biogeography and development in the humid tropics || the impact of hydroelectric development on the...

The Impact of Hydroelectric Development on the Amazonian Environment: With ParticularReference to the Tucurui ProjectAuthor(s): Chris BarrowSource: Journal of Biogeography, Vol. 15, No. 1, Biogeography and Development in the HumidTropics (Jan., 1988), pp. 67-78Published by: WileyStable URL: http://www.jstor.org/stable/2845047 .

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Journal of Biogeography (1988) 15, 67-78

The impact of hydroelectric development on the Amazonian environment: with particular reference to the Tucuruf Project

CHRIS BARROW Centre for Development Studies, University College of Swansea, University of Wales, Swansea SA2 8PP

ABSTRACT. Brazil has begun to exploit the hydroelectric potential of Amazonia. The Tucurui Dam is the first of many large hydroelectric projects planned for Amazonian Brazil to be completed. Without doubt, the environmental impact assessment studies carried out at Tucurui have great value for planning future Amazonian (and other humid tropical) hydroelectric projects.

A review of information on the environmental impacts of the Tucurui Project is presented together with observations made by the author during field visits to the Tocantins Basin and Belem region in 1981, 1983 and 1985. It is concluded that there is a need for more study of impacts downstream of Tucurui, also for some assessment of the effects of increasing the number of turbines operating there, and for an examination of why some predicted difficulties have not in practice been avoided.

An attempt is made to gather together the available information on other hydroelectric projects under construction or proposed for construction in Amazonian Brazil.

Introduction

Hydroelectricity generation was already an important source of energy in Brazil when, in 1973-74, OPEC raised petroleum prices. For some years little or no reserves of petroleum or natural gas were found and, faced with expensive imports of oil, Brazil had to find an alterna- tive. Large dams were seen as the solution and between 1969 and 1979 hydroelectricity production more than tripled. The trend continued, by 1985 roughly 40% of Brazil's total energy needs were provided by hydroelectricity (Mono- sowski, 1986).

Brazil has a mis-match between centres of energy consumption and areas with hydroelectric potential. The greatest demand (over 70% of total consumption) is in the

industrialized south-east which has only about 14% of Brazil's hydroelectric potential, much of which is already exploited. There is therefore increasing interest in damming rivers in north and north-east Brazil. In recent years Amazonia, with enormous untouched potential, of at least 85,000 MW according to Goodland (1980: 20), has attracted the attention of ELETRONORTE (Centrais El6tricas do Nort6 do Brasil S.A.), the subsidiary of the national power company ELETROBAS (Centrais El6tricas Brasileiras S.A.) in charge of electricity generation and supply in the north and north-east of Brazil and in Amazonia. ELETRONORTE has ambitious plans for dam construction in Amazonia. By AD 2000 it plans to generate about 40% of Brazil's total projected electricity requirement (roughly 22,000 MW)

67



68 Chris Barrow

from about forty large dams in Amazonia (Anon, 1978a; Caufield, 1982; Barham & Caufield, 1984).

Although some of the dams under construction or planned are mainly intended to generate power for cities, like Manaus or Santar6m, development of much of Amazonia's hydroelectric potential will be for the purpose of feed- ing power to consumers in the south-east and in the rapidly industrializing north-east of Brazil. There is also an expectation that hydroelectricity will play a key role in stimulating mineral resources exploitation and industrialization within Amazonia. Hydroelectric power is being made available close to rich mineral deposits at low prices to attract Brazilian and foreign mining and metal processing companies into Amazonia (in effect a local market is being created for the electricity). For example, in the Serra dos Cara- jas (between the Rio Tocantins and Rio Xingu) rich iron ore deposits are being mined with the help of electricity from the Tucurui Dam, the ore is transported by a 960 km long electrified rail- way to a deepwater Atlantic port at Itaqui near Sao Luis, where it is processed, again with the help of power from Tucuruf. Alumina deposits mined along the Rio Trombetas are being processed with power from Tucuruf by plants at Vila do Conde and Barcarena a few kilometres west of Bel6m. In Amazonia hydroelectric development is likely to have considerable indirect impact on the environment in addition to the direct problems caused by the dam, reservoir and transmission lines as there is likely to be pollution related to mining and mineral processing.

The Tucurui Hydroelectric Project and its environmental impacts

There is an extensive literature on the environmental impacts of large hydroelectric projects in the humid tropics of Africa, Asia and South- East Asia (for example: Interim Mekong Com- mittee, 1982; Szekely, 1982; Barrow, 1983; Goldsmith & Hildyard, 1984: vol. 2; Lelek, 1984; Petts, 1984), but there is little on impoundments in the humid tropics of Central and Latin America apart from Surinam (Leentvaar, 1967, 1975), Guyana, Mexico and Panama (Hunter & Munroe, 1978; Henningsgaard, 1981). Aspelin & Coelho dos Santos (1981) examined the

impact of hydroelectric development on Amazo- nian Indians, but the only other easily available studies which refer to Amazonia are assessments of the Tucurui Project (Goodland, 1978a, 1978b).

UHE Tucurui (the abbreviation UHE is used to denote Usina Hidrelectrica - Hydroelectric Utility) is the first large hydroelectric project to be completed in Amazonia Legal (Brazil's Amazonian administrative region). Brazil has considerable experience of building large dams; however, little or none of this relates to humid tropical forest environments. The Tucurui Dam was begun with little attempt at pre-project pre- diction and avoidance of environmental (or socio-economic) problems and has continued to generate controversy, as a consequence a significant component of what has been written on the Project has come from journalists rather than academics or consultants (for a good example see Caufield, 1985).

