Fundamentos geográficos do planejamento do Município de Corumbá

Resumo

The River Plate plain is divided into 3 natural ;regions: the Pampas, the Chaco and the Pantanal. The latter is located in the central ,part of South America, to the southeast of Brazil and of Mato Grosso State.

The Pantanal consists of a vast interior base level plain, upon which rises the massif of Urucum (approximately 1000 meters high), composed of a substratum of basic complex (granite and gneiss), covered by dolomitic chalks of the Bodoquena series (ordovician?). Over these are deposited the arcosies and jaspilitic arcosian sandstone of the Jacadigo Series (eodevonian), these being very hard and containing strong layers of hematite and cryptomelane lenses. These rocks were faulted in the tertiary, during the orogenesis of the Andes. The colossal talus on the western slope were made up during the Cenozoic, under climatic conditions of concentrated rainfall.

The city of Corumbá is located on an glacis at the northern foothill of Urucum massif. Its declivity, of 3.2% bevel, cuts the tipped-up layers of the Bodoquena series. (Fig. 5). This slope makes up a "bajada", upon which the Xaraiés limestone was deposited in arid climatic conditions. Towards the Bolivian frontier, it bends in to the SW and the "Inselberge" beaconing its upper part become more widely spaced, facilitating the wind circulation from south to north. The lateral erosion of the Paraguay River bites the lower section of the glacis, where the districts of the Porto and the Cervejaria (Brewery) are nestled. The Cristo Redentor (Christ Redeemer) and New Popular suburbs have spread out from the "bajada"; they are located in sink holes with a very hot micro-climate and communicating with downtown through gorges.

The expression "Marsh" (pantanal) is incorrect since it qualifies a region subject to floods; the average width of the Paraguay floodplain reach there, however, 25 kilometers, in the average, for 21\0 kilometers total width of the "Graben". The Mato Grosso Pantanal covers a surface of around 100,000 square kilometers. Its peculiar hydrography created severa! regional terms: "baías" are small lakes, generally round; a "barreiro" is a temporary "baía"; "salinas" are small brackish water lakes, having evaporate deposits around; "vazantes" are periodic streams linking two "baías"; if a permanent connection is established, they are named "corixos". "Cordilheiras" are sandy mounds around 3 meters high.

The Pantanal sands are of desertic facies. The isolated limestone hills are true "Inselberge". The travertine deposits of Xaraiés formation, the dunes, the Corumbá "bajada", the great talus of the Urucum massif, the "salinas" and the fossil remains of gigantic animals attest to an arid paleoclimate, probably from pleistocene age.

The author interprets the origin of the "baías" as resulting from water accumulation in pseudo-karst depressions.

The Pantanal possesses 3 meteorological stations: Corumbá, Aquidauana and Cáceres. The former is more representative of! the regional climate; it has an annual mean temperature of 25º.1; its mean temperature for the hottest month (December) is 27º.4, and for the coldest one - July - 21°.4. The Pantanal climate is typical of the outer tropics, with continental characteristics (Corumbá is at 1200 kilometers from the nearest point on the coast line, as the crow files). The difference between extreme temperatures in the Pantanal stations exceer 40ºC, whereas in Rio de Janeiro, on the coast, at about the same latitude, that difference is a little above 30°.

Rainfall in the Pantanal varies between 1000 and 1500 millimeters per year. The winter semester is dry; the summer is rainy. Summer rains are usually accompanied by thunderstorms and lightnings. From November on the equatorial continental air mass (Ec) prevails over the Pantanal. But tropical Atlantic air mass (Ta) stays longer in the region. Between April and October the polar Atlantic air mass (Pa) invades it once or several times, causing the phenomenon known as "friagem" (coldness). The temperature drops then to values not far from 0ºC. This is probably the reason why there are no insect lavras to be found on cattle raised in the Pantanal.

The Paraguay River is of fundamental importance for the economic life of the region. The following data were taken from the article by Eng. L. Tossini (see bibliography). That river is a right bank tributary of the Paraná River, at the boundary between Paraguay and Argentina. It is a lowland river, 1453 kilometers long, with a very regular flow.

