THE RIVER-ROUTES
The use of the river before steam navigation--Floods--The
river plain--The bed of the Parana and its changes--The
estuary and its shoals--Maritime navigation--The boats on the
Parana.
The problem of the use of the river-routes of the Parana and the
Paraguay is not of interest to Argentina alone. It affects the whole
history of colonization in South America. The very name of the Rio de
la Plata is a reminiscence of the anxieties of the early navigators who
landed there, chiefly in search of a route to the mineral districts of
the Andes [Plata = silver]. It is remarkable that the Amazon, which
opens a more direct and better route to the Andes, was never used for
reaching Peru. It was at the most, and only occasionally, used as a
return-route, whereas expeditions to the Cordillera were organized on
the banks of the Parana during the whole of the sixteenth century. The
routes linking the Parana and the Paraguay with the tableland furrow
the whole plain of the Pampa and the Chaco, from the latitude of the
estuary to about 16 deg. S. lat. (expedition of Nuflo de Chavez in 1557).
An especially close network starts from the river between 18 deg. and 22
deg. S. lat. and ends at Santa Cruz, the most northern centre established
by the Spaniards on the plain, at the foot of the Andes, as a consequence
of the use of the Parana.[118]
[118] There is still a certain amount of goods traffic in this
latitude between the river and the Santa Cruz district by the
Puerto Suarez and Puerto Pacheco tracks.
Spanish colonization, however, did not succeed in making permanent
settlements on the Chaco. The Indians, who were masters of it, disputed
their passage, and the only practicable route was the southernmost of
the roads to the tableland, south of the Rio Salado, which ends at the
estuary. From this time onward the prosperity of Buenos Aires eclipsed
that of Asuncion. The river ceased to be a great continental route.
The division of the Parana between the Spanish and the Portuguese was a
check upon the full development of the river-route. The Portuguese held
the upper part of its basin, which now belongs to Brazil. They expelled
the Spanish missionaries from the upper Parana about the middle of
the seventeenth century, and made themselves masters of the Paraguay
north of 20 deg. S. lat. Their forts at Coimbre and Albuquerque prevented
any from ascending. D'Azara insists that it would have been Spain's
interest to disarm these forts; it would have enabled them to go up the
river as far as the Spanish missions to the Mojos and the Chiquitos. On
their side, the Portuguese only used the upper section of the river,
where it is joined by the Paulist road north of the Coimbre, as a means
of access to the gold mines of the Matto Grosso. Even now, although
the Parana is open to every flag, the development of the river-route
is not independent of political conditions. In making the railway from
Saint Paul to Corumba, and so creating on its own territory a means of
direct communication with the upper Paraguay, Brazil diverts from the
lower districts part of the traffic which ought normally to go there.
Again, the ports of southern Brazil and the lines which go to them try
to attract to the Atlantic the produce of the basins of the Uruguay and
the upper Parana, which would have followed the thread of the river
to foster the trade of Buenos Aires if the frontiers had been fixed
otherwise.
Before the Revolution the river-trade was confined to exchanges between
the Misiones and Paraguay on the one hand, and Buenos Aires and the
Andean provinces on the other. After the extinction of the missions
Paraguay was the chief centre of traffic on the river. At the close of
the eighteenth century it had a fairly large population. According to
D'Azara, it amounted to 97,000, and 47,000 for the area of the former
Missions (Misiones), while Buenos Aires, Santa Fe, Entre Rios and
Corrientes had not more than 103,000 inhabitants collectively. Paraguay
exported tobacco, _mate_ and timber by the river. The Buenos Aires
Estano received 800 tons of tobacco a year. The exports of _mate_ from
Paraguay to Peru, Chile and the interior provinces amounted to 1,725
tons, and 2,250 tons went to Buenos Aires. The timber came mostly from
the Tebicuary, where the _angadas_ (loads of timber) were formed. The
chief constructive sheds also were on the Tebicuary. Boats of twenty to
200 tons were launched there; and they had armed boats, when they went
down the river, to detect ambushes of the Indians, who were masters of
the right bank north of Santa Fe.
The development of navigation on the Parana during the first half of
the nineteenth century was checked by the disturbances and wars of the
period of the emancipation and unification of Argentina. The river was
blockaded several times and traffic interrupted. Only a few smuggling
schooners succeeded in getting through the side branches, which the
ships stationed in the river could not watch. Robertson escaped the
Spanish vessels in this way. The picture which D'Orbigny has given
us of the life of the river belongs to the year 1827. At that time
the estuary was blockaded by the Brazilian fleet in the whole area of
the delta as far as San Pedro. Piracy was so rife, and the insecurity
so great, on the Uruguay and the Parana, that few ventured as far as
Buenos Aires, the ships being linked in convoys. Up stream, Corrientes
was the limit of navigation. The dictator Francis closed the Paraguay,
and even the small boats no longer sailed on the upper Parana, along
the frontier of Paraguay. The Correntinos, who spoke _Guarani_, could
merely get permission at rare intervals to send a few boats up river.
Armed boats convoyed these as far as Neembucu, and they returned with
hides and _mate_. Corrientes thus became the market-centre of the upper
river and replaced Asuncion in the trade. The flotilla on the Parana
included flat-bottomed barges, which were only used in coming down,
and strong keeled ships--schooners, sloops and brigs--with their ropes
made of leather. Down stream there was a little more diversity in the
traffic. The island sent cargoes of firewood and charcoal to Santa Fe
and Buenos Aires. The orchards of the delta provided Buenos Aires with
oranges and peaches. Hides for export were shipped at Goya and Santa
Fe. But the chief freight was lime from La Bajada, which was burned in
the kilns on the Barranca, at the outcrops of the beds of conchiferous
limestone.
