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close this bookManagement of Latin American River Basins: Amazon, Plata, and São Francisco (UNU, 1999, 338 pages)
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View the document1. Sustainable water-resources development of the Amazon basin
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View the document3. The Amazon Cooperation Treaty: A mechanism for cooperation and sustainable development

1. Sustainable water-resources development of the Amazon basin

B. Braga, E. Salati, and H. Mattos de Lemos

Introduction

The Amazon region includes the greatest area of tropical rain forests and the largest river basin in the world. Contrary to popular belief, the region comprises a great number of different ecosystems, with varied geological, geomorphological, soil and climatic characteristics, resulting in a highly diversified flora and fauna. In spite of its immense natural resources - huge amounts of wood, water, and rich mineral deposits - scientists today are convinced that its greatest value lies in the vast biodiversity and the potential locked up within it. In the Brazilian Amazon, the approximate value of the known mineral resources (iron, bauxite, copper, gold, manganese, nickel, silver, and tin) have been estimated at $l,600bn (Comision Amazonica de Desarrollo y Medio Ambiente, 1994). The value of the biodiversity of the region is not known yet, although the market value of the existing commercial wood was estimated at $1,700bn (Mattos de Lemos, 1990).

A 1982 US National Academy of Sciences report estimated that a typical 4-square-mile patch of rain forest may contain 750 species of trees, 125 kinds of mammals, 400 types of birds, 100 of reptiles, and 60 of amphibians. Each type of tree may support more than 400 insect species. Just for comparison, the temperate forests of France contain only about 50 species of trees. As one of the last unexplored regions of the earth, the Amazon exerts much fascination over the imagination of mankind, especially among those who live in less luxuriant ecological settings (Repetto, 1988). Since the fall of the myth which professed the Amazon to be the "lungs of the world," scientists have attempted to understand its precise influence on the maintenance of the global climate system. Roughly half of the rain that falls in the Amazon is generated inside the region, resulting in a hot and very humid climate throughout most of the basin.

The largest part of the Amazon basin is a plain below 200 m above sea level, more than 3,400 km wide from east to west and 2,000 km long from north to south. This large plain is surrounded in the north by the Guyana plateau, at 600-700 m, in the south by the Brazilian plateau with an average height of 700 m, and in the west by the Andes mountain range rising to heights above 4,000 m. The main river system, namely Amazonas Solimões-Ucayali, extends for 6,671 km, which is 91 km longer than the Nile river - once considered the longest in the world. The Amazon river, with more than 1,000 tributaries, discharges into the Atlantic ocean between 200,000 and 220,000 cubic metres per second - about 60 times the rate of the Nile. The discharge of the Amazon river is equivalent to 15.47 per cent of all the fresh water entering the oceans each day (Mattos de Lemos, 1990). Although the gradient of the river is very pronounced in the Andean region, from the foothills to the estuary, the gradient drops only 107 m between Iquitos in Peru and the estuary in Brazil over 2,375 km. The water level varies considerably during the year from 6-10 m near the mouth to between 10 and 15 m in the middle stretch.

The high dependency of the population and the region's economy on the waters of the river, in terms of fresh water for domestic use, fishing activities, transportation, and energy generation, makes protection of the rivers and lakes a top priority - particularly against pollution, overfishing, erosion, mangrove destruction, and drainage of marshy areas. The water quality in the basin is still very good (the amount of dilution is enormous). New techniques for the recovery of the used mercury in gold mines in the Brazilian Amazon are underway. In this huge waterway live approximately 2,000 species of fish, more than all the aquatic fauna found in the Atlantic ocean. The quantity of animal protein from these fish that can be sustainably exploited is potentially enormous. This could provide a sensible alternative to efforts to produce animal protein from cattle raising - an activity extremely destructive to the Amazon ecosystem.

Even though the Amazon region has more than 40,000 km of roads (the majority are still unpaved), the rivers continue to be the main corridors for transportation with several thousand km of waterways navigable more than 90 per cent of the time. The alternatives for energy production using resources of the region include hydropower, fossil fuels (oil and gas), biomass, and solar energy. With respect to hydropower, the best sites are in the surrounding mountains, especially on the Andean side. Important hydropower reserves can also be found on the Amazonian plain, where Brazil has about 45 per cent of its hydropower potential. However, the reservoirs for this purpose cover extensive areas, and therefore their proposed construction has met strong opposition from environmentalists.

This paper describes the Amazonian basin from a physical and ecological point of view and indicates the current tendencies for sustainable use of its water resources. It has a first chapter on the natural system where the hydrology, meteorology, and ecology of the region is discussed. The second chapter deals with the water use for hydropower and navigation in the basin and the third chapter describes the legal and institutional arrangements in this basin at the Brazilian national level and in the realm of the Treaty for Amazonian Cooperation.

The natural system

General description

The so-called "Amazon region" extends its limits beyond the Amazon river basin. This "Amazonian dominion" (figure 1) comprises nine South American countries including, Bolivia, Brazil, Colombia, Ecuador, Guyana, French Guyana, Peru, Venezuela, and Suriname over an area of approximately 7.5 million km2. Besides the Amazon river basin this dominion includes part of the Tocantins and Orinoco river basins and some small basins draining directly to the Atlantic. The Brazilian Amazon represents approximately 50 per cent of the country. In 1966 a presidential decree instituted the Legal Amazon which encompasses today eight states (Acre, Amazonas, Pará, Roraima, Amapá, Rondônia, Mato Grosso and Tocantins) and part of the state of Maranhão. The population of this area is 18 million distributed among 629 municipalities with a progressively high urban concentration (approximately 60 per cent).


Fig. 1: The Amazonian dominion in South America

The total drainage area of the Amazon river basin is 6,112,000 km2. The average annual precipitation is of the order of 2,460 mm/year and the average annual flow 209,000 m3/s which implies a specific flow of 34.2 l/s/km2. The average annual evapotranspiration totals 1,382 mm/year. As it can be appreciated in figure 2 this is by far the largest basin in the world in terms of discharge. Some of the tributaries of the Amazon are among the longest rivers in the world. Inside the Brazilian territory the Amazon basin occupies 3,900,000 km2, with an average annual precipitation of 2,220 mm/year, a specific flow of 30.8 l/s/km2 and an evapotranspiration of 1,250 mm/year.

The Tocantins river basin, which is partially inside the Amazonian dominion, has an area of 557,000 km2 and an average precipitation of 1,660 mm/year. The flow at the mouth is 11,800 m3/s with a specific flow of 15,6 l/s/km2. The evapotranspiration is in the order of 1,168 mm/year. The rivers from the Amapá state, draining to the Atlantic ocean, between the Oiapoque and the Araguari river basin, comprise an area of 76,000 km2. The precipitation in this region is of 2,950 mm/year, being the total flow in this stretch of 3,660 m3/s. The specific flow is of 48.2 l/s/km2. The evapotranspiration is in the order of 1,431 mm/year.


Fig. 2: Comparative chart for average flow of Amazon river with other rivers in the world (Salati et al., 1983)

While being a region with a predominantly hot and humid climate, and having a vegetal cover of primarily forest, the Amazon is far from being a natural homogeneous region. Recent studies, taking into account both the biotic and the abiotic characteristics of the ecosystems, have identified 104 systems inside the Amazon, according to the classification of the Natural Landscape Systems (IBGE, 1995). Soils are particularly of low fertility, but are generally covered with a biota extremely rich in species, showing one of the largest natural biodiversities on the planet. The low soil fertility, particularly over the so-called A stable ground surface, together with the climatic conditions, have turned out to be one of the main difficulties for the implementation of a colonization based on agricultural activities.