The Tucurui Dam is situated about 300 km south of the city of Bel6m on the Rio Tocantins (see Fig. 1). For much of its length the Tocantins is paralleled by the Rio Araguaia. Both have relatively gentle gradients (roughly 400 m in 2000 km) and flow for about two-thirds of their courses through a seasonally-dry savanna environment. Rainfall is higher in the northern third of the Tocantins-Araguaia Basin where there is a natural cover of humid equatorial forest. At Bel6m, at the mouth of the Basin, rainfall is typically between 2500 and 2750 mm/year with no month dry enough to check plant growth. At Tucurui municipality about 5 km from Tucurui Dam, rainfall averages 1750 mm/year and there is a distinct dry period (June-August) during which rainfall may be as low as 60 mm/month (Barrow, 1987).

Construction began at Tucurui in 1976, the Dam was closed in September 1984 (3 weeks ahead of schedule) and installed capacity generation (variously stated to be 2160 or 4300 MW, but more likely to be the latter) began in 1985. Planned installation of a second set of turbines, probably in the late 1980s, should raise power output to about 8000 MW (Monosowski, 1984: 192). In its first stage generating around 4000 MW, Tucuruf will produce power equivalent to burning 400,000 barrels of oil a day (Caufield, 1982: 243). Even at today's low oil prices of about US $9 per barrel, this represents a saving on imports of US$3,600,000 daily.



Hydroelectric development and Amazonian environment 69

If the generation capacity of Tucurui is raised to around 8000 MW, the flows released from the Dam and the levels of the Reservoir will differ from those experienced at present. Wildlife, farmers and fishermen, particularly downstream of Tucurui, will have to try to adapt again in 5 or 10 years time (no impact assessment so far made seems to have recognized this).

Power is carried from Tucurui to Bel6m and alumina processing plants near the city, by 230 kV transmission lines; 500 kV lines also transfer power from Tucurui via Imperatriz municipality to the grid of the north-eastern power supply company CHESF (Companhia Hidro-el6trica do Sao Francisco). CHESF will distribute electricity to other parts of Brazil and there is a further benefit, that dams on the Rio Sao Francisco should need to supply less electricity to the north-east and could release more water in the dry season for irrigation (Anon., 1985). There are plans to site a factory in Bel6m, which would use electricity generated by Tucuruf to make fertilizer (Anon., 1978b, 1978c). Cheap supplies of fertilizer in Amazonia could have considerable impact on farming. Fearnside (1983: 75) noted that trial applications of artificial fertilizer to poor soils along the Bel6m-Brasilia Highway (which runs roughly parallel and to the east of the Tocantins) proved most effective in raising crop yields.

An environmental impact assessment (EIA) of UHE Tucurui was commissioned by ELETRONORTE in 1977, 1 year after the Pro- ject had been started (1976) and the findings were published by Goodland (1978a, b). Although based on only 1 month of field study, and hindered by a weak database, Goodland's EIA was wide-ranging and detailed (Skillings, 1984: 48). Although an EIA, like that of Good- land's, initiated after a project has begun, can- not influence choice of site or style of development, it can be valuable for predicting side-effects and suggesting mitigating measures. Above all, such an EIA ensures information is collected and made available to planners.

In addition to the EIA by Goodland, ELETRONORTE initiated a series of studies on the environmental impacts of UHE Tucurui, most have been conducted by the Tucurui Pro- ject Group based at INPA (Instituto Nacional de Pesquisas da Amaz6nia), Manaus. INPA established a research station at Tucurui and also began to conduct studies on the impacts of

UHE Curua-Una, UHE Balbina, and UHE Samuel (Table 2). The Tucurui EIA studies seem to have identified most of the problems which have arisen so far, but lack of co-ordina- tion between various agencies involved in planning and managing the Project has meant that some warnings went unheeded (Monosowski, 1984: 14; Goodland, 1985: 5-9).

Problems due to Tucurui Reservoir flooding forests

Large dams in forested areas of the tropics have frequently generated difficulties because developers failed to clear vegetation before it was flooded. Failure to clear timber is also a waste of resources, in the case of Tucurui, an estimated 20 million m3 of high quality timber was lost (Monosowski, 1984: 14). The water conditions of a tropical reservoir may prevent flooded timber from decaying - this was the case with the Gatun Lake (Panama Canal), Lake Kariba (Zambia) and Lake Volta (Ghana) the Upper Pampanga Dam (Philippines) and several Thai dams (Lawson, 1970; Garzon, 1984). If standing timber does not decay, it is a hazard to shipping and fishing and may provide anchorage for aquatic weeds. In the short term at least, there are going to be problems with standing timber at Tucurui because the average forest canopy height was 35 m and the reservoir has a mean depth of only 20 m so many treetops will protrude (Goodland, 1985: 7). Long-term problems of non-decay of timber seem unlikely at Tucurui because there is a reasonable throughflow of water which should help ensure that it eventually rots.

Goodland's EIA warned of the risks of failing to clear timber but in the event most of the timber remained uncleared. Desperate but ill- managed attempts to clear the forest caused unwanted environmental impacts, a case of an EIA itself having environmental impacts. In response to warnings of the need to clear timber, ELETRONORTE, after much delay (probably because of the costs involved), awarded a contract to CAPEMI (Caixa de Peculio dos Militares - a large diversified company with more experience of handling the Brazilian Army's Pension Fund than logging) to clear parts of the Reservoir and the transmission line routes. CAPEMI began clearing in 1983 and then went bankrupt having removed a mere frac-



70 Chris Barrow

tion of what it was supposed to have (Caufield, 1985: 22). There have been reports that ELETRONORTE, left with a logging problem and little time to solve it, resorted to the use of chemical defoliants: Barham & Caufield (1984) reported the use of 350 drums of PCP (sodium pentachlorophenol). They suggested that some of these drums of highly toxic compound, possibly as much as 16 tonnes, were lost or abandoned in the area that was flooded to form Tucurui Reservoir or along transmission line routes. Livestock and human deaths and illness were reported to have resulted from the spraying of this defoliant or because people handled empty drums or somehow became contaminated (Monosowski, 1984: 15). In spite of these problems, ELETRONORTE is reported to have considered using defoliants at UHE Balbina (DelQuiaro, 1985).