[Illustration: CONFLUENCE OF THE YGUASSU AND THE PARANA.
_In the foreground is the left bank of the Yguassu, on Argentine
territory. The right bank is Brazilian territory. At the back, on the
right bank of the Parana, is Paraguayan territory._
PLATE XX. To face p. 236.]
The navigation was fairly easy, the journey from Corrientes to Buenos
Aires (675 miles) lasting, as a rule, from fifteen to twenty days.
Going up, the time was more irregular. They had to stop when there was
no south wind, or a little progress was made by hauling (_silgar_).
D'Orbigny took a month to travel up.[119] In 1822, before the war with
Brazil, there were 651 boats entered at Buenos Aires for coasting trade
on the rivers and 1,035 at San Fernando or on the Tigre, the advance
port of Buenos Aires. In 1833 Isabelle put at one thousand the number
of vessels at work on the Parana and the Uruguay.
[119] The local south winds which help the voyage upward below
Rosario may be due to the high temperature of the water of the
river; this also gives rise on the lower Parana to thick fog
of which warning is given.
In 1841 Rosas forbade navigation on the river. There was then a double
blockade checking the trade of Argentina. The Franco-British fleet
closed the Rio de la Plata and blockaded Buenos Aires, where the
Government of Rosas was established. In addition, Rosas's troops on the
_barranca_ of the right bank prevented any from going up the Parana,
and cut off the interior provinces from the rest of the world. The
injury then done to interests which were already fully self-conscious
may be gathered from the agitation provoked by the decision of France
and England in 1845 to break the blockade of the river. A convoy was at
once organized at Montevideo, consisting of no less than ninety-eight
ships, of 6,900 tons in all (MacKann). It went up the Parana under the
protection of war-ships, which removed the chains slung across it by
Rosas. The convoy dispersed up river as soon as it was out of range of
Rosas. But it had needed so great an effort that the attempt could not
be made again before the fall of Rosas.
The closing of the Parana compelled a diversion of the trade of
Paraguay toward the south-east. It crossed the isthmus of Misiones,
between the Parana and the Uruguay, and passed down the Uruguay. At
this time the whole commercial activity of Paraguay was concentrated
at Itapua, on the upper Parana. The prosperity of the Uruguay was some
compensation for the misery that reigned on the Parana. The populations
of Paysandu and Montevideo greatly increased.
In 1852, at the fall of Rosas, the modern period began for the Parana.
The river-population changed rapidly. It ceased to be exclusively
creole. Basques, and later Italians, had settled upon the Uruguay ten
years before, and they now spread along the Parana. In 1850 MacKann
found fifty vessels, of 20 to 100 tons, belonging to Italians at
Santa Fe. This wave of immigration coincided with the development of
relations between the Parana and the port of Montevideo. From 1852 to
1860 Buenos Aires was isolated, and it remained outside the economic
life of Argentina. Montevideo took its place. Urquiza's administration
sought, in addition, to establish direct maritime communication between
over-seas ports and the ports on the river: Gualeguy in Entre Rios, and
Rosario in Santa Fe. Under a system of preferential duties (1857-59),
which reduced the burden on goods carried by the river, Rosario grew
rapidly, and between 1853 and 1858 increased its population from
4,000 to 22,700. The period from 1852 to 1860 was also the time when
steam-navigation was developing, and this doubled the value of the
river-route. From 1860 onward Buenos Aires was connected by regular
services of steamboats with Rosario, Santa Fe, Corrientes, Asuncion
and Cuyaba. On the upper Parana goods (timber, tobacco and oranges)
were still carried by sailing boats between Corrientes and Apipe, where
they stopped at the commencement of the rapids. Steamboats did not sail
up the rapids of Apipe until 1868.[120] From 1850 to 1860 there were
repeated explorations of the Salado and the Bermejo, as the interior
provinces hoped to be able to find a connection with the vivifying
artery of the Parana (voyage of Page on the Salado from Salta in 1855,
and of Lavarello on the Bermejo in 1855 and 1863).
[120] According to Rengger, sailing ships sometimes succeeded
in crossing the Salto d'Apipe.
In 1860 the entry of Buenos Aires into the Confederation re-established
the normal condition of free competition between Buenos Aires and
Rosario. From that time the life of the river reflects the advance of
colonization in the Pampean region. The Parana became the highway for
the export of cereals.
The two rivers, of which the Rio de la Plata forms the common estuary,
differ considerably in their features. The Uruguay has irregular
floods, especially in autumn (May) and at the end of the winter
(August-October). Low water is in summer (January-February). Its basin
belongs to the temperate zone, and does not extend northward as far as
the area of tropical summer-rain. The Uruguay also differs from the
Parana in its low capacity for transport and alluvial deposit. While
the Parana has built up a vast deltaic plain, the Uruguay ends in an
ordinary estuary, with rocky or sandy bed and clear water. The estuary
of the Uruguay is 130 miles long and five or six miles wide. The
eastern shore is rocky and broken. The Argentine shore is low. It is
formed in the south by the deposits of the delta of the Parana, while
further north, from Gualeguacha to Concepcion, the hills of Entre Rios
are hidden behind a screen of flat islands covered with palms, formed
by the stuff brought by the streams of Entre Rios. The river-floods are
lost in the great sheet of the estuary. The tide in the estuary or a
flood in the Parana is enough to turn the current.
Maritime navigation goes beyond the estuary and beyond Paysandu, as
far as the rapids which prevent further advance at Salto. The twin
towns of Concordia (right bank) and Salta (left bank) mark the limit
of navigation on the inner course of the river. It begins again above
the falls, at Monte Caseros, from which the river-boats go to San Tome
and occasionally to Concepcion. Small ships go higher, as far as Salto
Grande in Misiones (27 deg. 20' S. lat.).[121]
[121] At one time the boats on the upper Uruguay saved
transport by going from Salto to Arapehy, midway between Monte
Caseros and Concordia (see Isabelle).
