SECTION 2
GEOGRAPHICAL BACKGROUND,
PANTANAL AND HIDROVIA
This section establishes the geographical background for this
study, as it relates to the
Pantanal of Mato Grosso and the Paraná-Paraguay Waterway (Hidrovia)
Project. It is
divided into four subsections:
1.The Paraná-Paraguay River Basin,
2.The Paraguay and Upper Paraguay River Basins,
3.The Pantanal of Mato Grosso, and
4.The Paraná-Paraguay Waterway (Hidrovia) Project.
This study focuses on the impact of the proposed Paraná-Paraguay
waterway project
on the Pantanal of Mato Grosso, which lies within the Paraguay river
basin, a major
tributary of the Paraná-Paraguay basin system. The reference sources for
the informa
tion contained in this section are listed in Appendix 1.
The figures
and tables for all
sections are included in Appendices 2 and 3, respectively.
2.1
The Paraná-Paraguay River Basin
The Paraná-Paraguay river basin is the most important of the La
Plata basin system,
in terms of both discharge (75 percent) and catchment area (84 percent)
(Bonetto,
1975). The La Plata system is the second largest in South America, after
the Amazon.
The Paraná-Paraguay basin drains an area of 2 605 000 km2, in
Brazil, Argentina,
Paraguay, and Bolivia. As its name indicates, it is composed of two major
rivers: the
Paraná and the Paraguay. The Paraná is the largest of the two, draining 1
510 000 km2
(58 percent), while the Paraguay, draining the remaining 1 095 000 km2
(42 percent), is
the most important tributary of the Paraná.
The geographical distribution of the Paraná river basin is: 59
percent in Brazil, 37.4
percent in Argentina, and 3.6 percent in Paraguay.
The geographical
distribution of the
Paraguay river basin is: 33.4 percent in Brazil, 33.3 percent in
Paraguay, 16.7 percent
in Argentina, and 16.7 percent in Bolivia (Anderson et al., 1993). The
combined
Paraná-Paraguay river basin drains substantial portions of these four
South American
countries. The Paraná river is divided into three sections (Bonetto,
1975):
1.The Upper Paraná, from the headwaters of the Paraná river in Brasilia,
Brazil, to
the conflunce with the Paraguay river.
2.The Middle Paraná, from the confluence with the Paraguay river to
Diamante,
close to the city of Santa Fé, Argentina, a distance of nearly 600 km
downstream.
3.The Lower Paraná, from the city of Diamante, a distance of about 300 km
down
stream to the La Plata estuary.
2.2
The Paraguay and Upper Paraguay River Basins
The headwaters of the Paraguay river are located in the Serra de
Tapirapuã, in the
proximity of Vila de Parecis, in the state of Mato Grosso, Brazil
(EDIBAP, 1979). After
flowing in a general southern direction for a distance of 2800 km, the
Paraguay river
reaches the Paraná at Confluencia, north of the Argentinian cities of
Corrientes and Re
sistencia (Fig. 1).
The Paraguay river is divided into three sections (Anderson et al,
1993):
1.The Upper Paraguay, flowing through Brazil, Bolivia, and Paraguay, from
its head
waters to the confluence with the Apa river, a distance of 1873 km.
2.The Middle Paraguay, flowing through Paraguay and Argentina, from the
conflu
ence with the Apa river to the confluence with the Tebicuary river, a
distance of 797
km.
3.The Lower Paraguay, flowing through Paraguay and Argentina, from the
conflu
ence with the Tebicuary river to the confluence with the Paraná river, a
distance of
130 km.
With some exceptions, notably the Pilcomayo and Bermejo rivers,
tributaries of the
Middle and Lower Paraguay, respectively, which descend from the Andes to
the West,
and the eastern tributaries of the Middle and Lower Paraguay, which flow
over hilly ter
rain, the rest of the basin comprises an immense inland plain, with
extremely flat relief.
This peculiar geomorphologic setting has led to the existence of the
Pantanal of Mato
Grosso, an extensive wetland located wholly within the confines of the
Upper Paraguay
river basin (Tricart, 1982). Since this study focuses on the Pantanal,
the remainder of
this section deals only with the Upper Paraguay river basin.