In newly formed tropical reservoirs, drowned soil and vegetation may release nutrients causing the water to become eutrophic, the activity of microorganisms can cause the water to become deoxygenated and contaminated with the pro- ducts of decomposition. Some reservoirs become 'stratified' with layers of deoxygenated water persisting for a very long time. In some cases deoxygenation may become so bad that virtually no fish can exist in the reservoir. Releases of deoxygenated water may cause fish kills for a hundred or more kilometres downstream of a dam; for example, releases from the Brokopondo Reservoir damaged fish stocks for at least 50 km downstream (Goldman, 1979; Caufield, 1985: 20).

If large quantities of hydrogen sulphide are generated by decomposition of drowned organic matter in a reservoir, it can taint the water mak- ing it unusable for domestic consumption or irrigation. There may also be a smell that makes life unpleasant even at 20 km distance. Another important impact of high levels of hydrogen sulphide, though not an environmental problem, is that generation equipment gets corroded. Water from the Brokopondo Reservoir caused damage estimated in 1977 at US$4 million (over 7% of the total project costs) (Caufield, 1982: 210; 1985: 17). At Curua-Una the problem caused over US$5 million (at 1982 prices) between 1977 and 1982.

The Tucurui Reservoir is relatively shallow, which means that sunlight can penetrate enough to ensure phytoplankton, algae and aquatic

weeds produce sufficient oxygen to reduce the risk of deoxygenation and hydrogen sulphide build-up. Wind, inflowing streams and diurnal temperature variations should also ensure that the Tucurui Reservoir mixes and does not become too stratified. Water in the Tucurui Reservoir changes six or seven times a year, much more often than is, for example, the case with the Brokopondo Reservoir (which took 10 or 12 years to fill) or at UHE Balbina, where problems are likely because of slow throughflow.

Tucurui Reservoir: weed growth problems

While Tucurui Reservoir is unlikely to suffer long-term deoxygenation, it is possible that there will be aquatic weed growth problems, at least for the next few years (longer if more turbines are installed). The problem has been well studied, particularly in Africa (Gaudet, 1979; Barrow, 1983: 457). Goodland (1978a: 117) listed weeds which might cause difficulties at Tucurui, the most likely nuisance is the water hyacinth Eichhornia crassipes, which colonized over 400 km2 of the Brokopondo Reservoir and caused problems at UHE Jupia (on the Rio Parand south of Amazonia Legal - not to be confused with the Rio Parand, tributary of the Tocantins) (Junk, 1983). A floating plant Azolla spp. is being grown in agricultural stations within a few hundred kilometres of Tucurui and is being promoted as a 'green manure' for rice 'polders' (vdrzea fields that are bunded and flooded). It is possible that this could spread to become a pest, although there have been no problems with it in South and South-East Asia. Azolla microphylla, A. caroliniana, A. pinnata and A. filiculoides have been reported in the Bel6m region (Nasci- mento & Homma, 1984: 274), and were seen by the author in trials fields in Bel6m in 1985.

Heavy weed growth may hinder electricity generation, navigation and fishing. The surface cover may exclude light and dead weeds may rot and cause oxygen depletion; both affect the aquatic flora and fauna. Aquatic weeds can provide a habitat in which disease-carrying mosquitoes or snails can breed; this is likely to be one of the main risks with the Tucurui Reservoir. To avoid excessive weed cover, reservoir managers may be tempted to use herbicides, as was the case with the Brokopondo Reservoir. Defoliants have already got into the lower Tocantins and




Para 'estuary', any further contamination with harmful chemical should be avoided at all costs.

Reservoir siltation problems

The Tocantins is, or rather was, a 'clear' seasonally 'white' water river, that is, its waters were oligotrophic but carried enough silt during floods to form vdrzeas (lev6es and floodplains) along its mid and lower course. Throughout this chapter mid-Tocantins refers to that section of the river from Maraba to about 100 km below Tucurui; lower-Tocantins refers to the River from 100 km below Tucurui to the confluence with the Pard 'estuary'. Over the last three or four decades, forest clearance and settlement has greatly increased the rates of erosion in the upper- and mid-Tocantins-Araguaia Basin, and increasing quantities of silt are supplied by a tributary, the Rio Itacaiunas. The Itacaiunas falls from the Serra dos Carajas with quite a steep gradient (c. 500 m in 360 km) draining a humid tropical catchment that is being rapidly cleared for mining and agricultural development.

Whether the Tocantins above UHE Tucurui could still be called a 'clear' water stream is debatable for there is enough silt being carried to make the silting-up of the Tucurui Reservoir a significant possibility. A number of large dams have silted-up before they could even recoup construction costs, for example the Anchicaya Project (Colombia) lost 80% of its storage capacity within 12 years (Allen, 1972). About half of Tucurui Reservoir's storage is 'dead storage' (depressions in a reservoir bed that can- not contribute water to turn turbines) which could fill with silt without affecting electricity generation and give the authorities time to mount an erosion control programme in the basin. If siltation becomes a problem, UHE Tucuruf may be forced to make large volume water releases during the flood season to 'flush' out silt, and this may have marked downstream impacts on wildlife.