The navigable system of the Parana is four times as large. The first
survey of the river was made about the middle of the nineteenth century
by the British Navy. At the beginning of the twentieth century the
Argentine Government took up the study of the bed and the peculiarities
of the Parana, and the Ministry of Public Works published a map, on
the scale 1:100,000, of the course of the river between Posadas and
San Pedro, at the beginning of the delta. A precise survey was made,
and twenty-six fluvio-metrical scales were established, the zero of
which represents mean low-water.[122] Transverse soundings were taken
at equal distances of 670 and 1,000 feet, the distance being reduced
to 160 and even 80 feet at critical points. Thanks to this work, the
Parana is now, no doubt, the best known of all rivers of that size.
[122] It is as well to notice that the profile determined by
the altitude of the zero of these different scales, or the
low-water profile, is of a purely theoretical character. The
river is never at low-water over its whole course. The real
profile is always varied by slight movements of flood and ebb.
Its output is estimated at 6,000 cubic metres a second at mean
low-water, in the latitude of Rosario, and 25,000 to 30,000 cubic
metres a second during flood at a height of six metres above
low-water.[123] Its features bear the mark of its tropical origin.
The tropical character is typical on the Paraguay, which is, by its
situation in the central South-American plain, the real continuation of
the lower Parana. The slightness of the fall of the Paraguay, however,
and the extent of the marshes over which it spreads in Brazil and
Paraguay, have the effect of regulating and retarding the flood, which
only attains its maximum at Asuncion in May. The flood of the Paraguay
extends the period of high water on the lower Parana until the end of
autumn. The upper Parana has most of its basin in the tropical zone
of summer rain. But its behaviour is also influenced by the spring
or autumn rains of the southern part of the Brazilian tableland. Its
floods are sudden and violent. They reach a height of sixty or seventy
feet in the region of the confluence of the Yguassu. They sweep rapidly
down stream, and reach the lower Parana before the flood of the
Paraguay, which they hold back.
[123] Observations of the sediment held in the water have been
made at Campana, 32 miles from the estuary. At this point
the Parana only holds in suspension fine particles of clay,
but sand travels slowly along its bed. The weight of the
clay in suspension varies from 179 grammes per cubic metre
in March during the flood, to 42 grammes at low-water in
July. The stuff mostly comes from the Bermejo, which carries
5 kilogrammes of sediment per cubic metre. The load of the
Parana is much heavier than that of the Uruguay, but far lower
than that of the Mississippi.
From Posadas the flood-waves reach Corrientes in five days (235 miles).
From Corrientes they reach Parana in eight days (380 miles), travelling
about two miles an hour. That is one-third the speed of the current, as
the flood is retarded, and more or less absorbed, by the ramifications
of the broader bed in which it moves.
At Bajada Grande the lowest water is in September. The flood appears
in December or January, though sometimes in October or November. The
maximum is in March or April. The rise is rapid at first, but it
gradually moderates, and the level of the water is raised about one
metre per month during three months. It then sinks in corresponding
order. The ebb is often interrupted in June, and sometimes as late
as August, by a sudden leap upward of the curve, representing an
ascensional movement of the water three times as rapid as that of the
main flood (one metre in ten days). The level reached in this late
flood is sometimes higher than that of the normal flood in April or
May. The range of the ordinary flood-movements is from ten to sixteen
feet. Exceptional floods rise to a height of twenty-three feet above
the low-water mark.
The curves established for the years 1908 to 1910 by the Argentine
hydrographical service enable us to analyse the mechanism of the flood
with a good deal of confidence. The beginning of the flood at Bajada
Grande in October corresponds to the first flood of the upper Parana.
During this first phase the curve of the Bajada is parallel (thirteen
days later) to that of Posadas. There is the same parallelism in
November, December and January. If the summer rains are light on the
upper Parana, the flood is late on the lower Parana, and the water is
still low there in December (0.20 below the low-water mark on December
31, 1910). At the beginning of March, before the maximum of the flood,
the curve of Bajada Grande differs from the curve of Posadas. It is
the time when the flood of the lower river is caused by the rise of
the Paraguay. The secondary floods of June and July again have their
origin in the upper Parana, but, as they are added to the flood of
the Paraguay on the lower river, they reach a higher level there than
at Posadas; the difference gradually disappears as the flood of the
Paraguay subsides. It is the addition of the late floods of the upper
Parana to the flood of the Paraguay that causes on the lower river the
abnormal floods that occur there at irregular intervals (in 1825, 1833,
1858, 1878, 1905 and 1917).
Below the Bajada the height of the floods progressively declines. On
the estuary they are no longer perceptible; variations of level are
due entirely to the tides. In the channels of the delta of the Parana
the tide does not reverse the current as it does in the estuary of the
Uruguay, but it causes a slight rise of the water; and this has been
observed sometimes, at very low water, as far as Rosario.
It is near Corpus, about forty miles above Posadas, that the upper
Parana escapes from the restraint of the Brazilian tableland, which
imprisons its valley, from the falls of the Guayra, in a deep fissure
between lofty basalt cliffs. Below Posadas the river leaves the
region of hills and red earth. Below Corrientes it flows everywhere
over its own alluvia. Even above Corrientes its form has surprising
characteristics of youth. The precise survey done on its banks has
brought to light a very distinct break of its fall above Villa
Urquiza, about 400 miles from Buenos Aires. The fall, which from
Corrientes onward remains between sixty and forty millimetres per
kilometre, sinks suddenly to thirteen over a stretch of twenty-five
miles, and then rises again to thirty to forty-five millimetres.[124]
Below Rosario the mean descent is twelve millimetres to the kilometre,
below San Pedro only six.
