Public Disclosure Authorized
LATENDissemination Note # 5
An Analysisof Flooding
in the ParaniYParaguay
River Basin
September1993
Public Disclosure Authorized
Public Disclosure Authorized
19820
September 1993
Public Disclosure Authorized
..N
. ...
,a,g-X Z S~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~.
RobertJ. Anderson,Jr.
Nelsonda FrancaRibeirodos Santos
HenryF.Diaz
The World Bank
Latin America TechnicalDepartment
EnvironmentDivision
t
LATEN Dissemination Note # 5
An Analysis of Flooding in the
Parana'/Paraguay
River Basin
September 1993
Robert J. Anderson, Jr.
Nelson da Franca Ribeiro dos Santos
Henry F. Diaz
The World Bank
Latin America & the Caribbean Technical Department
Environment Division
FOREWORD
Late in 1991, unusually heavy rain began to fall in the catchment
areas of the Parana, Paraguay, and Uruguay Rivers. In 'normalH years, the
average precipitation in this basin varies between 200 mm per year in the
western part, the mountain range of the Andes, and 2,000 mm in the
southeasternpart, consisting of the Iguazu River basin. The rains are almost
incessant during the year in the southern and southeasternparts of the basin.
This rainfall distributionproduces high river flows in the basin that begin in
October/Novemberand peak between February and June/July.
As in most flood years, torrential downpoursin the Brazilian part of
the Paran; River Basin between January and May 1992 produced massive
flows in the Parana River. In addition, heavy rains in the middle to lower
Paraguay River basin during March and May led to peak flows in this river
that were coincident with the peak flows of the Parana River. The Parana
thus peaked in April/May 1992 at almost four times the yearly average. The
initial data on the 1992 flood indicate that the peak flow was about 56000
m3/s. This caused serious infrastructure damage and forced the evacuation
of about 120,000 people from seven Argentine provinces - Buenos Aires,
Chaco, Corrientes, Entre Rios, Formosa, Misiones, and Santa Fe. Although
it is too early to attempt a precise estimate, indications are that the damage
may be on the same order of magnitudeas that caused by the 1983 flood,
which cost about US$ 1 billion to repair. Apart from the capital stock
damage, Argentina will also face substantialeconomic losses (e.g., lost
production of grains, livestock, and cotton). Losses in Paraguay and Brazil
were also severe.
In September, 1992, the World Bank approved a loan to Argentina to
cover a portion of the costs of repairing the damage due to this flood. The
Bank also initiated the identification of a possible subsequent operation that
would aim at improving Argentina's preparedness to deal with severe
flooding. During the processing of the rehabilitation operation, the Bank
became aware of satellite imagery evidence that heavy siltation appears to be
occurring along stretches of the Parani that are bordered by agriculture.
This led the senior managementof the LAC Region to question whether
deforestation may be making the basin more prone to floods. Regional
senior management asked the Region's Technical Department to examine this
issue.
Disentangling the impact of deforestationfrom other factors on
flooding is a difficultundertaking under the best of circumstances. The
quantity and quality of historical data on land-use changes and other
interventions affecting the hydrology of the basin and basic hydrologic data
are reasonably good by developing country standards. Records of Parana
River flows exist since 1901 and land-use data extend back perhaps 40 years.
There are, however, serious gaps in meteorologicalinformation, and the
hydrology of this large basin is extremely complex.
This paper, writtenby a team led by RobertJ. Anderson,Jr.,
formerlyof LATEN,and comprisedby Dr. Nelsonda Franca Ribeiro dos
Santosof the Organizationof AmericanStates,and Dr. Henry F. Diaz of the
NationalOceanicand AtmosphericAdministration,draws upon these data to
reach preliminaryconclusionsabout the recent frequencyand severityof
flooding,and about the possiblerole that land use changesmay be playing.
Duringthe preparationof the paper, Drs. Anderson,da Franca Ribeirodos
Santos,and Diaz benefittedfrom the commentsof workshopin whichseveral
distinguishedscientistsand practitionersparticipated.'
While the data are far from perfect, the evidenceexaminedindicates
basin has indeedbeen both more
that floodingin the ParanAfParaguay
frequentand more severein recent years. Ten-yearflood dischargerates are
now over 15%greater than they were in the early years of the 20th century.
Mean dischargerates and extremelow dischargerates are higher too. The
analysisalso showsthat changesin precipitationrates and patterns are by far
the mostimportantexplanatoryfactorsin these observedchangesin
streamflow. Recentprecipitationhas been higherin the wet season,and
lowerin the dry season.
Reservoirson the Upper Parandhavealso playeda role, particularly
in increasinglow flows. When these other factorsare held constant,there is
no systematicevidencethat any other factorsuch as land use changesin the
upperbasin is playinga significantrole in flooding.
Theseconclusionsnotwithstanding,the apparentlack of association
betweenfloodingand land use changesis no reason to be complacentabout
these changes. Data examinedduring the course of the researchparticularlythe satelliteimagerysuggestiveof heavy sedimentloads suggestthat land use changesin the upper basins maybe exactinglarge
privateand socialcosts in terms of lost productivityin agricultureand
infrastructure,and lost biodiversity.
Like other papers in this 'DisseminationNoteswseries, the findings,
interpretations,and conclusionsexpressedare entirelythose of the author(s)
and shouldnot be attributedto the WorldBank, membersof its Board of
ExecutiveDirectors,or the countriesthey represent.
DennisJ. Mahar
Division Chief
EnvironmentDivision
Latin American& the Caribbean
TechnicalDepartment
(Orgaiion
includedDr. KirkRodgers
in additonto theauthors,
Workshop
participants,
of American States), Professor Rafael Bras (Massahusetts Instituteof Technology), Mr.
StephenOliver(IBRD),Mr. ArmandoAraujo(IBRD),and Mr. Sri-RamAiyer (IBRD).
AN ANALYSISOF FLOODING IN TIHE
RIVER BASIN
PARANA/PARAGUAY
Robert J. Anderson, Jr.
Nelson da Franca Ribeiro dos Santos
Henry F. Diaz'
'The authors are respectively Principal Sector Economist, India Country Department, The
World Bank, Water Resources Senior Specialist, Department of Regional Developmentand
Environment, and Climatologist,National Oceanic and AtmosphericAdministration. Dr.
Anderson led the team and was prinarily responsiblefor analysis and for preparation of the
main body of the paper. Dr. da Franca Ribeiro dos Santos was primarily responsible for the
preparation of Annexes A and C. Dr. Diaz was primarily responsible for preparation of
Annex B.
The views expressed in this paper are solely those of the authors and do not necessarily
reflect the views of organizations with which they are associated.
AN ANALYSISOF FLOODINGIN THE
RIVER BASIN
PARANAIPARAGUAY
Introduction
1.
Torrentialdownpoursin the Upperand MiddleParanaRiver BasinbetweenDecember
1991and May 1992and in the Middle and Lower ParaguayRiver BasinbetweenMarch and
Mayproducedmassivefloodingin Argentina,Brazil, and Paraguay.These floodscaused
seriousinfrastructuredamageand forcedthe evacuationof about 120000 peoplefrom the
Argentineanprovincesof BuenosAires, Chaco, Corrientes,Entre Rios, Formosa, Misiones,
and SantaFe, as shown. In Paraguay,more than 70 000 peoplewere evacuatedin the cities
of Asunci6n,Concepcion,Alberdi,and Pilar. In Brazi, heavyrains and the floodsin these
basinsforcedthe evacuationof thousandsof peopleand also causedseriousinfrastructure
damage.
TableI: MostSevereMaximumFloods,1901-92
ParanA-Posadas
Year
1905
1983
1992
1990
1936
1987
1966
1923
1929
1982
date
45 000 May 25
m 3 /s
43 330
41 850
37 500
34 500
34 500
33 900
33 750
32 450
31 350
July 12
June 25
Jan 25
June 12
May 23
Feb 23
June 21
March 5
Dec 5
Paraguay-Asunci6n
Year
1983
1905
1992
1919
1982
1988
1931
1912
1979
1913
m3/s date
11 740 May 29
11 170
10 530
8 770
8 730
8 500
8 240
7 820
7 580
7 420
June 23
June 1
June 13
July 29
June 10
July 1
Jan 15
June 14
May 15
Parang-Corrientes
Year
1983
1992
1905
1966
1990
1982
1912
1929
1987
1923
date
54 700 July 18
m 3 /s
50 800
50 000
43 800
43 800
42 600
39 100
39 100
38 900
38 100
June 8
June 5
March 1
Feb 1
Dec 11
Jan 7
March 10
May 30
June 27
The 1992floodscappeda decadeof unusual(by historicalstandards)flood activity.
2.
Five (5) of the ten (10) most severe (measuredin terms of annualdaily peak discharge)
floodsrecordedin the Parani/ParaguayRiver Basinduring this centuryhave occurredsince
1982 (TableI).
This apparentrecent "bunching"of relativelyseriousflood eventshas led to
3.
speculationthat some systematicstructuralchanges(as opposedto purely randomvariations)
may have occurredthat may have made/bemaldngthe basin more prone to flooding. Any
such changes,if present, clearly wouldhave far-reachingimplicationsfor the future
developmentof the central-easternregionof SouthAmerica. The larger La Plata Basin,
whichis comprisedby the Parand, Paraguay,and UruguayRiver Basinswith an area of 3.1
millionkm2 in Argentina,Bolivia,Brazil, Paraguay,and Uruguayconstitutesthe economic
River Basin encompasses2.6 million km2 (84%
heart of this region. The ParanA/Paraguay
of the totalarea of the La Plata Basin)in the four countriesexcept Uruguay. It containsa
multitudeof naturalresources: water, minerals,and arable soils. As a result, the area has
the most developedagriculturaland industrialzonesof the continent;it holds some of the
moreimportanthydroelectricdams in Latin America(Itaipuand Yacyreta);it containsan
extensiveriverine and terrestrialtransportationnetwork;it generatesaround 80% of the
Gross DomesticProductof the countriesand it is home to some 100 millionpeople.'
Three majorchangeshave occurredsincethe 1960sthat potentiallycould affect the
4.
hydrometeorology
of the region:
o
Agriculturaland industrialproductionin the basin has grownrapidlyand the
frontierof agricultureand livestockproductionexpanded. In Brazil, land in
the UpperParana Basinhas been convertedfrom coffeeplantationsto
soybeansand sugar canefor alcoholfuel production. In the ParaguayBasin,
deforestationand the expansionof the agriculturalfrontier to establish
croplandand pasture, have been extensivein both the Brazilianand
Paraguayanportionsof the basin. These land use changesmay have increased
runoff, streamflow,siltationand may be implicatedin recent flood episodes.
O
Hydroelectricdevelopment,mostlyin the Upper Parara Basin, has expanded
significantly. Some20 hydroelectricpowerplants of more than 1000MW
includingbinationalplants for Brazil-Paraguayand Argentina-Paraguayhave
been installedor are under construction. Overallpotentialin the basin is now
approximately42,000 MW and the total amountof water stored in the
reservoirsis approximately350,000hm3 , of which 120,000hm3 are active
storage. Reservoiroperationmay have increasedthe flow of the ParanaRiver
at the confluencewith the Paraguayat the time that the ParaguayRiver peaks.
o
Wet season rainfallin the region of the Paranaand ParaguayBasinshas been
relativelyhigh sincethe early 1980s,raising the possibilitythat a changein
climate (as opposedto simplerandomvariationin precipitation)may have
occurred. It also begs the questionwhetherany suchchangecould be due to
humaninfluenceson the environment(e.g., increasedconcentrationsof
atmospheric'greenhouse' gases, worldwidedeforestation,stratosphericozone
depletion,and increasesin anthropogenicaerosol loadingof the atmosphere
could be contributingto these recent precipitationextremes).
Basinis containedin AnnexA.
'A basicdescriptionof the ParanL/Paraguay
2
This paper examines some of the evidence bearing on these developments and their
5.
possible effects on the hydrometeorologyof the Basin. In particular, it considers two
questions'
i
Has flooding in the basin become more frequent and/or more severe?
ii
Can observed variations in streamflow in the basin be explained by random
variations in precipitationalone, or do other factors such as changes in
climate, land use, or operations of reservoirs also appear to have played a
role?
Definitive answers to these questions are beyond the reach of the paper given the present
state of the data. This limitation notwithstanding,however, the evidence is reasonably strong
that flooding was significantly(in a strict statistical sense) more frequent and more severe in
recent years, and that this was due primarily to unusually concentrated (in time and space)
precipitation. There is no strong statistical evidence to indicate that any other factor played a
significant role in flooding. There is, however, some evidence that when precipitation is not
extremely high, some change has taken place that causes streamflow to be greater than
otherwise would have been expected.
Has Flooding Become More Frequent or Severe?
6.
The data presently available only permit a partial and preliminary analysis of the
frequency and severity of flooding in the Basin. This analysis is based on examination of
discharge/stage extrema (i.e., maxima and minima) and mean discharges at a limited number
of stations
Annual Maximum Daily Discharges/Stages Since 1900
Data on annual maximum daily discharge rates/stages at Corrientes are shown in
7.
Figure 1.2 Other things being equal, if flooding were no more frequent in the latter years
of the sample than in the early years, the proportion of the time that peak discharges exceed
a given level would be about the same as in the earlier years of the sample. Visual
inspection of the data shown in Figures 1 is not conclusive, but does suggest some bunching
of relatively high peak discharge rates toward the end of the sample period. A statistical
analysis of the data in Annex C for Corrientes and other stations (based on binomial
probability distributions estimated from the data in these tables) rejects the hypothesis that the
frequency of extraordinary (i.e.. ten-year) floods was the same in the latter years of the
sample (Table II). This conclusion is not sensitive to the point at which the sample is divided
in the cases of Corrientes, Posadas, and Porto Murtinho. The frequency of extraordinary
2Annualmaximumdaily dischargerates/stagesat
Corrientes,Posadas,Asuncidn,Porto Murtinho,
Ladario,Guaira,and Jupia are reportedin AnnexC.
3
60000
50000
AII
40000
20000
t0000
0
i:
:IiI,,ii:nt
itt
uuuu:i
tt
uu:
uI
111111:
Wtn
F"igure1: Corrientes - Annual MaximumDaily Discharge Rates (m3Is)
floodsis significantlyhigherin each of theseplaces over all divisionsof the sample,while
floodingin Guaira,Asunci6n,and Ladaniois significantlymore frequentpi Ix when the
sampleis split at 1980. Splittingthe data at 1970or 1960yieldsinconclusiveresults at these
latter sites.
8.
To determinewhetherthe seveity o loo~dsappearsto be increasing,log normal
cumulativedistributionfunctionswere fitted to the maximumdischargedata over two sample
periods of equal length (1901-46and 1947-92)for Posadasand Corrientesand the resulting
fits testedto determinewhetherthe distributionshad changedsignificantlybetweenearly and
later sampleperiods.3 The tests reject the null hypothesisthat the post-1947cumulative
3Thecumulative
distribution
functions
werefittedby estimating
thefollowingexpression
by ordinary
regressionmethods,
N+1
whereF, is the reportedmaximumdailydischargerate in yeart, N is the totalnumberof yearsin the
subsample,R, is the rank in the subsampleCinorder of decreasingdischargerates,withthe highest
dischargeraterankedfirst, andso forth)of thete observation,ande, is an errorterm. An analysisof
variancetest wasperformedin the contextof theseregressions.Thistest partitionsthe data intotwo
4
Table II: Probability Analysis of Frequency of Extraordinary Floods
River
SampleSplit
Station
Asuncion
0.00972
0.07492
0.22555
0.00001
0.00001
0.00177
Ladario
0.02095
0.01069
0.25724
Corrientes
Posadas
Guaira
0.00318
0.00021
0.16540
0.02346
0.01193
0.71984
0.00120
0.00133
0.37953
Porto Murthinho
Parana
1960
1970
1980
Paraguay
At
Table m: Estimated Flood Discharges (m31s) Corresponding to Alternative Return Periods (years)
StationlSample
Significance
Subperiod
Level of Test
Posadas
1901-92
1901-46
1947-92
Corrientes
1901-92
1901-46
;
1947-92
l
Return Period (Years)
10
20
50
100
32700
32653
33653
36986
36968
38273
42653
42672
44382
46939
46987
49002
39204
37542
44584
42659
51696
49423
57076
54540
41734
47694
55574
61535
0.0990
0.0000
distribution function is the same as the pre-1947 distribution function, although the
significance level of the test at Posadas is only about 10% (Table Im). At both sites, higher
flood peaks were associated with any given level of probability in the post-1947 period, or
equivalently, the flood for any given return period was more severe.
9.
While the samples of data analyzed as described above span relatively long time
periods (i.e., 92 years in Corrientes and Posadas, and between 49 and 89 years at other
locations), it should be kept in mind that a longer sample period might well lead to different
subperiods(in this case of equal length)and tests whetherthe estimatedcoefficientsare, for statistical
purposes,identicalover the two subperiods.
5
conclusions.There exist referencesto extraordinaryfloodsthat occurredin Corrientesin
1612and 1748(stage< 10.50 m), as well as in 1812, 1858, and 1878. Table IV reports
extraordinaryfloodsin Corrientesprior to 1905in comparisonwith the floodsof 1983and
1992. It is not clear whetherthis is a completerecord of extraordinaryfloods during the
1800s.However,these three large floodsduringthe 1800sunderscorethe point that, if the
statisticalrecord could be extendedback into the 1800s,the conclusionsconcerning
frequencyand severitystatedabove mightnot stand.