Alteredflow regimes and water quality below the Tucurui Dam

The Tocantins has a markedly variable flow with a recorded range between 1511 m3 s-1 and 68,400 m3 S-1 (PRODIAT, 1982a: 53; and perso- nal communication with ELETRONORTE

staff, 1981). Before closure of the Tucurui Dam, extensive flooding in the mid- and lower-Tocan- tins was a seasonal occurrence, marks left by floods just before Dam closure were clearly visi- ble on buildings at Nazar6 dos Patos (about 20 km below Tucuruf). These indicated a level 20 m above the river level at the time of the author's visit - which was the low water season (July 1985). Flooding still takes place, but it reaches lesser heights. To consider the regulation of flooding a 'benefit', which most commen- tators do, is misguided; wildlife and people are (or were) adapted to flooding, even dependent upon it. Many fish species enter the flooded vdrzeas and forests to feed, spawn or to escape predators, some fish and invertebrates are stimulated to spawn by floods and people who dwell along the Tocantins have strategies which actually exploit flooding (Welcomme, 1979; Barrow, 1985).

Before closure of the Tucurui Dam, low water flows at Tucurui averaged 2000 cusecs (56.6 m3 s-1) and mean flows were 9203 cusecs (260.4 m3 s-1), since dam closure minimum flows are said to be not less than 6000 cusecs (169.8 m3 s-1) (interviews with Tocantins pilot and with various government personnel, 1985). The effect of reduced flood levels and maintenance of greater low water flows has been to reduce the amount of vdrzeas exposed. This has affected small- holder agriculture, at least in the mid-Tocantins; smallholders in several riverside locations between Tucuruf and a point about 60 km downstream who were interviewed by the author in July 1985 complained of the loss of cultivatable vdrzeas). To argue that such farmers have 'gained security' through the reduction of flooding is pointless, for they always made allowance for crop loss and by and large avoided flood damage.

Whether, as a result of reduced vdrzea areas, smallholders will turn to clearing forest and farming terra firme - drylands on which it is less easy to sustain cultivation without soil degrada- tion - remains to be seen. Vdrzea cultivators, in both the mid- and lower-Tocantins, rely on floods to deposit silt on their land; reduced flooding and silt deposition may well affect the sustainability of this flood-recession agriculture, especially in the mid-Tocantins.

Some might argue that the Tucuruf Dam is trapping the silt resulting from human activities in the upper-Tocantins and that downstream



72 Chris Barrow

conditions are 'restored' to something like their natural condition. This seems unlikely in view of the comments from farmers and fishermen who reported problems with water quality since Dam closure. Fishermen between Tucurui and a point about 50 km downstream who were interviewed in July 1985, reported that waters were now so clear that they were forced to fish by night or to buy expensive nylon nets in order to catch fish. They also claimed that there had been a change for the worse in the types of fish caught. One farmer about 30 km below Tucuruf commented that for about 12 years he irrigated his vdrzea lands with water from the Tocantins, but that since Dam closure his crops have been damaged and he has had to cease irrigation. The indications are, therefore, that waters below Tucurui, at least in the low water season, are much clearer than they were in the past, which will affect plankton production and higher organisms right down to the Pard 'estuary'. Why the water should now damage crops is unclear, it may be a relatively short-term increase in hydrogen sulphide in the Reservoir due to decomposition of drowned organic matter. It may be contamination with herbicide/defoliant or even sewage pollution from the considerably enlarged municipality of Tucurui. What is clear is that more studies are needed of the downstream impacts of UHE Tucuruf.

In the lower-Tocantins reduction of flooding may not be such a disadvantage. Vdrzeas tend to be lower and wider than those in the mid-Tocan- tins and there is a trend towards rice-growing using 'polders' constructed by bunding (Barrow, 1981b, 1983, 1985). Regulation of flows will, if anything, help such cultivators. In addition, these lower-Tocantins farmers rely on tides to 'back-up' river water and flood their polders. River regulation helps them avoid unexpectedly high inundation and predictable tidal influence seems to have increased since Dam closure; boatmen at Tucurui reported regular 'half- metre' tides, where previously there was little or none.

Doubtless reduced silt loads will affect the fish and invertebrates of the lower-Tocantins/Pard 'estuary', but another impact on river faunas will be the reduced saltwater intrusion resulting from regulated low water season flows maintained at about 3 times the pre-Tucuruf minimum. Whether this will affect fisheries, especially those of the prawn (Macrobranchium

amazonicum) of the lower-Tocantins, remains to be seen. Altered freshwater flows may lead to changes in the way silt is flocculated in the lower Tocantins/Para 'estuary' which may alter the pattern of mudbank and vdrzea formation. In the mid-Tocantins, according to a riverboat cap- tain interviewed in 1985, sandbank formation has changed, and this now means that one-third less course corrections are required during the low water season, considerably reducing upstream voyage times.

Human health impacts

There is a large literature on the human health impacts of large tropical hydroelectric projects (e.g. Stanley & Alpers, 1975; Gangstad, 1978: 36-38), and a list of the main communicable diseases of Amazonia is given by Goodland & Irwin (1974: 170). The level of the Tucuruf Reservoir will rise and fall 12-14 m which will create a 'drawdown zone' (an alternately flooded and exposed zone) of between 900 and 1000 km2 (Goodland, 1978a: 13; Monosowski, 1984: 9), disease-transmitting mosquitoes, snails, flies and rodents may well breed in this zone and be difficult to control.