[124] The district on the right bank of the Parana, above
Santa Fe and Parana, seems to be due to a recent subsidence.
The river is, on the other hand, compelled to effect active
erosion in crossing the high lands between Santa Fe and Buenos
Aires. It is curious that the break or fall at Villa Urquiza
occurs precisely above the bend of the Parana. A less marked
break has been recognized further north, in the latitude of
Lavalle, above the Goya bend. It seems that the diminution in
the excavation of the valley is due to the erosion which the
current effects laterally on the cliffs of the left bank.
Above Corrientes the width of the main arm of the Parana varies, as
a rule, from 2,600 to 6,500 feet. The width of the river-plain over
which the floods spread is still more irregular. Between Santa Fe and
Parana, where it is especially narrow, it is still ten miles wide.
Lower down it gradually broadens to a width of sixty-five miles at the
head of the estuary. The scenery is not the same in all sections of it.
The vegetation on the islands is richer and more varied up river, and
tropical essences (laurel-timbo) are found below the Bajada, forming
clumps of trees covered with creepers.
[Illustration: THE PARANA AT CORRIENTES.
_Banks and islands partially fixed by vegetation._
Photograph by Widmayer.]
[Illustration: THE _BARRANCA_ AT PARANA (ENTRE RIOS), LEFT BANK.
_It is composed of clays and of beds of conchiferous terrestrial
limestone, which have supplied the lime-kilns for more than a century._
Photograph by Boote.
PLATE XXI. To face p. 244.]
But the different scenes of the river region are most of all due to
different conditions of erosion and formation. Above Rosario the
configuration is due to floods. Each succeeding flood alters it and
leaves some trace of itself in the topography. The beds of sand that
it lays down are fixed by rushes and floating weeds, then by willows
(_Salix humboldtiana_). This screen of vegetation encourages accretion,
and the edges tend to rise higher. In the middle of the island are low,
marshy lands. The irregularity of the alluvial deposits causes marked
undulations in the whole region of the river, and everywhere gives rise
to alternate beds of clay and sand. Below Rosario the river gradually
loses its power. The islands become more stable and flatter. Clumps
of willow and spiny _ceibos_ (_Erythrina cristagalli_) still cover
the edges of them, and sometimes spread over the interior. But as the
climate is now less humid, the vegetation fixes the soil less firmly,
and the wind becomes the chief sculptor of the landscape. It heaps up
the sand during the low-water season, and makes dunes which rise above
the level of the greatest floods. These dunes form an unbroken line
along the land in the southern part of Entre Rios, in the north of the
main arm, with ridges at right angles, advancing toward the south,
which rest upon the river clay; like the one which the Ibicuy railway
follows across the floodable area. The cattle of the district take
refuge on the dunes during floods. During periods of drought, on the
other hand, they retain a quantity of water, and this is drawn from
surface-wells at their base.
The limits of the zone of the river are clearly marked on the whole
of the lower Parana. It is enclosed on both sides by high _barrancas_
(cliffs), vertical in places where the main current washes their feet,
but sloping slightly where there is only a secondary arm with little
erosive power. The cliff is broken only at the confluences of small
valleys, the flat, filled-up bottoms of which are on the level of the
alluvial plain of the Parana. The cliffs are at their highest in the
district of Villa Parana, where they rise in places to a height of 300
feet. On the right bank the cliffs show a section of the upper layers
of the Pampean clays. On the left bank there are aeolian clays only at
the top of them. Below these are Tertiary marine strata (marls and
sandstones with beds of shells). The cliffs of the left bank stretch
northwards, with a few breaks, as far as Corrientes, and even into
Misiones. Their height gradually diminishes, and the Tertiary marine
strata are replaced by granitic red sandstone.[125] On the right bank
the height of the cliffs gradually diminishes up river. They are still
conspicuous at the confluence of the Carcarana, but at Santa Fe they
rise only about thirty-four feet. North of 31 deg. S. lat., and for some
distance beyond Pilcomayo, the plain of the Chaco is very low, and it
is impossible to define exactly the limit of the alluvial zone of the
Parana. The fine clays, grey and white, which form the soil of the
Chaco, reach the left bank north of Corrientes, in the _esteros_ of
Neembucu. The red sandstone hills of the Asuncion district rise like an
archipelago out of this level bed of lacustrine deposits.
[125] In the space between the frontier of Entre Rios and the
Rio Empedrado, south of Corrientes, the cliffs expose, above
the red sandstone, beds of sand and clay, fluvial alluvia
left by former beds of the Parana, the traces of which can
be followed from the north-east to the south-west diagonally
across the province of Corrientes.
There is no obstacle to navigation in the entire stretch from Posadas
to the falls of the Guayra on the Parana and the Salto Grande on the
Yguassa. Sixteen miles below Posadas the Parana passes through a series
of graduated rapids for about sixty miles (1,467 kil. to 1,558 kil.
from Buenos Aires) wrongly called the Salto de Apipe. The current then
rises to a speed of eight knots, and the depth is three feet at low
water. These rapids are due to beds of melaphyre, which emerge amongst
the granitic sandstone, and the water makes its way between large rocky
islands. At Ituzaingo (1,455 kil.) the current loses force. There is,
however, still a rocky bottom lower down, for ninety miles, at a depth
of five feet. Below this the rock only appears on the left bank, and in
a few ridges near the bank, or in isolated reefs which it has been easy
to mark with buoys.