TableIV:ExtraordinaryFloodsin CorrientesBeforePrior to 1905Comparedto the Floodsof 1905
and 1992
Stage
lGM1
m
m
m3 /s
1812
1983
1858
1878
9.53
9.02
8.93
8.65
50.93
50.42
50.33
50.05
58 000
54 700
52 000
51 000
1992
8.64
50.04
50 800
1905
8.57
49.94
50 000
Year
Discharge
sboveswalevel-Instituto
I-Gage-dacUm
Gcog~iSco
MiIk, Aretn
Other StreamflowCharacterisics
10. Two other streamflowcharacteristics,annualminimumdaily dischargerates and mean
monthlydischargerates were examinedto determinewhetherchangesappearto have
occurredin theseparametersas well. Figure 2 suggeststhat annual minimumdischargerates
have tendedto increase. Regressionestimationfittinglog normalcumulativeprobability
distributionsto the annual minimumdaily dischargerate data for Corrientesand Posadasand
statisticaltestingconfirmsthat minimumdaily flowswere significantlyhigherat these
stationsduring the latter part of the sampleperiod.4
'Data on annualminimumdaily dischargerates/stagesat Corrientes,Posadas, Guaira, Asunci6n,
Porto Murtinho, and Ladario are reported in Annex C. Estimationand testing was carried out in
accordancewith the proceduredescribedin footnote3 above.
6
258000-
20000
15000
10000
5000
20.1n a
Flgure 2: Annual Minimum Discharge Rates (m3Is) at Corrientes
4
1910-92,g
".0
190_ -9
5.0
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Gep
Oct
Nov
Dec
at Corrientes
Figure 3: Monthly Mean DischargeRates (m3 /sec)
7
11. Figure 3 showsa distinctshift in the patternof mean monthlyflowsin Corrientes
over two subperiods(1901-67and 1968-92).5Visualinspectionof the figure suggeststhat
two changeshave occurred. First, mean dischargesseemgenerallyto have increased. Mean
annualdischargewas between15 and 20 percent higherduring the secondsubperiod(196892) than in the earlier period. Second,there was a shift in the intra-annualpatternof
discharges,with mean monthlyflows becomingmore uniformover the year due to
significantlyhigher (in the secondsubperiod)mean flowsin the monthsof May through
December. This latter shift in the distributionis what wouldbe expectedto occur as a result
of the operationsof reservoirsin the UpperBasin.
12. In sum, the analysesdescribedabove suggestthat the entire streamflowdistribution
was shiftedtowardhighervaluesin the later years of the sampleperiod. Maximumannual
daily dischargerates, minimumannualdaily dischargerates, and mean annualdaily
dischargerates all were higherin the later years of the sampleperiod. Thereis also some
evidenceof a changein the intra-annualdistributionof streamflow.
What Accountsfor Greater FloodFrequency and Severity?
13. The dischargedata reviewedabovethus are generallyconsistentwith the hypothesis
that floodswere both more frequentand more severein the latter years of this centurythan
in the earlier years. It is of fundamentalimportancefor the future developmentof the Basin
to try to understandwhetherthis is due to purelyrandomvariationsin precipitationor
of the basin.
whetherit representsa structuralchangein the hydrometeorology
14. This is a complexundertaking. Runoffwithina basin dependsnot only on the
amountof rainfall but also upon its temporaldistribution,vegetal cover, evapotranspiration,
infiltrationrates, soil moisturestoragecapacity,the amountof moisturein storage, surface
storage,rate of groundwateroutflow,lossesdue to deep percolation,and a host of other
factors. Many of theseparametersare interrelated. An extensiveprogramof reservoir
constructionover the sampleperiodon the UpperParara introducesadditionalcomplications.
For thesereasons, the analysispresentedhere is indicative,but not conclusive.
UnusuallyHeavyPrecipitation
15. The most obviouspossibleexplanationfor recent heavy floodingis that it could have
been"causedby too much rain fallingin too short a period, or prolongedrain fallingon land
that is already saturatedwith water."6 Figure 4 showsan annualtime series of precipitation
anomalies(i.e., deviationsof precipitationfrom its meanvalue) over the region of the
Basinsduring a three-monthperiod (March-May)derivedfrom stationdata
ParanA/Paraguay
'Data on mean monthlyflowsare presentedin AnnexA.
LawrenceS. *TheRecentBangladeshFlood Disaster Was No Causedby Deforestation
%Hamilton,
Alone." EnvironmentalConservation,1988,pp 369-370.
8
4
ma
2-
.~~~~~a
iO
20
30
40
50
60
70
|_PRECIP
Figure4:
March-May
Preupitation
Anomalies and Annual Maximum
80
90
.MAXFLOW|
Daily Dischages
at
Corrientes (Normnalized)
within this region.' Clearly, the temporal behavior of the rainfall anomaly sen'es agrees
quite closely with that of the peak annual flow series. The correlation between the two series,
weighted by the number of station at which measurements were taken for each observation,
is roughly 0.95. This means that variations in weighted precipitation explain about 90% of
the variation in the annual weighted maximum daiy discharge rate series.
The correlation
between the two unweighted series is about 0.67.
Ilhe March-May period was chosen because five of the ten maximum discharge rates recorded at
Corrientes occurred in May, June or July. Two others occurred in March. See Table I.
9
TableV: RegressionResultsfor MonthlyPrecipitationand MeanMonthlyDischargeRateData
Regression1
Coefficient
Constant
PRECIP
PRECIP(-1)
PRECIP(-2)
PRECIP(-3)
PRECIP(4)
PRECIP(-S)
PRECIP(-6)
AR(1)
R2
Dubin-Watson
Observations
0.6241
0.0256
0.0423
0.0228
0.0113
0.0129
0.0140
0.0202
0.8004
0.6520
1094
Regression2
t-statistic
0.8821
7.9090
12.6846
6.7791
3.3709
388398
4.1640
6.3313
Coefficient
t-statistic
11.4019
0.0107
0.0325
0.0136
0.0029
0.0038
0.0027
0.0039
0.7889
0.9048
2.0502
1093
13.5376
5.0276
15.8547
6.5997
1.4015
1.8169
1.3181
1.8969
40.3219
16. Monthlydata on precipitationand streamflowalso shedsome light on the extent to
which precipitationaccountsfor apparentdifferencesin streamflowcharacteristics. Two
regressionsreportedin Table V suggestthe samerelativelytight relationshipbetween
precipitationand streamflowevidentin the annualdata describedabove.' In the first
regression,monthlymean dischargerates are regressedon monthlyprecipitationanomaliesin
the current monthand six precedingmonths. The multiplecorrelationbetweenthe estimated
linear combinationof explanatoryvariablesand streamflowis a little greaterthan 0.7. The
secondregressioncorrects for autocorrelationin residuals,increasingthe multiplecorrelation
coefficientto about 0.9.
of the Basin
Changesin the Structureof the Hydrometeorology
17. It is clear that variationsin precipitationexplaina great deal of the apparentshift in
streamflowdistributionparametersand, more specifically,the recent spate of severeflooding
in the Basin. This does not mean that other factors were unimportant. Three possibilities
merit consideration:(i) climatechangesleadingto increasedprecipitation,particularlyin
cntical monthsfor flooding;(ii) reservoirconstructionand operation;and (iii) changesin
land use that increaserunoff.
reportedin paragraph15basedon annual
'Tle regressionsreportedin TableV, likethe correlation
wasthe numberof
data, are weightedregressions.The weightingfactorappliedto eachobservation
stationsreportingprecipitationobservationsin eachmonthdividedby the meannumberof stations
reportedherebasedonmonthlydataalsoholdfor regressionsdonewith
reporting.Alloftheconclusions
data.
unweighted
10
440.00
40.
00
20.00
l0.00
Jan
Pab
Mar
APr
way
Jun
Ju I
Aug
Sep
OCt
Nov
Des
Figure 5: Mean MonthlyPrecipitation (mm)
18.
Climate Change. Monthly precipitation data suggest that the rainy season has become
somewhat wetter and the dry season slightly drier (Figure 5). Also note that relatively large
positive March-May precipitation were more frequent in the 1980s and early 1990s than in
earlier periods (Figure 3). These changes may represent a purely random perturbation (a
statistically unlikely one, to be sure), a cyclical fluctuation, or a change in the climate of the
region.
19.
The climate change hypothesis is broadly consistent with extensive recent work on
predicting global climate change and analyzing large scale atmospheric disturbances. Global
climate models, developed to study the effect of accumulationof greenhouse gases in the
earth's atmosphere, generally predict that precipitationin the vicinity of the basin will
increase in the early and late months of the calendar year, as seems to be occurring
(Figure 5). These models also predict that the El Nino phenomenon, which is empirically
closely related to flooding in the ParanA/ParaguayBasin,' will intensify. However, due to
the high variability present in precipitation data, considerably more data would be needed to
discriminate statistically among the random perturbation, cyclical fluctuation, and structural
climate change hypotheses.
20.
Reservoirs. There has been a considerable expansion of active storage capacity in the
Upper Parana River Basin over the last 40 years. Active storage has increased from 2500
hm3 in 1956, to over 150,000 hm3 today (see Table VI). Much of this capacity
(approximately 125,000 hm3) came on line during the 1970s and 1980s. These reservoirs
'AnnexB describesthe relationshipbetweenEl Ninophenomenaandfloodingin theParanTlParaguay
Basin.
11
reducepeak floodsby roughly 10-20%during heavyrainfall months,and increaseninimum
flows during the dry months. This may accountfor the fact that the statisticalresults on the
stabilityof maximumdischargerates as betweenearly and late periods are weakerat Posadas
than they are at Corrientes, whichreceivesunregulatedflows from the ParaguayRiver and
is well belowthe last reservoiron the ParanaRiver.10 The effectof reservoirsis also
reflectedin the data on low flowextrema: most of the extremelow flows recordedfrom
1901in Posadasand Corrientesoccurredprior to 1970.
Table VI: Brazilian Reservoirs
-
Upper Parana River Basin'
Active
Year
Storge
hm'
1956
1958
1962
1963
1963
1966
1968
1969
1970
1971
1973
1973
1973
1974
1975
1975
1975
1976
1978
1979
1980
1980
1980
1982
1982
1982
1983
1984
2500
0
2890
16089
2556
04
1250
IS0
045
1295
12866
296
233
50
00
310
Name of
hm'
the Dam
2500
2960
850
1939
2449
24999
249
6399
9444
0739
3605
3901
134
C84
S1994
2434
1134
924
124
5724
9974
74
700
790
204
13600
250
600
300
12700
00
800
80
1. DmimCauhw
tmulated
108S74
110874
111674
1S954
Pizoto
C
o
lurann
Furnas
Bar Bonita
raninha
upin
Esiruito
Xavates
'puar(
SolIhrn
PoateNova
Pto Colombia
Voha Grand
PrDmiuJo
ixndo
ahoono
aprn
Sio Smbo
AguaVermIelba
InhiPrn
Faz do Atia
T874
ru Inrbc.
E
io
NovaAvanhandava
River
Grande
Grand0
PSapn
net.
randc
paner
g
iota
rnd
u
runde
guaqu
ne
Mt.
Santiago
ag
21. Prior to 1970, mean monthlydischargesof the ParanaRiver at Posadaswere
considerablylower during the monthswhen meanmonthlydischargesof the ParaguayRiver
reached their highestlevels. Since 1970, however,mean monthlydischargerates at Posadas
have increasedaround 15 to 30% during the mid monthsof the year, and hencecoincide
with the period of high average dischargerates in the ParaguayRiver. This changein the
"MThe
resultson extremelow flows are equallystrongat both sites,however.
12
monthly distribution of streamflow could also be due to a change in the monthly distribution
of precipitation, or in the intertemporal relationship between precipitation and streamflow in
the Upper Parana Basin.
Deforestation/Land Use Changes. Significant changes in land use have taken place
22.
over the last 100 years in the upper and middle basins of both the Parana and Paraguay
Rivers. Most of the land use changes in the Upper Paranr Basin took place in the 1930s and
1940s when land was put into coffee production, and again in the late 1960s when land was
converted from coffee plantations to production of soybeans and sugar cane. In the Paraguay
River Basin, particularly in Western Brazil and Eastern Paraguay where agricultural potential
is greatest, there has been a progressive conversion of forest to agricultural land. In
Paraguay in 1945, approximately 55% of the land area of the Eastern Region was forested.
During the 1960s, the Paraguayan Government, under pressure to respond to growing
demands for employment and income, began to encourage the expansion of the agricultural
frontier to the east. As a consequence, forested areas in this region declined to about 45%
by the mid-to-late 1960s, 35% by the mid-1970s, 25% by the mid-1980s, and only about
15% by the early 1990s.1'
Other things being equal, one would expect to observe an increase in streamflow
23.
associated with deforestation and/or other land use changes that tend to increase runoff.'2
The results on flooding frequency and severity reported above are thus broadly consistent
with the land use effect hypothesis. They are, however, also consistent with the heavy
rainfall hypothesis. Some additional examination of the data is thus necessary to discriminate
between these hypotheses. Consistent time series data on land use in the Basin are not
presently available. It is not possible, therefore, to proceed directly by introducing land use
variables into the regression analysis to determine whether or not they contribute significantly
to explaining streamflow variations. Inferences of the possible effect of land use changes can
only be drawn indirecty by analyzing whether the rainfall-runoff relationship seems to have
changed in ways that could be explained by land use changes. To this end, note that if land
use change were an important contributor to streamfiow, the relationship between
precipitation and streamflow should differ between early and late subsamples: in particular,
the same rainfall should generate more streamflow in the later part of the sample period than
in the early part.
This possibility was investigated using the two sets of data (i.e., annual and monthly)
24.
on precipitation and streamflow analyzed above. First, the annual data on March-May
"Bozzano,BernadoandJorg H. Weik.El Avancede la Deforestaciony el ImpactoEconomico.Serie
N. 12. Proyectode Planificaciondel Manejode los RecursosNaturales(MAG/GT-GTZ).Asunci6n,
Noviembre1992.
'A detaileddiscussionof hypothesesconcerningrelationshipsbetweenland use changesand runoff
is availablein Hamilton,LawrenceS. TropicalForestedWatersheds:Hydrologicand Soil Responseto
MajorUses or Conversions,(Boulder: WestviewPress), 1983.
13
Table VII: Analysis of Variance Test for Stability in the Relationship Between Precipitation
Anomalies and Annual Maximum Daily Discharge Rates (F-test Significance Level)
Sample Period
1901-92
Sample Break Point
1930
1940
1950
1960
1965
1970
1975
1980
1985
Regressions
CONSTANT
PRECIP
R2
Durbin Watson
0.3481
0.0986
0.0344
0.0126
0.0314
0.0025
0.0003
30581.507
112.189
0.8538
1.5397
1901-60
i
1961-92
0.7863
0.5517
0.8292
0.2996
0.1717
0.8691
27670.084
35.020
0.6270
1.9169
31295.372
123.705
0.5668
1.5566
precipitationanomaliesand amual maximumdischargerates were split into early and late
subsamplesand examinedto see whetherthe relationshipbetweenprecipitationanomaliesand
maximumdischargediscussedin paragraph15 is stableC(ableVIU).Three differentsample
periods (1901-92,1901-60,and 1961-92)are considered. The first columnof the table
reports results obtainedanalyzingthe data from the full sampleperiod. The numbers
reportedin the upper sectionof the table (i.e., the rows in the 'Break Point' sectionof the
table) are F-statisticprobabilitiesassociatedwith an analysisof variance test like that
describedin footnote3. The numbersreportedin the lower sectionof the table are
3
regressionsummarystatistics."
25. The probabilitiesshownin Table VII are interpretedas follows. Considerthe period
1901-92. When the 1901-92sampleis dividedinto two subsamples- for example 1901-79
1 Theresultsreportedin TableVIIarebasedon weighted
regressionsinwhichthenumberofstations
reportingprecipitation
observations
is relativeto the meannumberof stationsoverthe wholesample
period(i.e., 1901-92)is usedas the weightingfactor. Thisgivesmoreweightto observations
that are
basedon moremeasurements
of precipitation.An analysis(notreportedin detailhere)parallelingthat
in Table VII was carried out using unweighted regressions. The results and conclusions of this
unreported analysis are exactly the same as those reported here.
14
and 1980-92- the probabilityis only 0.0003of gettingan F-statisticas large as was
obtainedin the analysisof variancetest if the relationshipbetweenprecipitationanomalies
and maximumdischargeswere in fact the samein both subsamples.
26. Three conclusionsflowfrom the results (and, moreimportantly,the pattern of results)
summarizedin the table. First, the data stronglyreject the hypothesisthat the relationship
betweenMarch-Mayprecipitationanomaliesand maximumdischargerates was unchanging.
For break pointsat 1960or after, the test rejects the null hypothesis(i.e., no change)at the
0.035 level of significanceor better. Second,the changein the relationshipappearsto occur
sometimein the 1950sor 1960s. As can be seenin the columnheaded"1901-92",the null
hypothesiswouldbe rejectedonly at muchlower levelsof significance(i.e., higher
probabilityvalues)if the samplewere splitat 1950or 1940. This conclusionis confirmedby
two additionalcuts of the data. In the columnof the table headed"1901-60",stabilityof the
regressionrelationshipwithinthe 1901-60subperiodis examined. As can be seen, the test
fails to reject the null hypothesisat any reasonablelevel of significance(i.e., the highest
level of significanceobtainedis 0.55). The sameresult is obtainedfor tests of splits within
the subsample1961-92(i.e., the highestlevel of significanceobtainedis 0.17). Third, the
regressioncoefficientsbehavequalitativelyas they wouldbe expectedto if some changehad
occurredwhichincreasedthe runoffproducedby any givenquantityof rainfall: the
coefficientof the precipitationvariable(PRECIP)is muchhigherin the secondsubsample
(1961-92)than it is in the first (1901-60),taldnga valueof "123" versus "35".
27. The relationshipbetweenmonthlyprecipitationand averagestream flowsexhibitsthis
samegeneralpatternof -instability (TableVmI). The relationshipis significantlydifferent
in the latter part of the sampleperiod. However,analysisof the post-1960data indicates
significantdifferencesin the relationshipwithinthe post-1960samplesubperiod.