Although there is little scientific and technical knowledge about the region, large advances have been attained, particularly in the past 30 years with the creation of some specialized institutions such as the National Institute for Research of the Amazon, in Manaus and the State of Pará Emilio Goelde Museum, in Belém. In the past 30 years the number of published works about the Amazon has been growing exponentially, addressing both the biotic and the abiotic aspects. Many of those have been spread out through an incredible number of publications, calling for some efforts to compile and systematize the available information in the form of books and technical journals. Among the scientific journals can be mentioned the Acta Amazônica, the Amazoniana and the Museu Goelde Bulletin. Some of the books presenting extracts from publications are the following: Amazônia: Development, Interaction and Ecology, by E. Salati et al. (1983); The Amazon, edited by Herald Sioli (1984); and Amazonian Deforestation and Climate, edited by J.H. Gash et al. (1996).

Human occupation of the Amazon Region after its discovery by the Europeans can be divided into three phases. The first phase is from 1500 to 1840 and corresponds with the recognition and occupation of the territory. During this period, environmental impact was small, but the interaction of the European settlers with the Indians produced a drastic reduction of native tribes, particularly along the rivers. It has been estimated that more than 3 million Indians lived in an area corresponding to the present Brazilian Amazon. This population was reduced to approximately 160,000 individuals by the second half of the twentieth century. The second phase of colonization covers the period 1840-1912, and is characterized by a drastic increase of rubber exploitation and other plant cultivation such as chestnut trees, as well as hunting and fishing for a few species of animals and fishes. The economic centres of Manaus and Belém experienced considerable growth during this period, and the Brazilian Amazon region received 600,000-800,000 immigrants, particularly from the Brazilian north-east.

In the past five decades a period of modern and intensive colonization can be identified. Roads were built, crossing the region from east to west and from north to south (figure 3). The four-century riparian occupation, particularly along large rivers, expanded inland through the so-called "terra-firma" ecosystem, causing a large environmental and cultural impact on the indigenous communities living in these areas. This wave of modern colonization brought about an incredible increase of deforestation activities. The cleared land, which was only 0.5 per cent of the Amazon region by 1970, expanded to 469,978 km2 or 9.4 per cent of the Legal Amazon by August 1994 (Barbosa, 1996). The transformation forces prevailing during those decades are associated with the exploitation and use of the natural resources, renewable and non renewable. Main activities were associated with road and hydroelectric plant construction, oil extraction, exploitation of forest and fishing resources, cattle raising, tourism and commerce, particularly following the installation of the duty free Manaus zone.


Fig. 3: Highways crossing Brazil and other countries in South America (Salati et al., 1990)

Ecological characteristics of the region

Geomorphology

Over most of its extensive area, the Amazon river basin is formed by geological clusters with altitudes below 250 m above sea level. These lowlands are limited in the west by a semi-circle formed by the Andes mountains with altitudes of over 4,000 m. To the north they are limited by the Amazon residual plateau (Guyana plateau) with an average altitude of only 1,200 m, but showing high summits such as the Neblina peak of 3,014 m. To the south, the Amazon plateau is limited by the Brazilian central plateau with average altitudes varying from 100-400 m. In this way, the Amazon basin has the general format of a horse-shoe with the open side turned to the Atlantic ocean. This physical structure and its geographic position, crossed by the equator, has established important regional characteristics. The water vapour carried from the Atlantic ocean by the trade winds (hot and humid) and the abundant solar energy determine the climate prevailing in the region, with high rainfall rates.

Recent studies have shown that the Amazon river starts at the Nevado de Misme, a mountain in the south of Peru. The waters spring up from the north side of the Chila mountain range in a slope called "quebrada" Carhuasanta, 5,300 m above sea level. The main contributor to the Amazon river, the Apurimac - Ucayalí runs towards the north and, after joining the Marañon river, to the east. Subsequently it takes in water from the Napo river just before crossing the frontier between Peru and Brazil, and is then known as the Solimões river. In Manaus the Solimões takes in the Negro and, from there to its mouth is called the Amazon river. Nowadays, the Amazon river is considered the biggest river in the world, not only in terms of its water volume but also in length, slightly surpassing the Nile at 6,671 km. The real length of the Amazon river is still unknown due to difficulties associated with the exact location of its mouth.

It is important to stress how small is the slope of the main course of the Amazon river; from Iquitos, Peru, to the Marajó island estuary, the river runs for 2,375 km with a total drop of only 107 m. However, an important feature of this relatively flat area is that it is cut by several tributaries, which have carved deep channels with steep slopes at 45 degrees. Then, when considering the large amount of flat land below the forest, what is actually found is a scarred area, impairing the implementation of agricultural activity and highly susceptible to erosion when the original vegetal cover is removed.

Climate

Solar energy

The quantity of solar energy reaching the upper atmosphere in the Amazon region varies very little, since it belongs to the equatorial region. By taking the city of Manaus as an example, we will verify that the maximum of solar energy is equivalent to 885 calories per cm2/day in January with a minimum of 730 calories in June. In the same way, the length of the diurnal period has also a short variation, going from a minimum of 11.36 hours to a maximum of 12.38 hours. The available energy at ground or at tree top level is controlled by the nebulosity, which is very large in most of the Amazon region, particularly along its central part. The average insolation and the nebulosity are shown in tables 1 and 2, and the incident energy, measured in Manaus, is in table 3, for years 1977-1979.

The most important factor for heat balance is associated with the high nebulosity index and the high values of air humidity. As a result, the temperature remains quite stable with little variation on either daily or annual average.

Air temperature

One of the important characteristics of the Amazon region is the small temperature variation, particularly in lower altitude areas forming the large Amazon plateau. In the city of Belém, for example, the highest monthly temperature is 26.9°C, occurring in November and the lowest is 24°C, in March. In Manaus, the highest monthly average is 27.9°C and the lowest is 25.8°C, both occurring in September. In the city of Iquitos, Peru, the highest monthly average is 32°C occurring in November and the lowest is 32°C, in July. This isothermical condition is a consequence of the large quantity of atmospheric water vapour and the small variation in available solar energy during the year. Table 4 shows the monthly average temperatures occurring in some of the Brazilian Amazon cities.

Table 1: Mean daily hours of sunlight measured in Amazon cities (hours and minutes)

N (OMM)

Stations

Lat.

Long.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

82,067

Iauaretê

0°36'N

69°12'W

4:24

3:54

3:54

3:30

3:36

3:42

3:48

4:42

5:12

4:48

4:47

4:24

82,331

Manaus

3°08'S

60°01'W

3:48

3:55

3:36

3:48

5:24

6:54

7:54

8:12

7:29

6:36

5:54

4:54

82,106

Uaupês

0°08'S

67°05'W

5:13

5:30

5:13

4:31

4:54

4:54

5:13

6:00

6:36

6:07

6:00

5:30

82,741

Taperinha

2°24'S

54°51'W

3:12

3:25

3:24

4:11

6:05

7:49

8:30

8:18

5:43

5:05

4:12

3:29

82,191

Belém

1°28'S

48°29'W

5:01

4:00

3:17

4:13

6:18

7:55

8:37

7:31

7:48

7:55

7:18

6:49

82,243

Santarém

2°45'S

54°42'W

4:35

3:43

3:25

3:48

4:42

5:54

6:49

7:49

7:24

7:24

6:30

6:05

INEMET (1979).

Table 2: Mean cloud cover (in tenths of sky covered)

N (OMM)

Stations

Lat.

