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Study
Sites
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Santos Estuary
Site description
Watershed
Hydrography
Urban and industrial sources
Agriculture data
Estuary
Stakeholders
Data campaigns
Sampling strategy/methodologies
Monitored parameters
Preliminary results
Hydrographic features
Nutrients
Dissolved oxygen
Phytoplankton
Conceptual model
Based on collected data
Modelling applications
Modelling strategy
Preliminary results
Scenarios
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Site
description |
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Located at the Southern Brazilian Coast,
the estuarine system of Santos comprises
3 major estuarine channels, namely São
Vicente, Santos and Bertioga,
interconnected in its inner area. Santos
and São Vicente channels comprise an
approximate area of 44,100 m2, with an
average depth of 15 meters in the
central dredged channel of Santos and 8
meters in São Vicente channel.
The Santos Estuary, in
Brazil, is a highly changed ecosystem,
after 500 years of urban, industrial and
port use (it’s the biggest port in Latin
America). It has extensive areas of
mangrove, partially degraded.
Nevertheless, there are still some well
preserved areas and the region is an
important tourism area for the
population of São Paulo. It is located
at latitude of about 24º S. Santos is a
major port and tourism area, located
downstream from Sao Paulo (a city of 15
million people) and Cubatao, major
industrial area. The Santos Estuary used
to receive raw sewage from Sao Paulo and
industrial and hydroelectric powerplant
discharges from Cubatão. High levels of
oxygen-demanding substances, phenols,
metals (e. g., copper and zinc), and
pesticides have been detected in the
water, and metals and pesticides have
been found in sediments.
A lot of research has been done in the
past in this estuarine area, some of it
by teams participating in this project,
but all dealing with partial aspects of
the ecosystem. An integrated approach is
much needed to support local definition
of sustainable development strategies,
based on the data already available.
Some decisions concerning port
development and restoration of mangrove
areas have to be taken by local
stakeholders of the system. Stakeholders
have shown their interest towards the
project including local government,
university and educational system,
industrial and harbour consortiums and
NGOs (environmental protection).
Aerial photography of
Santos where the high levels of men
occupation is evident. Slum quarters
amount for a great percentage of this
occupation.
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Watershed |
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Hydrography
Six main rivers discharge in santos
estuary: Piaçabuçu, Boturoca, Cubatão,
Mogi, Quilombo e Jurubatuba. The areas
of São Vicente Island, Santo Amaro
Island and Cabuçu have many small rivers,
and also artificial channels, which
drain rainfall in those areas. These
artificial channels make the collection
of rain drainage water and the
clandestine domestic waste.
The high rainfall in
the summer period is characteristic to
this region which is dominated by a
tropical and subtropical climate.
Average annual values of rainfall in the
area are mainly between 2500 mm and 3000
mm.
Three types of land cover dominate
around Santos Estuary: i) Mata atlantica
ii) Urban area and iii) Mangroves.
Watersheds like Quilombo and Jurubatuba
are mainly occupied with natural
landscapes with “Mata Atlantica” and
Mangroves, while for example São Vicent
Island is mainly urban area. In terms of
municipalities, urban areas and natural
areas seem uniformly distributed.
Santos
model domain bathymetry and main rivers
around
Land
cover around Santos estuary
Urban and industrial
sources
The Baixada Santista region is, at the
same time, a turistic, industrial and
port center. The main beaches are
located at São Vicente and Santos cities
with the most important port of Latin
America in the latter. Cubatão city has
a remarkable industrial pole with some
kinds of industries mainly those linked
to the petroleum products, fertilizer
production and very remarkable steel
production. Some kinds of hazardous
compounds are dispensed into this
estuarine system such as nutrient salts,
heavy metals, organic compounds,
petroleum hydrocarbons.
Main municipalities in Santos estuary
area.
The main sources of
pollution at this region are: (a) the
Billings water reservoir which receives
used water from some parts of São Paulo
City (the second most populated city in
the world), this water crosses the
Cubatão hydroelectric system and flows
into the Cubatão river; (b) the Santos
port and ships which are involved in the
spillage and loss of shipped products
and sanitary installations discharge;
(c) the industrial pole of Cubatão; (d)
the domestic waste of São Vicente and
Santos cities (which are mainly
discharged through an emissary) and (e)
the garbage dump of the Baixada Santista
region. These pressures in the
estuary will have impacts not only in
the estuary but also in Santos Bay and
adjacent beaches: Praia Grande e Guarujá.
