensive construction of reservoirs 2.1 General
Issues
in many countries and watersheds in Latin America and
particularly in Brazil, has produced a great number of artifi cial
The general ecological consequences of river impoundments
systems, which have interfered with the hydrology and ecology
are related to several factors, among which the most important
of several basins, sub-basins, and large rivers. Most of the
are size, reservoir, volume, residence time of the water, and
reservoirs were built up initially for power generation but lately
geographic location. Many papers published in the international
they have been used for multiple activities, such as irrigation,
literature have reviewed and discussed their effects: inundation
recreation, navigation, fi sheries and/or aquaculture. In Brazil,
of valuable agricultural land; impairment of fi sh migration; loss
there has been large-scale construction of reservoirs for the
of terrestrial vegetation and fauna; changes in the river fauna
purpose of hydroelectricity production, as shown in Table 1.
and vegetation; hydrological changes downstream; interference
in sediment transport regimes; the spreading of waterborne
At present, approximately 30% of the hydroelectric potential
diseases by producing a favorable environment for vectors; the
of Brazil is being exploited. Several large-scale hydropower
loss of cultural/historical heritages; social effects on the local
projects are concentrated in the southeastern rivers, specifi cally
populations including relocation; and changes in economic
in the watersheds of the Tietê-Rio Grande, Paranapanema, and
activities and traditional land uses and practices. Geophysical
Paraná rivers, all of them sub-basins of the La Plata Basin
problems due to water accumulation have also been pointed
(3,000,000 km2). The production of hydroelectricity in Brazil
out and several downstream changes reported (Ackerman et
is strategic for the country's development since approximately
al. 1973; Balon and Coche 1974; J. Van der Heide 1982; Barrow
70% of the country's energy is generated by large hydropower
1982 and 1987; Tundisi et al. 1993). All these consequences are
reservoirs. One of the problems, however, is that most of the
due to direct or indirect impacts.
hydroelectric potential is concentrated in the north, far away
from the large urban centers and industrialized regions, The multiple uses of reservoirs combined with biogeophysical
demanding extensive transmission lines. These new reservoirs
and social characteristics produce many complexities,
cause impacts on regional and local ecosystems and in the
economic and hydro-social cycles.
Table 1. Generation of Energy in Brazil.
Reservoirs in Brazil, therefore, provide a reference point in
Power
Type
Number
%
(MW)
river systems since their evolution, changes in water quality
and eutrophication, and alterations in fl ora and fauna refl ect
Hydropower plant
138
64,197.6
70.91
existing watershed management, policies and the use of
Small hydropower
208
896.7
0.99
the land system (Straskraba, Tundisi and Duncan 1993). As
projects
intermediate systems between rivers and lakes, reservoirs
Central hydroelectric
144
78.4
0.09
have many mechanisms of functioning and the process of
generator
following up their changes is a theoretical and practical study
Thermoelectric plant
654
13,113.2

14.48
of high signifi cance. The main uses of reservoirs in Brazil are:
Thermonuclear plant
2
2,007

2.22
· Hydroelectricity;
Central wind generator
9

22

0.02
·
Water storage for irrigation;
Subtotal
1,155
80,314.9
88.70
·
Water storage for drinking purposes;
Importation
8
8,170
9.02
·
Production of biomass (fi sheries and aquaculture);
Emergency generation
54
2,049.5

2.26
·
Transportation and long distance navigation;
·
Recreation and tourism; and,
Total
1,217
90,534.4
100
·
Water storage for cooling purposes (industry).
Source: ANEEL
(2003).