The Upper Paraguay river is the upstream section of the Paraguay
river, from its
headwaters in the Serra de Tapirapuã to the confluence with the Apa
river. The latter
marks the border between Brazil (to the north) and Paraguay (to the
south). The basin
lies between 14o and 23o S, and 53o and 60o W (Fig. 2).
The basin contains the Pantanal of Mato Grosso and its headwaters,
located wholly
within Brazilian territory, and portions of Bolivia and Paraguay to the
West.
While the
precise western limits of the basin are uncertain (the Bañados de Izogog,
in Eastern Bo
livia), the northern and eastern limits are delimited by mountain ranges,
all within Brazil.
To the East, the basin is limited by the Maracajú, Caiapó, and Saudade
ranges; to the
North by the Parecis range, and partly by the Azul range.
The Upper Paraguay river basin comprises 496 000 km2, in two
distinct regions
(DNOS, 1974):
1.The area to the left of the Paraguay and Jauru rivers, wholly within
Brazilian territory,
encompassing 336 000 km2; half of this area is above the altitude of 200
m.
2.The area to the right of the Paraguay and Jauru rivers, encompassing
160 000 km2,
of which 145 000 km2 are in Bolivian and Paraguayan territory, and the
remaining
15 000 km2 are in Brazil; 19 percent of this area (31 000 km2) is above
the altitude
of 200 m.
The principal tributaries of the Upper Paraguay river are (Fig. 3):
1.Sepotuba,
2.Cabaçal,
3.Jauru,
4.Cuiabá, and its tributaries São Lourenço and Piquiri-Itiquira,
5.Taquari, and
6.Miranda, with its tributary the Aquidauana.
Other tributaries, primarily intermittent, include the Negro,
Aquidabã, Branco, Tereré,
and Amonguijá. All these are left-margin tributaries, located wholly
within Brazil.
Table 1 shows selected hydrographic characteristics of the Upper
Paraguay river.
Table 2 shows selected hydrologic data at gaging stations along the Upper
Paraguay
river (Fig. 3). Table 3 shows valley slopes along the Upper Paraguay
river and its major
tributaries.
Table 1 shows that the Upper Paraguay river is quite sinuous,
particularly upstream of
Corumbá, where the sinuosity, i.e., the ratio of river length to valley
length, can be as
high as 2.92 (the reach comprised from 40 km downstream of Porto
Conceição to Re
fúgio das Três Bocas: 161 km/55 km = 2.92).
Table 2 shows that the difference between maximum and minimum
observed water
levels along the Upper Paraguay river is smallest (2.61 m) at
Descalvados, remaining
small (less than 3.5 m) for about 200 km downstream (at Porto Conceição
it is 3.28 m;
at Bela Vista do Norte it is 3.27 m).
Table 3 shows that valley slopes in the Upper Paraguay river basin
decrease gradually,
from 15-50 cm/km close to the mountains to the north, east, and south, to
7-15 cm/km
along the major tributaries, and to 0.7-6.5 cm/km along the mainstem
Upper Paraguay
river.
2.3
The Pantanal of Mato Grosso
The Pantanal of Mato Grosso is a seasonally inundated depression
wholly contained
within the Upper Paraguay river basin, encompassing approximately 136 700
km2 (Pro
jeto RADAMBRASIL, 1982). The Pantanal is geomorphologically and
hydrologically
positioned to attenuate and reduce the annual runoff from the basin.
Tricart (1982) has
stated that the mountains to the south of the Pantanal "strangle" the
valley of the Upper
Paraguay river close to the location where it exits Brazilian territory.
In fact, the Pan
tanal is a huge natural reservoir receiving distributed inflows from a
large number of
tributaries and concentrating runoff at the basin outlet, the Apa river
confluence, 63 km
downstream of Porto Murtinho.
