General Characterization

The Hydrographic Region of the Amazon River (Figure 1), the most extensive inland hydrographic network on the planet, occupies a total area of 6,925,674 km²², from its sources in the Peruvian Andes to its estuary on the Atlantic Ocean in the north of Brazil, encompassing territories of Brazil (63.88%), Columbia (16.14%), Bolivia (15.61%), Ecuador (2.31%), Guyana (1.35%), Peru (0.60 %) and Venezuela (0.11%).

The estimated mean discharge rate at the mouth of the Amazon River is 209,000 m3/s, considering the contribution of the parts of the basin situated outside Brazilian territory. The average annual variation of the level of the Amazon river at Óbidos is 10.55 m. In the mid and lower courses, the Amazon river shows average flow speeds in the order of 2.5 m/s.

Figure 1 Hydrographic Region of the Amazon River

In the Brazilian section of the hydrographic region of the Amazon River, the main tributaries on the right side are the Javari, Purus, Madeira, Tapajós and Xingu rivers. From the left are the Iça, Japurá, Negro, Trombetas, Paru and Jarí rivers. The Brazilian section, excluding the part corresponding to the Tocantins-Araguaia basin, comprises an area of 3,899,419 km² (56 % of the total area of the basin) and encompasses seven states (100 % of Acre, Amazonas, Rondônia and Roraima, 76.2 % of Pará, 67.8 % of Mato Grosso and 31.3 % of Amapá).

The population of the states in the Amazon totals 12,073,620 inhabitants. Considering only those within the hydrographic region, and excluding the highly populated cities, such as Belém and Cuiabá, that are outside the boundaries of the basin, there are 7,575,333 inhabitants, constituting a demographic density of just 1.93 inhab./km²². The average for Brazil is 19.8 inhabitants/km. Table 1 clearly demonstrates the low occupancy levels of the region. Only Rondônia has a demographic density of over 5 inhab./km²², while in the Amazon Region and Roraima the density is less than 2 inhab./km²². The state capitals of Manaus, Rio Branco, Porto Velho, Boa Vista and Macapá, and the municipalities of Santarém (PA) and Sinop (MT) are the largest urban centers among the 245 municipalities in the hydrographic region of the Amazon River.

Average annual temperatures for most of basin range between 24ºC and 26ºC. The hottest months of the year are September and October, and the coldest from June to August.

Average rainfall in the region is 2,236 mm/year, oscillating between 1,500 and 3,300 mm throughout the basin. Close to the mouth of the Amazon River, on the coast of Pará, and in the eastern section of the basin, total annual average rainfall exceeds 3,000 mm, with no dry season. In the central-north and south-southeast sections, rainfall is lower, in the region of 1,500 mm.

Average annual insolation varies between 1,500 and 3,000 hours, representing from 35% to 60% of the total hours of insolation and characterized by heavy mists.

Average annual humidity is relatively uniform throughout the basin, at around 80%. March is the most humid month, with humidity tending to decrease in August, similar to the rainfall.

Average annual evaporation is 1,424 mm, varying between 800 and 1,900 mm. During the year, evaporation rates are higher in the 3-month period from August to October and lower from February to April.

One of the characteristics of this region refers to the deforestation that has taken place. Up to January 1978, the deforested area in the states within the Amazon basin totaled 85,100 km², the result of human activity in the basin over a period of more than four centuries. From the 1970s onwards, there has been a significant increase in the occupation of the region, and as a result an increase in the deforested areas. In 1999 this reached 440,630 km². Data published by the INPE indicates that for 1999 and 2000 the deforestation rates were 17,259 and 19,836 km² per annum.

The rainforest, despite being the most significant characteristic of the Amazon, does not conceal its wide variety of ecosystems, among which the most important ones are: dry land forests, flooded forests, meadows, floodplains, open fields and savannas. The Amazon contains an infinite number of species of plant and wildlife: 1.5 million catalogued plant species; three thousand species of fish; 950 different birds; in addition to insects, reptiles, amphibians and mammals.

The great geological diversity, allied to the varied topography, has resulted in the formation of the most varied types of soil, influenced by the high temperatures and precipitation, characteristic of the very humid and humid hot equatorial climates. However, the soils are naturally poor, in contrast to the exuberance of the rainforests that flourish there. The Amazon rainforest is a self-sustaining ecosystem, maintaining itself with its own nutrients in a permanent cycle. The Amazon ecosystems are carbon sinks, contributing to the equilibrium of the global climate.

In terms of socio-economic profile, the Gross Domestic Product – GDP per capita ranges from R$ 2,558.00, in Roraima, to R$ 5,577.00, in Amazonas, the latter being close to the national average, of R$ 5,740.00. The Human Development Index (HDI) for the region, calculated on the basis of a weighted combination of indicators, such as life expectancy, adult literacy, school enrollment and GDP per capita, can be inferred from the HDI indexes for the states in the Amazon basin. The HDI indexes vary between 1.703 (Pará) and 0.820 (Rondônia) and are below the national average. The Infant Mortality rate (per 1,000 live births) in Brazil is 33.55. Of the states in this region, Acre has the highest rate (43.76), though it has improved significantly since 1996, when it was 50.4. Mato Grosso, which has 67.8% of its territory in the Amazon basin, is the state which has the lowest infant mortality rate, 27.03. The rates in the other states range from 30.74 to 38.05.

Table 3 Availability and demand of water resources

 

Reinforce actions to contain uncontrolled deforestation and to preserve biodiversity Discipline the expansion of agricultural areas, especially in the sub-basins of the Madeira, Tapajós and Xingu rivers Implement programs to recuperate degraded areas, particularly in areas which have been mined. Expand and improve the waterway transport along two main sections in Brazilian territory, Lower Amazonas, from the estuary to the River Negro (1670 km); and in Central-Amazonas, from the confluence of the River Negro to the estuary of the Javari river (1611 km); Implement and improve the sewerage treatment system of domestic and industrial waste in the capitals and major urban centers, as well as the treatment and final disposal of solid wastes.	Map, quantify and implement measures that eliminate or minimize water contamination and the different impacts caused by minimg activities, especially in the Madeira, Tapajós, Amaná, Juruena and Teles Pires rivers. Expand and improve the fluviometric, sedimentalogical and water-quality monitoring network. Develop the hydroelectric power potential through new enterprises that are compatible with environmental conservation, multiple uses of water and integrated to local and regional development. Stimulate the practice of fishing as a means of local subsistence and to supply other markets in the country. This basin has the largest diversity of fish in the world (between 2,500 and 3,000 species) Ecoturism looks to be the most promising alternative economic activity for the basin.

The conditions of basic sanitation in the hydrographic region of the Amazon River can be evaluated from the data shown in Table 2, that show a summary for urban households.

Roraima stands out positively, with 93.6% of households served by public water supply. Acre is the state least well served, with only 43.9% of urban households having access to public water supply and with internal plumbing. In terms of sewerage disposal, this is poor in all the states, as the percentage of households served by the sewerage collection network ranges from 0.6% (Roraima) to 34.2% (Acre), levels that are below the national average. The percentage of treated sewerage in the region is very low, with practically all the levels below the national average. The exception is the state of Roraima, with 25.9% of urban households being served by sewerage treatment facilities. However, if we consider that in this state only 0.6% of the population has access to the sewerage collection network, the basic sanitation system in this region is still precarious.