The main sources of pollution are mainly
industrial sources. The discharge of
domestic waste waters are scattered, due
to the existence of only 3 WWTP.
Industry point
Sources close to Santos Estuary (CETESB)
The industrial
activity is the most important for the
economy of the region, generating in
2000, 49,03 % of the aggregated value.
The most relevant industrial
sectors are those of petroleum and
alcohol refinetion, chemical
manufacturing and basic ironworks, that
together account for almost 90% of the
aggregated value of the regional
industry. The city of Cubatão has one of
the greatest and most important
industrial centers in the country, made
up by 24 large industries and efficient
logistics in reception of raw materials
and production outlet, due to its
location and a port terminal.
The city of Santos is mainly connected
to the port activities and tourism.
The cities of São Vicente, Praia
Grande and Guarujá too stand out in the
sector of services connected with
tourism, with segments turned to leisure
and culture, lodging, food and real
state market. Guarujá, besides tourism,
has in commerce and in the port and
important employment generator. Cubatão
is the only one of the five cities that
has no activity turned to tourism.
Instead, existing services in Cubatão
are structured to support the industries
and the port that exist in the city.
Santos, Cubatão
and S. Vicente cities and adjoining
region have around 1 000 000 inhabitants
and in the vacation period, this number
is almost doubled. In the case of
Santos, population increases only by
32.5% during summer.
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Discharge of water contaminated with
urban waste waters
ETE – WWTP
(Waste Water Treatment Plants)
Urban Sources (Lamparelli
et al. 2001 - CETESB)
Agriculture data
The presence of any agriculture can only
be inferred from census data relating to
urban vs rural population. In fact since
1940 rural population has decrease in
most municipalities. For example In
Cubatão municipality this population has
decrease from 70% to 0.5% in the present
day. Assuming that rural population is
associated with agriculture, one can
infer that this activity as decreased in
the same proportion.
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Estuary |
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The Santos and São Vicente estuary area,
being among the most studied estuaries
of the Brazilian coast, still lacks
proper ecologic research works.
Convincing answers are missing for some
important questions about the primary
producers and benthos communities. The
estuarine system has a considerable
ecological importance because it has a
natural high productivity and is a
natural habitat for many animals like
birds, mammals, fish and numerous kinds
of invertebrates.
Santos and São Vicente estuarine system
is surrounded by mangrove forests and
therefore this ecosystem can be the most
important organic matter producer. The
majority of works done so far refers to
the Bertioga channel area, mainly oil
spills stressed areas. The portion of
the estuary near to the Cubatão and São
Vicente cities was practically not
studied. With the available data it is
not possible to determine the
contribution of the mangrove forest to
the estuary production, nor to
characterize its fitosociology in the
entire region.
Beyond mangrove
forests in the estuarine system of
Santos and São Vicente, there are others
primary producers like the phytoplankton.
Recent studies show that in general
these organisms aren’t in good
physiological conditions inside the
estuary, showing that this group
probably isn’t the main local primary
producer (Moser 2002). Other important
primary producers in the region are the
seaweeds, conspicuous in many areas in
the soft substratum of mangrove forests.
Another important primary producer is
Spartina spp, which occupy many
mangrove fringe areas.
Estuaries have unique characteristics
associated to drainage waters
from rivers, sewage and the entering of
salt water influenced by tide
variations. In summer period, the
estuarine system of Santos and São
Vicente are characterized by more stable
water column stratification, because of
the major contribution of fresh water
and high intensity of solar radiation.
During winter, the water column is more
homogeneous because of cold fronts which
provide higher mixture of water masses.
The average temperature of water can
vary from 27 to 29oC during
summer and between 18 and 19oC
during winter. Due to salinity, in
summer less salinity was observed with
progressive increase till spring varying
between 20 and 36.