Between its sources, on the slopes of the Central Plateau and the Jauru river mouth, is found the A zone, of the sources. The valley is here around 270 kilometers long and the river bed about 400 kilometers. The waters descend from the 300 meters level to 125 meters, running between bluffs 5 to 10 meters high. Then follows the B zone, of expansion or damming, 770 kilometers long, from the Jauru river mouth to that of the Apa, at altitudes between 125 and 83 meters, respectively. The course of the river extends for 1262 kilometers. The section is subdivided in to two parts: the upper one, corresponding to the Pantanal properly speaking, from the mouth of the Jauru of the Fecho .dos Morros; the lower one, from this point to the mouth of the Apa. They have, respectively, the following characteristics: coefficient of tortuosity - 2,2 and 1,3; grade - 132 and 33mm/km; breadth - 100 and 300 meters; average depth of the thalweg 4 and 10 meters.

The C zone, of discharge, begins at the mouth of the Apa and ends at the Itapiru point, at Lamas Valentinas, in a valley extension of 410 kilometers, the course covering 576 kilometers. The beginning of this zone is marked by a step which rises the river bottom almost 10 meters. Its average gradient is of 59 mm/km, between the 83 and 45 meter levels at both ends. The coefficient of tortuosity is 1.45; the average breadth is 650 meters. The average depth of the thalweg is equal to 8 meters, with interruptions caused by sand banks and stone pavements.

The zone of the mouth (D) runs from Lomas Valentinas to the mouth, a distance of 230 kilometers which the river covers in a course of 350 kilometers, with a coefficient of tortuosity of 1.52. The confluence of the Paraguay-Paraná rivers is 48 meters above sea level, there being therefore a unevenness of 11 meters in this section, resulting in a mean gradient of 48 mm/km. The thalweg gradient there is only 29 mm/km, with a dry-season average width of 9 meters, which is reduced at the "passes" to 2 meters, though attaining up to 17 meters at the dead waters.

The flow of the Paraguay River is of utmost regularity at the periodical variation, surpassed only by the Rhine in Europe. This is due to 3 main factors: a) the very regular periodic rains that fall on the basin; b) the vast damming-up area formed by the Pantanal; c) the gentle longitudinal profile. The highest floods inundate 80,000 square kilometers of the Pantanal, but the micro-relief of the region forms a branch-like system of depressions, whose waters converge into two places: to the North of Paiaguás district, where the Cuiabá, S. Lourenço and Pequiri rivers meet; close to Corumbá town where the Paraguay, the Taquari and the Miranda rivers converge.

The rising of waters begins in Corumbá (end of December-January) 3 months later than the start of rainy season (September-October), and the flood-peak (May-June) comes 4 months after the maximum of rainfall (December-January). The flood wave moves over the Pantanal at a rate of the kilometers per day, before the river overflows, and of 9 kilometers per day at the peak of flood.

The curves of the fluviograms of the River Paraguay, drawn by L. Tossini, enable us to divide the floods into three categories: a) Extraordinary when the waters reach a height of 6 meters or more; the rise of waters is at its lowest in December and the maximum rises are precocious (in May); but already in March a conspicuous rise enables a flood to be foreseen. b) Ordinaries,. with a maximum between 5 and 6 meters read on the rule; it occurs in June, after a minimum ebb in December. c) Minors, with water level always below 5m, on the rule. The minimum ebb, in this case, ts precocious (October or November), but the maximum comes late (June-July), in such a way that in March the waters never go over 3,5 meters on the rule.

The map of the isorheocrones (lines uniting the points of equal times of delay, in relation to the river mouth) shows how the waters flow slowly in the Pantanal region.

The data supplied by Tossini enable one to foresee the floods at Corumbá, with a minimum antecedence of one month and a fair degree of reliability. Foreseeing the importance of navigate on on the Paraguay River. Eng. Lisoni is making farther studies on fluvial hydraulics, sponsored by the UNESCO. Although it has been abandoned to the laws of nature, the Paraguay and its tributaries afford to Brazil, a navigable network 2000 kilometers long, although somewhat precarious.

In view of the variety of formations, the vegetation of the region has been known as the "Pantanal complex". The forest formations that enter into its composition are: a) Semideciduous forests of mountain slopes, on the hillsides of the Urucum massif, with canopy 15 to 20 meters high, plenty of lianas and rare specimens of palms and "mandacaru" cactae. They cover red latosoils. b) Deciduous shrub forests. On the less hilly land South and West of Corumbá town, a low-forest growth has emerging trees 10 to 15 meters high and a dense canopy 5 meters high, with a great number of shrubs. It has more creepers and more "mandacaru" cactae than the latter formation. Around Corumbá they have been degraded by mau. They cover Grey or light-yellow mediterranean soils, with good agricultural potentialities. c) Forest of calcareous "Inselberge". This is a deciduous forest, with man specimen of "barrigudas", creepers and thorny plants. The foot of the "Inselberge" is covered by a homogeneous ring of "carandá" palms.