28. The statisticalrelationshipbetweenprecipitationand streamfiowis widelyheld to be
highlynonlinearand to dependcruciallyon the temporalpatternof precipitationas well as its
amount. At higherprecipitationrates, other thingsbeing equal, streamflowshouldincrease
more than in proportionsince the other ways in whichprecipitationcan be 'dissipated" (e.g.,
infiltration,evapotranspiration,surfaceretention)have very definitemaxima. The results
reportedin Tables VII and VIII could thus simplybe a reflectionof the fact that precipitation
has been far above "nonnal"throughoutmuch of the 1980sand early 1990s. In the annual
data, the fact that the coefficientof the precipitationvariablein the secondsubperiodis over
three times as large as it is in the first subperiod(i.e., 123versus 35), whichwouldbe an
implausiblylarge effectto attributeto structuralchangesin rainfall-runoffrelationships,
suggeststhat nonlinearitymay be at work. In the monthlydata, the instabilityof within
subsampleregressioncoefficientin the post-1960periodcould also be associatedwith
nonlinearity.
29. If nonlinearitywere Ie explanationfor apparentchangesin the relationshipbetween
precipitationand streamflow,we shouldexpectto find significantdifferencesbetween
relationshipsfitted to subsamplesclassifiedby precipitationranges, and little if any
15
Table VIII: Test of Stability of Statistical Relationship Between Monthly Precipitation and Mean
Monthly Mean Discharge Rates at Corrientes (F-test Significance Level)
SamplePeriod
1901.01-92.08
SampleBreakPoint
1930.01
1940.01
1950.01
1960.01
1975.01
1980.01
1985.01
0.1183
0.0333
0.0001
0.0000
1901.01-59.12
1960.01-92.08
0.9737
0.0374
0.4341
0.0000
0.0000
0.0000
Table IX: Test of Stability of Statistical Relationship Between Precipitation Anomalies and Annual
Maximum Discharge Rates: Marimum Flood and Non-Maximum Flood Years
Nul Hypothesis
F-test Levelof Significance
Relationshipbetweenprecipitation
anomaliesand maximumdischagerates
fittedto datafor 1905,1912, 1923,and
1929is statisticaUyindisinguihablefrom
the elationshipfittedto datafor 1966,
1982, 1983,1987, 1990,and 1992.
0.9998
Relationshipbetweenprecipitation
anomaliesand maximumdischargerates
fitted to pre-1960years otherthan 1905,
1912, 1923,and 1929is stadsticaly
indistinguishable
from the relationship
fittedto post-1960yearsother than 1966,
1982, 1983, 1987, 1990and 1992.
0.5757
difference between early and late subsamples within precipitation ranges. If nonlinearity
were an explanation, along with some time varying factor such as land-use change, then
significant differences would be expected both between subsamples defined by precipitation
ranges and within subsamples defined by precipitation ranges across time.
16
30. Supportfor the "nonlinearityhypothesis"is providedby further analysisof both
annual maximumand monthlymeandata alongthese lines. Table IX reports the results of
analysisof variancetests for differencesbetweensubsampleswhen the annual data are
partitionedinto 4-subsamples:(i) pre-1960years in whichone of the ten highestmaximum
dischargerates occurred(i.e., 1905, 1912, 1923, 1929); (ii) other pre-1960years; (iii) post1960years in whichone of the ten highestmaximumdischargerates occurred(i.e., 1966,
1982, 1983, 1987, 1990,and 1992);and (iv) otherpost-1960years. If nonlinearitywere
responsiblefor the apparentstructuralinstabilityin the annualrainfall-runoffrelationship,
relationshipsfitted to the data thusly disaggregatedmightnot show significantdifferences
betweenearly and late periods. In fact, tests fail to reject the null hypothesesthat pre- and
post-1960relationshipsbetweenprecipitationanomaliesand maximumdischargerates were
the samein the pre- and post-1960periods.
Table X: Test of Stability of RelationshipBetween monthly Precipitation and Monthly Mean
DischargeRates - Data Grouped by Three-MonthCumulativePrecipitation
Precipitation
ThroeMonthCumulative
CP < 190
190 <= CP < 240
240 <= CP < 290
290 <= CP < 330
330 <= CP < 370
370 <= CP < 410
410 <= CP <460
460 <= CP < 520
520 <= CP
F-testLevelof Significance
0.0120
0.0000
0.0087
0.0232
0.0106
0.9077
0.1634
0.5812
0.0393
31. Monthlyprecipitationand mean dischargedata, when disaggregatedby level, also fail
to show consistentlysignificantdifferencesbetweenrelationshipsfitted to pre- and post- 1960
data. Two differentdisaggregationswere examined. In the first, the 12 monthsleadingup
to the flood eventsat Corrientesshownin Table I are separatedfrom the other
observations(TableX). The test fails to reject the null hypothesisthat pre- and post- 1960
relationshipsare identicalin this subsample. The hypothesisof stabilityis stronglyrejected,
however,in the complementarysubsample. The seconddisaggregation(TableXI) divides
the sampleinto 9 subsamplesbased on the cumulativeprecipitationover three months(i.e.,
the current and two precedingmonths). In general,tests show significantdifferences
betweenearly and late periods at lower cumulativeprecipitationlevels, but differences
betweenearly and late periods at highercumulativeprecipitationlevelstend to become
insignificant.
17
Table XI: Test of Stability of Relationship Between Monthly Precipitation and Monthly
Mean DischargeRates - Data Grouped by Three-Month Cumulative Precipitation
ThreeMonthCumulative
Precipitation
F-testLevel of Significance
CP < 190
190 <= CP < 240
0.0120
0.0000
240 <= CP < 290
0.0087
290 <=
330 <=
370 <=
410 <=
460 <=
520 <=
0.0232
0.0106
0.9077
0.1634
0.5812
0.0393
CP <
CP <
CP <
CP <
CP <
CP
330
370
410
460
520
Conclusions
32. Takentogether,these results tend to suggestthat the unusuallyheavyprecipitationof
the 1980sand early 1990swas the most importantfactoraccountingfor the floodingof these
years. There is no consistentstatisticalevidencein the data examinedhere that any other
factor playeda significantrole. This conclusionis not surprising. When precipitationis
concentratedin timeand space, as it typicallyis during flood years, it simplyoverwhelms
other factors: floodingwill occur other factorsnotwithstanding.There is some evidencein
the data examinedhere that, at less extremelevels of precipitation,the basin may be
producingmore runoff todayfor a given quantityof precipitationthan it did in the early
years of the century.
33.
In sum, the conclusionsthat emerge from the previousanalysisare as follows:
o
Floodingwas both morefrequentand more severein the latter part of the
1900s than previously;
o
Extremelow flows were both less frequentand less extremein the latter part
of the 1900sthan previously;
o
Total streamflowwas greaterand its intra-annualdistributiondifferentthan in
the latter part of the sampleperiodthan during the early years;
o
Variationsin precipitationexplainmuchof the variationin streamflowsand
flooding;
0
Changes in intra-annual variation in streamflow appear to be due to some
combinationof changesin the intra-annualdistributionof precipitation,and to
18
the operationof reservoirson the Paranawhichdelay the propagationof
floods;and
o
There is no consistentevidence,statisticalor otherwise,that changesin
rainfall-runoffdynamicsassociatedwith land use changeshave playedan
importantrole in recentfloodingin the Basin.
19
Annex A: Description of the Parana/Paraguay River Basin
This annex summarizesbasic information and data on the Parana/Paraguay River
1.
Basin. Much of this information derives from international compacts established to manage
the basin's resources.
Intergovernmental Cooperation on Hydrometeorology in the La Plata Basin
In 1969, the Foreign Affairs Ministers of Argentina, Bolivia, Brazil, Paraguay and
2.
Uruguay signed the Plata Basin Treaty in an effort to institutionalize the Plata System. An
IntergovernmentalCoordinating Committee-CICwas created to promote, coordinate, and
implement the multilateral actions as defined by the Ministers including the hydrometerology
and floods in the Basin. Several resolutions dealing with floods have been approved by the
Ministers. (Table A. 1)
Furthermore, expert Groups and Ad hoc Working Groups on Hydrometeorology and
3.
Flood Warning System were formed and have met with the CIC periodically since 1982, in
order to exchange information and recommend actions to be considered by the Foreign
Affairs Ministers. Consequently, the countries have established an information exchange
network, especially for periods of flood warning. Selected stations of the flood warning
system are shown in Table A.2.
Table A. 1: Plata Basin Resolutions Dealing with Hydrology and Floods
ResolutionNo. Meeting Year
network
1977 Paraguayriver hydrometeorological
IX
88
informationamongthe Plata
1977 Exchangeof Hydrometerological
IX
91
Basincountries
1980 Floods in the ParaguayRiver
XI
153
1981 Floodsin other internationalrivers
XII
174
network
1981 Plata Basinhydrometerological
XII
176
1986 Plata Basinfloodwarningsystem
XVI
195
1986 Technicalcooperationactionsincludingwaterresources
flEx
2Ex
1987 Flood warningsystemand water quality
XVII
302
The Paranf River Basin
The Parana River Basin is the most important in the La Plata Basin system due to the
4.
magnitude of its discharges, the extension of its area, and its overall length. It encompasses
1 510 000 km2 (excluding the area of the Paraguay River Basin, its most important
tributary). Of this area, 890 000 km2 is located in Brazil, 565 000 km2 in Argentina, and 55
2000 km2 in Paraguay. The total area including the Paraguay River extends to
2 605 000 km2 . Its length from its origins at the Paranaiba River until the confluence with
the Uruguay River reaches 3 740 km. The ParanAis divided into the Upper Parana ( 972
050 km2 upstream of its confluence with the Paraguay River), the Middle Parana (between
the confluence with the Paraguay River and the Salado River) and the Lower Parana (from
the confluence with the Salado River to the confluence with the Uruguay River)
Table A.2: Parand-Paraguay Flood Warning System-Selected Stations
River
Parana
Parana
Parana
Iguagu
Parana
Parana
Parana
Paraguay
Paraguay
Paraguay
Paraguay
Paraguay
Tebicuary
Paraguay
Bermejo
Parana
Parand
ParanE
Station
Area km2
478 000
Jupia
670 000
Sao Jos6
802 150
Guafra
SaltoCataratas 67 300
901 545
R-8 Itaipu
910 000
Libertad
933 600
Posadas
258 000
Ladario
Porto Esperanga 363 500
Porto Murtinho 474 500
600 000
Concepcidn
797 000
Asunci6n
21 000
V. Florida
925 000
Pilar
91 950
El Colorado
2 067 050
Corrientes
2 457 050
SantaFe
2 480 000
Rosario
Observations
Country
since
1926
1963
1921
1915
1976
1931
1901
1900
1963
1939
1910
1904
1945
1917
1969
1903
1925
1884
Brazil
Brazil
Brazil
Brazil
Brazil
Argentina
Argentina
Brazil
Brazil
Brazil
Paraguay
Paraguay
Paraguay
Paraguay
Argentina
Argentina
Argentina
Argentina
5.
The distinguishing feature of the Upper Parana is its delineation in "stepped' plateaus,
creating 'saltos" in the river channel, now flooded by the reservoirs of hydroelectric dams.
Other smaller falls and the presence of rapids, the majority of which are now also flooded by
the reservoirs of around 40 hydroelectric dams, characterize the landscape. Most of the
reservoirs were constructed between 1960 and 1990 in the Braziian portion of the basin.
The width of the Paran River vaies dramaticaly from 4 000 m north of town of
6.
Guaira in Brazil to 60 m below Itaipu Dam. Near Posadas, in Argentina, its width ranges
Annex A - September 2, 1993
-2-
between 150 and 2 500 m. Downstream of Posadas, the river flows through a series of
islands, covering a 25 km-wide area. The river is 4 200 m wide at Corrientes, 2 600 m at
Bella Vista, and 2 300 m near Santa Fe. However, its flood plain gradually spreads out,
especially over its right bank, which is lower than its left bank. The width of this flood plain
varies between 13 km near Corrientes to about 56 km near Rosario-Victoria. The delta of
the river is 18 km wide at its beginning, growing to a width of about 60 km. Then through
its numerous branches, the Parana flows into the La Plata..
The Paraguay River Basin
7.
The Paraguay River Basin encompasses 1 095 000 km2 , of which nearly 365 000 km2
are in Brazil, 365 000 km2 in Paraguay, 182 500km2 in Argentina, and 182 500 km2 in
Bolivia. The origin of the Paraguay is found in Brazil, and the river, after flowing 2 800 km
(Table A.3) reaches the Parana river, north of the Argentinean cities of Corrientes and
Resistencia. In its northeast portion (i.e., the Bafiadosof Izozog in Bolivian territory), the
basin boundaries are not clearly defined.
Excluding the headwaters of the Pilcomayoand the Bermejo, which descend from the
8.
Argentine-Bolivianplateau in the Andes, and in the southern part of the left banks of the
Paraguay River, between the Apa River and its confluencewith the Parana - which presents
a wavy relief with slopes of certain magnitudes- the rest of the river basin extends over an
immense alluvial plain, very slight slope and extensive flood plains.
In the Upper Paraguay, the river banks are low and prone to floods, creating a zone
9.
known as the 'Pantanal' , a vast flood plain that covers close to 100 000 knmand that is
periodically covered by water. The terrain slope is very slight, as is the slope of the river
channel. The river bed is sandy, very unstable, and the river meanders. There are some
rocky stretches, but they do not affect the general character of the river.
In the area that extends from the Apa River to the confluence with the Tebicuary, the
10.
flood plain is restricted to a width that varies from 5 to 10 km, occupying mainly the right
bank. The mouth of the Paraguay river extends from this point until its confluence with the
ParanA (approximately 130 km). During floods, water rises over both banks in this region,
occupying a strip of land 10 and 15 km wide. The major characteristics of the Paraguay
river in this section are the enormous amount of sediments carried from the Bermejo River,
and the backwater phenomena produced by the waters from the Paranr at its confluence with
the Paraguay River.
Annex A - September 2, 1993
-3-
Table A.3: Limits and Slopes- Paraguay River'
Limits
Zones
Distances
Lower
Paraguay
Confluence-Tebicuary
River (260km
south of Asuncion)
130 km
Middle
Parguay
Tebicuary-Apa
River (an 927, bordering 797 km
Brazil-Paraguay)
Upper
Paraguay
ApaRiver-headwaters
(km2 800)
1 873 km
MedianSlopes/
Observations
5 cm/km. Sufferseffect
of the Parana whenthe
river is rising. The
BermejoRiveris at km
87 and Pilar is at km 89.
6 cm/km. Asunci6nis at
km 390 and Concepcidn
at km 700.
3,1 cm/km.Includesthe
Pantanal.Porto Murtinho
is at kan999, Porto
Esperancaat km 1395,
andLadariois at
km 1 530.
1I-AS, 1992
Basic Basin Parameters
11.
The concluding section of this annex (previous studies) contain a listing of data
sources and of relevant previous studies of the hydrometeorologyand floods of the ParanA
and Paraguay river basins'. Many of these have been utilized in the preparation of this
paper. A wealth of information remains to be exploited, however.
12.
The hydrometeorolgy of the Paranr-Paraguay River Basin is very complex. Several
small sub-basins have particular hydrological characteristics. Previous studies of the basin
have divided it into seven major sub-basins (EBY,1979):
'Datapresentedin AnnexC on annualmaximumandminimumdailyfloodsandstages,meanmonthly
flowand stages, and annualandmonthlyprecipitationat selectedstationswereprovidedby the Instituto
Nacionalde Cienciay TecnicaHidricas(Argentina),Departamento
Nacionalde Aguase EnergiaEletrica
(Brazil),and Direccionde Meteorologiae Hidrologiaand AdminsitracionNacionalde Navegaciony
Puertos(Paraguay).
Annex A
-
September 2, 1993
-4-
Upper ParmnfRiver upstreamGuafa
(802 150 kn2)
*
Upper ParaguayRiver UpsreamPorto Esperan(363500 km)
*
*
Middle ParaguayRiver betweenP. Esperanzaand
Asunci6n (433 500kmn)
* Upper PamnrRiver betweenGuain and
Confluence(169 900 km:
*
Lower ParaguayRiver betweenAsunci6nand
Confluence (29S000 km)
*
MiddleParani RiverbetweenConfluenceand Santa Fe/ Parani
(390 000 kin)
*
Lower ParaniRiver downam
(197 950 km2)
SantaFeI Pararn
Precipitation
The runoff basins of the Parana and Paraguay Rivers are located in a region of heavy
13.
precipitation that is prevalent almost throughout the year. Situated east of the Andes,
between approximately 150 S and 30 0 S, the region is subject to rain-producing systems of
both tropical and extratropical (frontal-type)origins. The annual mean rainfall in the Parana
basin varies from 1100 to 1600 mm, except in the upper basins of the Tiete, Paranapanema
and Iguacu with the annual mean reaching 2 200 mm. In the Paraguay Basin, it varies from
400 to 1800 mm.
Mean Discharges
14.
The Parana river system, shows a predominance of summer-fall discharges over those
of winter-spring. The variability is more evident in the upper portion -due to the tropical
regime of rains- with high waters between December and April, pealing in February, and a
period of low waters in the winter, with minimumsin August and September. South of
Guaira, the tributaries of the Parant, like the Iguagu, exhibit a somewhat different seasonal
pattern: lower waters in the summer, and high waters in the winter and spring due to the
greater persistence of rains during the entire year. After its confluence with the Paraguay,
which also exhibits increased flows during the winter (June, July) due to the retardation
effect created by the Pantanal, the flows in the Parana exhibit less seasonal variability.
Table A.4 summarizes the mean monthly and mean annual discharges for 1901-1992, 19011967 and 1968-1992.