---

confl icts, and diffi culties demanding innovative procedures, · Energy
production;
new approaches and innovative solutions for adequate ·
Control of transport of suspended material;
management. In addition several of these artifi cial systems are
·
Sources of water supply;
spatially complex, have a dendritic pattern, many side arms,
·
New opportunities for recreation and tourism;
and narrow channels near the tributaries.
· Enhanced
aquaculture;
· Navigation;
In general the reservoirs in Brazil, besides the problems ·
Increased potential of water for irrigation;
addressed above, produced, after fi lling, serious impacts due
·
Flood control and river regulation;
to water quality deterioration as a consequence of watershed
·
Fishery increased and aquaculture;
uses, as well as, discharge of industrial effl uents, residues of
·
Low-energy water purifi ers; and,
agricultural uses, and untreated sewage disposal. Populations
·
New economic alternatives in regional systems.
living along the river have had to adapt to the new hydro-
social cycle created as a result of reservoir construction and
The time of stabilization of the new hydro-socio-economic-
operation. The main problems of reservoirs in Brazil are:
water quality-limnological system varies from region to region,
with watershed uses and with the degree of urbanization
· Eutrophication;
and economic development, as well as with the general
·
Increased toxicity and general contamination;
characteristics of the reservoir and its construction.
·
Siltation and rapid fi lling-up with sediment;
·
Spreading of waterborne diseases;
2.2 Amazonian
Reservoirs
·
Salinization (in reservoirs in northeast Brazil);
·
Anoxic hypolimnion and severe downstream impacts The Amazon Basin with 6,000,000 km2 of drainage area
(mainly in Amazonian reservoirs);
has a tropical warm climate and a discharge of 3,767.8 km3
·
Low diversity of fi sh fauna as compared to rivers;
a year. The average humidity is 80%. One of the important
·
High internal load and toxic sediment;
characteristics of this region is the high water-level fl uctuation
·
Extensive macrophyte growth associated with eutrophication;
between the rainy and dry seasons promoting a corresponding
·
Loss of arable land; and,
hydro-social cycle (fi sheries, fl oodplain exploitation, local
·
Relocation of population.
navigation) (Tundisi 1994 and 2003; Junk et al. 1987).
Despite these impacts, reservoir construction in Brazil has In the Brazilian Amazonian region there are 5 reservoirs in
produced many positive results related to the national operation: Couracy Nunes, Curua Una, Tucurui, Balbina,
economy (hydroelectricity production) and regional and Samuel. Table 2 gives information on the technical
development by stimulating new alternatives for economic characteristics of these Amazonian reservoirs. These
and social exploitation of the water-impounded resources. The
Amazon reservoirs produce several alterations in the aquatic
positive achievements of reservoir construction in Brazil are:
environment, related to the high amount of organic matter
Table 2. Characteristics of the Five Amazonian Reservoirs.
Reservoir
Technical Characteristics
Coaracy Nunes
Curuá-Una
Tucuruí
Balbina
Samuel
Location (State)
Amapá
Pará
Pará
Amazonas
Rondônia
Main river
Araguari
Curuá-Una
Tocantins
Uatumã
Jamari
Drainage area (km2)
25,000
15,300
803,250
18,450
15,280
Filling phase (month)
-
-
6
18
5
Operation
Nov/75
1976
Mar/85
Feb/89
Jul/89
Power plant (MW)
40
40
4,000
250
216
Retention time (month)
-
1
1.7
11.7
3.5
Operational depth (m)
120
68
72
50
87
Inundated area (km2)
23
78
2,875
2,360
560
Total volume (km3)
0.138
0.472
45.5
17.5
3.2
Average discharge (m3/s)
1,045
-
11,000
577
350
Maximum length (km)
-
56
170
210
140
Maximum width (km)
-
4
40
75
20
Maximum depth (m)
-
18
75
30
-
Average depth (m)
-
5
19
11
-
Source: ELECTROBRAS/DNAEE
(1997).
422 Tucurui
Reservoir