Long.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Average

82,704

Cruzeiro do Sul

7°38'S

72°36'W

8.4

8.5

8.4

8.0

7.4

6.5

5.7

5.6

6.9

7.8

8.0

8.2

7.4

82,113

Barcelos

0°58'S

62°57'W

7.1

7.2

7.1

7.7

7.7

7.2

6.7

6.3

6.5

6.8

6.4

6.8

7.0

82,425

Coari

4°05'S

63°08'W

6.7

6.7

6.8

6.7

6.4

5.6

5.2

5.1

5.4

6.0

6.0

6.3

6.1

82,212

Fonte Boa

2°32'S

66°01'W

7.3

7.1

7.2

7.7

7.2

6.9

6.8

6.3

6.3

6.6

6.7

7.0

6.9

82,727

Humaitá

7°31'S

63°02'W

7.5

7.6

7.4

7.0

5.6

3.9

3.1

3.3

5.0

6.2

6.6

7.0

5.8

82,067

Iauaretê

0°36'N

69°12'W

7.6

7.7

8.0

8.2

8.0

7.9

7.7

7.4

7.3

7.7

7.5

7.5

7.7

82,331

Manaus

3°08'S

60°01'W

8.3

8.4

8.5

8.5

7.9

6.9

6.4

6.1

6.9

7.6

7.8

8.0

7.6

82,103

Taracuá

8°10'S

70°46'W

7.3

7.4

7.2

7.6

7.6

7.6

7.4

7.0

6.6

7.2

7.2

7.1

7.3

82,106

Uaupês

0°08'S

67°05'W

8.0

7.8

7.9

8.2

8.1

8.0

7.7

7.4

7.1

7.7

7.6

7.7

7.8

82,741

Taperinha

2°24'S

54°41'W

8.2

8.3

8.2

7.5

5.9

3.6

2.9

3.6

6.4

7.4

7.7

8.1

6.5

82,191

Belém

1°28'S

48°29'W

7.7

8.3

8.6

8.2

7.4

6.1

5.6

5.2

5.6

5.5

6.0

6.8

6.8

82,243

Santarém

2°45'S

54°42'W

6.5

7.0

7.2

7.1

6.5

5.4

4.5

3.7

3.9

4.5

5.0

5.5

5.6

INEMET (1979).

Table 3: Global radiation at surface (Qs) in Manaus; measurements made by Eppley pyranometer (in cal.cm-2.day-1)

Year

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sep.

Oct.

Nov.

Dec.

1977

-

-

-

-

-

-

-

425

348

325

360

267









(51)

(40)

(36)

(41)

(30)

1978

295

277

305

323

335

432

404

462

486

499

407

363


(33)

(31)

(34)

(38)

(42)

(57)

(52)

(56)

(56)

(56)

(46)

(41)

1979

337

395

412

-

-

-

-

-

-

-

-

-


(38)

(36)

(44)










Note: The numbers in brackets show the percentage in relation to solar radiation reaching the top of local atmosphere (Q0).

Ribeiro et al. (1982).

Precipitation

Rainfall is quite irregular in the Amazon region, as far as spatial distribution is concerned. Figure 4 shows the monthly variation from 34 meteorologic stations. It is immediately obvious that there is a difference in the distribution of monthly precipitation between stations located on the south side of the equator and ones located on the north. The south stations show a dry period from May to August, while the ones from the north indicate, in the same period, the maximum values of precipitation. Another important observation is that precipitation increases going westward, reducing, in the same way, the length of the dry periods. In the north-east of the Amazon basin there is almost no drought through the year.

From the point of view of total precipitation, the minimum values observed for the Amazon basin are in the order of 1,600 mm, along the transition area towards the central Brazilian plateau, and the maximum occur on the slopes of the Andes mountains, showing precipitation above 6,000 mm/year. Precipitation of over 3,000 mm can also be observed on the shores of Amapá and the northern region of the Marajó island. Figure 4 indicates the rainfall distribution and Figure 5 the lines of equal monthly average precipitation (isohyets).

Water balance - origin and recirculation of water vapour in the Amazonia

The water balance area of the Amazon basin is of 6,112,000 km2. The average yearly precipitation is 2,400 mm/year and the flow of the Amazon river is 209,000 m3/s. The evapotranspiration corresponds then, to a value of 1,382 mm/year. These are the data published by DNAEE in 1992. Based on this information, the Amazon basin takes in a total of 15.04 x 1012 m3 of water per year, discharges to the ocean a total of 6.59 x 1012 m3 of water per year and returns to the atmosphere, through the process of evapotranspiration, a total of 8.45 x 1012 m3 of water per year. The importance of the water vapour generated by evapotranspiration is absolutely relevant for the dynamic process, leading to the formation of clouds and originating the precipitation of the whole region. Research was developed during the 1970s and 1980s with the objective of determining the importance of this large vapour mass on the process of cloud formation and precipitation on the Amazon region. There were three lines of investigation (Salati et al., 1984). The first one was directed to the establishment of the water balance for the Amazon basin as a whole as well as for other basins of importance. The second one was to determine the water vapour fluxes, using the available information of radio wave analysis. The third line aimed to determine the spatial distribution of oxygen18 and deuterium isotopes in the water. The combination of these studies provided the following conclusions:

(a) the primary origin of the water vapour that penetrates the Amazon river is the Atlantic ocean, as shown in figures 6, 7, 8, and 9, which indicate the flux of the water vapour;

(b) the vapour flux is higher in the region of lower longitude, diminishing towards the west. The precipitable water, however, increases from the east towards the west. The total water vapour from the ocean is of the same order of magnitude as the water vapour produced by evapotranspiration from the forest of the Amazon basin; and

(c) the variation of the spatial distribution of oxygen18 concentrations in rain water is lower than expected assuming the precipitation had had the Atlantic Ocean as a single source of water vapour.


Table 4: Mean temperatures for several regions of the Amazon river basin


Table 4: Mean temperatures for several regions of the Amazon river basin (cont.)


Fig. 4: Rain distribution on the Amazonic basin in relation to the following stations: (1) Boa Vista; (2) Iauaretê; (3) Tarauacá; (4) Uaupês; (5) Barcelos; (6) Manaus; (7) Benjamin Constant; (8) Fonte Boa; (9) Coari; (10) Cruzeiro do Sul; (11) Caruari; (12) Rio Branco; (13) Porto Velho; (14) Humaitá; (15) Alto Tapajós; (16) Taperinha; (17) Conceição do Araguaia; (18) Imperatriz; (19) Belém; (20) Clevelândia; (21) Amapá; (22) Macapá; (23) Parintins; (24) Porto Nacional; (25) Cuiabá; (26) Pirenópolis; (27) Serra do Cachimbo; (28) Jacareacanga; (29) Altamira; (30) Tema; (31) Average of the region; (32) Iquitos; (33) Apolo; (34) Average of the region (Salati et al., 1983)


Fig. 5: Normal precipitation in the Amazon basin in mm/yr (Salati et al., 1978)

As a consequence of the above observations, a model for water vapour recirculation has been proposed. According to the model, the rain from a specific region originates from clouds formed by a mixture of primary water vapour coming from the ocean, and also from the water vapour from plant transpiration. The model has allowed, in the first instance, for a better explanation of rain distribution and the observed spatial concentrations of oxygen.18 The main consequence of these conclusions is that the dynamic balance of the atmosphere above the Amazon region is dependent on its green coverage, that is, on its forest.