An analysis of the origin of the Parani River flow is shown in Table A.5. Roughly
15.
78% of the mean annual flow originates in the Upper Parand. From Corrientes to the
confluence with the Uruguay River (around 540 000km2) the discharge of the Parani River
increases only 10%, less than 2 000 m3 /s. Generally, the rainfall in the Upper Parana (i.e.,
upstream of.Guaira) is the main source of the flows in the Middle and Lower Parana river,
but in some years torrential rains between Guafra and the confluence with the Paraguay River
(including the Iguacu River Basin) and between Asunci6n and Confluence are the main cause
of the floods registered in Asunci6n, Posadas, Corrientes and downstream.
AmnexA
-
September 2, 1993
-5-
Table A.4: Mean Montly Discharge in Posadas and Corrientes-ParandRiver 1OOm3Is
M
A
M
I
Jl
A
S
0
16.5
15.7
13.6
12.0
12.0
10.5
9.0
9.3
14.5
16.3
16.1
13.6
11.
11.2
9.6
8.1
1968
1992
16.1
16.8
14.7
13.7
13.5
13.9
12.9
Corrients
19011992
17.6
20.3
20.3
18.6
16.7
17.0
Corrientes
19011967
16.7
19.6
20.S
18.5
15.8
Corentes
19681992
20.1
22.1
19.8
19.0
19.1
Station
Period
I
F
Poudas
19011992
14.9
Poaadas
19011967
Pouda
16.
N
D
AVG
10.8
11.0
11.9
12.3
8.3
10.1
10.2
11.1
11.7
11.4
12.0
12.9
13.1
14.1
13.8
15.1
11.6
12.2
13.8
14.2
15.0
16.1
15.8
13.8
11.3
10.7
12.5
13.1
13.0
15.2
20.2
18.6
16.1
16.1
17.2
17.1
18.0
18.6
An analysis of the ozigin of the Parand River flow is shown in Table A.5. Roughly
78% of the meanannual floworiginatesin the UpperParani. From Corrientesto the
confluencewith the UruguayRiver (around540 000km2) the dischargeof the ParandRiver
increasesonly 10%, less than 2 000 m3/s. Generally,the rainfallin the Upper Parari (i.e.,
upstreamof Guaira)is the main source of the flowsin the Middle and Lower Parandriver,
but in some years torrentialrains betweenGuafraand the confluencewith the ParaguayRiver
(includingthe IguacuRiver Basin) and betweenAsunci6nand Confluenceare the main cause
of the floodsregisteredin Asunci6n,Posadas,Corrientesand downstream.
17. The hydrologicalregimeof the Upper Paraguayin Cuiabais similarto the Upper
Parand, but the principalcharacteristicof the ParaguayRiver regimeis the intra-annual
variationwhich occurs along its course. In the Upper Paraguay,before reachingthe lower
and flood-pronearea of the Pantanal,the maximumlevelsare reached in February and the
minimumsin August-September.Howeverin Corumba,Ladario,and in the Middle
Paraguayin Asunci6nand Concepci6n,the period of high flowsis practicallyreversed, with
the maximumin June-July,and the minimumin December-January.This waterflowpattern
variationis causedby the storageeffectproducedby the Pantanal,which createsa delay of
about 3 monthsin the flood propagation,beforearriving in Asuncionand at the confluence
with the Parana.
Annex A - September 2, 1993
-6-
Table A.5: Origin of the Dischargesof the Paranf River in Posadas and Corrientes
Flowin
Posadas'
Corrientes'
AreaKm2 Percent Originatedfrom
933 600 78% UpstreamGaufra
12% IguaquRiverBasin
10% Intermediatearea
2 067 050
72%
Upstream Posadas
16% UpstreamAsunci6n
12% Intermediatearea
CorrienteS2
2 067 050
61 %
Upstream Guafra
17% betweenGuafraand the ParaguayRiver
22%
I-ELETROBRAS, 1978
ParaguayRiver Basin
Area km2
802 150
68 000
63 450
933 600
797 000
336 450
802 150
169 900
1 095 000
2-EBY, 1979
Minimum Discharges
18.
The percentage of the occurrence of annual extreme low flows and stages in selected
stream flow gauging stations of the Paraguay and Parana rivers are shown in Table A.6.
Most of the extreme low flows occurs in November, December, in the Paraguay river.
From August to October, November, and even December, and January in the Parana River.
In the Iguacu River they may occur during the whole year especially in January, May, and
August.
Maximum Discharges
Most of the maximumannual floods in the Upper Parana (Guafra and Posadas) occur
19.
in January, February and March while in the Middle and Lower Paraguay (Asunci6n), they
occur in May, June, and July.2 In the Middle Parana (Corrientes), they occur in February
and March. In the Iguacu River Basin (Cataratas) floods occur generally in October,
November and in June and July. The percentage of the occurrence of annual maximum
floods in each month of the year for those stations is shown in Table A.7.
High precipitation in the lower part of the Upper Parani Basin is more effective in
20.
producing peak discharge at Guaira (and Posadas) than the same average basin rainfall spread
uniformly over the basin or concentrated in the upper end.
21n the ParaguayRiverBasinthe volumeanddurationof the floodsare as importantas the peak flood
due to the area, shapeand topographyof the basin.
AnnexA - September2, 1993
-7-
Table A.6: Percentage of Occurrenceof Eitreme Low Flows and Stages by Month
River
Station
J
F
M
Paraguay
Ladario
19
2
* 0
0
*
ParanA
Guafra
4
0
0
0
*
Iguagu
Cataratas
14
6
21
Parana
Posadas
9
*
Parana
Corrientes
12
0
A
4
1
9
0
1
0
M
J
JI
A
S
O
N
2
7
13
29
%
28 100
1
16
40
28
7
4
100
6
1
13
7
7
4
8
100
4
2
5
21
24
16
11
7
100
4
1
10
28
22
12
12
100
O
N
D
%
1
22
4
4
3
2
12
6
6
9
6
12
100
100
100
100
100
0
0
D
Table A.7: Percentage of the Occurrence of Annual Maximum Floods by Month'
River
Station
J
M
A
M
Parang
Iguagu
Parana
Paraguay
Parand
Guaira
Cataratas
Posadas
Asunci6n
Corrientes
19 2727
* 5 5
19 29 19
13 7 2
8 23 25
7
8
5
5
9
6
2
5
i-It should be notedth
F
7
3
J
JI A
S
4 0
1 0
14 15 6
5
10 2
0 2
30 10 i
2
1
11 4 0
5
3
1
the mots ezxtorimay floodsin Poadas and Comfent occurrd in May, June, and July.
The most criticalconditionsfor floodsat Guafra,(Posadasand Corrientes),wouldbe with storms
over the wholeParandBasinfor the first few months,givinghigh base flowsand peak discharges
from the upper part of the basin, followedlater by stormsconcentratedin the lower part of the Upper
Basin. This combinationshouldproducethe greatestpeak dischargeat Guafra,Posadasand
1972). This is whatoccurredin 1982, 1983,and 1992,for
Corrientes(ELETROBRAS/ANDE,
example.
21.
The flood-travel time in the ParanARiver between Jupia and Corrientes,
and Salto Osorio and in the Iguagu River between Salto Cataratas is shown in Table A.8.
(ELETROBRAS, 1978). According to EBY, 1979 the flood-travel time between Posadas and
Corrientes in the Parna river is 5 days and between Corrientes and Rosario 30 days
(i.e., 788 km at 0.3 mls).
AnnexA - September2, 1993
-8-
22.
Table A.9 presents the difference between ordinary and extraordinary floods
according to EBY, 1979 (An extraordinary flood is considered equal or superior to a 10 year
recurrence flood.)
Table A.8: FloodTravel rime in Parana and IguaguRivers
Zone
Distance
km
Flood Travel
days
Jupia-Guarfa
Guafa-Posadas
Posadas-Corrientes
S. Osorio-S.Cataratas
499
664
376
270
4
2
5
1
River
Parana
Parana
Parana
Iguagu
Velocity
m/s
1.4
3.8
0.9
3.1
Table A.9: Ordinary and Extraordinary Floods in the Parana and Paraguay Rivers
River
Station
Paraguay
Paraguay
Paraguay
Parana
Parana
Parana
Ladario
P. Murtinho
Asunci6n
Guafra
Posadas
Corrientes
Warning Extraordinary
Floods
Ordinary
Floods
m m31s
m
m3/s
4.0
6.0
6.3 6300
4.5 4000
2.0 15000 2.8 24000
3.5 21000 6.0 30000
5.5 24000 7.0 35000
Gauge
Datum
abovesea level
m
82.15
70.15
53.09
218.00
73.09
41.40
23.
In the Iguagu Basin, due to its area, topography, and shape, the peak floods are high,
but for shorter periods of time. The maximum peak floods recorded since 1926 in the Iguacu
river basin are:
1983July 31 000 m3 /s
1936June 28 600 m31s
1992May 18 700 m3/s
Annex A - September 2, 1993
1987May 17 500 m3/s
1928May 17 500 m3/s
1932April 16 000 m'/s
1938July 15 500 m3/s
1937Nov 15 000 m 3 /s
1989June 14900 m3/s
-9-
Table A.10: Sedimentsin the ParanA- Paraguay river basins
Mean Sedimementston/year
Annual (*106)
Flow 1977' 1992
River
Site
ParanA
Guaira
Observations
W/s3
23.72 Since 1982, most
9350
12000
26.5
6*
2750
4.3
4.5*
Paraguay
ConfluenceParang 4000
100.9
100*
Parana
Corrientes
16000
126.1
106*
Parana
Confluence
Paraguay
Paraguay
Asunci6n
of the sediments
are depositedin the
reservoirof Itaipu
dam.
Includesthe
contributionof the
Iguaguriver basin
and other
tributaries
Mostof the
sedimentsof the
Brazilianportion
are depositedin the
Pantanal
Includesthe
contributionof the
Bermejoriver basin
Most of this
sedimentreaches
the port of Buenos
Aires
I-EBY, 1979
2-ELETROBRAS, 1992
*-Estiriated
Sedimentation
At present, data for only two years (1977 and 1992) have been obtained and
24.
examined. These are shown in Table A.10.
25.
In 1992 ELETROBRASpublished an updated report on the sedimentological
conditions of the most important Brazilian rivers. This report shows three areas of higher
production of sediments in the Paran6/Paraguay River Basin, mainly caused by the erosion of
sedimentary rocks, mostly sandstone. In the Parand River Basin, the areas are located in the
upper part of the Araguari river (Paranaiba basin) and between the Paranapanema and Ivaf
rivers (Caiud sandstone). Both areas are upstream from Guaira and the Itaipu dam. In the
Annex A - September 2, 1993
-10-
Paraguay River Basin the area of high production of sediments is located in the upper part of
the Pantanal.
As far as the Paraguay River Basin is concerned most of the sediments in the
26.
Brazilianportion are deposited in the Pantanal. The same occurs with the production of
sediments in the Parana River that remain deposited in the reservoirs of the hydroelectric
dams.
The most important production of sedimentsin the Parana/Paraguay River Basin
27.
occurs in the Bermejo River Basin (94 350 km2 ) that originates in the Andean slopes of
Argentina and Bolivia. Almost 100 000 000 tons of sediments are transported each year into
the Paraguay and Parani Rivers.
Previous Studies
The La PlataBasin
AISIKS,E.G. 1985. 'La Gran Crecidadel Rfo Paranade 1983".BuenosAires
CIC. 1982. 'Reunionesde las ContrapartesTecnicaspara el Programade AlertaHidrol6gicadela
Cuencadel Plata". Alsothe reportsfrom 1984,1989, and 1991meetingsheld in BuenosAires.
Quantitativoe Qualitativo
COIMBRA,R.M., OLIVEIRA,E., CUDO,K.J. 1992. "Monitoramento
das Aguasda Bacia do Prata' (ProjetosAlertaHidrologicoe Qualidadedas Aguasdo CIC - Comit6
Coordenadorda Baciado Prata). Brasfia.
Intergovernamental
DIAZ, H.F. 1993. 'TemporalPatternsof Precipitationin the Paranaand ParaguayRiver Basinsand
its Relationshipto the El NinloPhenomenon".NationalOceanicand AtmosphericAdminstration.
EnvironmentalResaearchLaboratories.Boulder.Colorado.
Brasilia
DNAEE. 1987. 'Inventariodas Estac6esPluviom6tricas".
Brasilia
DNAEE. 1987. 'Inventariosdas EstacoesFluviometricas".
EBY. 1979. "Estudiode CrecidasRfos Paranay Paraguay. Estudiorealizadopor MOTOR
COLOMBUSY Asociadospara EntidadBinacionalYacireta.BuenosAires-Asunci6n.
dosPrincipaisRios Brasileiros".
ELETROBRAS.1992'Diagn6sticodas Condi06esSedimentologicas
Institutode PesquisasHidraulicas-IPH.Rio de Janeiro.
OEA. 1969. 'Cuenca del Plata. Estudiopara su Planificaci6ny Desarrollo.Inventariode Datos
Informedel estudiollevadoa cabopor la Unidadde Recursos
Hidrol6gicosy Climatol6gicos".
Naturalesen 1967y 1968.Washington,D.C.
OEA. 1971. 'Inventarioy Analisisde la Informaci6nBasicasobre RecursosNaturales". Cuencadel
Rfo de la Plata. Estudiopara su Planificaciony Desarrollo.Washington,D.C.
AnnexA - September2, 1993
-11-
OEA. 1969. " Indice Anotado de los Trabajos Aerofotograficosy de los Mapas Topograficos y de
Recursos Naturales". Cuenca del Rio de la Plata. Estudio para su Planificaci6n y Desarrollo.
WashingtonD.C.
OEA. 1985. 'Infraestructura y Potencial Energetico en la Cuenca del Plata'. Washington, D.C.
The Paraguay River Basin
ANNP. 'Anuarios Hidrograficos". Asunci6n
ARMADA NACIONAL. "Anuarios Hidrograficos'. Asuncidn
ARMADA NACIONAL. 1979. 'Estudio del Comportamientodel Rfo Paraguay y su Litoral Desde
Concepcidn Hasta Confluencia'. Asuncion.
CARVALHO, N. de O., AYRES R.M., ROCHA, J.P.G. 1992. 'Estudos Sedimentoldgicosda Bacia
do Sao Lourengo, MT'. ELETROBRAS/UniversidadeFederal de Mato Grosso. Cuiaba.
CARVALHO, N. de O., MONTEIRO, A.E. 1991. 'Sistema de Alerta e Provisao de Cheias do
Pantanal'. ELETROBRAS/Companhiade Pesquisas de Recursos Minerais. Rio de Janeiro.
DMH. 1992. 'Balance Hidrico Superficialde Paraguay". Asunci6n.
DNPVN. 1973. 'Estudo Hidrologicodo Rio Paraguai. Perfodo 1966-1972Relat6rios Parciais e
Relat6rio Final'. Hidrologia Comercial Ltda. Rio de Janeiro
DNOS. 1974."EstudosHidroldgicos da Bacia do Alto Paraguai%.4 Volumes. Rio de Janeiro.
GIUSTI, E. V., LOPEZ M.A., 1984. 'On the Hydrology of the Paraguay River'. USGS. Selected
Papers in the Hydrologic Sciences. Reston.
HALCROW AND PARTNERS. 1973. 'Estudio de Navegabilidaddel Rfo Paraguay al sur de
Asuncicn'. Asunci6n.
JICA. 1985. 'Storm Drainage System. Improvementin Asuncion City'. Asunci6n.
LOPEZ, M.A. et alli. 1983. 'Hydrologic Hazards in Paraguay with Special Reference to the floods
of 1983.' USGS. Reston.
OEA. 1974. 'Alta Cuenca del Rio Bermejo. Argentina-Bolivia'. Estudio de los Recursos Hidricos.
Washington, D.C.
OEA. 1977. "Cuenca Inferior del Rfo Bermejo. Argentina". Programaci6n para su Desarrollo.
Washington, D.C.
OEA. 1975. ' Proyecto Aquidaban. Desarrollo de la Regi6n Nororiental del Paraguay". Washington,
D.C.
AnnexA - September2, 1993
-12-
OEA. 1979. "Caracteristicas da Vegetacio da Bacia do Alto Paraguai" Informe preparado por el
consultorJorge AdAmolipara o 'Estudo de DesenvolvimientoIntegrado da Bacia do Alto Paraguai
(EDIBAP)". Brasilfa.
OEA. 1992. "Proyecto de Reconstrucci6ny Desarrollo Integrado del Area Meterol6gica de Asunci6n
y de los Entidades de Concepci6n, Alberdf, Pilar Afectadaspor Inundaciones." Informe de las Misi6n
Preliminar de la OEA/DDRMA. Washington.
PNUD. 1975. "Proyecto de Mejoramientode la Navegaci6ndel Rfo Paraguay". PAR/TS/006.
Asunci6n.
PNUD. 1979. "Estudio de Inundacionesdel Rfo Paraguay". Asunci6n.
PNUD. 1980. 'Modelos Estadlsticospara Previsi6n de Niveles del rfo Paraguay". PAR1801002.
Asunci6n.
SUDECO. 1979. "Estudo de DesenvolvimentoIntegrado da Bacia do Alto Paraguai-EDIBAP".
Convenio Governo Brasileiro PNUD-OEA Brasfia.
USCE. 1972. 'Application of the SSARRmodel to the Upper Paraguay River Basin". Portland,
Oregon.
UNESCO/UNDP. 1973."Hydrologicalstudies of the Upper Paraguay River Basin (Pantanal) (19661972) Technical Report". Bra. 66.521. Paris.
Parang River Basin
AyEE/DNCPyVN/CONCAP. 1973. "Estudio Hidrol6gico y Sedimentol6gicodel rio Alto Parand."