Bathymetry of Santos
estuary and bay area
(source:Instituto
Oceanografico Brazileiro)
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Stakeholders |
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CETESB – Technology
and Environment Sanitation Comp
345, Professor Frederico Hermann Jr.
Av Alto de Pinheiros - São Paulo – SP -
05459-900
Profile/Activities
• To promote the improvement and to guarantee the quality of the
Environment in the State of São Paulo,
aiming the sustainable social and
economic development.
• Responsible for the control,
monitoring and licensing of pollution
generating activities, with the basic
concern to preserve and to recuperate
the quality of waters, air and land.
• It is the controlling agency of the
activities that can harm the environment.
SABESP - Basic Sanitation of São Paulo
128, São Francisco
Av. Santos/Sp – 11045-410
Profile/Activities
• Preservation of sources, rivers,
barrages and water capitation.
• Collecting and treating of sewer.
• It establishes quality control of
Water and launchings of sewer, directly
responsible for the depleted and not
depleted areas of the estuary of Santos.
IBAMA - Brazilian Institute of the
Environment and the Natural resources
SCEN Trecho 2 - Ed. Sede - Cx. Postal nº
09870 - CEP 70818-900 - Brasília-DF
Profile/Activities
• Targets to guarantee that the natural
resources of the country are explored
rationally, in accordance with the norms
and regulations established for its
sustainability, aiming to diminish the
predatory action of the man on nature.
• Control of the Environment possesses
in 3 institutional spheres: municipal or
district, state and federal.
DPRN - State Dept of Protection of
the Natural Resources
36, Itororó St. - Santos/SP
Profile/Activities
• Agency of the Secretariat of the
Environment of the State of São Paulo,
tied with the Coordination of
Environment Licensing and Protection of
Natural
• Resources-CPRN Responsible for the
licensing of the activities and works
that implies in the suppression of
native vegetation, cut of native trees,
intervention in areas of permanent
preservation and handling of the wild
fauna.
COSIPA - São Paulo Siderurgical
Company
Km 06, Piacaguera Road,- Cubatão / SP
Profile/Activities
• The thick Cosipa plates are used in
many sectors of application, as
industrial machines, pipes of great
diameter, wagons, boilers, pressure
vases, reservoirs, medium and heavy
profiles, oil platforms, agricultural
implements, road and railroad equipment,
naval industry and civil construction.
• Known as one of the great polluters of
the estuary of Santos.
FISHING INSTITUTE OF SANTOS
192, Bartolomeu de Gusmão Av. - Santos/Sp
Profile/Activities
• The basic function of the Museum of
the Fishing Institute is to develop
scientific-cultural actions, making the
community acquire knowledge of the
importance of the preservation and
rational use of the aquatic environment.
PRODESAN - Progress and
Development of Santos
10, Expedicionários Sq. - Santos/Sp
Profile/Activities
• Caring for the necessities of the new
times, it is an operating company in
public services, beating records of
asphalt mass production with the
development of new technologies, giving
computer services, fiscalizing the
services of urban cleaning, executing
public works and services of engineering
and elaborating diverse projects in the
city.
• Management, fiscalization, execution,
projects and studies, expedient and
archive.
SMA - Secretariat of Environment
of the State of São Paulo
Profile/Activities
• Functional structure to manage the
environment reality of the State of São
Paulo. For each environmental question,
the Secretariat has mechanisms of
interaction with that specific reality.
AGEM - Metropolitan Agency of the
Santos Region
Joaquin Távora St, Santos/Sp
Profile/Activities
• To integrate the organization, the
planning and the execution of the public
offices of common interest in the
Metropolitan region of Santos.
• They elaborated the Metropolitan
Cartographic System, with maps, aerial
photos and digitalized, very important
for the Ecomanage project.
CODESP - Harbor Company of the
State of São Paulo - Supervision of
Quality, Environment and Normalization
32, Esmeraldo Soares Tarquínio De Campos
Filho Av.
PO 11015-250, Macuco, Santos - SP
Profile/Activities
• Control of the Dredging and the
launching area of the Port.
• Selective garbage collection, control
of dengue fever, pigeon Control.
• Codesp forbids any type of ousting,
including the ballast water, on wharf
and piers and monitorates the marine
environment.