---

accumulated due to the inundation of tropical rain forest, new
covered with tropical rainforest, situated in the area of the
physicochemical gradients in the water column (related to Tucurui reservoir project. Table 3 gives the average monthly
thermal stratifi cation, conductivity, dissolved oxygen, and pH),
fl ows of the Tocantins River at the town of Tucurui.
excessive growth of macrophytes, and insect proliferation.
Downstream, the main negative impacts are related to changes
3.2
Biogeophysical Features of the Reservoir and Its
in the hydrological cycle interfering with the fl ood pulse of the
Basin
fl oodplains, and alterations in the water chemistry.
Tucurui Reservoir has a surface area of approximately 2,430
3.
The Tucurui Hydroelectric Plant and Its
km2, with a storage capacity of 45 km3. The reservoir has a
Reservoir
complex dendritic pattern and has inundated a vast area of
tropical rainforest, most of which was not removed during
3.1
General Background: The Tucurui Reservoir Basin
the fi lling phase. A power construction plant was initiated in
1975, and operation started in 1984 with an installed capacity
The watershed of the Araguaia
and Tocantins rivers (Figure 1),
has an area of 803,250 km2
(IBGE 1991) and an average
discharge of 11,000 m3/s. The
Tocantins River has an length
of 2,500 km and the Araguaia
is a fl oodplain river 2,115 km
long. The area of the Tocantins
River is shared by the states of
Tocantins (58%), Mato Grosso
(24%), Pará (13%), Maranhão
(4%), and the Federal District
(1%). A large basin is formed
by
the Araguaia-Tocantins
Rivers, and several tributaries
of regional importance.
Sedimentary rocks contribute
with a very high concentration
of suspended matter and,
therefore, confer high turbidity
on the Tocantins river water.
The soils are composed mainly
podsols and latosols of low
fertility and high acidity. There
are no fl oodplains in the high
and middle Tocantins River;
therefore, the tributaries are
important contributors of
organic matter, and are regions
of nursery grounds for fi sh
fauna. The Tocantins watershed
is a continental one, with a
large latitudinal extension, and
a well-defi ned fl uvial period
consisting of high discharge
(December to May) and low
discharge periods (August to
October). More than two-thirds
of the watershed is covered by
"cerrado" (dry savanna), and
the annual rainfall is between
1,500 to 2,000 mm. The lower
portion of the watershed is Figure 1. The Tucurui Reservoir Basin.