Buenos Aires.
AyEE. 1970. "Resumen de la EstadfsticaHidrol6gica Hasta 1967". Buenos Aires.
AyEE. 1960. "Estudio Hidrol6gico del Rio Alto Parana". Buenos Aires.
AHLQUIST, 0. 1906. "La Gran Creciente de 1905 del Rio Parana y sus Afluentes". Buenos Aires.
BERGER-BROKONSULTA.B. 1973. "Mejoramientode la Navegaci6n del Rfo Parana. Buenos
Aires.
BRAZILIUNDP.1966. "Power Study of South Central Brazil-SaoPaulo Group-Hydrometerology
Report."Appendix No. 8. Canambra Engineering ConsultantsLimited. Montreal.
CARVALHO, N. de O., CATHARINO, M.G. 1992. 'Avaliacao do ssoreamento do Reservatorio da
UHE Itaipu". ELETROBRAS, Diretoria de Planejamento e Engenharia. Rio de Janerio.
CARVALHO, N. de O., 1991. 'Producbo de Sedimentosda Area de Contribuisao ao Reservat6rio de
Itaipu". I Reuniao sobre Erosao e Sedimenta§bo,Curitiba.
Annex A
-
September 2, 1993
-13-
COMIP. 1977. 'Aprovechamiento del Rfo Paranl en el Tramo Limitrofe Comprendido Entre la
Desembocaduradel Rfo Iguazd y la Seccidn Encanaci6n-Posadas, con particular atenci6n a la zona
de Corpus-FaseI" . Lahymer-Harzay Asociados. Buenos Aires.
CONCAP. 1970. 'Modelo Matematico de la Cuenca del Plata - Informe Preliminar de la Fase I Factibilidad Tecnica de las Fases 2-3". Buenos Aires.
CONCAPlDNCPyVN/AyEE. 1973. 'Estudio Hidrol6gico y Sedimentol6gicodel rio Alto ParanA".
Buenos Aires.
COTTA, D. 1973. "Influencia Sobre el Rfo Parana del Material Sdlido Transportado por el Rfo
Bermejo. Buenos Aires
DNCPyVN. 'Anuarios Hidrograficos". Ministerio de Economfa de la Replblica Argentina. Buenos
Aires.
EBY. 1973. "Estudio de Factibilidad Tecnica, Econ6mica y Financiera para el Desarrollo del Rfo
Parand en el Area Yacyreta - Apipe". Consorcio Harza y Asociados. Asuncidn. Buenos Aires.
ELETROBRAS/ANDE. 1972. "Rio ParanAStudy. Appendix A. Hydrology and Meterology",
prepared by EECO-International EngineeringCompany of San Francisco, California and ELCElectroconsult of Milan, Italy. Rio de Janeiro/Asunci6n.
ELETROBRAS. 1978. "Estudo da Genese das Vaz6es do Rio ParanA".5 volumes realizados pelo
Consorcio Nacional de Engenheiros Consultores SA. Sao Paulo.
ELETROBRAS/GCOI. 1992. "AnAliseda Operacao de Controle de Cheias para as Bacias dos Rios
Parana e outros na Estagao Chuvosa 1991/1992". Subcomite de Estudos Energeticos. Rio de Janeiro.
ELETROBRAS/GCO1.1992 'Analise da Operacao Hidraulica dos Aproveitamentosda Bacia do Rio
Iguagu durante a Cheia Maio-Junhode 1992." Grupo de Trabalho de Hidrologfa Operativa. Rio de
Janeiro.
EINSTEIN, H.A. 1972. -Report on the Sediment Problems Connected with the Apip6 Project on the
ParanARiver. Buenos Aires.
FESQUET, H.B. 1975. 'Pron6stico de la Fecha de Culminaci6n de las crecientes del Rio Parana".
Publicaci6n N°15, Serie Hidrometeorol6gica.Buenos Aires.
INCyTH. 1975. 'Cuenca Superior del Rfo Parana - Estudio de la Crecida Maxima Probable". Buenos
Aires.
OEA. 1973. *Noroeste do Estado do Parana-Brasil. Estudo para o Controle da Erosao". Washington,
D.C.
PNUD. 1977. 'Proyecto Mejoramiento de la Navegacidn del Rio Parana, Mediciones de Transporte
de Sedimentos en el rfo Parana a altura de Corrientes", por J. Lelievre y E. Navntoft. Buenos Aires.
PNUDIINCYTH. 1974. "Estudio del Sistema Fluvial Parang-SantaFe' SFIARGI66I521. Buenos
Aires.
Annex A - September 2, 1993
-14-
RAFFO, J.M. 1951. 'Pron6stico de las Crecientesdel Rfo Parana, S.M.N., Publicaci6n N0 2. Serie
Hidrometeoroldgica.Buenos Aires.
STUCKRATH, T. 1969. 'Movement of Ondulationon the Bed of the Parang River". Buenos Aires.
VANONI, V. 1967. "Review of SedimentationProblems of the Proposed Parana-Fe Tunnel". Buenos
Aires.
ACRONYMS
ANNP
Administaci6nNacional de Navegacidny Puertos (Paraguay)
AyEE
Agua y Energia Electrica (Argentina)
CFI
Consejo Federal de Inversiones (Argentina)
CIC
Comite IntergubernamentalCoordinadorde la Cuenca del Plata
COMIP
ComisionMixta Argentina Parguaya del rfo Parang
CONCAP
Comisi6nNacional de la Cuenca del Plata (Argentina)
DEPVN
Departamientode Puertos y Vfas Nagigables (Aregentina)
DRDE
Departmentof Regional Developmentand Environment
ELETOBRAS
Centrais Eletricas Brasileiras SA
DMH
Direcci6n de Meteorologfae Hidrologfa (Paraguay)
DNAEE
DepartamentoNacional de Aguas e Energia Eletrica(Brazil)
DNCPyVN
DepartamentoNacional de ConstruccionesPortuarios y Vfas Navigables
(Argentina)
DNPVN
Departamento Nacional de Portos e Vias Navegaveis (Brazil)
DNOS
DepartamentoNacional de Obras de Saneamento(Brazil)
EBY
Entidad BinacionalYaciretA(Argentina/Paraguay)
EDIBAP
Estudo para o DesenvolvimentoIntegrado da Bacia do Rio Paraguai (Brazil)
GCOI
Grupo Coordenadorpara a OperagaoInterligada (Brazil)
JICA
Japan International Cooperation Agency
IECO/ELC
Consultoras "Intemational Engineering*San Francisco / "Electroconsult" Milan
IGH
Instituto Geogrlfico Militar (Argentina)
Annex A
-
September 2, 1993
-15-
INCyTH
Instituto Nacional de Ciencia y Tdcnica Hfdricas (Argentina)
IPH
Instituto de Pesquisas HidrAulicas(Brazil)
LAC
Latin America and the Carribbean
MIT
MassachusettsInstitute of Technology
NOAA
National Oceanic and AtmosphericAdministration
OAS
Organizationof American States
SMN
Servicio Meterol6gicoNacional (Argentina)
SUDECO
Superintendenciado Desenvolvimentoda Regiao Centro Oeste (Brazil)
SUCCE
Subunidad Central de Coordinacidn para la Emergencia del Ministerio del
Interior (Argentina)
UNDP
United Nations DevelopmentProgramme (PNUD in spanish)
UNESCO
United Nations Educational, Scientific, and Cultural Organization
USAID
United States Agency for InternationalDevelopment
USCE
United States Corps of Engineers, North Pacific Division
USGS
United States Geological Survey
AnnexA - September2, 1993
-16-
Annex B: Large Scale Atmospheric Disturbances
and Flooding in the Parana/ParaguayRiver Basin
1.
Large-scale atmospheric disturbancesand their temporal variability may play a role,
via precipitation, in producing year-to-year changes in streamflow in the Parana\Paraguay
Basin. In particular, a characteristic feature of the climate of the tropical Pacific Ocean is a
biennial tendency in equatorial sea surface temperature (SSI) and associated atmospheric
fields such as the surface winds, sea-level pressure, and rainfall. In general, conditions
along the equatorial Pacific are such that warm surface waters and heavy rainfall are
restricted to its western areas (west of the International Dateline). During so-called El Nifio
events, warm equatorial Pacific waters are found much further east than usual, heavy rainfall
shifts eastward, and between about December and March, can become excessive along the
normally dry coasts of southern Ecuador and Peru.
2.
The shifts in rainfall pattems in the tropical Pacific perturb large scale atmospheric
circulation patterns all over the globe. Because the weather patterns associated with El Nino
events can persist for about one year, the anomalous weather conditions that can be
experienced in those regions affected by the phenomenon can also be long-lasting.
3.
In 1991-92, a moderate El Nifo event occurred in the Pacific. In the last decade, we
have experienced three moderate to very strong El Nifio events - in 1982-83, 1986-87 and in
1991-92. The 1982-83event is considered the strongest such event in this century. The type
of climatic anomalies experienced in any one part of the world depends on its geographic
location, and it also tends to be seasonally dependent.
4.
The pattern of anomalously high and low precipitation is quite characteristic of the
typical season response to El Nino events in this region (Kiladis and Diaz, 1989'; Diaz and
Kiladis, 19922). In particular, heavier than normal rainfall is experienced in the
Parana/Paraguary Basin and along the northern coast of Peru, and dryer than normal weather
is experienced in the Nordeste region of Brazil. Although this is the typical or characteristic
response of the precipitation regime in South America, it does not necessarily occur in every
El Nifio event to the same degree, whether in its spacial features or in its seasonal
distribution. Nevertheless, the frequency with which this typical response is observed, and
the fact that significant alterations of the normal climatologicalfeatures in the affected
regions can occur, suggest that having knowledge of the expected climatic patterns when an
El Niinoevent is underway would be helpful in planning for the safety of life and property.
'Kiladis,G.N. andDiaz, H.F., 1989:Globalclimaticanomaliesassociatedwiththe extremesof the
2:1069-1090.
SouthernOscillation.Journal of Calimate,
2Diaz,H.F. andKiladis,G.N.,
associatedwiththeextremephases
1992:Atmosphericteleconnections
of the Southern Oscillation.In Diaz, H.F. and Markgraf, V. (eds.), El Mflo: Historical and
PaleoclimaticAspectsof the SouthernOscilation, CambridgeUniversityPress, Cambridge,pp. 7-28.
Table B. 1 shows a close correspondence between El Nino events and the occurrence of extraordinary floods'.
Table B.1: El Niiio Episodes and Floods in the ParanDIParaguay River Basin'
El Nifno
Year of
Yearof
Occurrence Extraordinary
(warmevent) FloodsRecorded
1992
1991
1986
1987
1982-83
1982
1976
1977
1972
1974
1965
1965-66
1963
1957
1953
1951
1939
1932
1930
1925
1923
1918
1913
1911
1904
1877
1963
1957
1954
1951
1939
1932
1931
1926
1923
1919
1913
1912
1905
1878
3Extraordinary
flood years are years in whichan extraordinaryflood (i.e.
10-yearsflood)occurred
at one or more of the folowing sites: Jupia, Guafra, Posadas,Corrientes,Ladario,Porto Murtinhoor
Asunci6n.
ANNEX B -AugUSt 31, 1993
-2-
The warm events in the Pacific are not the only critical feature of this phenomenon.
5.
The Southern Oscillation (SO), a large scale "seesaw" of atmospheric mass between the
western and eastern tropical Pacific, is also an important tropical feature.
In essence, the SO defines two predominantclimate regimes in the tropical Pacific
6.
Ocean. In one mode, sea-level pressures (SLP) are relatively high over the subtropical South
Pacific and the Southeast Trades are strong, upwellingalong the equator is well developed,
and rainfall is heavier than usual in the western tropical Pacific, while very dry conditions
prevail along the equator east of the dateline and along the Peruvian coast. In the other
mode, pressure gradients are weaker, and, in response, the Southeast Trades are also
weakened resulting in anomalously warm water along the Equator from the coast of South
America to the dateline, and anomalously heavy rainfall over these same areas. The El Nino
is the manifestationof the latter extreme phase, whereas, so called "La Nifia" events
comprise the opposite phase of the SO. Some of the great droughts of this century in parts
of the Parana/Paraguay Basin have occurred in associationwith La Nina events.
Table B.2 summarizesthe impact of the extremes in the El Nihio/SouthernOscillation
7.
(ENSO) in terms of the average percent of normal annual peak flow measured during warm
and cold ENSO events in this century for the available streamflow record at the three
recording sites. The figures show that the climatic patterns associated with the extreme
phases of the ENSO phenomenon have resulted in about a 20% differential in peak flows on
the Upper Parand-ParaguayRiver Basin. The data displayed in Figures of the main text
suggest that since the about the early 1980s wet season rainfall and annual peak streamflow
in the region of the Parana and Paraguay River Basins have been relatively high. The
question thus arises as to whether the recent increase in wet season rainfall represents a
change in climatic conditions (i.e., a structural change), or whether it is simply a random
perturbation within the same climatic structure. Indeed, if this increase to a higher level of
runoff is real and climatically driven, this would have serious implications for the planning of
development projects that are affected by streamflow levels.
Table B.2: Mean Deviationfrom Long Term Mean Annual MaximumDaily Discharge(percent
of normal)
ANNEX B-August
La NifiaYear
GaugingSite
El Nifno
Posada
110
93
Corriente
113
89
Asuncion
118
94
31, 1993
_3.
ANNEX C: DATA TABLES
This annex presents in tabular fonn the data that were used in the
analyses reported in the text of the paper. These data are available in Lotus
format on request from Robert J. Anderson, Jr.
Table C.1
Parana River in Posadas: Mean Monthly
Discharges
Table C.2
Parana River in Corrientes: Mean Monthly
Discharges
TAbleC.3
Parana River: Extreme Annual Low Flows
Table C.4
Paraguay River: Extreme Annual Low
Flows/Stages
Table C.5
Parana River: Annual Maximum Daily
Discharges
Table C.6
Paraguay River: Annual Maximum Daily
Discharges/Stages
Table C.7
Monthly Precipitation in the Parana/Paaguay
Basin
I
Table C.1
Parana river in Posadas
Mean monthly dischargs m/s *1000
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Ann
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
21.6
15.3
13.6
17.5
20.1
19.7
17.2
18.6
13.6
23.9
14.8
16.3
16.9
23.8
23.3
17.6
22.4
13.7
21.2
19.9
16.9
12.1
20.4
23.5
19.9
16.7
13.4
20.5
16.7
10.7
9.0
19.7
22.4
12.5
12.1
11.4
16.3
14.4
9.7
7.7
29.4
13.5
10.6
10.7
9.5
12.2
16.0
9.6
7.9
25.5
13.4
12.0
10.4
9.8
10.2
10.7
9.0
11.0
17.1
10.2.