Fig. 6: Values of vectorial field

. Mean of period 1972-1975, March, obtained for the 5° latitude x 5° longitude squares (1 cm = 2000 gv/cm). Broken line: precipitable water in mm (Marques et al., 1979)

This conclusion indicates that the forest is not just a simple consequence of the climate but that the present climatic conditions are dependent on the forest itself. From this point of view, the geomorphological characteristics, as well as the geographical situation, allowing the interception of moist and humid winds into the general circulation of the atmosphere, and the intertropical convergence, lead to factors determining the establishment of a hot and humid climate, which enables the development of an equatorial forest. The development of the Amazonian ecosystem through time and its present state of equilibrium, has produced the water balance as it is known today. The primary source of water vapour is the Atlantic ocean. However, studies of the water vapour dynamics of the region have indicated that only about 50 per cent of the present precipitation originates from this primary source of water vapour. The indigenous plants which have developed under the initial conditions of the evolving ecosystem, are today the basic constituents and, as such, basic elements for the established equilibrium, supplying through evapotranspiration the other 50 per cent of water vapour needed to produce the present level of rainfall. This maturing of the Amazonian ecosystem took place through several stages of equilibria and of selective and progressive experiments, in parallel with a constant and dynamic interaction between the biosphere and the atmosphere.


Fig. 7: Values of vectorial field

. Mean of period 1972-1975, September, obtained for the 5° latitude x 5° longitude squares (1 cm = 2000 gv/cm). Broken line: precipitable water in mm (Marques et al., 1979)

This leads to the conclusion that a large-scale deforestation would affect not only the biosphere but also the prevailing climatic conditions, including the water balance of the Amazon region and its surrounding area. Based on this information, Salati (1983) reached the following conclusions:

(a) Overall, deforestation will change the volume of water along the basin, increasing river flows during the rainy seasons while the diminishing volumes of groundwater reservoirs will reduce river flows during dry periods. A reduction of the forest area will imply less availability of water vapour in the atmosphere and, will lead to a reduced rainfall, particularly during dry periods. Climate change may take place, causing a long, characteristic dry period, with a water deficit in the soil and a broader variation of temperature;

(b) since the Amazon region is a source of water vapour for surrounding regions, large-scale deforestation will cause a reduction of the water vapour which is the source of rain in the central region of South America. Therefore, deforestation would bring about a reduction of the potential hydroelectric power available to some Brazilian regions;

(c) the solar energy reaching the region at tree top level is about 420 calories per cm2 per day. It is estimated that 50-60 per cent of this energy is utilized for the evapotranspiration process within the forest system. In this way, deforestation changes the energy balance. A large portion of the energy utilized by the plants to stimulate water evaporation, either by transpiration or by direct evaporation of the intercepted water, would instead be used for warming up the surrounding air.


Fig. 8: Values of vectorial field

. Mean of period 1972-1975, June, obtained for the 5° latitude x 5° longitude squares (1 cm = 2000 gv/cm). Broken line: precipitable water in mm (Marques et al., 1979)


Fig. 9: Values of vectorial field

. Mean of period 1972-1975, December, obtained for the 5° latitude x 5° longitude squares (1 cm = 2000 gv/cm). Broken line: precipitable water in mm (Marques et al., 1979)

On the other hand, there are parts of the Amazon region where different results can be observed between areas covered with pastures and areas covered with forests. An example would be Marajó island, where forested land shows a better distribution of precipitation throughout the year, with a monthly minimum close to 80 mm. In pasture areas, the precipitation is zero during dry periods. The total rainfall of the two areas is practically the same. It has been observed that the daily temperature variations are larger on pasture land, indicating a smaller availability of atmospheric water. Observation of the clouds has shown that the locally formed cumulus are smaller, and in higher altitudes of pastures area, rather than in areas covered with forest.

Those conclusions published by Salati (1983) have been confirmed by several articles in Amazonian Deforestation and Climate, edited by Gash et al., in 1996. These studies have indicated an air temperature increase close to the ground (Souza et al., 1996; Hodnett et al., 1996).

The model by Lean et al. (1996), concludes that large-scale deforestation, that is, a total forest clearing, leads to climatic modifications towards the reduction of precipitation in the Amazon area under consideration. The model forecast for total deforestation indicates a reduction of 7 per cent on precipitation, a reduction of 19 per cent on evapotranspiration and an increase of 2.3°C on ground temperature.

Preservation of the biodiversity

Considering that the Amazon region has one of the largest diversity indices of the planet, the Brazilian government has made, during the last few decades, a great effort towards the implementation of conservation units. Presently, the Brazilian Amazon contains 112 conservation units, covering an area of 43,496,837 hectares, corresponding to 8.7 per cent of its territory.

Table 5 indicates the number and the corresponding areas of the conservation units, according to Ryland (1995), for the different types of conservation units established by the Brazilian law. In table 6 are listed the national parks, the biological reserves and the ecological reserves of the Brazilian Amazon. The location of the stations listed on these two tables is shown in figures 10 and 11.

Water resources development

As previously explained, the Amazon region is rich in water and other natural resources. Of the 6.1 million km2 of the Amazon basin, 3.85 million km2 are located in the territory of Brazil. This area represents 45 per cent of the Brazilian territory, estimated at 8.5 million km2. It is then quite reasonable to assume that these natural resources will be developed by the Brazilian authorities in the near future. Next to water supply for domestic purposes, the most important water uses in this basin are hydropower and navigation. Flood control, from a practical standpoint, can only be approached from a non-structural viewpoint (flood warning, flood insurance etc.). Water quality in reservoirs created by hydropower development is an issue of great importance for appropriate environmental management. In this section we examine the utilization of Amazonian water resources for hydropower and navigation and the associated water quality issues in rivers and reservoirs. For reasons mentioned above the discussion will concentrate on the Brazilian Amazonia.

Table 5: Conservation units

Category of conservation unit

Number of units

Area (ha)

Direct use (sustainable management)



Federal




National forest

24

12,527,986


Federal reserve for extraction

08

2,199,311


Federal area for environmental protection

02

82,600


Area of relevant geological interest

02

18,288

State




State forest

11

1,401,638


State reserve for extraction

03

1,438,978


State area for environmental protection

10

6,922,257

Subtotal

60

24,591,058

Indirect use (integral protection)



Federal




National park

10

8,301,113


Biological reserve

08

2,902,800


Ecological station

11

2,007,666


Ecological reserve

03

457,574

State




Park1

10

3,880,953


Biological reserve2

03

105,878


Ecological station

03

1,244,678


Ecological reserve

01

3,000

Subtotal

49

18,903,662

Complementary category (RPPN)

03

2,117

Subtotal

03

2,117

Total

112

43,496,837

1 The state park of Serra do Araçá, Am, is mainly covered by the National Forest of the Amazon, Am.

2 The state biological reserve of Morro de Seis Lagos, Am, is contained by the limits of the National Park of Pico da Neblina, Am.

Note: The total area of the conservation units which form the Brazilian Amazon, taking into account the overlap of the above referred areas, is of 41,641,237 ha.

Hydropower

Hydropower in Brazil is managed and controlled by Eletrobrás, a government agency, responsible for the planning and operation of electrical generating, transmission, and distribution systems. According to the Brazilian Constitution, it is a prerogative of the Federal Government to explore, directly or by concession, authorization or permission for exploitating the hydropower potential of river courses in co-operation with the states where the those potential sites are located. Eletrobrás operates all over Brazilian territory through the different power-generating companies under its control. In figure 12 the different concessionaires in various parts of the country are shown. The whole Amazonian basin is operated by Eletronorte.