From Corrientes to La Paz the river flows from north to south at
the feet of the Corrientes cliffs. These line the main stream
between Corrientes and Empedrado, and for thirty-five miles south of
Bellavista. In the latitude of Riachucho, especially about Bellavista,
the cliffs form a series of creeks and capes, in which the west winds
create a heavy sea that was dreaded by ships of light draught coming
down the river. North of Bellavista, and for more than a hundred miles
south of Goya, the main stream is separated from the cliff by a series
of alluvial islands; behind these are lateral arms (_riachos_) into
which pour the rivers of Corrientes. These arms were much used by the
early navigators.
Between Esquina and La Paz the main bed, which is not in touch with the
land on either of its banks, flows in a meandering path for some seven
miles, the scale of the bends being double that of the meandering of
the Paraguay north of the confluence. The islands are very small, and
are strung in a rosary at the top of each bend. The depth is sixty feet
at the top of the bend. The shallows are in a line with the islands at
the point where the current runs evenly again before the next curve.
The depth here is seven, and sometimes even five feet.[126] These
shallows change their places quickly, and it is not always the same bad
spot that determines the maximum draught for ships that are to be used
in this section. This migration of the shallows is very different from
the permanence of the rocky bottom of the stretch between Corrientes
and Posadas.
[126] In point of fact, the ridge is lower at the time of low
water, when the current is concentrated in the main channel,
so that one always finds one or two feet greater depth there
at low water than soundings taken at high water would lead one
to expect.
From La Paz to Parana the main course is outlined by the Entre Rios
cliffs. There is no further meandering. The cliffs of hard rock offer
far more resistance than the soft alluvia over which the river wanders
freely. The permanence of the bed in front of the cliffs leads to
a depth of as much as eighty feet. Only here and there a fringe of
alluvial stuff separates the channel for a time from the cliff. These
curves seem, as a rule, to coincide with the confluence of rivers,
which bring a heavy load of clay from the tableland; as, does, for
instance, the San Feliciano, north of Hernandarias. They are marked
by shallows, in strong contrast to the great depths of the straight
sections. The San Feliciano _paso_, which is twelve feet broad to-day,
was only six feet broad in 1908. It appeared on Sullivan's map in
1847.[127]
[127] A little above its actual position.
Below Parana, as far as the estuary, the careful observations that
have been made since 1903 on the movement of the river have enabled us
to learn some of its laws.[128] We can distinguish four sections of
unequal length. From Parana to Diamante the river remains in touch with
the cliffs of the left bank. It is not straight; it describes a series
of linked crescents of equal radius, which seem to be traces of so many
meanders. Only one in two of the windings of the cliff is followed by
the channel. The wandering of the river is confined within limits as
in a fixed mould. The Paracao shallow, which for a long time prevented
ships from reaching Santa Fe (gradually deepened by dredging from eight
to nineteen feet between 1907 and 1911) is at the angle where two of
these curves meet. On the right bank the secondary arms continue to
follow the river (Parana viejo, Riacho de Coronda).[129]
[128] In studying the variations of the bed of the Parana it
is necessary to avoid comparing maps drawn at dates separated
by long intervals. The differences of such maps are such
that they do not enable us to follow the processes by which
the actual forms have been derived from earlier forms. The
analogies which they show are sometimes due, not to the
permanence of the topography, but to the return of a complete
cycle of changes, or of conditions analogous to the earlier
conditions.
[129] The secondary arms of the right bank, north of Santa
Fe, were not explored until 1870. Sullivan's map (1847) only
mentions the Riacho de San Jeronimo, which is visible for a
short distance below 20 deg. S. lat. The right bank was the domain
of the Indians, and the Correntinos would not venture near it.
In 1870 ships began to use the San Javier arm, on which many
colonies arose. Further north the Parana Mini has been used
since 1890 for exporting _quebracho_ timber.
Below Diamante the river leaves the cliff on the left bank and slants
across the alluvial plain to the cliff on the right bank, which it
reaches at San Lorenzo. Over the whole of its thirty miles width it
resumes the freedom and regularity of features which it had above La
Paz. A comparison of the successive maps of the river shows that the
scheme of its movements, which one would be tempted to draw up with a
regular migration of the islands and loops down river, would not be
accurate. The changes of the bed of the river are essentially due to
variations in the volume of the different arms, which are constantly
changing their size and adapting their shape to the body of water that
flows in them. The radius of the curve of each arm is proportional
to its volume. A long island is formed between two arms of equal
size which both describe symmetrical curves. If the volume of one of
them is reduced, its original curve is replaced by sinuosities of
smaller radius, and these nibble the edges of the island and give it
an irregular shape. If the volume increases again, the winding bed is
abandoned and becomes a dead bed, and a larger meander begins. The
track followed by the ships then breaks up into a series of meanders
over a course of about eight miles and a half, and this means the
concentration in a single channel of the greater part of the water of
the river, and in narrower bends in the sections where the current is
divided between several arms.
From San Lorenzo to San Pedro the river flows by the cliff of the
right bank. It is remarkably regular, and has only one slight bend:
an exceptionally good site, on which the town of Rosario is built. At
almost equal intervals, differing by only about ten to thirteen miles,
the river leaves the cliff, and is separated from it by an alluvial
strand, or by an insular zone a few miles in width.[130] Below this
bend the current again touches the cliff and landing is easy. The
small, older ports of the Parana--Constitucion, San Nicolas, Puerto
Obligado and San Pedro--are built on similar sites. It does not seem
that the islands at the foot of the cliff tend to extend downward in
front of these ports; the points where the river reaches the cliff are
fixed. The depth is often considerable at the foot of the cliff (138
feet opposite Puerto Obligado). The shoals are distributed irregularly
at the bends, where the channel moves away from the cliff. They all
have to-day a minimum depth of twenty-one feet.[131] On the left bank
the secondary arms sprawl over the alluvial plain for thirty-five miles
north of the river.