12.9
9.2
7.7
14.7
7.6
8.6
8.1
14.7
7.7
9.9
8.8
5.7
9.2
9.2
6.2
9.8
12.5
7.2
15.9
8.3
5.7
7.9
10.8
9.2
12.8
10.7
7.7
17.3
13.4
7.6
6.4
12.4
9.5
16.6
9.1
7.9
17.1
14.2
9.6
10.6
17.7
9.7
13.9
13.1
9.7
16.3
15.5
9.8
14.5
13.8
10.7
11.8
18.0
13.8
14.9
13.3
9.7
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
10.9
7.7
21.5
16.9
8.5
10.8
10.7
12.4
8.9
12.5
15.6
10.4
22.1
14.9
12.4
8.4
13.7
14.6
15.6
19.4
14.9
9.0
23.8
13.8
13.0
7.7
12.0
15.3
12.9
15.2
12.1
11.2
16.9
11.9
9.5
9.5
12.0
12.8
9.3
14.2
9.1
10.1
13.1
9.3
6.8
10.4
8.8
9.6
8.4
13.7
10.2
8.7
11.7
8.7
8.7
13.7
8.3
7.2
12.1
14.5
8.8
9.9
8.8
7.3
12.8
8.1
8.4
7.0
9.0
10.8
8.1
10.1
8.9
6.6
8.6
6.6
6.2
5.5
8.0
7.5
7.2
13.0
9.1
6.8
8.4
9.7
8.4
5.5
7.2
8.2
8.7
18.9
10.6
5.9
10.1
16.3
8.9
8.7
10.5
10.7
7.3
14.8
12.8
5.6
12.8
10.5
5.1
6.7
11.0
17.3
6.2
22.1
12.3
5.6
12.7
9.8
7.9
6.3
12.3
16.7
9.9
12.2
14.2
9.4
10.3
10.1
9.2
9.3
10.4
13.3
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
18.0
18.7
11.4
13.0
11.6
13.4
19.1
18.3
6.6
21.5
17.9
23.0
17.8
15.5
16.0
9.5
22.6
15.9
11.7
27.0
17.7
17.0
20.9
17.0
17.5
8.3
17.3
17.0
13.9
27.1
13.3
13.6
18.9
16.9
13.4
8.8
21.5
13.1
16.2
18.2
10.0
9.0
18.7
13.9
11.6
9.7
16.1
9.3
13.4
12.3
9.7
8.5
18.1
19.7
12.3
7.6
15.4
9.2
17.7
13.2
11.3
8.6
14.4
12.4
8.8
6.6
15.5
7.7
11.7
9.2
8.5
7.8
12.6
8.4
6.7
4.9
9.8
6.0
11.6
8.1
8.9
11.0
10.1
11.6
5.8
4.5
8.7
13.0
11.1
14.2
9.5
12.9
10.7
13.9
4.8
7.2
7.1
9.2
17.7
16.2
11.6
7.2
9.6
16.9
5.5
11.2
8.6
12.7
9.3
13.8
14.0
6.1
9.8
11.4
7.2
13.8
10.7
7.1
11.5
12.4
12.5
11.9
14.4
14.2
10.1
8.8
14.1
11.5
12.7
16.0
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
16.4
19.6
15.6
17.8
12.6
14.4
16.5
19.1
15.5
14.6
20.6
19.2
19.5
16.6
12.3
15.5
9.5
15.0
17.1
16.0
15.6
24.6
17.8
14.1
11.4
17.1
13.5
14.6
12.3
12.7
11.6
19.3
19.3
11.0
9.9
13.7
10.9
13.3
11.7
10.6
10.6
19.9
14.6
9.5
8.9
10.6
10.6
10.9
12.8
11.7
8.5
17.9
15.1
7.1
6.2
11.0
16.5
9.8
14.2
10.0
7.0
13.0
11.9
6.5
5.1
9.5
8.9
7.1
15.7
9.3
7.4
8.8
9.2
5.5
4.3
12.2
9.7
6.1
8.7
6.6
7.5
10.8
9.0
5.4
4.7
10.6
10.3
6.3
6.7
7.0
12.4
10.4
13.6
7.1
6.2
24.8
8.6
9.5
6.5
6.8
13.4
8.8
9.7
6.9
4.3
14.7
7.6
15.2
8.3
12.8
14.1
12.6
15.8
8.3
9.0
12.3
9.9
13.9
9.6
19.4
12.0
15.4
14.2
9.6
7.9
13.9
11.0
11.7
11.6
11.4
1940
1941
1942
1943
1944
1945
1946
1947
17.3
13.8
14.6
16.1
10.6
7.1
20.0
14.8
17.5
15.9
16.5
18.8
10.5
14.9
23.1
18.0
18.1
11.3
19.3
17.7
15.0
15.3
24.4
21.7
15.0
10.1
18.6
12.6
10.4
14.7
16.7
18.6
12.9
14.1
15.6
9.0
7.5
9.6
13.6
13.8
10.1
9.9
14.3
11.5
5.8
7.5
13.1
12.2
8.0
8.9
11.7
7.9
4.7
10.3
16.5
9.7
7.0
12.1
9.3
7.0
3.7
5.8
9.6
9.4
5.3
9.2
8.3
6.0
3.6
4.7
7.3
12.4
5.0
10.9
9.7
9.3
3.1
5.5
10.7
12.9
8.7
11.8
7.6
11.4
6.7
7.3
10.1
9.4
10.2
17.8
9.6
10.1
7.5
12.2
11.8
10.4
11.2
12.1
12.9
11.4
7.4
9.5
14.7
13.6
Page
1
Table C.1
Parana river in Posadas
Mean monthly dischargs mI/s *1000
1948
1949
Jan
14.4
10.8
Feb
16.4
15.5
Mar
16.3
15.0
Apr
13.6
10.8
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
11.2
14.3
7.7
9.0
11.7
9.2
12.5
13.0
10.5
14.5
17.9
21.4
13.0
8.5
12.2
9.0
8.7
17.6
16.6
18.9
18.1
23.0
18.1
8.5
12.2
8.3
10.7
16.0
14.4
14.4
14.3
15.8
13.7
11.2
8.3
10.3
14.3
15.4
13.1
14.7
10.9
9.4
7.9
8.1
16.4
9.5
15.2
11.4
10.1
10.4
8.7
8.1
9.2
8.2
18.4
15.2
17.6
9.6
11.3
9.3
8.1
7.2
7.6
5.7
12.4
14.1
12.7
15.0
8.5
7.2
5.8
5.5
5.2
4.4
7.4
8.2
14.9
18.9
8.6
7.2
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
11.2
17.6
12.1
18.8
7.9
32.0
22.0
17.2
14.0
12.5
16.6
16.9
16.5
17.2
13.5
19.4
23.6
18.8
13.2
10.3
15.2
23.8
18.4
13.7
12.5
23.5
21.3
19.8
12.6
9.3
12.5
18.8
12.8
11.4
10.9
16.5
15.3
13.0
9.1
10.6
9.7
15.2
9.5
8.5
9.5
19.6
11.3
9.3
8.3
8.5
8.9
11.6
8.8
7.4
7.5
14.1
10.6
9.5
6.4
13.2
8.1
8.7
6.5
5.7
7.6
17.8
9.8
8.9
6.0
9.1
8.7
6.5
5.6
4.9
8.4
11.4
7.6
8.0
5.6
5.8
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
11.8
18.0
11.7
18.4
19.4
15.6
15.3
22.7
15.9
13.0
13.2
9.5
16.9
19.6
15.9
13.5
16.7
24.6
12.6
15.3
15.5
10.6
16.5
15.3
14.8
12.6
15.0
11.6
12.6
13.6
9.3
9.7
12.9
14.4
18.5
12.4
13.1
14.4
9.2
10.5
8.5
12.1
8.5
12.3
12.5
9.7
9.8
10.7
8.0
15.3
9.1
13.7
10.5
12.7
12.5
9.2
16.1
10.5
9.0
10.2
11.1
12.4
10.7
13.7
13.6
9.0
10.7
9.4
10.5
9.5
5.7
9.5
12.1
11.6
9.8
9.5
12.9
8.7
10.6
11.0
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
15.7
18.9
18.7
24.9
21.6
13.5
9.9
10.4
13.9
15.0
22.0
16.5
19.1
29.9
17.1
19.3
12.3
15.4
14.1
21.5
19.8
10.9
16.8
31.7
12.0
17.5
12.8
12.5
16.2
16.3
13.3
10.0
18.2
24.1
12.4
16.7
13.0
13.8
13.3
13.5
13.3
11.0
11.5
30.7
11.9
15.9
14.2
20.5
16.5
13.8
11.1
9.6
15.0
34.6
14.1
13.1
13.0
18.0
16.8
12.5
11.2
0.6
21.6
33.7
11.5
12.2
12.4
15.0
12.2
12.4
1990
1991
1992
26.9
11.2
13.5
16.7
17.9
17.8
11.6
13.1
15.0
13.2
19.6
17.5
14.5
14.7
24.8
19.0
13.4
24.8
15.6
12.9
16.3
May
9.2
9.6
Jun
8.3
8.8
Jul
6.4
6.1
Page
2
Aug
8.4
6.1
Sep
5.9
6.3
6.3
6.5
6.4
7.4
7.5
8.9
10.3
21.1
11.3
6.5
Oct
7.5
6.3
Nov
10.8
5.8
Dec
9.5
7.7
Ann
10.5
9.0
9.5
9.7
11.7
11.7
11.0
5.8
8.2
13.9
10.1
7.0
8.9
9.1
12.5
14.0
7.8
7.2
7.3
12.3
11.3
7.1
12.7
10.2
7.9
10.8
7.5
7.7
7.3
12.8
12.1
9.7
11.0
11.7
10.1
8.9
11.1
9.4
11.6
14.7
11.4
10.5
9.7
9.4
12.5
8.0
8.0
16.6
10.8
7.1
7.0
11.9
12.9
12.0
9.8
16.0
8.5
14.0
13.5
8.0
8.4
13.4
11.1
10.4
11.0
10.2
10.1
20.1
11.4
11.5
8.6
10.6
11.0
13.2
10.9
10.5
9.4
16.2
13.8
11.5
8.7
10.0
7.6
7.5
15.3
14.2
10.5
10.2
12.8
8.8
10.9
12.8
11.7
9.4
22.0
15.2
8.3
15.6
13.0
9.5
8.6
13.9
7.6
7.2
17.0
12.6
11.2
12.5
15.7
10;3
10.0
15.8
9.6
10.2
17.2
12.0
11.2
16.0
17.6
14.7
9.9
15.0
10.0
10.8
14.3
14.3
13.1
12.1
14.0
12.9
10.7
13.0
10.8
8.4
13.2
19.7
14.0
12.6
12.3
11.6
11.2
15.3
13.4
8..
11.1
19.7
12.6
12.3
12.8
10.8
12.5
20.6
13.3
9.9
9.3
24.9
13.3
10.3
12.8
12.2
8.8
14.6
12.3
11.0
19.3
22.1
15.1
11.0
11.3
15.4
11.4
12.7
13.5
19.7
27.0
19.8
15.3
10.2
12.1
13.2
9.9
12.8
14.1
11.9
16.7
26.3
14.2
13.7
12.4
14.0
13.0
15.1
16.7
11.2
15.0
20.5
10.0
15.0
18.9
12.7
16.2
16.2
11.S
17.0
13.7
14.3
17.9
16.9
13.5
17.6
8.4
8.3
7.5
4.6
8.2
9.9
8.6
8.1
5.2
4.8
Table C.2
Parana river in Corrientes
Mean monthly dischargs m/a *1000
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Ann
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
17.0
15.2
13.1
20.1
25.1
21.5
16.5
21.7
18.2
17.9
14.4
15.9
19.2
27.0
24.7
17.4
26.4
16.5
16.6
19.2
20.4
14.4
29.0
24.5
21.8
22.9
16.9
15.9
19.3
14.3
11.1
25.1
26.0
13.3
17.2
16.1
13.5
15.0
12.5
9.2
31.7
15.6
11.0
14.2
13.5
10.6
16.6
12.3
9.4
40.3
15.0
12.0
17.2
13.8
9.4
12.8
11.1
12.9
28.3
13.0
12.7
14.3
10.1
12.4
8.6
10.2
10.3
24.0
10.4
10.0
11.7
7.4
9.6
9.7
7.5
11.4
19.7
9.4
14.6
9.2
6.6
7.9
10.7
8.5
15.1
17.5
8.8
17.2
15.4
8.1
6.7
11.4
11.2
20.2
15.5
7.8
19.6
18.5
10.4
9.5
18.7
13.1
21.8
17.4
9.1
17.2
20.7
11.6
12.2
14.3
12.5
14.6
25.0
15.4
15.3
17.4
12.4
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
11.9
7.7
33.8
18.9
9.7
15.1
11.5
12.4
9.1
14.2
16.7
11.5
28.7
20.3
13.8
11.8
17.5
15.6
16.6
20.9
18.6
11.8
31.7
18.8
16.6
9.9
14.5
17.8
16.3
20.6
16.7
14.3
23.8
19.9
15.3
15.7
14.1
15.2
13.2
16.9
14.9
13.9
18.0
18.2
12.9
15.4
11.5
12.4
12.0
18.1
12.8
12.7
16.0
15.8
11.9
18.4
12.3
9.4
17.4
23.6
10.2
12.4
12.7
13.3
14.8
10.7
11.7
9.0
14.9
20.6
9.6
12.9
11.8
11.4
11.4
7.5
9.1
8.0
10.5
11.5
7.6
14.0
11.1
11.3
10.3
10.0
9.4
7.5
8.2
10.2
8.9
21.9
13.2
10.3
12.1
17.2
9.6
10.8
10.9
11.2
8.2
16.9
14.5
9.3
16.2
12.0
6.5
8.8
13.1
20.0
7.6
30.2
15.1
7.5
20.7
11.8
7.6
6.6
14.9
25.5
12.0
15.0
19.2
14.6
13.8
13.0
11.3
11.1
13.1
17.7
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
25.8
25.2
12.4
15.8
16.8
14.6
20.2
20.4
8.5
24.3
24.3
33.1
23.1
20.7
18.2
12.9
30.9
20.9
12.5
33.6
25.9
27.3
26.7
20.4
21.0
10.4
23.2
20.3
15.3
35.5
20.1
25.2
26.4
21.7
17.4
11.8
25.3
16.5
21.7
25.4
15.1
17.1
26.5
19.2
13.5
15.1
22.2
12.8
21.1
16.5
15.0
14.5
27.2
24.4
15.8
11.9
20.4
11.5
24.0
16.4
17.4
14.7
24.0
21.9
12.8
9.0
16.0
10.4
18.3
12.8
15.1
13.2
19.9
12.8
9.1
7.2
13.2
8.5
13.9
11.2
13.7
14.2
15.7
14.5
8.2
6.3
12.1
13.5
14.5
16.8
16.3
22.2
13.9
18.8
6.9
8.4
10.4
11.0
22.4
23.6
17.2
13.8
13.1
24.4
6.9
13.2
11.2
14.6
15.7
19.5
22.3
9.3
12.4
19.0
8.0
16.9
13.0
8.8
13.1
14.6
19.0
19.1
20.1
19.4
12.9
11.5
18.1
14.0
16.7
20.7
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
21.0
25.5
19.1
22.1
13.9
16.1
21.3
19.2
16.2
14.7
26.1
23.5
23.1
22.6
14.9
17.2
12.4
18.5
21.9
16.8
23.5
32.3
23.8
20.6
13.8
22.1
14.5
16.7
15.1
15.6
15.4
27.0
25.7
15.9
13.2
16.7
12.2
15.0
13.4
15.1
14.7
28.9
22.7
13.9
12.8
13.6
12.7
13.4
13.5
14.8
13.5
29.1
22.5
11.7
8.9
13.7
20.1
12.4
16.8
14.2
10.7
22.0
19.8
10.6
7.7
13.4
12.6
9.0
19.6
12.2
10.4
14.4
15.4
9.5
7.1
16.7
11.5
7.5
9.9
8.4
10.6
14.6
13.9
8.8
6.9
13.6
10.9
7.6
7.2
8.4
13.1
15.3
19.3
9.9
7.6
29.0
9.6
9.1
6.7
9.4
18.2
14.5
15.6
9.8
6.3
23.2
8.2
14.2
8.4
14.8
16.7
16.3
20.1
9.3
9.0
17.6
9.5
15.4
9.5
26.5
16.1
21.9
20.1
13.7
10.2
17.8
13.0
13.1
13.1
14.2
1940
1941
1942
1943
1944
1945
1946
1947
22.2
14.7
18.4
15.9
12.9
7.3
21.1
17.4
20.6
19.0
17.9
20.9
11.7
14.7
28.0
21.5
23.4
14.8
22.2
20.6
17.3
18.4
31.1
24.8
22.5
19.8
23.5
16.1
13.2
17.4
25.0
26.1
19.8
17.6
23.2
11.1
9.4
12.0
19.3
19.4
18.1
13.8
22.8
14.5
7.7
9.2
21.1
18.7
14.7
12.0
18.5
12.3
6.7
12.1
21.9
15.4
13.6
14.0
13.9
9.8
5.6
8.6
16.1
13.8
10.8
10.5
11.4
8.5
12.1
13.3
11.2
4.7
7.9
12.5
17.4
10.5
12.4
10.7
14.3
6.7
8.7
13.9
12.3
12.9
20.9
10.5
14.1
8.0
11.8
14.8
10.8
16.5
15.1
17.2
14.1
9.1
11.3
19.5
17.7
Page
1
8.4
4.9
7.5
10.3
14.9
Table C.2
Parana river in Corrientes
Mean monthly dischargs m/s *1000
Aug
9.6
8.0
Sep
7.3
7.5
Nov
11.7
6.4
Dec
10.4
8.3
Ann
12.4
11.0
11.1
7.6
13.8
13.2
15.6
7.3
13.4
22.8
16.6
13.7
10.6
10.9
16.4
19.9
12.5
8.4
13.1
16.1
17.6
12.7
14.7
12.5
11.6
14.4
8.7
8.3
10.9
16.4
20.6
15.4
14.6
14.7
13.6
12.0
15.6
12.0
16.9
19.9
16.6
17.7
12.3
11.4
8.5
7.7
10.1
12.9
10.2
9.2
6.6
6.1
13.3
12.8
14.2
8.8
9.3
19.6
10.8
8.2
8.1
12.7
19.1
15.3
11.6
18.8
9.5
19.6
15.7
8.6
11.1
16.0
15.0
15.8
11.2
14.2
11.3
23.2
13.2
11.6
9.0
14.9
15.8
19.1
13.5
14.2
11.6
21.8
19.6
13.9
10.4
12.5
7.4
11.8
12.9
14.1
14.9
12.6
15.3
12.7
14.8
18.6
8.1
8.8
18.2
17.0
15.5
13.1
15.9
12.3
13.8
20.4
13.7
10.1
26.3
18.3
11.7
19.7
16.0
12.8
11.8
22.0
9.3
8.6
20.1
15.1
14.2
16.8
20.0
12.9
13.0
23.7
9.1
10.2
25.8
14.8
14.3
21.4
20.3
18.7
13.2
22.3
11.5
14.0
17.2
18.4
18.3
16.2
17.8
17.7
14.1
19.7
18.3
13.9
32.2
48.2
16.4
18.9
18.0
22.2
20.3
18.0
17.6
12.7
25.5
33.5
16.8
20.2
15.3
16.4
18.2
19.6
19.5
12.1
20.2
25.4
15.7
19.5
14.2
13.6
17.6
28.4
19.4
13.0
17.7
33.3
16.9
14.8
16.4
13.4
13.0
23.2
18.7
13.6
24.9
29.1
19.4
14.1
13.7
17.9
13.4
18.7
18.9
22.7
40.6
25.7
21.5
11.7
14.1
16.6
10.6
14.8
20.6
17.3
25.2
37.8
19.2
19.9
16.2
18.8
17.3
19.9
21.7
18.0
27.4
21.4
14.1
21.5
28.1
12.5
20.7
25.6
15.4
23.5
22.5
13.6
26.8
17.3
16.4
26.6
22.4
16.7
25.5
1948
1949
Jan
15.3
11.9
Feb
18.1
17.1
Mar
19.5
18.7
Apr
17.7
13.2
May
12.3
12.3
Jun
10.7
12.0
Jul
8.5
10.0
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
14.1
15.0
9.2
10.3
14.4
10.3
14.0
14.2
15.0
22.6
21.0
25.3
15.2
10.1
15.2
11.3
12.4
21.7
19.9
29.3
23.9
30.5
21.5
9.9
16.9
10.5
12.8
23.4
19.1
22.9
21.4
25.4
20.4
13.3
11.6
14.2
19.6
20.9
18.6
22.4
14.9
13.5
12.1
12.7
19.0
13.0
23.0
17.4
16.1
18.2
13.2
11.2
13.5
13.6
27.7
17.9
25.6
15.4
15.7
16.4
13.0
9.9
11.8
10.3
21.5
20.8
20.3
19.3
12.9
14.1
9.3
8.1
9.1
7.4
13.5
10.6
22.3
24.1
13.0
12.8
8.1
7.2
8.8
8.6
11.1
11.6
15.7
26.4
14.2
13.2
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
17.3
20.6
14.8
20.8
9.7
17.1
33.3
20.2
14.0
16.1
22.7
21.2
19.2
22.7
13.7
24.5
33.4
22.3
17.4
12.6
20.9
30.1
23.3
18.5
16.9
31.1
36.6
26.0
14.7
11.1
17.9
30.5
18.0
16.7
15.0
25.1
26.6
18.4
11.0
12.6
13.8
26.1
12.7
12.9
15.5
26.1
17.9
11.6
9.8
10.9
13.2
19.5
11.5
12.0
10.3
25.0
15.0
10.9
8.3
17.4
12.8
15.4
8.9
10.2
9.0
22.3
13.1
10.6
7.7
12.5
11.7
11.1
7.9
8.4
9.0
15.2
10.1
9.6
7.1
7.6
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
12.5
22.4
12.5
23.8
23.1
19.9
20.6
28.5
19.1
15.8
15.3
16.7
16.6
26.3
24.7
17.9
22.1
34.0
18.3
19.8
17.7
15.2
20.7
21.5
19.7
16.2
20.1
18.9
16.5
19.4
12.1
15.3
15.8
18.5
26.7
16.4
17.6
18.6
13.1
16.2
9.9
16.9
10.5
17.4
18.0
14.9
12.8
15.8
11.0
21.3
10.0
16.5
13.6
16.6
18.2
12.7
20.0
13.8
12.0
19.0
13.0
16.0
13.1
18.4
19.1
12.3
13.9
14.4
12.7
17.5
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
21.1
25.7
27.0
38.3
27.3
18.8
10.9
15.0
16.4
14.4
29.4
27.5
24.7
40.4
22.9
24.2
13.1
19.0
16.5
25.6
28.9
18.6
22.5
45.3
15.6
24.0
16.9
18.5
19.4
23.0
18.3
15.5
27.6
38.2
17.6
25.3
19.8
18.7
16.4
19.4
18.8
17.6
18.0
46.5
19.6
24.7
21.0
26.0
20.8
18.4
18.6
15.0
21.4
50.2
20.7
22.8
20.3
28.5
24.7
16.6
1990
1991
1992
26.3
13.0
18.9
27.2
19.7
21.0
13.8
16.3
19.7
16.8
23.6
23.3
21.2
21.0
34.2
27.8
17.1
42.3
Page
2
Oct
8.4
6.9
Table C.3
Parana River Extreme Annual Low Flows
Year
Guaira
Date
Discharge
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
Dec 1
Jan 1
Sept 29
Sept 1
Sept 1
Aug 14
Sept 30
Oct 1
3850
5100
3350
2500
2550
4600
3500
3600
Date
Posadas
Discharge
Nov
Aug
Oct
Aug
Nov
Sept
Aug
Sept
Aug
5699
6949
5520
6097
8061
6686
8376
7983
5378
Dec
Jan
Aug
Dec
May
Aug
Nov
Sept
Sept
Oct
5026
5061
7404
4991
5096
5096
4271
4102
5735
6724
Sept
Dec
Jan
Aug
Nov
Sept
Oct
Aug
Jan
Aug
7175
5307
6464
7519
4169
3539
6097
5879
5807
7213
Corrientes
Date
Discharge
Nov
Aug
Oct
May
Nov
Nov
Aug
Sept
Sept
6154
7902
5962
8330
14107
7291
8851
8477
6096
Dec
Jan
Sept
Dec
Jan
Aug
Nov
Dec
Sept
Oct
6115
6077
10216
6531
8452
6470
5962
5962
7181
8501
Sept
Dec
Jan
Aug
Oct*NoV
Sept
Oct
Dec
Jan
Aug
2302
8477
9107
11452
6271
5812
9316
8138
7902
10762
8927
12662
12795
7203
5431
11238
7269
6674
5906
6756
Sept 30
Oct 1
Sept 24
Nov 24
Nov 16
Sept 1
oct 13
Sept 28
Oct 1
Sept 4
3600
3900
4450
3350
2500
2700
3800
3350
3400
3350
Oct
Aug
Aug*Sep
Sept
Nov
July
Nov
Sept
Oct
Oct
5735
7634
7299
4749
3572
7519
6464
5378
5237
5166
Oct
Sept
Sept
Dec
Nov
June
Nov
Oct
Oct
Sept
Sept 29
Oct 1
Sept 1
Sept 12
Oct 10
Oct 1
Oct 1
Oct 1
2900
2900
4450
3400
3500
2600
3200
4800
Oct
Nov
Nov
Sept
Oct
Sept
Sept
Dec
4474
7404.