Table 6: National parks, biological reserves, and ecological reserves of the Brazilian Amazon

State

Units

Date of decree

Area (ha)

National parks (10)





Tocantins

Araguaia

1959

562,312


Pará

Amazonia

1974

994,000


Rondônia

Pacaás Novos

1979

764,801


Amazonas

Pico da Neblina

1979

2,200,000


Amapá

Cabo Orange

1980

619,000


Amazonas

Jaú

1980

2,272,000


Mato Grosso

Pantanal Matogrossense

1981

135,000


Acre

Serra do Divisor

1989

605,000


Roraima

Monte Roraima

1989

116,000


Mato Grosso

Chapada dos Guimarães

1989

33,000

Subtotal



8,301,113

Biological reserves (8)





Pará

Rio Trombetas

1979

385,000


Rondônia

Jarú

1979

268,150


Amapá

Lago Piratuba

1980

357,000


Amazonas

Abusari

1982

288,000


Rondônia

Guaporé

1982

600,000


Maranhão

Gurupi

1988

341,650


Pará

Tapirapé

1989

103,000


Amazonas

Uatumã

1990

560,000

Subtotal



2,902,800

Ecological reserves (3)





Amazonas

Sauim-Castanheiras

1982

109


Amazonas

Jutai-Solimões

1983

284,285


Amazonas

Juami-Japurá

1983

173,180

Subtotal



457,574

Total



13,669,153


Fig. 10: National parks and biological reserves of the Brazilian Amazon

Although Eletrobrás operates in a decentralized way, its long and medium-range planning and operation is performed through a commission under the leadership of Eletrobrás with the participation of all the subsidiaries. The most recent plan of the electrical sector in Brazil is the so-called plan 2015 with a planning horizon for the year 2015. This plan is based on four different demand scenarios in which the GNP of the country would vary at rates ranging from 2 to 6 per cent per year from 1992 till 2015. As a result of these scenarios the forecast electrical energy consumption in Brazil is depicted in table 7. Electrical energy represents nearly 40 per cent of the total energy consumption in the country.

The electricity generating network in Brazil is predominantly hydro. The 228 TWh in 1992 had a contribution from hydroelectricity of 96 per cent. Thermal generation is utilized for isolated systems and in a complementary way to improve the reliability of the hydroelectric power system. There are three segments in the Brazilian hydroelectric system: the integrated system south/south-east/centre-west, the integrated system north/north-east and the isolated systems of the northern region. The main characteristics of these generating and transmission systems are: reservoirs with multi-year regulation, large distances between the generating plants and the demand centres, watersheds with hydrologic diversity, a high degree of electrical integration among distinct subsystems of different watersheds and a large potential of hydropower development, notably in the Amazon basin.


Fig. 11: Ecological stations and national ecological reserves of the Brazilian Amazon

Electric sources for Brazil for the planning horizon of year 2015 are depicted in table 8. It can be observed that almost the only alternative for the country for the next 20 years is hydropower. Hence, Eletrobrás will proceed to develop the potential sites for several reasons including the large potential available at lower cost when compared with other feasible options (only one quarter of this potential is developed or under construction); a renewable resource whose costs of operation do not depend on oscillations of fuel costs; available expertise in the country with respect to planning, designing and construction of hydropower plants; hydropower reservoirs can and should be used for multiple uses of water (irrigation, navigation, water supply, etc.) improving the national economy in other sectors and finally the availability of expertise in the country for transmission of electricity at large distances which would allow the development of the potential available in the Amazon.


Fig. 12: Geographic distribution of electrical energy concessionaires in Brazil

A more detailed analysis of the hydropower potential of Brazil (table 9) shows that more than 50 per cent of that potential is located in the Amazon basin, in particular in the state of Pará. The development of the Tocantins river will have the highest priority, followed by the Xingu river basin. The priority of the upper Xingu is to supply the south-east/south/centre-west regions while the lower Xingu should supply the north east region. The capacity of electrical interconnection between the Amazon basin and the north and north-east region is higher than 5,000 MW and the south-east/centre-west varies between 3,000 to 6,000 MW depending on the energy demand scenarios. Including the Madeira and Tapajós river basins there is an additional 11,000 MW. Four hydropower plants (figure 13) would provide this energy: Belo Monte (11,000 MW) and Altamira (5,720) in the Xingu river basin; TA-1 (9,528 MW) in the Tapajós river basin and MR-1 (6,854 MW) in the Madeira river basin.

Table 7: Forecast of GNP and energy consumption increase in Brazil


1992

2000

2005

2010

2015

Scenario 1







GNP (109 US$)

321.2

382.5

488.2

593.9

722.4


(%)

-

2.2

5.0

4.0

4.0


Energy (TWh)

224.3

293.8

384.0

467.2

563.0


(%)

-

3.4

5,5

4.0

3.8

Scenario 2







GNP (109 US$)

321.2

450.9

575.5

700.2

851.6


(%)

-

4.3

5.0

4.0

4.0


Energy (TWh)

224.3

329.5

430.6

523.9

631.3


(%)

-

4.9

5.5

4.0

3.8

Scenario 3







GNP (109 US$)

321.2

516.0

690.6

881.3

1,124.5


(%)

-

6.1

6.0

5.0

5.0


Energy (TWh)

224.3

360.7

473.2

589.7

731.4


(%)

-

6.1

5.6

4.5

4.4

Scenario 4







GNP (109 US$)

321.2

540.8

723.7

968.5

1,295.7


(%)

-

6.7

6.0

6.0

6.0


Energy (TWh)

224.3

377.6

495.4

642.6

826.4


(%)

-

6.7

5.6

5.6

5.2

Eletrobrás (1994).

Table 8: Energy resources for hydroelectric generation in Brazil

Source

Potential

Cost(US$/MWh)


Gw year

GW


Hydro

123.5

247.0

33% < 40




29% between 40 and 70




28% > 70

Coal

12.0

18.0

50 to 70

Nuclear

15.0

25.0

60 to 70

Total

150.5

290.0


Eletrobrás (1996).

Table 9: Brazilian hydroelectric potential as firm energy (MW-year)

Basin

Operating and construction

Survey/feasibility studies/design

Estimated

Total

Amazon

3,707.0

26,173.5

37,173.5

68,623.2

Atlantic N-NE

140.0

94.6

1,329.0

1,563.6

São Francisco

5,707.0

2,673.0

1,270.5

9,650.5

Atlantic E

909.7

5,579.9

1,327.0

7,816.6

Paraná

18,715.2

6,045.8

5,426.1

30,187.1

Uruguay

141.8

6,268.0

1,355.4

7,765.1

Atlantic SE

743.8

765.1

1,931.0

3,439.9

Total

30,064.4

47,619.7

51,361.9

129,046.0

Eletrobrás (1996).


Fig. 13: Transmission of electrical energy from the Amazon basin to different regions in Brazil

The installed hydropower capacity in the Amazon basin in 1996 was 4,734 MW (Tucuruí, 4,240; Curuá-Una, 30; Coaracy Nunes, 40; Balbina, 250 and Samuel, 174). Under the Eletrobrás 2015 plan a considerable amount of hydropower is to be installed in a highly environmentally sensitive region. Consequently, a very detailed multi-objective analysis is essential in siting the associated dams and reservoirs. All related variables, economic, social, political, and environmental are taken into account at the very first stage of the implementation of the system.

The utilization of simple indexes should be avoided (Goodland, 1996) such as the ratio of inundated area per MW installed or the number of people involuntarily resettled per MW installed, since they do not encompass multiple uses of resources and other economic aspects. Concepts such as regional insertion of the project in the local community and multiple uses of water resources should play a substantial role in defining the best site for the power plants and reservoirs.

In order to illustrate the importance of the hydropower potential for the Amazon the horizons of extinction of competitive hydro-power in Brazil for different development scenarios are presented in figure 14.

