1) Water  resources and management in Brazilian Northeast and the role of São Francisco Basin

Danilo Anton

The “nordeste brasileiro”, Northeast of Brazil, is located between the parallels 2^o and 16^o latitude South and the meridians 35^o and 46^o longitude West.

It includes the Brazilian states of Maranhão, Piaui, Ceará, Rio Grande do Norte, Paraiba, Pernambuco, Alagoas, Sergipe and Bahia with a total area in excess of 1,5 million km² (about 18% of the Brazilian territory) and a population of almost 50 million people (more than a quarter of the total population of Brazil)ⁱ.

The climate of this region varies from semi-arid to sub-humid. The semi-arid zone, also called “drought polygon” (poligono das secas), which is included within the 800 mm isohyet occupies almost half of the total Northeastern area (800,000 km²).

This drought polygon has been definedⁱⁱ as a region with the following characteristics and limitations:

1. xerophytic vegetation (mainly small thorny trees and bushes: caatinga)
2. predominant crystalline basement
3. shallow agricultural soils
4. high evapo-transpiration (above 2,000 mm per year)
5. low annual rainfall (less than 800 mm)
6. rivers without permanent flow
7. extreme hydrological events (droughts, floods)
8. reduced specific run-off ((4 liters/ second or 1260 mm/ha/year)
9. limited hydro-geological potential.

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Farming production has been, and still remains, one of the most important economic activities in the nordeste.

In the more humid areas (generally along the coast) the “nordeste” has been traditionally, and still is, dedicated to cane plantation. Presently, a large proportion of sugar cane is processed for the production of alcohol fuel.

Other products in coastal areas are tropical fruits (banana, pineapple, etc), palm trees (for production of palmitos, margarine, etc) and several subsistence crops (manioc, beans, etc).

In the interior (sertão), tougher plants are cultivated (some for industrial purposes, such as cotton, agave and sisal, along with other subsistence crops: corn, beans and squash). The sertão is also an animal production area (cattle, pigs and sheep).

During the last decades, as a result of the development of industries and services, urban population has grown considerably to about 70% of the regional population. Some cities have particularly developed into large metropolis with the subsequent environmental and social problems. It is the case of Salvador, Recife and Fortaleza, each with populations exceeding 2 million people in their urban-suburban areas.

States of the “Nordeste”ⁱⁱⁱ

States	Area, km2	Population	Density of population inh./ km2
Alagoas	27 819	2 822 621	101.5
Bahia -	564 273	13 070 250	23.2
Ceará	145 712	7 430 661	51.0
Maranhão	331 918	5 651 475	17.0
Paraíba	56 341	3 443 825	61.1
Pernambuco	98 527	7 918 344	80.4
Piauí	251 312	2 843 278	11.3
Rio Grande do Norte	53 077	2 776 782	52.3
Sergipe	21 962	1 784 475	81.3
Total	1 550 941	47 741 711	30.8

iReferences

According to IBGE the population of Brazil is 184.661.231 inhabs (Oct.2, 2005).

ii Source: Água doce no Semi-Árido, Vicente P.P.Vieira; in Aguas Doces no Brasil; IEAUSP and Academia de Ciéncias, pp.509-531, 1999.

iii Source: Wikipedia.org