Malaria was a serious problem in the Tucuruf municipality before Dam construction. Now that malaria-carrying mosquitoes, and many other organisms which in the past were pre- vented from dispersing by unbroken forest, can spread along roadside verges and in roadside ditches, the disease may become even more of a problem. Insecticide is already sprayed on houses in the Tocantins-Araguaia Basin at regular intervals to try to control malaria-carrying mosquitoes. If the incidence of the disease increased, the chances are that more insecticide would be used on mosquito breeding sites (like the drawndown zone), with ill-effects on wildlife in and around the Reservoir and downstream.

Mosquitoes which carry yellow fever may be able to breed in floating water weeds as well as their usual site: the rain-filled 'cups' of epiphytic bromeliad plants (Goodland, 1978a: 18). Forest clearance associated with the construction of Tucuruf and the relocation of at least 15,000 people from the area flooded by the Reservoir may have affected monkey populations which are the 'pool of infection' for yellow fever and various other mosquito-borne diseases. The combination of more mosquito breeding sites




and monkeys living in close proximity to people could result in increased outbreaks of yellow fever in the Tucurui region.

At least 14 million Brazilians have schistosomiasis, Schistosoma mansoni and S. haematobium were common in the Tucurui area before the Dam was built. However, the focii of infection were limited, because the snails which carry the parasite did not generally flourish in the neutral to acidic waters of the Tocantins. Snails capable of transmitting schistosomiasis (Biomphalaria spp., notably B. staminea and B. glaberata) are present in various localities, even locally on the Tocantins at Maraba (where limestone outcrops reduce the acidity of water). There is a real chance that water acidity may be reduced if farmers around the Tucurui Reservoir and downstream of the Dam apply lime and/or artificial fertilizers to their land (some may be forced to now annual supplies of flood-deposited silt are denied them). Once schistosomiasis transmission becomes widespread, it would be difficult to control and may prompt the authorities to use chemical molluscicides, which could affect wildlife in the region and for long distances downstream.

Onchocerciasis (river blindness), carried by blackflies of the Simulium genus can be a problem in parts of Amazonia. However, by restrict- ing settlement this may actually benefit wildlife. Henninsgaard (1981: 17) noted that it spread to Roraima and southern Venezuela after the Northern Perimitral Highway was opened through the north of Amazonia. Blackflies carry other diseases, plagues of blackflies, probably caused by deforestation-related environmental changes, coincided in 1972 with an outbreak of a (?viral) haemorrhagic disease in Altimira (roughly midway between Maraba and San- tar6m) (Hunter & Monroe, 1978: 131). Leishmaniasis, spread by sandflies, may increase if a belt of scrub is allowed to develop in the drawdown zone of the Tucurui Reservoir.

Another problem is Chagas disease (Try- panosomiasis cruzeii - South American sleeping sickness) which is spread by reduviid bugs (Triatoma sordida and Panstrongylus megistus). these bugs infest poor quality dwellings that are characteristic of newly settled regions, like that around Tucurui. Wildlife and people moving along newly-constructed roads help to spread the bugs (Bucher & Schofield, 1981). A major culprit for dispersing the bugs is said to be the

house sparrow (Passer domesticus). Sparrows spread the 1500 km from Brasilia to Bel6m within a very short time of the opening of the first road link in the early 1970s. Within a few years sparrows moved along new highways to colonize Maraba and the Tucurui region in 1973 (Good- land & Irwin, 1974: 171).

Rodents will invade new areas thanks to road construction and cleared electricity transmission line routes; they may also multiply if scrub colo- nizes the drawdown zone of the Reservoir. The main disease risk associated with such coloniza- tion would be bubonic plague, which is common in the Sao Francisco Basin east of the Tocantins. This can affect wildlife as well as humans and may kill a range of mammals.

Wildlife impacts

Inevitably there have been species losses due to the construction of the Tucurui Dam. The forests in the area flooded were particularly rich in Liana spp. and Brazil nut trees (Bertolletia excelsa) (Goodland, 1978a: 1-3). The Tocantins does not have a particularly rich fish fauna by Amazonian standards; there are only about 200 known species, but a significant proportion of these are migratory and/or depend on periodic inundation of vdrzeas (Junk, 1975). UHE Tucurui is not equipped with fish ladders so migration has been curtailed. This may be partly remedied if navigation locks are installed but, by the time that happens, damage will have been done. As further dams are constructed in the basin the migration of fish, and other aquatic fauna will be even further restricted.

What effect the Dam will have on populations of manatee (Trichechus inunguis), river dolphin (Satalia) and Amazon dolphin (Inia geoffrensis) is unknown. The young of turtles and caiman species should be able to survive passage through spillways or even through turbines, but young and adult aquatic mammals are unlikely to survive. In effect there are now separate, isolated breeding populations of dolphins, and possibly manatee, and this will only change if suitable navigation locks are built.

The impact of UHE Tucurui on conservation areas is difficult to assess because it is mainly indirect - by attracting people into the region and stimulating development there will inevitably be some effect. The cleared routes of transmission lines make it easier for people to gain



74 Chris Barrow

access to forest areas and this may lead to increased pressures on flora and fauna. A 562,000 ha national park, the Parque Nacional do Araguaia, which consists largely of the Ilha do Bananal (see Fig. 1), and the Campos do Moju biological reserve north of the settlement of Mocajuba (on the east bank of the Tocantins, about 160 km below Tucurui) are likely to suffer increased disturbance and the latter may be affected by reduced flooding (Padua & Quin- tado, 1982). There is a significant risk of pollution in the lower Tocantins/Pard 'estuary' from

the aluminium plants at Vila do Conde and Bar- carena near Bel6m.