• Control and removal of bees.
• Controls scenes of accidents in the
port of Santos.
City departments of Environment –
Santos, Cubatão, São Vicente and Praia
Grande.
SEMAN - Santos
10, Expedicionários Sq, 5th and 6th
floors
Gonzaga - Santos/SP
Profile/Activities
• Promotes events and action of
education and environmental awareness in
the scope of the public administration
• Organizes and participates of the
Campaign "Clean Summer."
• Fiscalizes the removal of sand from
the beaches.
• Laboratory of Environment Control -
Control of the water quality of Beaches
Besides answering for the analysis of
the conditions of water quality of
Santos beaches.
SEMAM – Cubatão
Km 60, Anchieta Road, Parque Cotia-Pará
- Cubatão/SP
Profile/Activities
• Defines the municipal politics of
environment, in accordance with the
principles of the sustainable
development, with approval of the City
council of Environment - COMDEMA;
• Elaborates the relative proposal of
Environment Code of the City and other
norms to the environment; - to integrate
the National System of Environment (SISNAMA)
and the State System of Environment
aiming the activation of the defense
actions of the environment quality in
the city;
• Articulates municipal and
intermunicipal plans and actions of
environment interest;
• Proposes national and international
accords of technical-scientific
cooperation with agencies and entities
with environment performance,
objectifying action in the environment
field and the formation of specialized
technical staff;
• Promots events and actions of
education and environmental awareness in
the scope of the public administration
in a way to extend the penetration of
the environmental parameters in the
scope of public school education or the
complementary education in a way to
enable the population to the exercise of
the citizenship;
SEMAN – São Vicente
384, Frei Gaspar St. - São Vicente/Sp
Profile/Activities
• Elaboration and Popular Project for
the construction of low income housing;
• Agreement of City hall x Association
of architects and engineers of São
Vicente for responsible technician in
popular constructions;
• Projects to gather resources from the
Federal Government for incentive of
Civil Construction and City Managing
Plan;
SEOP – Praia Grande
9000, Presidente Kennedy Av - Praia
Grande/SP
Profile/Activities
• To follow, to fiscalize the execution
and to receive the workmanships of
public nature, and also, to elaborate
the licitation bases and the practical
of the remaining necessary acts, until
the end of the procedure, pertinent city
works, services, purchases, alienations
and locations regarding this secretariat.
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Data
campaigns |
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Sampling
strategy/methodologies
The run up of the literature concerning Santos Estuarine System revealed
an important lack of information on the
hydrological and ecological
characteristics especially related to
the first level of the food web (in
water column as well as in the mangrove
area). Consequently, it became clear the
necessity of driven efforts to the
acquisition of complementary field data
in order to allow the better adjustment
of the MOHID model.
The main objectives of the field
campaigns for water column data were:
Identify the main forcing agents on
phytoplankton biomass distribution and
productivity in the estuarine area
Identify the critical eutrophication
areas in the estuarine system through
the evaluation of spatial distribution
and seasonal variation ranges of the
dissolved nutrients, phytoplankton
biomass, primary productivity and
heterotrophy/autotrophy ratio. Quantify
the contribution of the phytoplankton
compartment to the carbon cycle into the
system. Quantify the contribution of
other natural components (zooplankton,
mangrove and microphytobenthos) to the
organic matter available in the system.
Considering that Santos estuarine
system is located in a tropical region,
two field campaigns were established:
one in summer and another in winter.
This area is characterized by high
rainfall along the whole year, being
more intense during summertime (around
three times from those in the winter
period. The samplings were conducted
during neap tides in order to minimize
differences between high and low tide
along the sampling period. Also, in neap
tide the stratification is more
conspicuous, favoring the identification
between the estuarine water and marine
water. To characterize the different
portions of the estuarine system, 8
sampling stations were chosen in a joint
meeting with researchers responsible for
plankton, benthos and toxicology. The
decision took into account the
identification of some critical points
along the estuary and the optimization
of the field work efforts.
Santos
estuarine system (Southeast Brazil) and
the location of the 8 sampling stations
visited in winter (August 2005) and
summer (March 2006):1- Santos channel
inlet; 2- Santos channel; 3- Barnabé
Is.; 4- Piaçaguera Is.; 5- Piaçaguera
channel; 6- Pompeba bight; 7- São
Vicente channel; 8- São Vicente inlet.