Large portions of the Pantanal are flooded only during the annual
crest of the Upper
Paraguay river and its tributaries, and much nonflooded terra firma is
interspersed
throughout the region. The mixture of permanent swamp, seasonal swamp,
and non
flooded land, as well as the contiguity of the Pantanal to other major
South American
ecosystems (the humid Amazon rainforest to the north and northwest, the
subhumid sa
vannas of Central Brazil to the east, the humid Atlantic forest to the
southeast, and the
semiarid scrub forest of neighboring Bolivia and Paraguay to the
southwest) have condi
tioned the richness and variety of its vegetation and climate (Prance and
Schaller, 1982).
In turn, the Pantanal ecosystem supports a rich and diverse fauna,
including 658 species
of birds, 405 of fish, 1132 of butterflies, and other native species such
as the caiman,
giant anteater, capybara, marsh deer, jaguar, rhea, turtle, and maned
wolf (Bucher et al,
1993).
The name Pantanal of Mato Grosso hides the fact that the depression
of the Upper
Paraguay basin consists of not one but several seasonally flooded
regions, quite distinct
from each other; thus, the Portuguese name Planícies e Pantanais
Matogrossenses
(Flood Plains and Swamps of Mato Grosso).
The following Pantanais
were identified by
the Projeto RADAMBRASIL (1982) (Fig. 4): (1) Corixo Grande-JauruParaguay, (2)
Cuiabá-Bento Gomes-Paraguaizinho, (3) Itiquira-São Lourenço-Cuiabá, (4)
Paiaguás, (5)
Taquari, (6) Jacadigo-Nabileque, (7) Miranda-Aquidauana, (8) Negro, (9)
Tarumã-Jibóia,
(10) Aquibadã, (11) Branco-Amonguijá, and (12) Apa.
Adámoli (1981) has classified the flood plains and swamps of Mato
Grosso into ten
pantanais: (1) Cáceres, (2) Poconé, (3) Barão de Melgaço, (4) Paiaguás,
(5) Nhecolân
dia, (6) Aquidauana, (7) Paraguay, (8) Miranda, (9) Nabileque, and (10)
Abobral.
The peculiar characteristics of the pantanais have led to the use
of regional terminol
ogy to describe its most salient geomorphic features, namely baías,
baixadas, barreiros,
salinas, córregos, capões, cordilheiras, vazantes, and corixos. A brief
description of
each follows.
·The baías are lowlying areas of circular, semicircular, or irregular
shape, which have
standing water, sometimes saline; their dimensions vary from tens to
hundreds of me
ters.
·The baixadas are the portion of the baías that are subject to seasonal
inundation (Da
Silva, 1990).
·The barreiros are baías that have periodic water (Valverde, 1972).
·The salinas are lakes with saline water; they are covered during the dry
season with
salt crusts, and are for the most part unconnected from the seasonally
flooded baías
(Da Silva and Pinto-Silva, 1989).
·The córregos are small watercourses (Carvalho, 1986).
·The capões are vegetated earthmounds, of various sizes, and
approximately circular
or elliptical in shape (Ponce and Cunha, 1993).
·The cordilheiras are slight terrain elevations located between the
baías, with mean
elevations about 2-3 m above the water level in the baías. While they
are normally
dry, they are subject to inundation during exceptional floods. They
serve as high ar
eas for the location of cattle ranches, and as refuge for livestock
during extraordinary
and exceptional floods.
·The vazantes are large depressions situated between the cordilheiras,
lacking a
clearly defined channel (Carvalho, 1986). During the flood season, these
depressions
drain intermittent streams, extending for several kilometers. However,
many vazantes
are perennial, revealing the presence of substantial amounts of
subsurface flow.
·The corixos, unlike the vazantes, are small permanent watercourses
connecting adja
cent baías with narrower and much deeper channels.
When the corixo is
long and
has a well defined cross section, it is referred to as corixão (Carvalho,
1986).
The characteristics of the several pantanais which constitute the
Pantanal of Mato
Grosso are described in Volumes 27 and 28 of Projeto RADAMBRASIL (1982).
2.4
The Paraná-Paraguay Waterway (Hidrovia) Project
The Paraná-Paraguay river basin system encompasses an extensive
region in South
America, within the countries of Argentina, Bolivia, Brazil, and
Paraguay. The neighbor
ing Uruguay river drains portions of Argentina, Brazil, and Uruguay. The
confluence of
these two rivers is close to the city of Nueva Palmira, Uruguay. The
Paraná-Paraguay
and Uruguay rivers are the major tributaries of the La Plata basin
system.