[130] As between La Paz and Parana, it seems possible to show
some relation between these alluvial stretches at the foot
of the cliff and the confluence of the small valleys of the
Pampean plain.
[131] The Paso Paraguayo, which has cost the Argentine
hydrographic service most work, did not exist at the middle of
the nineteenth century. It seems that the channel then kept
to the cliff as far as Benavidez, and was continued as far as
the source of the Parana Pavon by a very pronounced buckle, of
which the Monriel lagoon is a scar. In 1895 the Paso was only
fifteen feet deep.
The delta begins at San Pedro. The Parana Guazu, or main arm, leaves
the cliff on the right bank and passes to the Uruguayan bank opposite
Carmelo. The Parana de las Palmas, which branches off from it to
the south and passes before Campana and Zarate at the foot of the
tableland, is deep and easy to navigate, but it is closed at the bottom
of the estuary by a six-foot bar, which makes it a sort of blind alley
opened only above. The arms of the zone of the delta differ from those
of the river-zone proper in the irregularity of their course. Flowing
between long islands, they sometimes lie in straight stretches and at
other times in meanders or almost perfect buckles. The channels of the
southern part of the delta, near Buenos Aires, are called _caracoles_
(snails) on account of their winding shape. The weakness of the
current, which is held up by the tide, is seen also in the distribution
of the greater depths; they are no longer uniformly found along the
concave edge of the bends, but are scattered irregularly. On the Parana
Guazu a depth of 130 feet has been ascertained. Its minimum depth is
twenty-two feet.
[Illustration: THE PARANA ABOVE THE ESTUARY.
_Right bank. The river has moved away from the_ barranca, _leaving at
its foot an alluvial plain of imperfect spiral form_.
PLATE XXII. To face p. 250.]
The study of the estuary may be taken separately from that of the
river. It consists of three parts, unequal in size, which open with
increasing breadth toward the Atlantic. The upper Rio de la Plata,
above Colonia and Punta Lara, has a width of about thirty-five miles.
The middle Plata, twice as wide, extends to the latitude of Montevideo
and Punta de las Piedras. Then the outer harbour opens between
Maldonado and Punta Rasa. The water is still fresh in the middle
estuary up to eighty miles below Buenos Aires.
The bottom is alluvial except in the channels between Martin Garcia and
Colonia.[132] Differently from up the river, where the channels have
sandy bottoms, while the banks are of fine clay, the channels of the
estuary have bottoms of mud and clay. In the outer harbour the pilots
recognize the approach of banks by the sand which is brought up by
the sounding-lead. The action of the waves, which is not found in the
river, accumulates stuff of comparatively large size and weight on the
banks.
[132] The granite which outcrops at Martin Garcia also forms
the platform of the English Bank in the outer harbour.
In spite of the conclusions embodied in the nautical instructions,
which describe the estuary as a theatre of rapid changes "occasioned
by the continual deposits of sand brought down by the Parana and the
Uruguay,"[133] the estuary is, as a matter of fact, in a remarkable
state of equilibrium, and there is no trace of a gradual accumulation
of alluvia, or of important changes of channel. The shore of the
delta north of the Parana de las Palmas, covered with rushes which
protect it from the attack of the waves, shows neither advance nor
retreat. The broad lines of the hydrography of the Rio de la Plata
are plainly indicated on Woodbine Parish's map. The English Navy map
of 1869 (on the basis of observations in 1833, 1844 and 1856) only
differs in detail from the present map. The stability of the channels
is surprisingly different from the changes in the bed of the river
in the flood-zone. The permanence of the bottom, in spite of the
loose deposits of the estuary, is explained by the regularity of the
currents. These currents, which determine the submarine topography of
the Rio de la Plata and the distribution of the banks, are not of river
origin. They are tidal currents.
[133] The water in the estuary, worked up by waves and tide,
contains more sediment than the water of the river.
There are two groups of shoals in the estuary. The first, the Playa
Honda, occupies the whole western part of it up to a line drawn from
Buenos Aires to Colonia. These banks leave a narrow passage in the
north, opposite the Uruguayan shore, and this is followed by ships
going to Uruguay and the Parana Guazu. The second group of shoals is
the Ortiz Bank, triangular in shape, which rests in the north on the
Uruguay coast below Colonia, while its point extends south-eastward to
eighteen miles north of the Punta de las Piedras. It keeps the zone of
deepest water in the middle estuary to the south, near the Argentine
shore. In the latitude of the point of the Ortiz Bank, on a line from
Montevideo to Punta de las Piedras, the middle estuary is separated
from the outer harbour by a bar (_barra del Indio_) with thirty-eight
feet of water, caused by the transverse currents which circulate from
point to point inside the English Bank.
The tide in the estuary is very irregular. The south-east winds
increase the flow and retard the ebb. When they are blowing, it often
happens that the level of the water in the upper estuary keeps up from
one tide to the next, sometimes for several days. The tide, which
is slight at Montevideo, is greater at the bottom of the harbour on
the Barra del Indio, sometimes rising nearly forty inches there. From
there it advances with difficulty northward, over the Ortiz Bank, along
the Uruguayan shore, whereas it passes freely into the deeper zone on
the Argentine side.[134] At Buenos Aires it still has a depth of thirty
inches. From there it advances northward by the Martin Garcia channels
beyond the Playa Honda. The channel of the Pozos del Barca Grande,
which crosses the Playa Honda bank from north to south, parallel to the
edge of the delta, is oriented in conformity with the tidal currents
and maintained by them. It is not attached to the river, and it is
separated from the mouths of the Parana de las Palmas or the Parana
Mini by shallows which are navigable only to small boats. The _Rias_
of the Uruguay, where the tide raises the water twelve inches, forms
a sort of reservoir which, at the ebb, feeds a strong current round
Martin Garcia and sweeps the channels there.