The principal open formations of the Pantanal are: the flood-plain grasslands, corresponding to treeless savannas, which during the long dry season, in certain portions, become bush savannas, Bunches of carandá palms follow the river courses. Little is known about the formations existing on the higher levels of the Urucum massif.

Worthy af note among the transition formations are: the paratudo savannas, which trees a1·e isolated specimen of the paratudo (Tecoma caraíba and T. aurea), that grow upon thermite mounds, spread over poor drained lands.

In the Nhecolandia. district. the vegetation of the western section is made up of three main formations, intermixed in a complicated pattern. Upon the "cordilheiras" the "cerradão" predominates; this is a forest formation with hard-woods (guatambu, aroeira, angelim, paratudo, piuva), already in exploitation to a large degree, plus some trees of cerrado species, of greater size and less crooked branches than in the latter formation, as well as other palm trees such as the carandá, the bacuri and babaçu. The spoiling of the "cerradões" by tire facilitated the spreading of the bromelia "caraguatá" in the underwood. The "pasto" is another formation of the savanna type, in which the grasses are predominant, but it has been invaded by lowtrees and shrubs as the "canjiqueira", "assa-peixe", the "araticum" (Anona sp.) and the "mercurio bravo". The "baías" are surrounded by a moor vegetation of gramineae and cyperaceae, but when they are periodic, as they become dry, their bottom is infested by invading shrubs. Not only domesticated animals gather for fresh grass in the "baias", but as well other mammals of great size and a wide variety of birds. In the eastern part prevails a cerrado similar to that the Central Plateau, to the point of becoming the most widespread formation of the Pantanal.

The Pantanal was inhabited by numerous native tribes, most of which belonging to the Guarany linguistic group (Fig. ) . They lived in the neolothic age and, in spite of their constant wars, they maintained a certain balance of force among themselves.

The Spaniards were the first to penetrate into the region (in the 16th. and beginning of he 17th. century), favored by the navigable river that drains the Pantanal through the wide pass of Fecho dos Morros: the "main door", It was, nevertheless a precarious occupation, always at the mercy of Indian attack, inasmuch as they disposed of neither troops nor sufficient settlers to guarantee a permanent settlement.

The Portuguese-Brazilian peopling of the land came much later (17th. and 18th. centuries) and was made through the "false door" - the Camapuã divide, 13,700 meters long, between the Pardo and Taquari rivers. Furthermore, from Porto Feliz to Cuiabá one should travel 3000 km by boat, through 113 cascades and rapids. Up to 1719, the Paulistas often penetrade into the region and hunted down the Indians, for the purpose of bartering them in Piratininga, In that year gold placers were discovered and Cuiabá was founded. The previous Indian barter expeditions caused the majority of the tribes to be enfeebled and the military supe1ior!ty of the Palaguás, who began to attack the paulistas' canoes, massacring the expedition members. Gold and other products of the Paiaguá raids were exchanged in Asunción with the Spaniards, who became their allies. The paulistas organized several punitive expeditions against the Paiaguás, but the latter in their speedy "ubás", made a wa11 of movement, avoiding decisive battles when they found themselves in inferior conditions.

The situation at Cuiabá reached a critical point, inasmuch as in addition to the ambushes of the Paiaguás, it suffered from pests injuring the crops, from the plague and very high government taxation. In spite of the convoys of canoes protected by soldiers, conditions in Cuiabá only improved when the Governor Luís de Albuquerque de Melo Pereira e Cáceres ordered the construction of fortified points along the river course. In this way were founded: Coimbra on Sept. 13, 1775; Albuquerque (now Corumbá) on Sept. 21, 1778 and Vila Maria (now Câceres). on Oct.6.1778.

The first permanent occupation of the Pantanal started then from the region of Cuiabá, by means of immense grants of land, conceded to Portuguese settlers, who established themselves in the valleys of Aricá, Cuiabá, and along the road that led from this town to Vila Bela. The Jacobina farm was one of the founding nuclei of this settlement; it was visited by Hercules Florence in 1825 and by F. A. Pimenta Bueno in 1880. It covered then an area of 240 leagues. People from Jacobina and other settlers occupied immense tracts, included today in the district of Nhecolândia; they spent a very primitive life, in an almost closed economy.