It can be observed that, without the Amazon potential, the extinction of the hydropower potential of the country takes place in the period 2003-2012, while if one considers the Amazon region this extinction takes place in the period 2012-2021 depending on the scenario adopted. The hypothesis of not using Amazonian hydropower implies the implementation of a significant thermoelectric programme for the country starting around 2005-2010 depending on the demand scenario. This programme would very likely rely on coal and nuclear plants. This would certainly result in higher energy costs to the final consumers and severe environmental problems related to air pollution at local and global scale and disposal of nuclear wastes. It thus becomes apparent that the adequate planning of the Amazonian hydropower plants, including economic, social, and environmental variables, is the only feasible alternative for the long-range supply of electrical energy in Brazil.


Fig. 14: Extinction horizons of competitive and environmentally feasible hydro-power in Brazil

Navigation

Brazil contains the largest river network in the world. Approximately 40,000 km of rivers are natural waterways for navigation. Unfortunately, due to its topography, most of the developed areas of the country are located near the coast, a region that presents great difficulties for navigation. Only 10 per cent of the land where development has taken place is located near those navigable watercourses (Cabral, 1996). Today, the migration of farmers and miners to the hinterland is allowing the use of part of this huge river network for exporting grains, minerals, oil, and construction materials and importing equipment with a load tonnage of more than 12 million tons a year. In the Amazon region large trucks of up to 45 tons of load use the roll-on roll-off system to go from Porto Velho to Manaus through the Madeira river or from Manaus to Belém through the Amazon river. Approximately 50 per cent of the 40,000 km of navigable waterways in Brazil are located in the Amazon region.

For decades fluvial navigation in Brazil has waited for a national plan that would integrate this transportation system with the general transportation system of the country, one which would compare favourably with alternative transportation systems. In 1989 Brazil's Ministry of Transportation elaborated the PNVNI - "Plano Nacional de Vias Navegáveis Interiores." This plan, with a horizon of 2002, has established load fluxes, a fluvial network and fleet, integrated with the hydropower and irrigation sectors and with planned legislation for interior navigation. Although the plan has no details of waterways interconnection, a preliminary analysis indicates that it would be possible to go from Belém to the Plata estuary through a transcontinental waterway of 8,000 km (figure 15). Unlike the Eletrobrás 2015 plan the navigation plan has not taken off and is being subjected to major revision by the government.


Fig. 15: Interconnection of waterways in Brazil

A more detailed view of the waterway network of the Amazon basin including harbours and cities is given in figure 16. The Amazonas-Solimões is a river that allows all-year-long navigation of oceanic ships from its mouth in the Atlantic up to Iquitos in Peru. The Madeira river is integrated in the highway system in Porto Velho and constitutes an important axis in the export of agriculture products from the centre west farms to Manaus. The other important waterways are the Negro, in whose riverbanks Manaus is located, the Branco, a tributary of the Negro, the Purus, and the Juruá. A major system in the Amazon dominion is the Tocantins-Araguaia (figure 17). This system crosses centre west Brazil, the new agriculture frontier of the country. It extends from its mouth in the Pará river up to the central highlands of Brasília nearly 3,000 km away. This waterway includes 715 km in the Tocantins, 1,701 km in the Araguaia and 425 km in the Mortes river and can be readily integrated with the harbour complex of Belém and the railway system of Carajás and the RFFSA (federal railway system of Brazil). The implementation of this waterway system depends on the construction of the locks in the Tucuruí hydropower plant to allow the transposition of 72 m of depth difference in the Tocantins river. In the Araguaia river the obstacle is the rapids of Santa Isabel which will be inundated by the lake to be created by the hydropower plant planned for this location. At Santa Isabel dam there will be locks to transpose 60 m of difference in water levels.


Fig. 16: The waterway system of the Amazon river basin


Fig. 17: The waterway system of the Tocantins and Araguaia rivers

The basic Amazonian waterway system encompasses in particular the Içá, Solimões, Amazonas, Juruá, Acre, Purus, Madeira, Tapajós, Xingu, Tocantins, Araguaia, Japurá, and Negro rivers. These rivers have contact points with the highway system in the Amazonia, allowing access to regions of low population density and are axes of inter-regional integration (Cabral, 1996).

This basic network has been under-explored for several reasons, including deficiencies in signalling and buoying systems in the several tributaries of the Amazon and Solimões, lack of appropriate harbour installations to allow the conjugation of the waterway and the highway and the existence of rapids that make it difficult to navigate during low waters. Consequently, the solution to this problem includes the construction of bypasses and reservoirs for regulation in the Negro, Uaupés, Tiquié, Içana, and Araguaia-Tocantins; construction of small harbours at the intersection of highway BR-230 and the tributaries of the right bank of the Amazon and the improvement of the existing harbour system in the main river (Tefé, Manaus, etc.).

Legal and institutional issues

Water resources and environmental issues in the Brazilian Constitution

The current Federal Constitution of Brazil, issued on 5 October 1988, emphasizes the environmental theme with a special chapter dedicated to the subject. Chapter VI, section 225 presents the National Environmental Policy which was based in the Federal Law 6938 of 31 August 1981. According to this section, all citizens have the right to an ecologically equitable environment. This is a major national asset and is essential for a healthy quality of life. The government, with the general public, must defend and preserve it for present and future generations. According to the first paragraph, to ensure the effectiveness of this right, the federal government has some important obligations with significance to water resources, such as:

- preserve and recover essential ecological processes and provide for the ecological management of species and ecosystems

- define, in all federate units, physical space to be specially protected

- impose environmental impact studies for licensing of civil works or any potentially harmful activity

- control the production, commercialization and usage of techniques, methods, and substances that imply threat for quality of life, life itself and for the environment.

Other constitutional statements related to water resources in section 225 are:

- the exploitation of mineral resources implies the obligation to restore the degraded environment, in compliance with the techniques suggested by the related public agency

- conduct and activities harmful to the environment will subject the infractor to criminal or administrative sanctions, independently of the obligation to mitigate the damage generated

- the Amazon forest, the Atlantic forest, the Pantanal, and the coastal zones are national assets which will be used under conditions that warrant the preservation of the environment including the use of natural resources.

Other sections of the Federal Constitution are related to the environment. Since our interest is specifically in water resources planning and management, the next items will discuss the constitutional precepts related to water.

Water as a public good in Brazil

Brazilian Civil Law (section 65), states that all goods in the territory belonging to the Union, states or municipalities are public, all other goods are private. Public goods are classified as (section 66):

(i) people's common use goods such as rivers, lakes, seas, roads, and streets;

(ii) special use goods, such as buildings or lots serving the federal, state, or municipal government;

(iii) national goods, that is, those goods belonging to the Union, states, or municipalities.

An important change introduced in the Federal Constitution of 1988 was the division of waters into federal and state property. Federal waters are those flowing in rivers that flow through two or more states or that divide two states. State waters are those flowing in rivers that flow solely in the state territory. In this way, municipal waters envisioned in the Water Act of 1934 no longer exist. According to this same statute (section 225) the environment will be considered a public good. Federal Law 6938 of 31 August 1981, in accordance with these precepts, considers the environment as in public ownership, defining it as: "the set of physical, chemical, and biological conditions, laws, influences and interactions that allow, hold and reign all forms of life." Among environmental resources this law includes the interior waters, surface and groundwater, the estuaries and the territorial seas (section 3).

According to the Civil Code (section 67) things in public ownership cannot be transferred to the private sector. Pompeu (1992), quoting other counsellors, states that public goods of common use are not susceptible to the right of ownership, although the tradition allows the usage of the term to designate the holder of the judiciary relationship to whom is entrusted the care and management. In this respect the public agencies are the holders and the people and the state the beneficiaries of public goods. Section 68 of the Civil Code states that the common use of public goods can be free or charged according to specific legislation at the federal or state level. Similarly, the Water Act (section 36) states that the common use of waters can be charged in accordance with laws and rules of the administrative region where they belong. Public goods can be used by the private sector by specific authorization from the holders. In this situation the user shall pay the public agency for the right of use.

