Alfredini, P.

Arasaki, E.

Pezzoli, Alessandro

Rosso, M.

English

PORTO Publications Open Repository TOrino

1 INTRODUCTION 
The Juqueriquerê Catchment is the major in São 
Paulo State (Brazil) North Coastline (Fig. 1). The 
Juqueriquerê Waterway is a 4 km estuarine channel 
used by small piers and docks. The entrance bar 
doesn’t have any amelioration works and the boats 
maneuvers are difficult and dangerous. Beyond envi-
ronmental impacts, the cost - effective improve-
ments consists to bar jetties calibration, this solution 
means to talk about costs of 5 M €, or the permanent 
maintenance with local dredging works, which costs, 
in the long term of decades, will be the same. 
According to the IPCC forecasting, there is the 
awareness that conditions of bathymetry, tides, 
winds, currents and waves for next decades shall 
have climate changes impacts. The project goal is to 
overcome the contraposition that it emerges between 
the defence against the hydraulic risk and the man-
agement to preserve the environmental protection 
for nautical purposes. The risk is understood, in a 
qualitative way, as composed by Hazard, Exposure 
and Vulnerability (Kron 2008). 
2 SOME HISTORY 
Example of navigation possibilities in the waterway 
was the dock operation of the English Lancashire 
General Investments Company, owner of the Blue 
Star Line Navigation Company. In the period 1927 - 
1967, the “Fazenda dos Ingleses” (English Farm), 
has sent the tropical fruits production to England. 
The railway line of the farm had 120 km, with docks 
and warehouses in the right bank of the estuary. The 
Packing House, in the dock area, was considered the 
second of this type in South America. The cargo 
boats, more than 20 in the forties decade, had an in-
dividual load of 55 dwt (Fig. 2). In March 1967, a 
strong debris-flow, rain more than 600 mm in 2 days 
(monsoonal rates), combined with storm surge, 
caused  more than 400 casualties and material losses 
in Caraguatatuba. After that, the docks were closed 
(Arasaki 2010). 
In the last four decades, the nautical purposes of 
leisure and fishing boats increased. It is important to 
mention the recent interest as supplier area for the 
offshore LNG and oil. The plant for the gas treat-
ment is located in the left bank of the river and many 
of the facility heavy cargo equipments used large 
barges push-pulled by tugs (Fig. 3). 
3 TIDE VARIABILITY 
Considering the CDS (Companhia Docas de Santos) 
datum, extreme LLW level, in Figure 4 are present-
ed our study conclusions about São Paulo State 
coastline tidal variability for the last six decades 
(1944 - 2007). A consistent linear response shows: 
1. Overall period: rising rates (cm/century) for MSL 
(23.2), HHW (36.5) and LLW (41.8); 2. Period be-
fore 1969: 1.1, - 7.3 and 54.3 and 3. Period after 
1975: 40.9, 44.9 and 75.4. 
Coastal Area Prone to Extreme Flood and Erosion Events Induced by 
Climate Changes: Study Case of Juqueriquere River Bar Navigation, 
Caraguatatuba (Sao Paulo State), Brazil 
E. Arasaki 
Escola Politécnica da USP, Sao Paulo, Brazil;Instituto Nacional de Pesquisas Espaciais, S.J.Campos, Brazil 
P. Alfredini 
Escola Politécnica da USP, Sao Paulo, Brazil; Instituto Mauá de Tecnologia, Sao Caetano do Sul, Brazil 
A. Pezzoli & M. Rosso 
Politecnico di Torino, Turin, Italy 
ABSTRACT: According to the IPCC, the forecast for the year 2100 is an increasing of global average tem-
perature, whose impacts in winds, waves, tides, currents and bathymetry will produce real risks of extreme 
events due to climate changes. Juqueriquere River is Sao Paulo State (Brazil) North Coastline major water-
way. Due to minimum channel depths in the coastal bar, navigation is only possible for small leisure crafts 
and fishing boats and some cargo barges during higher tidal levels. This study case has been evaluated ac-
cording to the relative sea level and wave climate scenarios forecasting, based on the meteorological recogni-
tion patterns of the last decades data for tides and waves. The impact of climate changes is obtained from this 
knowledge. The main goal of this paper is to have the initial conceptual description about the impacts on the 
bar navigation conditions of Juqueriquere to obtain guidelines for master nautical plans. 
Human Resources and Crew Resource Management – Marine Navigation and Safety of Sea Transportation – Weintrit & Neumann (ed.)
 