During the Paraguay War (1864-1870), the Pantanal was invaded by Paraguayan troops, reaching Cáceres. The ranchers gathered up what they could and took refuge, with their families, in Cuiabá region. Once the invaders cast out, the ranches were found to be destroyed and the cattle decimated. Their former occupants came back to settle again southwards, down to the Negro River. Later on, a few ranches began to be sold in lots but the splitting-up was, in the majority of cases, due to inheritance. To the south of the Pantanal, on the contrary, some foreign capitalistic enterprises and River Plate settlers operate on immense tracts of land, with but small valorization.

The first heads of cattle to be taken to Cuiabá traveled by canoe from the Camapuã farm, by authorization of the Governor Rodrigo César on Nov. 8, 1725. The expedition which opened up the road from Cuiabá to São Paulo, via Goiás, in 1736, brought on the way back, the following year to that town, a herd of bee! cattle and horses. This cattle was entirely creole, just as that in the Iberian peninsula, and raised in open ranches.

Ten-year after the war with Paraguay, various Argentine and Uruguayan citizens began to set up plants for drying and salting meat on the navigable rivers banks of the Pantanal. Only sporadically did some cattle-dealers from Uberaba come to fetch live cattle and drive them away afoot. And this was only at the large ranches, i. e. those which raised from 10,000 to 100,000 cattle. Ranches with herds under 10,000 heads were considered small. A new breed began to be raised regionally, known as "pantaneira". The cattle was grown in open ranges on rough pastures. Patriarchalism: prevailed in the Pantanal society; habits were rustic. The young people went of! to study usually to Cuiabá.

In 1914 there occurred two important events affecting the region: World War I and the inauguration of the railway from Bauru to Porto Esperança. Meat began to rise in prices and the ranchers began to take interest in raising zebu cattle. Thus, economic relations with São Paulo became predominant. The Pantanal cattle ranches started to modernize. The cultural influences from that city and Rio de Janeiro were strengthened among the landowners' families.

During the zebu era, various improvements were introduced in the Pantanal ranches, specially from the World War II on. Although wide-open pastures continued to prevail, they started to be divided by barbed wire fences; only in small areas around the farmhouse, cultivated pastures were to be found. For watering the cattle, wells were dug: either "dredgewells", carved with a tractor at a periodical "baia" bottom down to the groundwater level, or by means of pipe-wells, pumping the water to an Australian pool. The bulls are neutered in a "brete", in order to reduce their suffering. The ranchhouse proper is, in present days, a comfortable country house, with garden, orchard, running water, electric light, radiotelephone and landing field. It is not uncommon to find landowners in the Pantanal having a college-level education.

Stockraising on the Pantanal continues, however, to be extensive, with low profits and cowboy/herd ratios. Landowners and their families are generally absentees, leaving as they do the care of the ranches up to a manager. As far as they turn into citydwellers, become they apt to develop innovator spirit.

Possibilities of reorganizing the economy of the Corumbá municipio are great. The hydroelectric power generated in the Urubupungá system now available in Campo Grande should be brought into Corumbá; the Noroeste dei Brasil R. R. should be improved and the navigation service on the Paraguay River should be equipped and put into operation. The .main industrial unit to be installed in Corumbá has to be a slaughter house. A tannery would enable the leathers to be processed on the spot. The tannin would have to be imported in the beginning, but the planting of "quebracho colorado" should be fostered. Meat salting and drying plants could be once again established, when the Santarém-Cuiabá highway allow the transport of salt from the alkali factory now in project at Aveiro (lower Tapajós) with return freight. Southeastern Amazonas and the center of Mato Grosso would be their main markets.

The steel mill burning charcoal, operating in Corumbá, should be reorganized on rational basis. Enlargement of the animal food industry, exploitation of marble quarries of the Serra da Bodoquena and manufacture of lime for correcting soil acidity are other suggested proposals.

For areal reorganization the author suggests that the so-called "Transpantaneira" highway, projected by the State government, makes connection between the navigation terminals of the Paraguay River and this tributaries, so as to create, in combination with this road, a regional transport system. This would render economic the planting of artificial pasture in the whole of the Corumbá municipio and thereby, its ranches would be able to sell only fat cattle, considerably increasing their revenue.