Monitored parameters
Physical parameters: Temperature,
salinity and density
Chemical parameters:
Nitrate, ammonia and phosphate
concentrations.
pH, Alkalinity
Oxygen and carbon dioxide (dissolved and
saturation)
Biological parameters:
Chlorophyll a (phytoplankton)
Total carotenes (phytoplankton)
Mangrove litter production and species
composition
Microbiological parameters:
Total and faecal coliforms
Sediment:
Organic matter (isotopic composition)
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Preliminary
results |
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Results will are
presented by the mean value computed for
the 3 sampling depths of water column at
each station. Stations are represented
according to the spatial sequence in the
map: from São Vicente channel inlet (st.
8) to Santos channel inlet (st. 1).
Hydrographic features
Water temperature in summer was around
6ºC higher than in the winter. The
vertical variation was low (see the
small SD), mainly in summer. Lower
temperature was generally found in the
inner stations (4 and 5). Salinity was
around 10 units lower during summer than
in the winter due to the high rainfall
events increasing the freshwater
contributions in the upper reaches (st.
5). As a result of high temperatures and
low salinities, water density in summer
was much lower than the winter ones. SD
bars indicate higher water column
stratification during winter. The
euphotic zone reached the bottom layer
in the majority of the stations in
summer. During winter low light
penetration was observed in São Vicente
channel.
Mean seawater
temperature (ºC) at the 8 stations along
the Santos estuarine system in winter
(Aug/05) and summer (March/06). Bars
represent the standard deviation.
Mean seawater salinity at the 8 stations
along the Santos estuarine system in
winter (Aug/05) and summer (March/06).
Bars represent the standard deviation.
Euphotic zone
thickness (m) at the 8 stations along
the Santos estuarine system in winter
(Aug/05) and summer (March/06).
Nutrients
Ammonium was the main inorganic nitrogen
form in both sampling periods (around
90% of the total dissolved inorganic
nitrogen). Its distribution pattern was
clearly associated to the estuarine
water, especially by the superficial
plume. In that way, the concentrations
observed in summer were higher than
those detected in winter due to the
increase of the land run off.
Silicate concentrations were also
greater in summer than the winter ones.
The maximum values occurred in the inner
stations indicating that the source of
this nutrient is the brackish waters.
Mean values of ammonium (mM)
at the 8 stations along the Santos
estuarine system in winter (Aug/05) and
summer (March/06). Bars represent the
standard deviation.
Mean values of
total dissolved nitrogen concentrations
at the 8 stations along the Santos
estuarine system in winter (Aug/05) and
summer (March/06). Bars represent the
standard deviation.
Mean
values of silicate (mM) at the 8
stations along the Santos estuarine
system in winter (Aug/05) and summer
(March/06). Bars represent the standard
deviation.
Inorganic phosphate concentrations
therefore tended to be higher during the
winter period and, except for st. 5 in
summer, inner stations presented always
higher values than the observed at
channels inlets, indicating that estuary
is an important phosphate source to bay
waters along the entire year.
Despite of the high DIN concentrations
verified in both periods, the N:P ratios
(Redfield, 1934) indicate disthrophic
conditions once the relative phosphate
concentrations resulted in a N:P ratio
always bellow 10.
Dissolved oxygen
Dissolved oxygen mean
concentrations and saturation percentage
were higher during the winter. DO levels
were always smaller in brackish waters
tending to increase towards the channel
mouths. Even during the summer values
were above the recommended minimum
limit. Over saturation were observed
only at the channel inlets.
 Mean
values of OD saturation (%) at the 8
stations along the Santos estuarine
system in winter (Aug/05) and summer
(March/06). Bars represent the standard
deviation.
Phytoplankton
Phytoplankton biomass, represented by
Chl-a concentration was slightly more
elevated during winter. Maxima were not
clearly associated to the inner regions.
Strong stratification was observed at
São Vicente Channel and the inner
regions, mainly during winter period,
following density stratification.