Experience and Lessons Learned Brief
423

---

of 4,000 MW in 12 units of 330 MW and 2 units of 20 MW. In
power plant is part of a large system for hydropower and
the second phase now in development, 11 units of 375 MW
multiple uses of reservoirs planned and in construction for the
are foreseen. Thus, Tucurui Power Plant will supply a total of
Tocantins. Currently in operation in this watershed (Tocantins
8,370 MW in the fi nal stage of its implementation, providing
River) are Tucurui (4,000 MW fi rst phase), Serra da Mesa (1,275
hydroelectricity for the states of Pará, Maranhão, and MW in the High Tocantins), Luis Eduardo Magalhães-Lajeado
Tocantins as well as for other states of Brazil; this will be done
(the Middle Tocantins, with 850 MW), and the second phase
by CHESF (the hydroelectric company of the São Francisco of Tucurui with 4,125 MW). Other reservoirs being planned or
River) and also in the south and southeast through operations
already under construction are Serra Quebrada (1,328 MW;
with FURNAS.
June 2006), Estreito (1,200 MW; October 2007), Tupiratins
(1,000 MW; February 2008), Canoa Brava (450 MW; July 2002),
The reservoir has produced, as the other reservoirs in the Peixe-Angical (1,106 MW; February 2008).
Amazon region, the following impacts:
The main objective of the fi rst phase of the Tucurui project was
·
Loss of biodiversity of terrestrial and aquatic fauna and
to supply energy and to facilitate navigation, linking the low
fl ora;
and middle Tocantins River. In this phase the energy produced
·
High concentration of organic matter in the water bottom
was 4,000 MW. In the beginning, energy production was
due to vegetation inundation and chemical changes in
basically for supplying power for the city of Belem, capital of
the water downstream;
Para State. However, later on the production of aluminum and
·
Large volume of anoxic water in the reservoir and the construction of two large industrial complexes operated by
downstream;
Albras (Alunorte near Belem and Alumar in São Luiz, Maranhão)
·
Loss of water quality (low dissolved oxygen, high became the priorities. In addition, the Carajás Programme Iron
conductivity, low pH, high content of dissolved and One Project received energy from Tucurui.
particulate, organic matter);
·
High concentration of aquatic macrophytes, during the
The second phase of the Tucurui protect will take advantage
fi rst years of reservoir stabilization;
of the hydrological periods and excess water available during
·
Reduction of fi sheries downstream;
the rainy season. The project will also produce other secondary
·
Weakened physical infrastructure in the area including
direct and indirect effects in the reservoir: morphometric
reduced means of access, equipment serving changes will occur with exposure of 20% of the area (roughly
communities, and basic sanitation;
560 km2). Changes will occur in the hydrological system
· Decreased
effi ciency in land use;
downstream, with possible further reduction in the average
·
Unresolved resettlement problems; and,
levels of dissolved oxygen in the water.
· Infl uence of mining operations on the reservoir itself.
3.4
Limnological Characteristics of the Tucurui
Several papers have reported on these impacts: (Monosowski
Reservoir
1990 and 1991; Valença 1992; WCD 2000).
Tucurui Reservoir, like other reservoirs, has special limnological
Morphometric and limnological reservoir complexity entails features resulting from its morphometric characteristics,
very great complexity in the management strategy since climatological and hydrological patterns, and relatively low
the several horizontal and vertical compartments differ in retention time (45 days). Several papers have reported on the
mechanisms of functioning, water quality, water chemistry, limnological characteristics of this reservoir, such as Barrow
as well as other limnological features whose impacts along
(1987) and Junk and Nunes de Mello (1987).
the horizontal gradients of the reservoir vary as a result of
local changes in land and water use (Straskraba, Tundisi and
Tucurui Reservoir is a monomictic system with short periods
Duncan 1993).
of circulation, and thermal and chemical stratifi cation. Van
der Heide (1982) investigated stratifi cation in Brokopondo
3.3
The Context of Tucurui Reservoir: Development
Reservoir and distinguished four main zones: the riverine
and Construction
fl ooded bank lacustrine wetland which is a turbulent zone
with levels of dissolved oxygen similar to those in infl owing
Tucurui was the fi rst large-scale hydroelectricity project streams; the fl ooded bank zone, with reduced turbulence and
implemented in the Brazilian Amazon tropical rainforest. The
depletion of dissolved oxygen; the lacustrine zone with strong
Table 3. Monthly Flows of the Tocantins River at Tucuruí (m3/s).
Discharge
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Ave.
Average
15,315
20,815
24,319
23,802
15,319
7,684
4,499
3,125
2,340
2,661
4,592
8,815
11,107
Maximum
35,803
44,249
55,300
49,443
33,300
14,344
7,740
5,557
4,377
5,641
10,297
18,561
18,884
Minimum
5,590
7,197
10,317
13,463
9,074
3,923
2,276
1,655
1,320
1,267
1,714
2,761
6,068
Source: ELECTRONORTE
(1977).
424 Tucurui
Reservoir