6649
5166
2928
4406
6538
6986
Oct
Jan
Nov
Sept
Oct
Jan
Sept
Dec
Page
1
8306
8526
9529
8019
4552
6154
9475
9030
Table C.3
Parana River Extreme Annual Low Flows
Year
1948
1949
Guaira
Date
Discharge
Oct 10
3200
Oct 20
2000
Date
Sept
Oct
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
Sept 7
Sept 1
Sept 1
Aug 24
Nov 11
Oct 6
Oct 1
Dec 1
Aug 31
Oct 1
2700
2700
2950
2700
2950
2600
2800
4100
4200
3250
Aug
Aug
Sept
Aug
Nov
Oct*Dec
Dec
June
Aug
Oct
5378
5378
4338
3836
5520
5378
5378
8376
6170
5413
Sept
Oct
Sept
Aug
Dec
Oct
Dec
Jan
Sept
Nov
7763
6390
7603
6592
8090
6861
9965
10762
10674
11118
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
Oct 2
Oct 16
Aug 29
Sept 22
Sept 28
Oct 1
Aug 30
Sept 1
Oct 10
Sept 24
3250
3900
4300
3600
3800
4350
5000
5050
3750
3150
July
Aug
Sept
Sept
Jan
Sept
Sept
Oct
Sept
Sept
6060
6097
5202
3935
6097
9176
6686
6464
4852
4440
Aug
Oct
Sept
Sept
Sept
Sept-Oc
Oct
Oct
Sept
Sept
9992
9882
7313
7181
7856
11982
8725
7763
6430
5868
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
Sept 1
Aug 29
Sept 1
Sept 1
Sept 29
Sept 5
Aug 1
Aug 25
Sept 1
Aug 19
3630
4500
4500
5750
5500
5600
5900
6200
6400
6500
Aug
Nov
May
Aug
Oct
Sept
May
Aug
May
July
4957
5988
7789
9748
7213
7289
8653
7827
7289
8455
Sept
Nov*Dec
May
Aug
Oct
Sept
May
Sept
Oct
Jan
6430
7247
9691
12400
10998
10558
11329
11856
10674
12761
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
Aug 1
Sept 23
Sept 1
Oct 1
July 5
Nov 29
Nov 8
Jan 1
Jan 1
Dec
6900
5800
6600
8050
7000
7800
6400
6900
7130
June
July
Oct
Sept
July
Dec
Jan
Jan
Oct
Jan
9790
7062
5520
13944
10205
8894
7673
8336
6761
8693
May
Sept
Oct
Sept
Aug
Dec
Jan
Oct
Dec
Jan
16862
11793
13193
23124
13787
10329
9609
12206
9772
9449
1990
1991
1992
Dec 31
7950
Aug
7300
March
Sept
Jan
10457
9339
11526
March
Nov
Jan
12465
11028
15708
-
Posadas
Discharge
5026
5378
Page
2
Corrientes
Date
Discharge
Sept
6674
Nov
6000
Table C.4
Paraguay River - Extreme Annual Low Flows and Stages
Year
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
Ladario
Date
Discharge
Jan 1
Nov 4
Novl
Oct 3
0.79
1.12
1.17
0.31
Dec
Nov
Dec
Jan
28
11
1
1
1.90
0.85
1.10
1.50
Nov
Nov
Dec
Jan
Jan
2
1
1
1
1
0.00
0.02
0.33
0.78
0.79
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
Nov
Dec
Nov
Dec
Nov
Dec
Jan
Nov
1
31
23
1
1
1
1
11
1.36
1.45
1.02
1.14
0.34
0.46
0.68
0.50
Jan 1
0.85
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
Jan
Nov
Jan
Dec
Feb
Dec
Nov
Sept 4
Sept 9
1.05
1.67
1.90
1.18
0.00
1.44
0.00
0.12
0.00
0.00
1940
1941
1942
1943
1944
1945
1946
1947
Oct
Oct
Nov
Jan
1
16
1
1
0.05
0.00
0.14
0.73
Sept 1
0.07
Dec 24
0.86
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1
1
1
7
28
1
11
Porto Murtinho
Date
Discharge
Oct 10
1.13
Oct 1
Nov 4
Nov 1
Nov 1
Sept 28
Oct 10
Jan 1
Dec 1
1.30
1.57
1.60
2.26
1.01
1.08
1.90
2.26
Page 1
Asuncion
Date
Discharge
Paraguay River
Ladario
Discharge
Year
1948
1949
Date
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
Nov 21
Dec 6
1.02
0.87
Nov 17
Nov 1
Nov 30
0.57
0.70
0.07
Jan 1
Jan 1
Dec 30
0.64
1.63
1.53
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
Dec 1
-
Table
C.4
Extreme Annual Low Flows
Porto Murtinho
Date
Discharge
Oct 4
1.28
Oct 1
1.26
Dec
Nov
Dec
Dec
Dec
Dec
Dec
Jan
Feb
Dec
1
14
29
26
30
3
1
1
8
22
1.86
2.17
2.19
2.04
1.80
1.51
1.92
1.94
3.17
3.00
Dec 30
Nov 27
2.72
2.15
Sept 26
Oct 1
Oct 16
Oct 18
Nov 1
Sept 28
0.81
0.87
1.28
0.80
0.94
0.86
Oct 1
Sept 25
Oct 1
Oct 5
Oct 1
Nov 23
Dec 12
Jan 1
Dec 25
Dec 16
0.98
0.73
0.77
1.25
1.31
2.80
3.10
3.11
3.96
3.78
Dec
Dec
Dec
Feb
Jan
Dec
3.99
3.66
3.43
3.54
3.91
2.82
0.16
Oct 11
Sept 6
Oct 3
Aug 8
0.00
0.00
0.00
0.00
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
Nov 11
0.00
Oct 12
Oct 1
Dec 1
0.00
0.08
1.30
Dec 5
1.95
1980
1981
1982
1983
1984
1985
Dec 1
Dec 6
1.89
1.71
12
4
1
1
1
31
Page
2
and Stages
Asuncion
Date
Discharge
Table C.5
PARANA RIVER - ANNUALMAXIMUM DAILY DISCHARGES
Year
Jupla
m/s
Guaira
date
m/s
Posadas
date
m/a
Corrientes
date
m/s
date
1901
1902
1903
1904
1905
1906
1907
1908
1909
25800
24500
20100
21100
45000
26150
23650
26600
15450
Feb 17
Dec 1
Feb 24
Jan 31
May 25
April 1
March 6
Feb 7
June 1
19400
23000
22100
25700
50000
27800
24300
29400
21300
Feb 22
April 10
March 25
Dec 31
June 5
April 17
March 14
Feb 12
Jan 2
1910
1911
1912
1913
18850
29550
29800
20800
17050
24650
18100
19850
21850
27550
March 2
Dec 30
Jan 2
Jan 27
Nov 17
Oct 11
Feb 7
Mar 8
June 21
Nov 29
22000
33200
39100
24200
22500
24100
20100
22100
24800
31000
March 3
Dec 31
Jan 7
Feb 1
Dec 16
June 6
Feb 12
March
13
June 26
Dec 6
1914
1915
1916
1917
1919
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
22000
19000
11600
26300
1930
1931
1932
1933
18900
25500
14600
14700
April 7
March 12
Feb 12
Feb 19
23700
19800
19600
19000
11400
25700
21000
15300
34900
Feb 11
April 2
March 18
March 9
Nov 28
April 15
Jan 21
March 26
March 3
23450
25800
25050
33750
18850
17250
27000
21000
29600
32450
Jan 7
Feb 13
April 2
June 21
March 10
Dec 15
Jan 30
Jan 28
Oct 22
March 5
30000
36000
30500
38100
22200
18600
33400
24300
31000
39100
Jan 13
Feb 20
July 5
June 27
March 14
Dec 19
Feb 5
Feb 3
Oct 27
March 10
Feb
Feb
Jan
Jan
21300
32800
20200
19400
Feb 11
March 1
Feb 5
Jan 23
23600
29900
26750
19700
Feb 15
March 3
April 24
Jan 26
30100
36000
32100
24600
Feb 22
March 10
April 29
Feb I
8
22
30
31
Page
1
Table C.5
PARANA RIVER - ANNUALMAXIMUM
DAILY DISCHARGES
Year
Jupia
Guaira
1934
1935
1936
1937
1938
1939
m/a
11200
17000
13700
14900
12800
15100
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
17400
12800
15300
19700
11900
15900
19500
21800
14600
15500
Feb 22
Jan 8
March 14
Jan 31
Feb 23
Feb 14
Jan 10
March 21
March 21
Feb 17
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
15000
17700
19300
9740
12500
9740
12600
17400
17000
15600
Feb 14
Jan 30
March 18
March 28
Feb 22
Jan 27
Jan 7
March 1
Jan 29
March 26
18000
20200
1960
1961
1962
1963
1964
15000
20200
15200
16600
13200
Jan 28
Feb 25
March 22
Jan 2
Feb 26
17900
25300
18400
21200
20300
1965
1966
1967
19300
20100
15000
March 11
Feb 13
Feb 17
25800
27400
20100
date
Jan 18
Feb 20
March 8
Jan 20
Dec 24
Jan 4
m/a
13600
19000
16700
24700
15200
16800
Posadas
date
Dec 31
March 12
Jan 9
Jan 19
Jan 29
Jan 10
14650
27650
34500
25800
25100
26600
20900
16400
20000
21000
15700
17700
25900
26500
17400
17300
Feb 28
Feb 11
March 21
Feb 3
March 21
Feb 19
March 5
March 28
Feb 25
March 6
21550
23750
22000
21700
17400
17800
28500
2i500
18800
17300
20300
23000
21400
11100
17900
13100
March 6
Feb 5
March 25
Apr1l
4
May 24
June 23
June 15
Feb 38
Feb 4
Feb 9
1850o
i18oo
e/
22300
25800
20900
19450
23900
22900
22050
26150
17800
23800
Feb 2
March 6
March 22
Jan 25
Feb 23
March 8
Feb 22
Feb 22
17800
26650
20700
21750
20500
30300
33900
21700
Page
2
date
Jan 27
Oct 13
June 12
Nov 21
July 4
Dec 7
Corrientes
r/s
16300
33500
31900
25800
26800
31000
date
Feb 2
Oct 23
June 17
Jan 27
July 9
Dec 12
Jan 21
Feb 13
April 19
Feb 8
March 24
Feb 22
March 6
March 30
Feb 25
March 8
25600
25500
25700
23000
20000
20100
33700
29600
21500
20400
April 7
April 27
March 29
Feb 13
March 28
March
8
March 12
April 9
March 4
March 20
March 9
March 22
March 28
Nov 4
June 19
June 24
June 7
Sept 27
Feb 7
Feb 12
26800
March
Feb 5
March 18
Feb 27
Nov 9
Feb 25
Dec 23
Feb 23
March 9
33200
25700
23200
30600
27300
29200
32400
23300
33800
23500
35100
24500
24400
22700
36400
43800
27200
15
March 27
March 31
Nov 8
June 24
July 1
June 13
oct 4
Dec 31
Feb 19
Feb 24
March 25
March 11
Feb 1
March 2
Dec 29
March l
March 14
Table C.5
PARANA RIVER - ANNUAL MAXIMUM DAILY DISCHARGES
Corrientes
Posadas
Guaira
Jupia
Year
1968
1969
rn/a
11600
8680
date
March 3
Nov 19
m/s
18300
13900
date
Jan 23
Nov 24
m/s
18800
23100
date
Jan 39
Jan 1
m/s
21300
23500
date
Feb 3
Jan 16
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
14800
11500
12400
13400
18soo
11000
14100
21270
l8830
15180
March 3
Dec 12
Dec 12
April 6
March 26
Jan 9
Dec 17
Feb 6
Jan 1
Jan 29
17100
16800
20000
22130
22880
16250
19770
28250
19890
17400
March 7
Jan 10
Oct 17
Jan 28
April 2
Jan 6
Dec 31
Feb'13
Jan 29
Feb 27
17100
23450
24600
25050
23500
22850
21050
28000
19700
25500
March 12
Jan 3
Oct 10
Jan 31
Jan 27
Dec 11
June 10
Feb 15
Jan 31
May 17
19600
27200
29800
29900
30400
26600
24400
36700
25000
29800
March 19
Jan 19
Dec 11
Feb 9
Feb 2
Dec 17
June 17
Feb 21
Feb 5
May 23
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
19000
13070
21220
28160
16080
16040
7920
7350
13970
12520
Jan 31
Dec 21
March 27
Feb 12
Jan 7
Feb 15
April 3
Jan 1
March 10
Feb 19
26380
21250
27190
39850
19840
19550
15140
21310
17020
March 7
Dec 29
Dec 1
June 15
Aug 9
Feb 18
May 21
May 23
March 14
26850
25900
31350
43330
23100
21750
21000
34500
23450
31250
March 8
Dec 30
Dec 5
July 12
Jan 6
Feb 19
May 22
May 23
May 27
Sept 16
34100
31000
42600
54700
28800
28300
27200
38900
26900
35200
March 15
Feb 5
Dec 11
July 18
Jan 19
Feb 23
May 28
May 30
June 3
Sept 23
1990
1991
1992
16040
22380
16680
Jan 9
Jan 13
May 6
34180
21390
22520
Jan 19
April 11
May 9
37500
22800
41850
Jan 25
April 14
June 25
43800
27500
50800
Feb 1
April 22
June 8
Page
3
I
PARAGUAY RIVER
Ladario
Year
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
4.32
4.39
5.00
2.71
5.00
6.62
5.61
3.69
3.69
2.77
date
June 25
June 10
June 4
May 16
June 3
May 11
May 6
July 13
July 23
May 27
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
2.00
2.17
5.10
6.39
3.57
1.51
3.26
5.13
3.45
3.00
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
m
-
Table C.6
ANNUAL MAXIMUM DAILY STAGES AND DISCHARGES
Asuncion
Porto Murtinho
date
m
W/s
m
date
6.40
8.80
5.38
3.60
5.96
5.31
6320
11170
4980
3320
5730
4900
Dec 11
June 23
Jan 1
Dec 31
March 21
Jan 1
March 23
June 21
June 17
April 8
July 10
April 12
July 25
June 18
July 22
July 8
3.31
7.00
7.30
7.08
5.84
4.84
4.85
3.89
5.40
7.78
3110
7280
7820
7420
5540
4400
4410
3550
5010
8770
March 19
Dec 31
Jan 15
May 15
Nov 30
June 9
Feb 20
Oct 16
June 18
June 13
6.37
6.07
4.26
5.50
3.41
2.30
5.47
4.07
2.87
5.31
May .12
April 7
June 12
June 14
July 4
July 20
June 18
July 2
July 9
June 4
6.14
6.02
5.99
5.85
3.57
4.94
4.85
3.42
5.46
4.35
5950
5780
5740
5560
3300
4500
4410
3190
5080
3940
Dec 6
July 18
Jul 30
Nov 19
Jan 1
May 13
May 28
May 5
June 17
Oct 16
5.20
5.50
5.98
5.11
June 6
June 3
May 27
May 16
4.80
7.52
5.91
4.96
4360
8240
5630
4520
Feb 17
July 1
July 4
Feb 1
Page
1
PARAGUAY RIVER
Year
3.99
5.74
2.25
2.43
1.60
2.01
July
June
June
July
June
June
date
1
11
12
12
9
16
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
5.03
1.96
5.25
5.03
2.05
5.24
4.15
4.57
1.92
5.32
June 12
May 28
June 28
June 23
June 13
June 19
July 15
July a
June 26
May 3
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
5.07
4.15
4.64
2.86
4.42
2.64
4.30
4.19
5.01
5.91
June 8
June 26
July 3
July 1
July 14
July a
August 3
July 22
June 25
May 9
1960
1961
1962
1963
1964
1965
1966
1967
Table C.6
ANNUAL MAXIMUM DAILY STAGES
AND DIScHARGEs
Ladario
m
1934
1935
1936
1937
1938
1939
-
4.92
4.34
2.25
4.47
1.33
2.74
2.48
1.63
May 25
June 21
June 10
June 19
April 1
April 8
May 22
April 24
Porto Murtinho
m
date
3.16
6.49
3.94
6.06
5.46
3.98
5.64
5.79
6.04
2.78
5.83
June 6
May 25
April 1
Oct 5
Aug 12
May 25
Aug 24
July 21
May 24
June 19
Auq 13
5.65
4.90
5.49
4.27
4.96
3.66
6.16
5.60
6.20
7.75
Aug 19
March 24
May 26
June 17
June 4
July 12
Sept 21
Aug 10
Oct 1
Aug 5
5.42
6.20
June 29
July 1
2.60
4.80
4.66
3.06
April 17
May 22
April 9
March 14
Page
2
Asuncion
m
m/s
date
May 12
Aug 23
June 21
May 21
Feb 18
June 14
2.87
5.03
5.04
3.52
3.26
4.60
2800
4600
4610
3260
3070
4170
6.36
4.50
5.06
5.07
3.11
3.02
6.50
5.43
1.48
3.61
6260
4080
4630
4640
2970
2900
6470
5040
1910
3330
June 10
April 23
June 22
Nov 28
Jan 1
Sept 13
June 1
June 3
May 3
July 1
4.12
5.27
4.52
4.87
6.38
3.01
6.45
5.45
6.02
5.80
3740
4860
4100
4430
6290
2890
6400
5060
5780
5500
April
22
June 6
June 11
June 6
June 18
July 15
May 17
April 11
oct 23
Oct 17
5.20
6.05
2.28
4.09
4.40
6.77
4.85
2.62
4780
5820
2420
3710
3980
6900
4410
2640
Jan 1
May 20
May 28
June 27
May 2
June 1
Jan 26
April 1
PARAGUAYRIVER
Year
-
Table C.6
ANNUAL MAXIMUM DAILY STAGES AND DISCHARGES
Ladario.