Figure 1. Location map with significant height and average period local wave roses. 
 
 
 
Figure 2.  Boats moored at the quay, dockyards warehouses and railway terminal (1940 decade) of the English Farm. 
 
 
 
Figure 3.Heavy cargo equipments using large barges push-pulled by tugs (February 2010). 
 
 
 
 
Figure 4. Annual tidal levels variability (1944 – 2007) for São Paulo State (Brazil) coastline. 
 
4 FLUVIAL MORPHOLOGY 
The Juqueriquerê Catchment has the following main 
features: area of 430 km2, long term average dis-
charge of 11 m3/s, heavy rainfall rates (around 3000 
mm/year) producing high fluvial sediment transport, 
floods and debris-flows. The last ones are due to the 
steep slopes and the altitude (~ 1000 m) of the Serra 
do Mar mountains near the coast, producing the oro-
graphic effect, which rapidly condensates the sea 
humidity.  
The fluvial dynamics is of high solid transport 
capacity and fluvial and coastal morphology trans-
formations, combined with recurrent and intense 
flood events that cause extensive risks and damages 
to population and infrastructures, causing riparian 
and coastal region with important anthropic impact. 
Strong debris-flows occur in this region, because 
events similar to monsoonal rain rates (higher than 
300-400 mm per day) occur in multi decadal peri-
ods. The region history records shows this type of 
strong events in 1859, 1919, 1944 and the last and 
more catastrophic in March 1967, Figure 5 shows 
the damage caused in the English Farm dock yard, 
warehouses and Packing House (Arasaki, 2010).  
5 WAVE CLIMATE 
According to Marquez & Alfredini (2010), the off-
shore climate may be described by the ECMWF – 
European Centre for Medium-Range Weather Fore-
cast – ERAS40 project. In Figure 6 are presented the 
Hs, significant wave height, and Tz, average period, 
for the nearest grid point 1958 -   2001 data series. 
The local wave climate may be described by the Hs 
and Tz roses in Figure 1, obtained from the coastal 
buoy data records survey of São Paulo State coast-
line (1982 - 1984) treated with the DHI software 
MIKE 21 NSW (Nearshore Waves). 
6 COASTAL SEDIMENTS AND 
MORPHOLOGY 
In general, sediment’s samples near the bar show 
dominance of material like fine sand, silt and clay. 
According to Venturini (2007), the grain size pro-
portion of clay and silt in the first 2.0 m from the 
bottom surface were 15 to 20% and 35 to 55%, re-
spectively.  
The waterway is strongly restricted by the mari-
time bar depth, 0.3 - 0.5 m according to Chart Da-
tum (MLWS) with MSL (Z0) of 0.7 m, and the en-
trance is instable, with seasonal migration. Indeed, 
according to Bruun (1978) criteria for overall stabil-
ity, the preliminary evaluation of Ω/Mtot, ratio of the 
spring tidal prism per total littoral drift, is 5 to 10. 
The Ω is of the order of 1.0 Mm3, including river 
discharge, and Mtot, based on local breaking wave 
climate, is around of 0.1 Mm3/year. For ratios less 
than 20, there are comprehensive bars with very 
shallow depth, being typical bar-bypassers, and in 
this case depending upon the strong flushing during 
the rainy season. 
The morphological behavior of the bar is being 
studied based on seasonal thalweg bathymetrical 
surveys (Fig. 7) correlated with meteorological con-
ditions corresponding to the three months before ac-
cumulated rain: April 2004: 382 mm; March 2009: 
688 mm; September 2009: 313 mm; February 2010: 
634 mm and September 2010: 463 mm. Wave cli-
mate is also considered. 
7 CONCLUSIONS 
Considering the awareness about the importance of 
climate changes impacts in a coastal area prone to 
extreme flood and erosion events, important issues 
to support confidence, or not, to the decision of con-
struct two jetties (rigid structures) solution, mainte-
nance dredging (flexible solution), or non interven-
tion in the waterway are:  
− 1. There is an overall sea level rising trend, which 
matches with the IPCC forecasting; 2. LLW has 
the highest rate of linear tidal rising (75 
cm/century); 3. There is an overall tidal range re-
duction; 4. The tidal prism will change, and the 
tidal currents velocity should increase, if the 
HHW levels will drown large fluvial areas, com-