[134] The current at high tide is stronger than at low tide,
and it has shifted to the north-east the streams which find an
outlet on this side.
The work done for the improvement of the estuary includes the deepening
to thirty feet of the Barra del Indio and the dredging of a straight
channel from that point to Buenos Aires. Steamers of large tonnage
going up the Parana leave this channel twenty-six miles east of Buenos
Aires, and turn north in order to pass east of Martin Garcia, and
enter the river by the Parana Guazu or the Parana Bravo. Since 1901
the Argentine Government has considered a plan of opening a direct
route from Buenos Aires to the Parana de las Palmas, either by cutting
an artificial canal at the foot of the cliffs, across the Tigre
archipelago, or by using the channel of the Pozos del Barca Grande and
cutting the narrow bar which closes the Parana de las Palmas below. If
this were done, the ports of the Parana de las Palmas would have direct
access to the sea. Moreover, the new route from the Parana to the
Atlantic would be entirely within Argentine territory, out of range of
the Uruguayan shore, and Buenos Aires would become a necessary port of
call both on departure and return.
Above the estuary, the work for the improvement of the Parana began
in 1904 and 1905. Since 1910 the material dredged from the bed of the
river has risen to 3,500,000 cubic metres a year on the average. The
experience gained in the course of this work has enabled the Argentine
hydrographic service to adjust its methods to the incomparable force
of the river. It is impossible to maintain a general rectification of
the bed and the banks, as is possible with European rivers. The only
thing to do is to submit quietly to the plan which the river sketches
for itself, and be content to deepen the difficult passages on the
line of the main arm. Suction dredges, which work easily in the sand,
attack each ridge or _paso_ from below, making a channel into which
the waters flow, so that it tends to enlarge itself up stream. The
dredges are shifted from bank to bank according as the soundings tell
of the formation of fresh obstacles to navigation. They were at first
concentrated below Rosario, where the Argentine Government had to carry
out certain engagements contracted with the Port Company; then they
were scattered as far up as Santa Fe. The actual equipment suffices to
carry out the programme that had been drawn up--to maintain a depth of
twenty-one feet as far as Rosario and of nineteen feet as far as Santa
Fe.
[Illustration: MAP VII.--ESTUARY OF THE RIO DE LA PLATA.
_The channels of the estuary are parallel to the direction of the
tidal currents, which account for their depth. Those which cross the
shoals of the Playa Honda, at the bottom of the estuary, finish as
no-thoroughfares, and do not give access to the southern arms of the
river. From Buenos Aires ships going up the river have to go round by
Martin Garcia and the mouths of the Parana Guazu._
To face p. 254.]
As regards the section above Santa Fe, the engineer Repossini advises
that, instead of adopting a programme of expensive dredging with
uncertain results, they should first think of adjusting navigation to
the natural conditions, and they are such as would be considered very
favourable in Europe. The hydrographic service would, however, still
have two functions: in the first place, the topographical study of the
river and the constant placing of buoys, and, in the second place, the
observation of its behaviour and anticipation of variations of level.
The utility of the work of foreseeing floods, which has been carried on
since 1907, has been abundantly proved. It published a daily bulletin
of forecasts, based upon observation of the pluviometric scales of
the upper river, which is equally valuable to the navigators and to
breeders in the floodable area. It enables the breeders to get their
cattle into safety before the floods come. On the other hand, the ship
can, thanks to the bulletin, foretell what depth of water it will find
at critical passages, and calculate exactly the load it can carry, and
so complete its cargo lower down. The service of forecast of floods
has morally improved navigation on the Parana by suppressing every
possible pretext for wilful stranding, which had become a current form
of speculation.
* * * * *
Nothing is more varied than the fleet which now serves the Parana. It
includes tramps, and long, slim European ships, which load up with
cereals and meat; large river boats, luxurious and light; barges
and tugs, lighters and schooners, which have compensation for their
slowness in their cheapness.
As regards navigation, the river is now divided into three sections.
Maritime navigation ascends as far as Santa Fe. At Rosario and Santa Fe
it goes right to the heart of the zone of cereals and to the fringe of
the forest area. The upper section, between Rosario and Santa Fe, is
less safe than the lower section, and this is reflected in the cost of
freightage from Santa Fe.
The ports of the lower Parana, between Santa Fe and Buenos Aires,
may be classed in three categories. The ports of the first group
are built on low land that is liable to be flooded. Every year the
floods threaten their traffic. That is the character of Colastine,
east of Santa Fe, which specializes in shipping _quebracho_ timber,
or Ibicuy, on the Parana Pavon, in the south of the province of Entre
Rios, which, however, is protected by excellent works. The small ports
of the _barranca_ of the southern bank, on the main river and on the
Parana de las Palmas, form a second group. They ship meat (Campana and
Zarate) and cereals (San Nicolas and Villa Constitucion), and they are
admirably adapted for this by their natural situation. Steamers come
right up to the cliff without any need of special works on the shore.
The sacks of wheat are let into the ships down sloping gangways from
stores excavated in the cliff or from wagons. None of these ports are
equipped for receiving imports. The third group comprises ports with
complete apparatus for both export and import. The chief of these is
Rosario. It was the increase of imports between 1850 and 1860 that
stimulated its early progress. To-day the tonnage of the goods unloaded
at Rosario is nearly one-half the tonnage of the cereals shipped there.