Future hydroelectric projects in the Tocantins-Araguaia Basin

Planning studies on the Tocantins-Araguaia Basin have been in progress for some years and have generated detailed proposals (PRODIAT, 1982a, b; a more recent planning study by PRO- DIAT was finished in 1985 but has not been

BELEM

Tucurui

MGrabd '22 3 Imperatriz

/ I,

1 67 E

t~ ~ ~~~1 A2 A

2 12 13ASLI

2 7~~~~~~~~~~~~~~~1

FIG. 1. Large hydroelectric projects completed, under construction or planned for the Tocantins-Araguaia Basin. The names of the dams numbered in this Figure and information on each is given in Table 1.




TABLE 1. Large hydroelectric projects, completed, under construction or planned for the Tocantins- Araguaia Basin. Numbers in this Table refer to numbers used in Fig. 1.

No. Name of River Status Approx. mean Approx. Approx. dam (Rio) area of installed maximum (UHE) reservoir power potential

(kM2) (MW) power (MW)

1 Tucurui Tocantins C 2160 4300 7960 2 Maraba Tocantins P - - - 3 Santo Antonio Tocantins * 627 970 1370 4 Farinha Farinha P 170 20 69 5 Carolina (Alto) Tocantins * 3860 1143 2227 6 Balsas II das Balsas P 50 42 90 7 Sono II do Sono P 222 82 179 8 Sono I do Sono P 288 57 116 9 Balsas I das Balsas P 458 62 115

10 Porto Nacional Tocantins P 1744 445 881 11 M.A. Nattividade M.A. Natividade P 416 32 62 12 Peixe Tocantins * 1960 590 1059 13 Palma Palma P 198 33 79 14 Parana II Parana P 282 56 145 15 Parana I Parana P 1607 77 128 16 Sao Felix Tocantins * 1492 648 1328 17 Tocantinzinho Tocantinzinho P 56 29 57 18 Almas das Almas P 50 41 48 19 Maranhao III Maranhao P 434 69 137 20 Maranhao I Maranhao P 615 72 122 21 Itacaiunas II Itacaiunas P 910 133 182 22 Itacaiunas I Itacaiunas P 1030 87 135 23 Santa Isabel Araguaia * 1680 1258 1761 24 Xavantina dos Mortes P - - -

25 Barra do Caiap6 Araguaia P 238 114 220 26 Torixor6u Araguaia P 30 121 220 27 Barra do Peixe Araguaia P 674 161 279 28 Couto de Magalhdes Araguaia * 34 109 220

C Completed at time of writing. *=One of the projects most likely to be completed. P=Preliminary investigations under way by 1982. For a map showing the likely extent of Rio Tocantins impoundments see O'Reilly Sternberg (1981). Sources: Pandolfo (1979), Anon. (1978a, 1981), Aspelin & Coelho dos Santos (1981: 51), PRODIAT (1982a: 42, 43).

released to the public). UHE Tucurui is part of an overall programme for the Tocantins- Araguaia Basin: the Tocantins River Basin Hydroelectric Project. This envisages a further six or seven large, and nineteen smaller impoundments on the Tocantins and five or six on the Araguaia (see Fig. 1 and Table 1).

If all the dams proposed for the Tocantins- Araguaia Basin were built, the chain of reservoirs formed would reach from Tucuruf nearly 2000 km south to Aruana (Goias State), only 125 km from Brasilia. Provided suitable ship locks were installed, year-round bulk transport of goods between the heart of Brazil and Amazonia/the Atlantic would be possible. There have even been suggestions that such a

navigation route could be extended to reach the Parana River system to give the Belo-Horizonte- Rio steel industries access to Amazonia (for charcoal) and the Atlantic (for export of finished steel) (O'Reilly Sternberg, 1981: 15). The impacts of such ambitious developments would make the impacts of UHE Tucurui insignificant as the riverine ecosystem would be largely con- verted to lacustrine ecosystems on a grand scale.

Amazonian hydroelectric development outside the Tocantins-Araguaia Basin

There is a limited amount of published information on Amazonian hydroelectric projects other



INSET MAP PAMAZONIA LEGAL : . : : + / 1 -- - X : :;EL (UN SH ADED) 1 RSIA- o HydroeLectric projects -:: ::: ::::;- X:: _ -.--

(Tocont ins -A roguolo project s -.-.-:... .-- seeF4... R al)a y 0 400ckm

FIG. 2. Hydroelectric projects completed, under construction or planned for Amazonia (excluding the Tocantins-Araguaia Basin). The names of the dams and the rivers on which they are sited together with available information is given in Table 2 (the numbers used on this map are those used in Table 2).

TABLE 2. Large hydroelectric projects completed, under construction or planned for Amazonia (excluding the Araguaia-Tocantins Basin)

No. Name of River (Rio) Approx. size Initial Status Reported dam reservoir installed impacts

(kin) power (see capacity notes (MW) below)

1 Balbina Uatuma 2100 250 + I, 0. D, F, R' 2 Porteiras Trombetas 1400 1191 UC N 3 Itapeuara Jari 1800 252 UC 4 Coaracy-Nunes (Paredao Reservior) Araguari 100 40 C W, F, 0 5 Samuel (Cachoeira Samuel) Jamari 645 216 C 6 Curua-Una Curua-Una 90 to 100 20 C W, F, 0, S2 3 7 Cararao Xingu4 1200 P 8 Babaquara Xingu4 6100 P 9 Jurua Xingu P

10 Carajari Inir P 11 Innr Innr P 12 Carajas Xingu4 P 13 Kaiapo Xingu P 14 Gorotire Xingu P

C=completed; + =nearly completed; UC=under construction; P=proposed. Data are approximate throughout this Table.

lEnvironmental impact assessment begun before project was finished, but not before project was started (studies at Tucurui began 1 year after pro ject had started and continue). At Balbina construction begun in 1981 and impact studies in 1982.