The Paraná-Paraguay basin is home to a population of close to 20
million people.
For centuries, this river system has been used as a waterway for
transportation. In Feb
ruary 1995, the United Nations Development Programme (UNDP) commissioned
an 18month engineering and environmental impact study to evaluate navigational
improve
ments to the existing waterway. This study includes the possibility of
extensive engineer
ing works to render 3442 km of the river navigable for ocean-going
vessels, from Nueva
Palmira to Cáceres, Brazil. Since the port of Cáceres is located
upstream of the
Pantanal of Mato Grosso, it is imperative to establish and evaluate the
shortand long-term impacts of the proposed navigational improvements on the
Pantanal prior to project implementation.
The project is commonly referred to as the Hidrovia project
(Hidrovia means "water
way" in both Spanish and Portuguese). The stated purposes of the
Hidrovia project are
to enhance current river transport via improvements to existing port,
channel, and navi
gation facilities, and to construct a year-round navigable waterway along
the 3442 km.
These efforts are being planned in two stages:
Phase 1 (Module A): Short-term intervention
This phase entails the improvement in navigational aids and the
required river engi
neering, including dredging and related works, along 80 percent of the
Hidrovia's
length, from the downstream port of Nueva Palmira, upstream to Corumbá,
in Brazil,
and neighboring Puerto Quijarro, in Bolivia.
Phase 2 (Module B): Medium- and long-term intervention
This phase entails the improvement in navigational aids and the
required river engi
neering, including dredging, channel modification, and other major river
interventions, to
encompass the entire length of the Hidrovia (3442 km), from Nueva Palmira
to Cáceres.
The executive agency for the Hidrovia project is the Comité
Intergubernamental de
la Hidrovia (CIH) (Intergovernmental Committee of the Waterway),
established in 1989
by the Ministers of Public Works and Transport of Argentina, Bolivia,
Brazil, Paraguay,
and Uruguay. The headquarters of CIH are in Buenos Aires, Argentina.
To this date, the only comprehensive document with enough detail on
the Hidrovia
project is the Internave report, commissioned by the extinct Empresa de
Portos do Bra
sil (PORTOBRAS), and completed in 1990 by the Brazilian company of the
same name
(INTERNAVE, 1990). This report is essentially an economic feasibility
study of the
Hidrovia. As such, it uses projections of economic benefits to justify
the costs involved in
project implementation.
The Internave report has been the subject of criticism,
particularly for its overly opti
mistic projections of benefits (CEBRAC/ICV/WWF, 1994). The IDB has
formally re
jected the Internave study and will use the Phase 2 feasibility study,
currently under exe
cution, to recalculate cost and benefits (Lammers et al, 1994). However,
the physical
aspects of the Internave report, which include channel straightening,
dredging, blasting
of rock outcroppings, and other structural interventions in the river,
some of them irre
versible, have remained the cause of significant concern among diverse
segments of the
national and international communities, including nongovernmental
organizations, scien
tific research institutions and universities, and professional
associations in Brazil, the
American continent, and the world at large.
Channel straightening by realignment and cutoffs, dredging, and
blasting of rocky sills
are being considered to improve navigational conditions along the
waterway (IDB,
1995).
The extent of these interventions, and their possible impact on
the hydrologic
regime of the Pantanal of Mato Grosso, will be better known once the
ongoing studies
are completed by the second half of 1996. The IDB has asserted that it
may not fund
the Hidrovia project through the Pantanal if serious environmental
impacts are antici
pated (Lammers et al, 1994). The present study is a contribution toward
the proper as
sessment and evaluation of these impacts.
The Internave report lists the various geographic locations along
the Hidrovia project,
starting from the port of Buenos Aires (Km 0), progressing upstream to
the port of
Cáceres (Km 3 442). For reference purposes, an abstracted list of
locations relevant to
this study is shown in Table 4. Minor discrepancies between river
distances in Tables 1
and 4 reflect the different sources for these tables: DNOS (1974) and
INTERNAVE
(1990).
_ _ _