Water use and water permits

According to the Federal Constitution (section 24-VI) the Union, the states, and the federal district are jointly responsible for legislation regarding forests, fisheries, nature conservation, protection of the soil and natural resources, protection of the environment and pollution control. However, the Union has the charge of legislating privately with respect to water and energy as well as to fluvial, lake, and coastal navigation. Section 22 allows the states to legislate as well (complementary) through specific legislation regulating these matters. The current constitution, however, does not allow the states to enact additional (supplementary) legislation to deal with the special situations in such a large territory as Brazil. Section 21-XII states that the federation shall explore, directly or through authorization, concession, or permission, the hydroelectric potential of the water courses. This exploitation, however, must be performed in combination with the states where the development is planned. Although the form of joint action depends on specific law, the constitutional principle allows the possibility for states to tailor any permits to their own requirements.

It is a federal duty to implement the National Water Resources Management System. Section 21-XIX demands the creation of this system by the federal government, which is also responsible for defining the criteria for issuing water permits in the country.

The Water Act is a pioneering legal instrument enacted in 1934. Many of its precepts are still valid even after the promulgation of two constitutions in the meantime. However, many precepts have not been put into practice due to the lack of specific legislation to regulate them. According to section 36, any citizen has the right to use public waters and the use of highest priority is domestic supply. In section 43 it is stated that public waters cannot be used for agriculture, industry, or hygiene without an administrative permit except in cases of insignificant usage. These permits are given for a fixed period of time, never longer than 30 years.

The national water-resources policy and management system

Complying with the statement of section 21, chapter 19 of the Federal Constitution, the Executive Office sent to the National Congress the draft of law 2249 in 1991. This draft defines the National Water Resources Policy and creates the National Water Resources Management System. In January of 1997 the president of the republic signed Law 9433 on 8 January 1997 which regulates water use in the territory of Brazil. According to this law the National Water Resources Policy (NWRP) seeks to ensure the integrated and harmonious use of water resources towards the promotion of development and social well being in Brazilian society. Section 4 presents different instruments of the NWRP such as:

- the concession of the right of use complying with criteria and priorities established in the Water Act and subsequent legislation

- water charges for water resources utilization cost sharing in multiple use water resources works

- the institution of areas for the protection of watersheds for domestic water supply.

The National Water Resources Management System proposed will have a national collegiate, basin commissions, and an executive secretary. The directives of the system as stated in section 6 impose:

- consideration of physical, hydrological, social, economic, cultural, and political peculiarities common to large countries like Brazil

- integration of federal, state, and municipal initiatives in the planning of water use adopting the watershed as the base for regional actions

- promotion of decentralization of some federal actions through the delegation to states and the federal district as long as there is explicit interest between the parties

- encouragement of technical, institutional, and financial cooperation among water users to achieve a larger participation in construction, operation, and maintenance of hydraulic works of common interest

- stimulation of public participation in the decision-making process.

Although the above directives show a typical decentralization proposal, in other parts of the document there are contradictory rules restraining the participation of state governments as well as water users in the decision-making process. In this respect section 12 attributes to the National Collegiate, formed with representatives of the federal government, the:

- approval of the water utilization plans of federal rivers in the whole country

- approval of the classification of water courses according to priority uses

- creation of watershed commissions establishing norms and procedures for their implementation.

The water-resources law is a major advance that the water resources sector in Brazil is experiencing today. The idea of water administration at the watershed level and the charging for water use and discharge are important concepts that will certainly bring about the improvement of water management in Brazil in general and in the Amazon basin in particular.

Initiatives of the Federal Government of Brazil

In Brazil the responsibility for development and conservation of the Amazon basin is given to the Ministry of Water Resources, Environment and Legal Amazon. This new institutional arrangement should minimize past mistakes made in the process of development of the Amazon region. In addition to the fact that only about 10 per cent of the forest has been used so far the rate of deforestation decreased substantially after the elimination (in 1991) of the subsidies provided by the government for the development of the area. In addition, the Brazilian government has already established several protected areas in the region, including national parks, biological reserves, ecological stations, national forests, extractive reserves, and Indian reserves. In November 1991, the total protected area in the Brazilian Amazon was over 116 million hectares (the Yanomami and Kaiapó reserves were established after that date), which represents about 25 per cent of the region.

The Brazilian Government is currently undertaking a major study concerning the sustainable development of the Brazilian Amazon, which will involve ecological and economic zoning of the area to avoid the repetition of the mistakes of the past. Ecological and economic zoning is the most important policy instrument for territorial management through the regulation of the dynamics of land use, according to the concept of sustainability. This policy instrument aims at integrating the available scientific and technological knowledge with the social aspirations of the people of the region. The zoning is, therefore, an instrument for negotiation and adjustment among the various development proposals for the region. Three basic types of zones are being considered in the region. They are dedicated to the following uses:

- productive zones: where the use of natural resources can ensure, with the use of improved technologies, better quality of life for the population;

- critical zones: which in view of their environmental conditions require special care for their management;

- special zones of two types: those which correspond to Indian areas, extractive reserves, and conservation units; and those which correspond to sites of relevant historical or cultural interest for ecotourism, or strategic areas (such as national boundaries).

After four years of work, the first step of the Ecological and Economical Zoning is concluding with the Environmental Diagnostic for the Region and the establishment of a computerized data bank.

The Ministry of Environment, Water Resources and the Amazon is responsible for making sure that development activities in the Brazilian Amazon Region are undertaken in line with the concept of sustainability. The National Council for the Amazon, presided over by the President of the Republic, approved in July 1995 the Integrated National Policy for the Amazon, which is the result of an extensive evaluation of past development efforts, their successes, failures, and limitations, and is an answer to current and future challenges, in our quest to achieve sustainable development. This policy takes due consideration of the paramount importance of the water resources for the Amazon region, not only because of the need for integrated management of its multiple uses, but also because water vapour generated in the region is a crucial element in the maintenance of the climatic conditions, at least at local and regional levels.

International Cooperation and TCA

At the international level the region has today an important mechanism for water resources management: the Treaty for Amazonian Cooperation (TCA). This treaty signed on 3 July 1978 in Brasília by the Governments of Bolivia, Brazil, Colombia, Ecuador, Guyana, Peru, Suriname, and Venezuela aims at the improvement of the quality of life of the Amazonian people. TCA states that while it is important to have economic development of the area it is important to preserve the natural environment. In this respect the treaty clearly proposes: "... conscious that either the socio-economic development or the environmental preservation are inherent responsibilities of each state sovereignty and that the cooperation among the contracting parties will facilitate the compliance of these responsibilities, continuing and enlarging the joint efforts that they have been making in terms of ecological conservation of the Amazon... resolve to subscribe to the present treaty."

The cooperation foreseen in the treaty encompasses the rational use of natural resources including water, the improvement of housing and navigation, rational utilization of the flora and fauna, coordination of the health services, scientific and technological research, implementation and operation of research institutions and centres of experimental production, organization of meetings and seminars, exchange of documentation and information, increase in the rational use of human resources, promotion of local commerce, increase in tourism at national and international level. As general principles the execution of the treaty should observe the following: unanimity in order to take any action, possibilities for the contracting parties to establish bilateral and multilateral agreements as long as they are not contrary to the aims of the treaty, recognition of the need to give special attention to the initiatives of less-developed countries that imply joint action of the parties, possibility of international organizations' participation in local projects in the region, unlimited duration of the treaty and sovereign equality of the parties.