2 Environmental impact assessment begun after project was finished. Four years of study at Curua-Una. 3Twenty manatee introduced in 1981 to try to control weeds. Rio Xingu projects most likely to be built in near future.

Key to impacts: F=fish; I=indians; 0=deoxygenation; W=weed problems; DF=use of defoliants; R=resettlement problems; M=malaria; S=schistosomiasis; N=flooding of nature reserve.




than Tucuruf. Projects built, under construction or planned are noted in Fig. 2. Table 2 summar- izes available details which include worries about the use of defoliants at UHE Balbina (DelQuiaro, 1985). Balbina's large shallow reservoir is also likely to suffer deoxygenation, hydrogen sulphide and weed growth problems. The Porteiras Dam now under construction may flood part of the Trombetas Biological Reserve and Curua-Una may well have problems with schistosomiasis as snails thrive there. After the Tocantins-Araguaia Basin, the Rio Xingu seems likely to be heavily developed; nine or ten dams are proposed or planned, and some would impound large reservoirs.

The indications are that large dams are going to be installed in Amazonia at regular intervals over the coming decades, and even with the best planning there are going to be considerable environmental impacts. Efforts need to be made now to find out as much as possible about likely impacts and how these might be best avoided.

Acknowledgments

The views expressed in this paper are those of the author, and do not necessarily reflect those of institutions or individuals mentioned. I am most grateful to the Nucleo dos Altos Estudos Amaz6nicos, Universidade Federal do Para, Bel6m, Brazil and to the British Council and University College of Swansea for support and funding. My thanks are also due to many staff members of EMATER, EMBRAPA, ELETRONORTE and to a number of smallholders who showed me warm hospitality during field visits.

References

Allen, N. (1972) The Anchicaya Hydroelectric Project in Colombia: design and sedimentation problems. The careless technology (ed. by M. Farvar and T. Milton), p. 318. Natural History Press, Garden City, New York.

Anon. (1978a) Aqui tem energia para dar e vendar Amaz6nia, IV (42), (outubro 1978), 6-12.

Anon. (1978b) Tucurui energia do Tocantins para o Norte e o Nordeste. Amaz6nia, IV (38), (junho 1978), 6-10.

Anon. (1978c) Nos aguas a forqa energ6tica da Amaz6nia. Carta da Amaz6nia VI (56) (janeiro- fevereiro 1978), 12.

Anon. (1981) Tucurui: energia e desenvolvimento, A. Provincia do Pard (caderno especial), 20 julho, 1981.

Anon. (1985) South, No. 57, p. 47. Aspelin, P.L. & Coelho dos Santos, S. (1981) Indian

areas threatened by hydroelectric projects in Brazil IWGIA Document 44, International Workgroup for Indigenous Affairs, Copenhagen, Denmark.

Barham, J. & Caufield, C. (1984) The problems that plague a Brazilian dam. New Scientist, 104, (1425), p. 10.

Barrow, C.J. (1981a) The health and resettlement consequences and opportunities created as a result of river impoundment in developing countries. Water Supply and Management, 5, (2), 135-150.

Barrow, C.J. (1981b) Development of the Brazilian Amazon, Mazingira, 5 (4), 46-47.

Barrow, C.J. (1983) The environmental consequences of water resource development in the tropics, Natural resources in tropical countries (ed. by Ooi Jin Bee), p. 439-476. Singapore University Press.

Barrow, C.J. (1985) The development of the vdrzeas (floodlands) of Brazilian Amaz6nia. Change in the Amazon Basin, Vol. 1: Man's impact on forests and rivers (ed. by J. Hemmings), pp. 108-128. Manchester University Press.

Barrow, C.J. (1987) The environmental impacts of the Tucuruf Dam on the middle and lower Tocantins River Basin. Regulated Rivers, 1 (1), pp. 49-60.

Bucher, E.H. & Schofield, C.J. (1981) Economic assault on Chagas Disease. New Scientist, 92 (1277), 321-324.

Budweg, F.M. (1982) Reservoir planning for Brazilian dams. International Water Power and Dam Con- struction, 35, (4), 48-49.

Caufield, C. (1982) Brazil, energy and the Amazon. New Scientist, 96, (1329), 240-243.

Caufield, C. (1985) In the rainforest. Pan Books, London.

Delquiard, R. (1985) Brazil to drown forest in herbicides. New Scientist, 105 (1443), 9.

Fearnside, P.M. (1983) Development alternatives in the Brazilian Amazon: an ecological evaluation, Inter9iencia, 8, (2), 65-78.

Gangstad, E.G. (1978) Weed control methods for river basin management. CRC Press, Palm Beach, Florida.

Garzon, C.E. (1984) Water quality in hydroelectric projects: considerations for planning in tropical forest regions. World Bank Technical Paper No. 20, Washington, D.C.

Gaudet, J.J. (1979) Aquatic weeds in man-made lakes. PANS, 25 (3), 279-286.

Goldman, C.R. (1979) Ecological aspects of water impoundment in the tropics. Unasylva, 31, 2-11.

Goldsmith, E. & Hildyard, N. (1984) The social and environmental effects of large dams, vol. 2: Case studies. Wadebridge Ecological Centre, Camelford.

Goodland, R. J . A. (1978a) Environmental assessment of the Tucurui Hydroproject, Rio Tocantins, Amazonia, Brazil. Eletronorte S.A., Brasilia, D.F.

Goodland, R.J.A. (1978b) Environment assessment



78 Chris Barrow

of the Tucuruf Hydroelectric Project Rio Tocan- tins, Amaz6nia. Survival International Review, 3 (2), 11-14.