---

thermal and chemical stratifi cation and anoxic deep layers;
of greenhouse gas would be 2.3-5.6 million tons of CH4 or
and the wetland zone, associated with the reservoir.
the equivalent of 56.4-128.9 million tons of CO2, using the
1994 IPCC 100-year integrating global warming potentials.
All these features are common in Tucurui Reservoir. The But, according to Fearnside (2002), this fi gure could be even
marginal areas and dendritic small inlets are permanently higher. The development of new technologies to improve these
stratifi ed with anoxic layers and have high conductivity. measurements will help to clarify this contribution.
The damming of some tributaries produced arms with high
retention time, and a special dynamic process in these areas;
The comparative study of gas emission (based on gross
the period of stratifi cation is greater, and high conductivity
emissions) from the surface of Tucuruí Reservoir with emissions
remains for longer periods in anoxic bottom water. These of generation from thermopower technologies shows that
limnological features of Tucurui Reservoir have the following
hydropower presents better results than thermoelectricity
consequences on the water chemistry downstream: until does. However more and improved methodology and research
40km downstream from the dam, the left side of the river has
must be done to detect emissions and carbon cycle studies.
low oxygen content and the right side of the river has higher
oxygen content.
The impacts on the fi sh fauna of Tucurui Reservoir can be
characterized as follows:
The biogeochemistry of Tucurui Reservoir is infl uenced by
the circulation or stagnation of the water masses, and by the
·
High reduction of fi sh diversity due to the change of
very high content of organic matter accumulated at its bottom
regime from riverine to lentic environments;
(estimated to be approximately 517 ton/ha of phytomass).
The bottom water of the reservoir contains signifi cant
· Modifi cations in the food chain due to the several
concentrations of ammonium (up to 1500 µg/l), H2S, CH4,
impacts on algae biodiversity and productivity; and,
and total organic carbon. Growth of macrophyte vegetation
was intense in the fi rst four years after damming, as shown in
·
Changes both in the aquatic fauna (fi sh, zooplankton,
Figure 2.
and benthos) due to low concentration of dissolved
oxygen and in water chemistry.
Tucurui Reservoir emits carbon dioxide and methane, as a
result of decomposing of the biomass existing in the fl ooded
These impacts occurred for a certain period and after
area before dam construction. As the dam ages, emissions
stabilization the fi sh fauna started to increase the biomass,
decrease (Rosa and Santos 2000). Table 4 shows the average
concentrated on certain species such as Cicchla occelaris.
gas fl uxes from Tucurui Reservoir. According to Rosa and Several studies organized and carried out during the pre-fi lling
Schaeffer (1995) and Fearnside (1997), the cumulative release
and post-fi lling phases have described the fi sh fauna, its
diversity, spatial distribution, and food habits (Merona 1985,
30
1986/1987).
25
3.5
The Relevance of Scientifi c Research and
Monitoring at Tucuruí Reservoir
20
The complexity of the tropical rainforest ecosystem associated
with terrestrial/aquatic ecosystem interaction is still diffi cult
15
to understand. This includes the hydro-social cycle along the
Amazon River and its tributaries, and the interactions with
10
fl oodplains (Junk and Numes de Mello 1997). The construction
Macrophyte Cover (%)
of Tucuruí Reservoir stimulated a great number of scientifi c
5
studies and many monitoring projects of limnology, zoology,
botany, climatology and hydrology, aquatic diseases, soil
0
capacity for agriculture and forestry. These studies contributed
1986
1988
1990
1992
1994
to improving knowledge of the Amazonian terrestrial and
Year
aquatic ecosystems impacts, and also resulted in some
Figure 2. Change in Macrophyte Coverage in Tucurui
management strategies for decreasing impacts of reservoir
Reservoir.
construction (ELETRONORTE/THEMAG 1987). Additional
Table 4. Mean Greenhouse Gas Fluxes from Tucuruí Reservoir.
Bubbles (mg/m2/day)
Diffusion (mg/m2/day)
Total (mg/m2/day)
Sampling trip
CH4
CO2
CH4
CO2
CH4
CO2
First sampling trip, 1998