Several meetings have taken place since the signing of TCA. They involved political as well as technical issues. Several committees have been created to implement the treaty including special committees on the following: Amazonian environment (CEMAA), transportation, communication and infrastructure of Amazônia (CETICAM), Indian affairs (CEAIA), Amazonian Tourism (CETURA), science and technology (CECTA), and health in the Amazon (CESAM). The treaty is being implemented in a gradual way taking into account the present economic and financial situation experienced by most countries of the world.

The following articles of TCA are concerned with water resource:

- Article V

Considering the important and multiple functions performed by the rivers in the Amazonian region, in connection with the economic and social development of the region, the contracting parties shall make every effort to ensure a rational use of water resources.

- Article XV

The contracting parties shall endeavor to maintain a permanent exchange of information and cooperation among themselves and with Latin American cooperation organizations, with respect to the action areas covered by this treaty.

Since the beginning of the 1990s the TCA member countries have made a series of commitments with respect to water management of the Amazon basin including: establishment of a hydrometeorological database of the Amazon region, promotion of the exchange of researchers in hydrology and meteorology for the purpose of research enhancement, undertaking of a surface and aerological water balance, creation of a regional centre on tropical hydrology, conducting basic research on agro-meteorology, fostering the use of remote sensing, strengthening technical cooperation at all levels in the fields of hydrology and climatology, holding biannual meetings in the field of hydrology and climatology and the establishment of a basic hydro-meteorological network for the Amazonian region.

When thinking about the conservation and sustainable development of the Amazon region, particularly its water resources, it is important to understand the joint responsibilities of the countries involved. In March 1989, the countries of the region met in Quito, Ecuador, and issued the Declaration of San Francisco de Quito, which among other things, established a special commission for the Amazonian environment and a special commission for Indian affairs. Furthermore, the presidents of the states party to the Treaty for Amazonian Cooperation, meeting in Manaus, Brazil, on 6 May 1989, adopted the Amazon Declaration, which stated:

We emphasize the need that the concerns expressed in the highly developed countries in relation to the conservation of the Amazon environment, be translated into measures of cooperation in the financial and technological fields. We call for the establishment of new resource flows and concessional terms to projects oriented to environmental protection in our countries, including pure and applied scientific research, and object to attempts to impose conditions in the allocation of international resources for development. We expect the establishment of conditions to allow free access to scientific knowledge, clean technologies and technologies to be used in environmental protection and reject attempts made to use legitimate ecological concerns to realize commercial profits.

Impacts of modern colonization and sustainable development

Sustainable development, while being a broad concept, stating that natural resources of today are to be preserved and made available to future generations, should be analysed through several objective and quantitative criteria. In this way it has been decided to utilize the criteria of economic, ecological, and social sustainabilities for the appraisal of projects supported by national and international agencies.

- Economic sustainability is achieved when the investment output reaches levels which are compatible with the specifications of the supporting agencies (they should at least cover related interests and the amortization of capital costs).

- Ecological sustainability is attained when system productivity is maintained over time and biodiversity is preserved.

- Social sustainability is reached when the output from the investment improves quality of life and leads to a better income distribution.

The projects implemented in the Amazon region during the last few decades have not necessarily attained the criteria for sustainable development, particularly the ones associated with the expansion of agricultural and cattle-raising activities, which have been shown to be the main factors contributing to the increase of deforestation in the region. These projects have been developed in conjunction with the construction of large highways, such as the Belém-Brasília, the Transamazônica and the BR 364, connecting Cuiabá to Porto Velho. Currently presently secondary roads have also been constructed to Rio Branco-Cuiabá, leading to a multiple interaction among governmental institutions and private enterprise, interested in timber exploitation and, recently, in agricultural and cattle-raising activities.

Unfortunately, the implementation of a long-term sustainable agriculture in the Amazon region has been no more than a challenge to administrators and scientists. The equilibrium attained by the original forest is based on a strong process of nutrient recycling, where the organic matter generated (leaves and small branches) is decomposed in the soil, by a large number of microorganisms, particularly the microarthropodes. From this interaction results the breakdown of organic matter, the release of nutrients and the maintenance of the soil chemical and physiochemical properties. Deforestation interferes with this dynamic process, particularly through the destruction of thousands of living animal and vegetable species, which would, otherwise, interact within the ecological system. On the other hand, conventional agricultural activities are associated with a continuous process of planting and harvesting of a reduced number of vegetal species. The heavy rain associated with cultivation practices, devoid of soil conservation techniques, leads to soil erosion by surface run-off, or by lixiviation.

Other types of project implemented in the Amazon are related to mineral exploitation, construction of hydroelectric plants, mining of gold ore and precious stones, as well as timber exploitation, not necessarily associated with farming activities. All these activities have caused, at different levels, heavy environmental drawbacks in the region. The observed impacts are sometimes due to direct action, such as mining, particularly of gold ore, which has brought about deforestation, the destruction of river banks, the contamination of water courses by mercury, and the promotion of negative contacts with the local Indian tribes. Indirect impacts have also occurred, such as the construction of large artificial lakes for power generation, leading to uncontrolled development and to several other negative effects such as the ones caused by filling the reservoirs without previously clearing the vegetation.

It is actually very difficult to find, within the Amazon region, a neat example of a project resistant to critical analysis of the three criteria to be attained, in order that the development associated with them is considered as sustainable. Notwithstanding, this situation does not imply that such a level of development is not possible. Recent analysis (Salati, 1997), aiming at the identification of the limiting factors needed to achieve sustainable development, led to the following classification:

- natural factors
- technological factors
- educational factors
- economic factors
- institutional factors.

When developmental projects are under analysis, one or more of these factors are usually identified as limiting factors. Apparently, the main problem lies on the insistence on or initiative in implementing intensive colonization in a region where the factors or forces maintaining the dynamic equilibrium are not fully understood. Looking at the Amazon forest from above, particularly over the high density forest, it is not possible to characterize lack of nutrients, and preliminary surveys have indicated a high rate of photosynthetic primary production. This large rate of primary productivity leads to the erroneous conclusion that monocultures would have the same long-term productivity efficiency. Many decades of research have been made necessary and large areas have been deforested before having these false premises dismantled. Nowadays, support agencies do not allow the substitution of forests by pastureland, and have ruled that more than 50 per cent of the original forests should be preserved on developmental sites in the Amazon region.

While lessons have been learned over time and the legislation has established conditions for a sustainable development, the lack of institutions able to control and to enforce the law is still the most important limiting factor for ecological balance in the Amazon region.

Conclusions and recommendations

This paper has presented an overview of the Amazon basin in terms of its ecological system, the alternatives for its sustainable development and the legal and institutional framework for the development of the region from a Brazilian perspective and in the realm of the Treaty for Amazonian Cooperation. The Amazonian dominion which extents beyond the Amazon river basin has much diversity in terms of ecosystems and flow regimes. The fragility of the ecosystems should be taken into account when considering alternatives for the development of the region.

The most immediate use of the water in the basin is for hydro-power and navigation. The energy matrix of Brazil shows very little resource other than hydropower. The available alternatives (coal, oil, nuclear) are more expensive and impose heavy environmental pollution. Consequently, the utilization of the Amazon basin to supply electrical energy markets in south and north east Brazil is being considered, beginning in the year 2000. Navigation is a natural transportation system in the Amazon. Today, large vessels sail from the ocean to more than 2,000 km inland. The integration of navigation with other systems (railway and highway) will be considered in the Brazilian navigation plan for the year 2000.

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