The maximum
primary production rate obtained in each
P-E curve was normalized by the
respective Chl-a concentration in the
sample, resulting in PP/B ratios. These
ratios in summer were always higher than
the ones observed in winter, despite of
the similar Chl-a concentrations in both
periods. The greater water temperature
observed in summer is an important
aspect in such feature.
Also, the ratios
observed for surface water samples were
always above than the detected in the
bottom samples. These differences are
more evident in summer. These results
suggest different physiological status
of the populations growing under
distinct light regimens along the water
column.
 Mean
values of Chl-a concentration (mg m-3)
at the 8 stations along the Santos
estuarine system in winter (Aug/05) and
summer (March/06). Bars represent the
standard deviation.
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Conceptual
model |
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Based on collected
data
The system is a partially stratified
estuary, with higher stratification at
the inner areas during the winter and
lower stratification mainly at the
Santos Channel. Light penetration is
usually low, with the euphotic zone
attaining the bottom due to the small
depth at the inner areas.Total
Nitrogen and Silicate concentrations
presented high values, attaining the
maxima during the rainy period.
Otherwise, phosphate concentrations are
higher during the dryer period.
In spite of the low N/P ratio,
nutrients are not limiting phytoplankton
biomass and productivity, due to the
high absolute nutrient concentrations.
The main forcing agents in respect to
phytoplankton productivity are
temperature, stability and light. Most
critical areas in respect to
eutrophication were represented by the
inner estuary and São Vicente Channel,
especially station 6.
In spite of the high nutrient load,
anoxic conditions are not observed,
which can be attributed to the high
productivity and mixing.
The lower values are observed at the
inner regions during the winter (around
50%).
Suspended matter presents strong
variability along the system.
The channel areas usually presented
the highest values due to mixing process.
Eventual increases in particulate
matter are not due to phytoplankton
biomass. Other sources of organic matter
may contribute to this.
During summer the pH decreases and
CO2 concentrations increases due to
heterotrophic activity (three times
higher than winter).
Both the autotrophic and
heterotrophic activity are higher during
summer, due to the increase in water
temperatures (circa 6oC higher than
winter).
Heterotrophy dominates the inner
portion of the estuary and São Vicente
channel.
The equilibrium between both
processes, estimated by the ratio CO2/O2
≈1 is only observed at the mouth of
Santos estuary.
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Modelling
applications |
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Modeling strategy
Grid – Modeled domain
The modelled domain encompasses the
inner estuarine area and the adjacent
bay area. The geographic location of the
domain is defined by grid origin
coordinates are 46.505º S and 24.135º W
(Southwest corner of the grid). Two
domains with different resolution are
used in this study, one with a fine
resolution and other with a coarse
resolution, but covering the same area.
The high
resolution domain is characterized by a
variable grid with 147x137 computation
points, with higher resolution inside
the estuary and in channel areas. The
coarse resolution domain is
characterized by a constant square grid
with 48x50 computation points, each cell
covering an approximated are of 0.25
km². The coarse resolution grid was
adopted to optimize the running time for
testing purposes (scenarios, different
sets of conditions, etc.).
Modeled domain
represented with a fine grid resolution
(top) and a course grid resolution
(bottom). Red dots mark the discharge
points: (1) river
Butoroca, (2) rivers Cubatão, Pereque
and Henry Borden, (3) rivers Mogi and
Piaçaguera, (4) river Quilombo, (5)
river Jurubatuba, and (6) Bertioga
channel.
Boundary
forcing
In this
application, the external conditions
include river discharges, forcing
functions (for example light intensity,
air temperature), and boundary
conditions (concentrations of each state
variable in the open Atlantic
boundaries).
Tides are imposed on the primary model
through a series of tidal stations
obtained from the global tide solution
FES95.2.
Six discharge points are defined inside
the modeled domain, corresponding to the
main rivers in the system and one
channel: a joint discharge of rivers
Cubatão, Pereque and Henry Borden
effluent, rivers Boturoca, Moji e
Piaçaguera (joint in one discharged),
Quilombo, Jurubatuba, and Bertioga
channel. River discharges are defined by
a flow value with a characteristic
temperature and salinity, but also by a
concentration of cohesive sediments,
nutrients, organic matter components,
and biological constituents.