13.15

0.15

192.21

10.433
205.36

10.433
Second
Sampling
Trip,
1999
2.47
0.07
10.90
6.516
13.37
6.516

Experience and Lessons Learned Brief
425

---

information on public health, waterborne diseases, and 3.7
Social Impacts of Tucurui Project
fi sheries and fi sh-catch downstream and in the reservoir was
included. Mitigation measures included tropical rainforest Tucurui dam construction and the inundation of 2,430 km2 of
clearing in the inundation area, rescue of terrestrial fauna, area displaced 4,300 families, 3 urban areas, 250 km of roads,
and aid to populations living downstream in order to alleviate
projects of colonization of INCRA and two Indian reserves. The
social impacts during the fi lling phase (Monosowski 1990).
civil works of the reservoir construction attracted a great deal
of new inhabitants, and between 1978-1979, there were 20,000
When Tucuruí Reservoir construction started very little workers at the dam site. The construction of Tucurui power
experience existed concerning such large hydropower impacts
plant promoted an acceleration of the territorial occupation
on the terrestrial/aquatic and socioeconomic environments of that region, with a very wide range of changes in the socio-
of the Amazon region. The research and monitoring program
economy of the region and several impacts on the hydro-social
considerably improved scientifi c knowledge of these impacts
cycle. For example, small-scale navigation was substituted by
but was unable to contribute to the prediction of indirect road transportation; there was also a change in the macro-
effects of the construction of Tucuruí Reservoir. This is economy through large-scale industrial and forestry projects,
relatively common in many hydroelectric developments (WCD
and agribusiness projects. Small businesses also developed
2000; Tundisi 2003). The capacity to predict the further very fast based on the demands from the rapidly increased
changes promoted by reservoir construction is still low.
worker's population (Valença 1992).
At the present time from the point of view of biodiversity losses
The hydropower plant of Tucurui attracted new activities,
and changes in the biota, three main impacts are considered as
resulting in the occupation of land, with a new confi guration
fundamental and of high relevance: changes in fi sh fauna; loss
of regional spatial structures and in the value of land, and
of the tropical rainforest and the destruction or displacement
new patterns of land use. Development of new urban spaces
of the terrestrial fauna; and growth of macrophytes and resulted in signifi cantly increased activity in the upstream
associated fl ora and fauna.
region (Valença 1992). However, changes downstream were
much more negative due to the decrease in fi sheries, the
3.6
Modeling Effort in Tucurui Reservoir
proliferation of mosquitoes and the high exploitation of the
natural resources of the area. Of the approximately 1,660
The modeling of Tucurui Reservoir was dedicated to the islands in the reservoir, many are occupied by resettled
development of knowledge of the impacts of organic matter
populations. Loss of fi sheries downstream represented an
decomposition and its effects on the water quality, as well
impact in the socio-economic structure of the region (WCD
as the relationships between the river intrusion as a density
2000). The changes in the hydro-social cycle will be continued
current fl owing into the reservoir and the periods of circulation
with construction of the second phase of Tucurui. The increase
and stagnation. It was a biogeophysical-chemical model in the capacity of power generation from 4,000 to 8,370
that considered the decomposition processes estimated by MW will produce further changes in the reservoir and in the
oxygen consumption and the horizontal and vertical circulation
structure and local of the local population. Resettlement
processes during two different hydrological conditions in 1986
programs to relocate approximately 1,500 families will be
and 1987 (Pereira 1994). The simulation carried out shows the
restarted with the second phase.
evolution of oxygen and ammonium concentrations at the water
surface and the bottom water. One of the main conclusions of
3.8
The Balance Between Development and
this model is that the degradation of the fl ooded vegetation
Environmental Impacts at Tucurui Dam
and the retention time of the reservoir infl uence quantitatively
the length and intensity of the anaerobic processes and the
If the changes in the general environmental characteristics
nutrient cycle. This has consequences in the reservoir and of the region and in the hydro-social economic cycles were
downstream.
extensive (WCD 2000); on the other hand, there was an
increase in the energy available and the inter linking with
The evolution of the water quality is dependent on the northeast and southeast systems was benefi cial to 13 million
hydrological cycle, the decomposition of the drowned inhabitants from Para and Maranhão states. ELETRONORTE
vegetation and the retention time. With the loss of carbon estimates that by 2006 more than 40 million people from
to the downstream ecosystems the water quality shows several states of Brazil will receive the energy produced by
improvements over the years. This has been considered an
Tucurui. The new environmental and social projects for Tucurui
important conclusion for Amazonian reservoirs: the lower hydropower reservoir and its area of infl uence include a new
the retention time the better water quality upstream and set of priorities such as:
consequently downstream. This is related to the size and
morphometry of the reservoir and has consequences on the
·
The Genome Bank, a joint project of ELETRONORTE
ecological responses of the terrestrial and aquatic systems.
and National Institute for Amazonian Research (INPA),
will promote better biodiversity preservation and also
increase reforestation with native plants;
426 Tucurui
Reservoir