m
1969
1969
2.05
1.80
date
June 6
May 31
1970
1971
1972
1973
1974
1975
1976
1977
1979
1979
2.13
1.11
1.97
2.09
5.46
4.33
4.95
5.52
5.36
6.25
June 16
May 4
May 25
June 19
June 5
June 16
June 22
April 20
May 2
April 1
2.96
2.77
3.18
4.86
6.87
4.98
5.59
6.97
6.41
9.15
1980
1981
1982
1983
1994
1985
1986
1997
1988
1989
6.14
5.46
6.52
5.36
5.07
April
18
May 19
April 21
May 10
June 1
Porto Murtinho
m
date
Jan 30
May 9
Asuncion
m
m/e
2.34
4.50
2450
4080
date
Feb 2
May 12
July 11
May 11
May 12
Dec 31
Aug 15
Aug 13
May 29
July 29
July 20
June 6
1.60
6.35
3.96
3.33
4.98
4.20
3.65
4.74
3.75
7.17
1980
6250
3610
3120
4550
3810
3360
4300
3440
7580
Jan 28
June 17
Jan 8
Feb 8
Dec 14
June 10
Jan 31
May 31
June 14
8.54
6.64
9.71
9.08
5.95
9.20
July 1
July 16
June 29
May 29
July 20
June 7
6.53
4.40
7.76
9.01
5.55
6.95
4.69
5.90
7.65
6.42
6520
3980
8730
11740
5180
7200
4260
5620
8500
6350
July 10
Jan 1
July 29
May 29
May 12
June 7
June 10
June 6
June 10
Sept 25
June 31
5.75
4.73
5430
4290
June 22
July 8
8.55
10530
4.36
3.82
1990
1991
5.49
6.64
1992
5.38
7.90
Page
3
June 1
I
Table C.7
Monthly Precipitation in the ParanafParaguayBasin (mm)
Year
Jan
Feb
Jun
JuL
54.33
53.00
90.25
69.50
65.50
103.75
44.00
70.75
69.75
66.75
63.67
125.33
51.25
114.00
60.25
102.75
28.25
153.50
146.00
128.75
104.68
93.82
162.05
80.80
33.35
76.25
97.38
75.15
73.70
30.40
62.40
72.28
15.28
60.98
99.40
130.32
45.86
66.48
79.70
74.52
49.72
129.22
108.92
70.14
42.02
36.72
114.68
40.10
112.64
132.52
30.00
83.57
52.00
37.33
64.75
135.00
95.75
56.00
69.75
130.75
50.00
68.50
83.67
36.67
30.75
111.75
47.50
82.50
80.25
68.75
61.33
95.75
41.00
76.68
54.25
14.67
29.12
85.95
22.50
66.38
68.12
51.12
26.36
59.24
8.74
15.08
108.08
87.08
54.38
33.92
43.62
225.00
58.34
47.58
53.40
18.50
89.94
79.60
85.52
103.50
37.78
45.22
10.86
43.29
Mar
Apr
91.33
116.33
195.25
99.00
118.75
74.50
111.00
86.50
115.25
121.50
105.50
51.00
171.25
203.00
172.00
46.75
83.25
217.00
107.00
125.25
185.40
109.45
78.57
85.88
39.33
78.57
188.57
129.68
119.97
155.88
96.24
176.16
39.72
107.40
80.56
90.40
168.02
107.20
180.40
178.68
213.62
181.66
111.94
102.86
143.30
207.30
90.12
174.38
212.76
186.82
220.86
142.00
131.33
100.33
92.75
97.00
175.25
109.25
129.00
79.75
88.00
215.00
133.00
136.33
146.67
201.33
281.00
69.00
123.75
122.75
89.33
104.00
105.75
133.45
146.93
104.30
263.80
104.50
101.25
270.15
27.73
93.22
213.36
187.20
73.26
66.04
59.40
146.34
95.12
125.70
89.94
140.34
241.56
104.26
39.06
56.26
64.58
98.62
146.56
163.42
74.66
82.52
45.14
62.71
90.00
81.00
49.75
108.50
263.50
62.75
57.50
119.00
67.25
94.50
113.67
115.33
61.75
127.00
170.25
220.25
36.25
206.00
142.50
104.75
51.10
168.52
146.77
93.25
184.15
129.10
28.20
175.62
71.68
114.40
143.34
103.22
56.62
77.88
33.16
96.28
54.54
128.22
125.86
160.62
135.10
127.36
101.20
29.06
62.76
165.60
176.08
68.78
43.68
116.14
57.29
119.29
150.50
168.67
116.71
196.Q0
163.14
108.43
180.50
137.62
187.41
138.60
100.90
158.90
176.50
124.82
33.31
72.35
131.97
71.71
119.17
128.17
125.09
71.83
229.33
95.33
157.67 101.00
85.43 143.86
80.00
81.00
92.29
72.S7
34.14
110.29
106.75
69.12
74.00
79.25
97.54
92.20
27.61
69.46
69.43
74.45
34.20
64.63
127.87
89.26
70.97
85.63
86.12
30.97
43.U
46.92
54.31
144.36
95.28 99.08
72.00
113.36
98.54
80.77
116.50 118.78
51.67
131.00
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
151.33
198.67
117.00
120.50
96.75
25.25
183.50
122.75
75.75
160.25
156.00
112.67
97.67
142.50
154.50
117.50
8.00
162.50
98.75
214.50
155.45
251.15
160.50
65.97
143.12
223.68
179.82
116.60
185.55
155.77
206.22
133.86
86.32
83.80
118.68
142.68
80.38
218.00
109.08
152.68
150.66
203.16
104.10
101.22
134.74
238.32
177.22
135.56
168.36
216.90
170.57
130.86
118.33
66.67
211.25
90.25
129.00
49.00
86.25
84.00
213.25
191.25
101.25
196.00
104.00
182.00
92.25
144.00
139.75
134.25
143.25
157.50
194.35
117.55
86.57
132.90
83.10
51.92
108.28
142.05
50.05
150.82
126.98
164.52
142.12
165.12
99.96
71.90
102.48
152.76
182.68
141.68
168.34
118.40
121.56
122.58
154.46
202.00
166.10
209.86
94.12
155.54
182.86
238.00
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
175.67
238.33
107.43
253.86
227.29
87.71
165.00
161.00
119.94
151.93
190.62
90.21
168.50
190.33
222.46
213.94
204.63
143.73
204.70
155.91
212.77
183.45
96.17
81.67
171.17 106.00
103.86 216.29
117.14 166.14
70.00
170.43
201.71 121.29
202.25 122.38
69.12
150.75
168.84 200.06
88.69 123.94
142.11 144.19
169.30 179.17
87.28
203.S2
167.94 202.56
218.92 154.96
75.46
105.80
129.00 105.08
138.04 148.81
143.73 200.82
185.27 128.45
114.85 191.08
166.18 143.17
May
26.67
90.83
57.00
137.57
98.57
67.14
66.88
45.12
42.90
24.24
28.49
37.08
86.37
41.43
74.32
46.58
26.93
39.77
91.62
57.08
65.67
33.91
1
Aug
105.67
72.33
127.00
85.75
104.00
64.00
103.50
65.75
34.50
31.50
77.33
52.00
36.67
93.75
90.75
68.00
28.25
23.25
41.00
41.00
56.25
74.03
53.33
21.55
33.12
40.28
27.88
56.00
96.72
118.05
33.52
59.46
26.66
48.48
122.22
73.10
52.80
24.24
74.46
99.40
90.72
66.04
24.82
33.56
23.78
42.46
54.80
41.00
30.10
15.70
21.29
33.29
29.83
30.50
36.43
50.57
79.71
35.71
62.50
92.75
33.26
35.56
20.49
8.86
65.61
40.38
39.70
87.56
12.93
48.63
39.00
106.38
88.82
86.10
Sep
Oct
Nov
73.00
81.33
45.75
141.75
108.00
71.75
104.75
76.25
97.25
103.33
141.00
65.67
103.50
77.75
73.25
66.25
127.00
71.75
37.00
140.00
189.05
89.03
80.40
75.47
140.80
99.90
95.22
219.90
163.75
50.88
52.80
98.46
60.60
74.56
117.16
83.76
93.02
66.32
143.72
66.98
120.10
83.16
54.46
49.52
95.54
86.88
132.64
101.30
75.38
85.64
49.14
92.14
99.67
137.00
194.00
204.25
274.50
75.25
112.00
198.50
80.75
61.00
108.33
76.67
166.25
224.50
137.00
59.50
104.00
124.25
176.00
118.25
153.80
108.00
171.80
33.53
182.30
99.12
109.70
211.25
183.32
124.68
187.54
149.42
164.02
81.86
165.82
108.16
87.40
116.40
202.48
98.02
51.22
88.70
112.06
116.84
108.76
176.30
95.32
123.18
88.04
116.92
160.86
143.43
137.33
212.33
84.75
119.25
151.00
76.50
129.75
119.00
68.75
104.00
213.33
159.33
133.25
189.50
69.25
72.50
44.75
216.00
205.00
136.67
49.75
97.57
102.43
119.35
196.43
185.10
215.45
97.40
102.22
106.20
79.12
167.88
63.16
119.58
172.56
66.20
176.98
103.76
193.78
147.80
197.16
59.98
142.12
102.28
125.32
161.36
41.06
162.66
121.26
145.06
132.43
157.00
136.83
121.00
21.86
57.86
163.29
119.71
75.62
72.00
104.53
94.62
89.21
88.13
94.13
49.02
40.76
72.12
93.21
159.74
50.92
87.58
64.42
32.27
201.00
237.17
104.71
197.71
144.14
103.14
147.25
206.62
158.90
134.09
95.40
70.30
230.91
160.73
97.90
164.73
200.61
130.76
96.83
138.33
169.00
148.18
140.83
32.67
68.57
42.00
116.00
238.71
119.00
174.00
223.21
96.11
182.79
119.46
133.69
107.02
100.08
82.72
212.14
93.90
78.75
257.40
125.73
119.73
Dec
67.33
240.67
280.25
147.75
148.00
115.00
231.00
228.25
109.00
69.67
230.67
154.00
68.50
133.50
143.75
139.50
94.00
197.50
134.00
186.50
105.85
100.78
228.35
71.25
112.65
148.50
111.32
104.75
131.25
178.15
166.56
124.66
143.54
137.98
226.50
125.58
81.62
93.92
175.00
152.74
141.90
84.36
110.48
64.84
132.20
180.52
66.18
52.06
196.54
179.28
131.14
67.17
116.83
133.83
152.14
96.57
169.00
271.14
172.75
135.75
136.17
116.72
125.65
177.30
281.30
158.90
99.59
165.61
73.99
162.02
99.64
145.25
247.45
155.Q0
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
95.50
202.21
255.80
127.00
123.93
149.57
180.64
72.29
252.64
203.33
66.29
111.69
109.54
89.60
103.80
136.71
122.00
155.40
195.50
178.80
100.27
148.54
194.54
128.20
137.47
73.43
78.00
126.00
117.47
145.83
189.20
196.20
163.36
184.15
131.73
68.80
32.67
139.14
95.23
109.33
80.13
225.13
110.53
137.10
32.42
119.27
81.29
67.91
129.85
134.36
60.08
79.33
268.20
104.20
115.53
84.38
35.87
64.64
33.21
23.92
58.14
73.47
165.21
72.29
52.71
30.57
69.62
26.14
42.29
63.50
57.00
33.60
13.71
57.62
94.27
11.93
89.64
61.54
64.29
50.36
50.50
90.29
68.73
43.40
94.00
10.27
60.13
57.86
1987
1988
1989
1990
1991
1992
195.86
139.54
227.50
220.21
157.18
118.78
179.00
104.17
139.69
111.50
109.89
279.00
96.86
128.38
178.92
163.00
138.00
186.83
162.92
145.92
142.08
256.08
144.15
207.00
135.86
84.50
34.69
138.43
122.83
174.80
85.00
28.42
80.85
87.31
99.71
54.12
82.15
8.83
53.25
72.82
26.22
42.00
39.77
12.23
106.70
84.64
19.17
100.38
1986 141.23 151.08 237.69 193.62 174.07
44.09
2
37.92
61.00
84.85 145.36
101.00 178.23
51.21
67.23
99.50 140.00
125.64 152.36
117.40 134.00
40.86 105.27
99.79 151.29
98.87 144.67
92.27 103.93
71.67
63.31
202.00
107.75
234.58
158.29
155.93
179.07
164.14
340.93
162.07
222.4
78.60
175.54
1K4.29
138.50
144.67
252.77
154.27
186.29
209.29
110.80
182.53
86.50
38.00
54.50
86.42
142.17
94.10
-1.00
149.00
97.83
102.71
136.69
129.82
-1.00
164.92
163.55
147.31
153.31
250.00
-1.00
88.93 125.21 175.07 170.82
129.83
119.15
130.93
142.85
98.00
-1.00