Mean monthly values are provided for the
flow and cohesive sediment
concentrations for each discharge. A
constant value of temperature (21ºC) and
salinity (0.4 PSU) are assumed for all
discharges.
Climatologically radiation levels were
used, calculated by the model for the
domain geographical coordinates. Air
temperature and relative humidity were
also used to force the model over the
entire domain, with monthly values taken
from field observations made at CODESP
meteorological station (Alemoa) during
1997.
Ecological
modelling
The model simulation for ecological
processes comprises a total period of 1
year (July 2006 – July 2007), starting
after a previous spin-up of 1 year with
hydrodynamic to establish a proper field
distribution for salinity, temperature
and sediments (both in the water column
and bottom).
The model runs with
a time step of 3600 seconds. The
state-variables included in the model
application are:
• Nutrients: nitrate, nitrite, ammonia,
inorganic phosphorus
• Organic matter: refractory dissolved
organic nitrogen, labile dissolved
organic nitrogen, particulate organic
nitrogen, refractory dissolved organic
phosphorus, labile dissolved organic
phosphorus, and particulate organic
phosphorus.
• Biological groups: phytoplankton and
zooplankton (assumed to be the closure
of the food web).
• Oxygen Each variable was initialized
with a homogenous horizontal
concentration field for the entire
domain.
Deposition and ressuspension is assumed
for the cohesive sediments, PON and POP.
Properties concentrations are always
expressed in mg l-1: nitrogen- and
phosphorus- related properties are
expressed in mg N l-1 and mg P l-1,
respectively; oxygen is expressed in mg
O2 l-1 and organism’s biomass is
expressed in mg C l-1. The model
estimates the light penetration in the
water based on cohesive sediments
concentration in the water-column.
Preliminary results
Model results agree in general with
the observations made so far. Nutrient
concentrations in model results are
usually higher during summer months, a
normal occurrence considering the high
flow regimes in rives during this period
of the year. Phytoplankton
concentrations are systematically higher
in winter. Even though nutrient
availability is higher in summer, higher
temperatures increases the limitation to
production.
Modeled
phytoplankton concentrations for Santos
estuary in Winter
Modeled phytoplankton
concentrations for Santos estuary in
Summer
Modeled phosphate concentrations for
Santos estuary in winter
Modeled phosphate concentrations for
Santos estuary in summer
Limiting factors
Limiting factors are
calculated for different areas of the
estuary, allowing a better perception of
the major controlling mechanisms in the
system. So far, the results show a major
control by light in the inner areas of
the estuary and of nutrients in the bay
area. Also, the temperature influence is
relevant in summer.
Integration boxes
used to assess the influence of
different limiting factors
Controlling
factor in boxes 7 (bay area) and 3
(inner area)
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Scenarios |
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Scenarios proposed by F.
Giordano for the Santos Bay according to
the DPSIR model
FIRST SCENARIO - HOUSING
Drive - New inhabitants areas
at the estuary edge
Pressure - Population growth; low
costs constructions
State - Mangroove and spartina
areas still remanescent doing ecossistem
services retaining soil and avoiding
expenses with the channel dredging
Impacts - removing the vegetation
of the estuarine edges could probably
causes diferences on the course of some
estuarine inner chanells. It can
promotes also floodness in many
different areas. Mud banks can move or
new mud banks could start to be formed
Response - Predictable scenarios
could lead us to avoid this situation of
estuarine area ocupation.
SECOND SCENARIO - INCREASE OF COLI
BACTERIA IN THE ESTUARINE WATERS
Drive - New inhabitants areas
at the estuary edge WITHOUT seawer
treatment
Pressure - Population growth; low
costs constructions
State - Mangroove and spartina
areas still remanescent doing ecossistem
services as a natural filter of sewer
and in some way avoiding increase of
colimetric idexes
Impacts - removing the vegetation
of the estuarine edges could probably
causes a worst balneability indexes for
the beaches and disturbing tourism
activities
Response - Predictable scenarios
could lead us to prevent the
construction of this kind of houses and
eventually predict how much sewer not
treated could reach Santos Bay From the
project.
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