---

·
The Native People settlements with several programs of
state and a vast geographic region of Brazil's north and
new reserves and relocation and stimulus to traditional
midwest. There are several projects of development in the
activities;
planning and implementation phase: new irrigation schemes
for agribusiness; new tourism activities; several projects for
·
New Conservation Units;
fi sheries and aquaculture; many new programs for recreation
and exploitation of the reservoirs water supply; and new
·
Improvement of monitoring and surveillance system on
navigation projects. Since recreation and tourism are a
the reservoir in Phase II; and,
relatively inexpensive activity for the population and these
artifi cial lakes are situated far inland, they have become
·
New projects on protection and studies of the fi sh fauna,
a special source of interest for developing these activities
including the economical aspects of the fi shery and and stimulating the economic potential derived from them.
fi sh biology. According to ELECTRONORTE, since the Therefore the future impacts of reservoir construction can be
revitalization of the fi sheries in the reservoir, a total of
even greater than those at the fi lling stage or immediately after
10,000 fi shermen and their families are operating in the
fi lling is completed. To control these activities and regulate the
area of the Tucurui Reservoir.
new ecosystem and its watershed is not an easy task. It will
demand a vast array of conceptual, technological, economic
Of the 280 fi sh species that dwelled in the river before the dam
and social tools and new institutional arrangements and
was constructed, 178 species are now dwelling in the reservoir.
organization.
Fisheries potential is estimated at 10,000 tons/yr. Large-
scale sanitation projects and environmental education are in
4. Lessons
Learned
progress. There is also a perspective of tourism development
considering attractions promoted by fi sheries, scenery of the
Over a period of 25 years, the project of the Tucurui
lake and other possibilities.
hydropower plant and reservoir incorporated several
ecological, economic, social and managerial experiences.
3.9
The Vulnerability of Large-scale Hydropower
Probably one of the most benefi cial results of the project was
Projects
the development of accumulated experience in the building
up of capacity for improving management of reservoirs that
Besides the impacts produced by the reservoir construction,
were constructed later in Brazil. In fact, one of the best results
there are several direct and indirect effects produced by the
was the incorporation of the environmental dimension in the
further development stimulated by a new structure and the
further operational procedures of the reservoirs. As pointed
changes in the hydro-social cycle. In general, there is a lack of
out by Monosowski (1990), the "environmental impact
predictive capacity of the environmental impacts studies on the
assessment (EIA) was one of the fi rst applications of this tool
post-construction development effects, either direct or indirect
in the Amazon region". There is no doubt of the contribution
(Tundisi 2003). The prediction capacity is improved with a of the methodology applied to Tucurui hydropower project to
better articulation of environmental, socio-economic and cost-
the electrical sector in Brazil. The scientifi c studies improved
benefi t analyses (Monosowski 1990). Strategic approaches to
considerably the knowledge of the Amazon ecosystems,
water resources development should consider the integrated
terrestrial and aquatic.
processes of multiple use objectives, optimization of the
projects at regional and local scale, and improved managerial
However, even considering these positive aspects and the
capacity with conditions and training to understand the trade-
effort to implement new methodologies and policies, several
offs between power producer region and consumption centers
problems needed special attention and should be considered
such as large urban and industrialized areas.
important lessons learned from this project.
New prospects and proposals for Tucurui Reservoir include ·
Environmental strategies require a wide spectrum of
several considerations for social and economic development:
approaches and techniques, applied with a systemic
vision of the whole process and not as a closed
·
Integration of community and decision makers;
technical-scientifi c-managerial operation. Despite the
·
Better use of scientifi c studies for improving the
several valuable scientifi c studies in Tucurui, this lack
management process and optimizing managerial
of integration of the several disciplinary efforts was
capacity;
responsible for weaker management strategies than
·
Improvement of negotiation strategies between stake
expected. There is an enormous effort to improve the
holders; and;
scientifi c knowledge on the impacts of the reservoir
·
Integration of watershed development and water uses
construction. The shortcomings of management
at the reservoir site.
actions were probably due to this lack of articulation
between science-management-social control and public
Tucurui dam is the last reservoir of a series of dams built
participation in the process.
up on the Tocantins River. This will certainly have enormous
infl uence on the economic and social development of this