Yet, in spite of appearances, it is the imports that account mainly
for the busy life of its quays. The port company does the unloading
itself, as well as the handling and storing of the goods imported, but
it is content to receive dues on all exports within the area for which
it has a monopoly. Only a small part of the cereals exported uses its
elevators. A deep-water port, equipped like that at Rosario for import
and export, has just been constructed at Santa Fe. Already it competes
with Colastine for the export of _quebracho_. Its import trade is still
small, as such trade requires large capital and a whole network of
relations with the adjoining country, and that is not the work of a day.
The second section of the river stretches from Santa Fe to Corrientes,
and is continued up the Paraguay. The transport of _quebracho_ timber
and tannic acid is the chief item of its trade. The maximum draught
of the vessels it admits at normal low water is six feet. Some of the
ports on the left bank (Esquina, Goya) and all the ports on the right
bank (Reconquista, Barranqueras, etc.) are at some distance from the
main bed, or lateral arms. The Chaco works have generally a flotilla
of steamers and barges. It is the exporters of timber and extract
of _quebracho_ to Europe who most strongly demand the deepening of
the bed of the Parana above Santa Fe. Sailing ships share with the
river steamers the transport of the products of the Paraguay and of
Corrientes (hides, tobacco and _mate_). The transport of oranges alone
from San Antonio, Villeta, Pilar and Humaita represents an item of tens
of thousands of tons.
The third section of the river stretches from Corrientes to Posadas,
and beyond. Sailing ships have disappeared from this section, as they
cannot make the Apipe rapids. Steamers of four and a-half feet draught
and 150 tons are now used on it, but they cannot proceed at low water.
They provide a direct service between Buenos Aires and Posadas, though
the service is not very economical, because it does not permit them to
use to the full the transport-capacity of the river below Corrientes.
Most of the goods for Posadas are, therefore, trans-shipped at
Ituzaingo, below the rapids, or at Corrientes. The steamboat companies
which serve Posadas are obliged, in order to secure the economical
transport of goods shipped on the upper Parana, to maintain lines which
go up the Paraguay as far as Asuncion, and take on at Corrientes the
goods that come from Posadas. Higher up, the falls of the Guayra and
the Yguassu set an impassable limit to the enterprise of Argentine
vessels. Boats on the stretch above Yguassu on the Parana feed the
railways of the Brazilian tableland. The traffic of the upper Parana
consists chiefly of _mate_ from Misiones and cedar-planks from the
Posadas saw-mills. Rafts of timber are stopped at Posadas and rarely
follow the river further.
The Argentine statistics of navigation are obscure. They confuse under
one heading the river-traffic between Posadas and Brazilian territory,
or between Corrientes and the Paraguay, and the exports of the Pampean
region to Europe. It is difficult to get from them an idea of the real
traffic, or to distinguish the tonnage loaded or unloaded at each port
from that which merely touches its quays in ships going up or coming
down the river. They credit a score of ports with a total tonnage of
(entries and clearances together) more than 500,000 tons.
At all events, they do enable us to distinguish between ports
exclusively devoted to river traffic and those with direct relations
to oversea ports. Nearly all the boats destined for the Parana touch
at Buenos Aires, which remains the chief importing centre, on the way
up, and unload there. They then go empty to Rosario, San Nicolas, or
Santa Fe to take on a full cargo of cereals or timber, and set out down
the Parana for Europe without calling at Buenos Aires. Clearances for
interior navigation at the port of Buenos Aires are far more numerous
than entries. From 1912 to 1914 Buenos Aires received on the average,
coming from interior ports, 1,750,000 tons, of which 1,635,000 were
cargo. It cleared for the same ports ships totalling 3,275,000 tons, of
which 1,580,000 were in ballast. The latter figure fairly represents
the tonnage of sea-going ships sent up river empty after discharging on
the quays of Buenos Aires. At Rosario, San Nicolas and San Pedro, on
the other hand, the tonnage of clearances for Argentine ports is much
less than the tonnage of entries.[135] The total movement of goods at
the port of Rosario is 410,000 tons entries and 375,000 tons clearances
for interior navigation, and 1,100,000 tons entries and 1,824,000 tons
clearances for navigation abroad.
[135] Movement of internal navigation at Rosario (average
1912-1914): entries, 1,108,000 tons, of which 690,000 in
ballast; clearances, 580,000 tons. At San Nicolas: entries,
400,000 tons, of which 440,000 in ballast; clearances, 4,000
tons. The difference between the entries and the clearances
represents ships starting straight for Europe.
According to Repossini's calculations the tonnage of exports on the
lower Parana south of Santa Fe rose in 1910 to 4,000,000 or 4,500,000.
The imports, almost entirely confined to Rosario, were about a fourth
of this figure. For the middle and upper Parana, Repossini estimated
the volume of the traffic at 800,000 tons, of which _quebracho_ was
two-fifths.
The navigation of the Parana is one of the chief sources of the
prosperity of Buenos Aires. Even if the development of the import
trade at Rosario or Santa Fe is partly at the expense of the capital,
and the boats laden with cereals do not stop at its quays, still the
coasting traffic on the river is in great part meant for Buenos Aires.
In returning, rather than go empty, the boats take cargoes of European
products bought from the Buenos Aires importers. By means of the Parana
the import-trade sphere of influence of Buenos Aires reaches beyond the
frontiers of Argentina, as far as Paraguay and part of Brazil. Buenos
Aires is, moreover, the main centre for equipping the steamboats of the
river. Its capital dominates the Parana. Lastly, the Parana supplies it
with an export freight which must not be overlooked. It is at Buenos
Aires that the hides, tobacco and timber and extracts of _quebracho_
for oversea markets, shipped on schooners in the upper reaches of the
river which are impassable for steamers, are trans-shipped for abroad.