pensating the velocity reduction due to the tidal 
range decreasing; 5. Considering the issues 
above, the river bar depth should increase and 6. 
The overall rise of the sea will produce more 
coastal erosion and littoral drift, in opposition to 
the outcome of issue 5. 
− It is possible to observe a general significant 
height and average period wave increasing for 
annual averaged figures over than 1.5 m and 8.0 
s, and the corresponding decadal maximum wave, 
from 3.9 m and 13.0 s in the sixties to 4.5 m and 
14.5 s in the nineties. It means increasing swell. 
Hence, should be a trend to increase littoral drift, 
reducing bar depth. 
− There are some areas of mud, which may be fluid 
sufficient to consider the nautical bottom concept 
(PIANC et al. 1997), in practice for mud density 
lower than 1250 kg/m3. In these cases it is possi-
ble to reduce the under keel clearance. The analy-
sis of September 2010 and March 2011 survey, 
with detailed samples of the bar and bathymetry, 
should provide confidence for this answer. 
− About the thalweg shifting migration, it is  possi-
ble to conclude: 1. Like for the monsoon weather, 
the main channel alignment depends upon flood 
periods, according to rain rate of; 2. The shifting 
between two adjacent thalwegs may be produced 
by extreme river flow conditions, or a storm 
surge. 
−  
Awareness with climate changes impacts im-
portance for the intervention’s plan must be consid-
ered to obtain a final balanced solution among struc-
tures, dredging and non structural measures for 
nautical master plan. 
It is important to recognize that great natural 
events are not avoidable, but great disasters are, as 
the ancient Greek Aristotle (384-322 B.C.) said, “It 
is probable that the improbable will happen” (Kron 
2008). Unfortunately, closing this paper, we have to 
recognize this historical truth: in January 2011,  a 
very large debris-flow phenomena (more than 600 
mm rain rate in two days) in the Serra do Mar moun-
tains of Rio de Janeiro State (Brazil), which border 
São Paulo State, killed more than 700 people, being 
considered by the ONU the eighth of this type since 
1900. 
We want to provide an intervention’s plan for 
Juqueriquerê Waterway for the next 50 years about 
geomorphologic, structural and no-structural hydrau-
lic shape in reference to: 1. Plani-altimetric histori-
cal evolution analysis of the coastal thalweg, validat-
ing migration model considering wave climate, tides 
and fluvial discharges; 2. Morphological analysis of 
bankfull, floodplains and perifluvial areas; 3. Grain 
size analysis of transported sediments; 4. Meteoro-
logical and oceanographic analysis (Pezzoli et al. 
2004a and 2004b; Cristofori et al. 2004) 5. Hydrau-
lic analysis by using software HEC_RAS of US Ar-
my Corps of Engineers. After, we want to draft a 
maintenance plan for Juqueriquerê Waterway reck-
oning on the basis: 1. Ordinary maintenance isn’t re-
placeable with structures; 2. Maintenance actions 
must be specific, pointed and planned; 3. Mainte-
nance works must be well-according with landscape 
and with the ecosystem. 
 
 
Figure 5. Destruction in the dock area and Packing House of 
English Farm after the debris flow of March 1967. 
 
 
 
Figure 6.  Deep water  wave data series of Hs and Tz (1958 – 2001). 
 
 
 
Figure 7.  Entrance channel thalweg in rainy (April 2004, March 2009, February 2010)  and dry (September 2009 and 2010) sea-
sons. 
 
8 ACKNOWLEDGEMENTS 
This paper has the financial support of CAPES, Hu-
man Resources Improvement Agency of Brazilian 
Government. The authors also want to thank the 
support of São Paulo University, Politecnico di 
Torino, Instituto Nacional de Pesquisas Espaciais, 
Instituto Técnico da Aeronáutica, Instituto Mauá de 
Tecnologia.  
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Coastal Area Prone to Extreme Flood and Erosion Events Induced by Climate Changes: Study Case of Juqueriquere River Bar Navigation, Caraguatatuba (Sao Paulo State), Brazil

Coastal Area Prone to Extreme Flood and Erosion Events Induced by Climate Changes: Study Case of Juqueriquere River Bar Navigation, Caraguatatuba (Sao Paulo State), Brazil

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