Goodland, R.J.A. (1980) Environmental ranking of Amazonian development projects in Brazil. Environmental Conservation, 7, (1), 9-26.

Goodland, R.J.A. (1985) Brazil's environmental progress in Amazonian development. Change in the Amazon Basin, Vol. 1: Man's impact on forests and rivers (ed. by J. Hemming), pp. 5-35. Manchester University Press.

Goodland, R.J.A. & Irwin, H.S. (1974) An ecological discussion of the environmental impact of the highway construction program in the Amazon Basin. Landscape Planning, 1, (1), 123-254.

Goudling, M. (1980) Thefishes and the forest. Univer- sity of California Press, Berkeley, California.

Goldman, C.R. (1979) Ecological aspects of water impoundment in the tropics. Unasylva, 31, 2-11.

Henningsgaard, W. (1981) The Akawaio, the Upper Mazaruni Hydroelectric Project and national development in Guyana. Occasional Paper No. 4, Cultural Survival Inc., Cambridge, Mass.

Hunter, 0. & Munroe, P.A. (eds.) (1978) Hydro- power and environment (Proceedings of the Inter- national Seminar on Hydropower and the Environment, Georgetown, Guyana, 4-8 Octo- ber, 1976). National Science Research Council, Georgetown, Guyana.

Interim Mekong Committee (1982) Environmental impact assessment: guidelines for application to tropical river basin development. Mekong Secretariat, c/o ESCAP, UN Bld., Bangkok 10200, Thailand.

IUCN (1983) Ecological studies and problems of Amazonia (Proc. Symposium, 18 March 1982, Sao Carlos, Brazil). IUCN Commission on Ecology Papers No. 5, IUCN (International Union for the Conservation of Nature), Gland, Switzerland.

Junk, W.J. (1975) Aquatic wildlife and fisheries. Pp. 109-1216 in IUCN: The use of ecological guidelines for development in the American humid tropics. New Series No. 31, IUCN, Morges, Switzerland.

Junk, W.J. (1983) Aquatic habitats in Amazonia. Pp. 24-34 in IUCN: Ecological structures andproblems of Amazonia (Proc. Symposium, 18 March 1982, Sao Carlos, Brazil). IUCN Commission on Ecol- ogy Papers No. 5, IUCN, Gland, Switzerland.

Lawson, G.W. (1970) Lessons of the Volta: a new man-made lake in tropical Africa. Biol. Conserv. 2, (2), 90-96.

Leentvaar, P. (1967) The artificial Brokopondo Lake of the Siriname River. Its biological implications. Atas do simp6sio sobre a biota Amazonica, Vol. 3 (Limnologia), pp. 127-140. Rio de Janeiro.

Leentvaar, P. (1975) The Brokopondo Research Pro- ject. Man-made lakes and human health (ed. by N.

F. Stanley and M. P. Alpers), pp. 179-192. Academic Press, London.

Lelek, A. (1984) Ecological aspects of the damming of a river in Borneo. Appl. Geogr. and Development, 24, 60-73.

Monosowski, E. (1984) Tucurui Dam in the Amazon: development at environmental cost. IIUG Preprint International Institute for Environment and Society (WZB), Berlin.

Monosowski, E. (1986) Brazil's Tucurui Dam: development at environmental cost. The social and environmental effects of large dams, Vol. 2: Case studies (ed. by E. Goldsmith and N. Hildyard), pp. 191-198. Wadebridge Ecological Centre, Wadebridge.

Nascimento, C. & Homma, A. (1984) Amaz6nia: meio ambiente, technologia agricola. EMBRAPA/CPATU, EMBRAPA, Bel6m.

O'Reilly Sternberg, H. (1981) Frontieres contem- poraines en Amazonie Bresilienne: quelques con- s6quences sur l'environment. Travaux et memoires de l'Institut des Hautes Etudes de l'Amerique Latine, Vol. 34, pp. 177-200. Centre de Recherche et Documentation sur l'Amerique Latine, Paris.

Padua, M.T. & Quintado, A.T. (1982) Parks and biological reserves in the Brazilian Amazon. Ambio, XI, (5), 309-314.

Pandolfo, C. (1979) Amazonia Brasileira e suas poten- cialidades. SUDAM, Belem.

Petts, G.E. (1984) Impounded rivers: perspectives for ecological management. John Wiley and Sons, Chichester.

PRODIAT (1982a) Pre-diagn6stico da Bacia do Araguaia- Tocantins (Sintese), Projeto Desenvolvi- mento Integrado da Bacia do Araguaia-Tocantins, Governo do Brasil, Brasilia D.F.

PRODIAT (1982b) Diagn6stico do Bacia do Araguaia-Tocantins, 20 vol. (Recursos Naturais), Min. do Interior-PRODIAT (Projeto de Desen- volvimento Integrado do Bacia da Araguaia- Tocantins), Governo do Brasil, Brasilia, D.F., 251 PP.

SCOPE (1972) Man-made lakes as modified ecosystems. SCOPE Report 2, International Coun- cil of Scientific Unions Working Group on Man- made Lakes, Paris.

Skillings, R.F. (1984) Economic development of the Brazilian Amazon: opportunities and constraints. The Geographical Journal, 150, (1), 48-51.

Stanley, N.F. & Alpers, P. (eds.) (1975) Man-made lakes and human health. Academic Press, London.

Szekely, F. (1982) Ecological aspects of large hydroelectric projects on tropical countries. Water Sup- ply and Management, 6, (3), 233-242.

Welcomme, R.L. (1979) Fisheries ecology of floodplain rivers. Longman, London.



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