Experience and Lessons Learned Brief
427

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·
The lack of predictive capacity related to the indirect
of society in order to improve negotiations between
effects of the impacts, such as the changes in the hydro-
decision makers, water users, private and public sector
social cycle, is another lesson to be learned. This is true
and the general public; methodologies for negotiations
for several hydroelectric projects, but for Tucurui, this is
and social control of projects should be implemented.
even more evident due to the environmental and social
complexity of the project.
·
The application of royalties resulting from the inundation
of the terrestrial systems should be amplifi ed to other
·
A complete evaluation of Phase I and Phase II of
types of compensation considering social, economic
the project could be made at the beginning of the
problems and other environmental processes. The
environmental impact assessment. This would probably
social control of the application of these royalties is
provide a better understanding of the local ecosystems
fundamental.
and the interaction between social and ecological
components and their evolution with time.
·
The strong scientifi c uncertainty of the hydroelectric
projects could be solved by the adoption of a systemic
·
The emphasis given to the evaluation of the direct
approach, the development of a predictive capacity and
impacts of the project on the biogeophysical components
a "precautionary principle" at all stages of the project
was correct but it was not suffi cient for predicting the
from planning to operation.
further impacts of Tucurui hydropower project at the
regional and local levels and the social and economic
·
The lessons learned from the Tucurui hydropower
components. This is common to all large-scale projects.
project should be used as a tool for the planning and
The consequences of the implementation of the new
future management of reservoirs in the Amazon region.
economic developments are diffi cult to predict and are
The analyses of the hydroelectric projects and their
not included as part of the environmental studies.
benefi ts to the whole national economy should also be
considered at the regional and local context including
·
A viable solution can only be found if the entire
the benefi ts to the watershed users and inhabitants.
watershed ecosystem is taken into consideration by
the management and a strong integration of science ·
Predictive, adaptive, and integrated management at the
and management is incorporated in the project.
watershed level is certainly the strategic tools of water
Integrated land use management and planning of water
research management for the future. New reservoir
uses is essential. In the case of the Tucurui project,
projects must refl ect this.
less importance, at least at the initial stages of the
environmental impact assessment, was given to the ·
The search for new economic alternatives for the local
watershed and downstream environment.
and relocated populations is fundamental as a social
tool.
·
Some important aspects considering the possible
long-term effects were not taken into account in the ·
Integration of water quality, eutrophication, sediment
beginning of the evaluation procedure.
transport and hydrodynamic models as well as the
studies on contributions from nonpoint sources from the
As a general contribution to the advances in management
watershed should provide better management capacity
and legislation the following recommendations could be
for the water quality upstream and downstream.
considered.
5. References
·
Future hydroelectric projects should incorporate
studies on the conceptual framework of regional and
Ackermann, W.C., G.T. White and E.B. Worthington (eds).
national strategic objectives for water uses and water
Geophysical Monograph 17. American Geophysical Union:
resources management in the environmental impact Washington, DC.
assessment. This should include not only in the study
on the hydroelectric potential but also in the evaluation
ANEEL (Brazilian Electricity Regulatory Agency--Agência
of social, economic and environmental impacts of each
Nacional de Energia Elétrica). 2003. Report.
alternative.
Balon, E.K. and A.A.G. Coche. 1974. Lake Kariba: A man-made
·
Long-range evaluation of the post-dam impact, tropical ecosystem in Central Africa. Junk Publication: The
with inclusion of cost-benefi t analysis, should be Netherlands.
addressed in the beginning of the environmental impact
assessment.
Barrow, C.J. 1982. "River Basin Development in Brazilian
Amazonia: a preliminary appraisal at the Araguaia-Tocantins".
·
A permanent evaluation of the whole watershed should
Latin American Regional Conference in Rio de Janeiro.
be considered with the participation of all components
428 Tucurui
Reservoir

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