Transcript Task 5.4.2

River discharge into the
Mediterranean Sea and estimation
of the associated nutrient load
Task 5.4.2
O.G.S.: Alessandro Crise, Cosimo Solidoro, Sebastiano Trevisani
ENEA: Salvatore Marullo, M.Vittoria Struglia
CIRCE MEETING Bologna, 2 May 2007
Summary
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Statement of the problem
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Aims of the task
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Description of planned activities
A view of the Mediterranean sea
Sea - Wifs image from EEA Topic Report 7 2001
Two sides of the same coin:
Eutrophication and Oligotrophication
Eutrophication refers to an increase in the rate
of supply of organic matter to an ecosystem,
which most commonly is related to nutrient
enrichment enhancing the primary production in
the system (Nixon, 1995).
Oligotrophication
is the reversal of the
eutrophication process and can occur as the
result of changes in precipitation and runoff
regime or of operation of advanced waste
treatment facilities on inflowing rivers
Impacts of eu/oligo-trophication
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changes in the structure and functioning of the marine
ecosystems;
reductions in biodiversity;
reductions in the natural resources of demersal fish and
shellfish;
reduced income from maricultures of fish and shellfish;
reduced recreational value and income from tourism;
increased risk of poisoning of animals including humans
by algal toxins.
The nutrients’ load
We focus our analysis on nutrients carried by rivers
as causes of eutrophication/oligotrophication.
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Total nutrient loads can be estimated by the time
integration of instantaneous fluxes
CxQ
(nutrient concentration x river discharge)
The temporal variability of river discharge is a
dominant factor in this process
Our aims
1.
2.
Evaluate the impacts of interannual and
decadal variability of river discharge on
the marine environment and ecosystem
under current climate conditions
Attempt a description of the impact that
climate changes may have onto the
nutrient loads.
Our plan
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An empirical model will be developed based on:
- land use information
- nutrient retention and loss within
river system
- river discharge data
A limited number of river basins, possibly
representative of the response of the European
and African coasts, will be selected as case
studies.
Results from this model will be compared with
available observed (satellite or in-situ) quantities
linked to riverine nutrient load.
Land use and nutrient load
Total nutrient load can be evaluated by means of different
methodologies characterized by different degrees of
complexity. For example for the Rhone T. Moutin et Alii made
the evaluation considering water flux and nutrients
concentration. Then, in the case of Nile, S. Nixon evaluated
nutrients load taking in to consideration the population,
sewage systems and fertilizer use.
T. Moutin et Alii, 1998, “The input of nutrients by the Rhone river into the
Mediterranean Sea: recent observation and Comparison with earlier data”,
Hydrobiologia, pp. 237-246.
S.W. Nixon, 2003, “Replacing the Nile: Are Anthropogenic Nutrients
Providing the Fertility Once Brought to the Mediterranean by a Great
River”, Ambio, Vol.32, No. 1.
Reasonably, in order to perform a scenario based analysis (climate
change, demographic variations, different land use, etc.) there
could be the need of numerical models (SWAT, MONERIS,
POLFLOW, POL, as an example) able to simulate the temporal
variation in nutrients load related to the set of physical and
chemical processes involved. The choice of the model to be used
is related to the hydrological characteristics of the basin, to the
data available and to the target of our analysis. Likely these
models should be linked or integrated in to a geographical
information system
S.L. Neitsch, J.G. Arnold, J.R. Kiniry and J.R Williams, 2005, “Soil and Water Assessment Tool Theoretical
Documentation”, Texas.
M. Tournoud, S. Payraudeau, F. Cernesson and C. Salles, 2005, “Origins and quantification of nitrogen inputs
into a coastal lagoon: application to the Thau lagoon (France)”, Ecological Modelling, 193, pp. 19-33.
M.J. M. de Wit, 2000, “Nutrient fluxes at the river basin scale. I: the PolFlow model”, Hydrological processes,
15, pp. 743-759.
L. Palmeri, G. Bendoricchio and Y. Artioli, 2005, “Modeling nutrient emissions from river systems and loads to
the coastal zone: Po river case study, Italy”, Ecological Modeling, 184, pp. 37-53.
River discharge data
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Current climate: historical time series from several on-line
database (GRDC, MMA, Med-Hycos, sage, UNESCO) are
available and will be analyzed respect to climatology and
interannual and decadal variability:
River
Years available
Rhone
1920-1997
Po
1918-1996
Ebro
1954-2001
Moulouya
1957-1988
Climate change: informations from other RL’s are expected
Contribution of major rivers to total runoff
Interannual variability in the
Adriatic Sea and in the Gulf
of Lion.
From Struglia et al. Journal
of climate, 2004
In a first instance three
Mediterranean rivers will
be considered: Rhone, Po
and Nile (these cover
around 1/3 of the total
riverine input into the
Mediterranean Sea)
In order to understand these rivers and their relations
with the sea two aspects should be considered:
 hydrologic and hydrochemical behaviour of the rivers
 hydrochemical characteristics and spatio-temporal
variation of marine coastal waters in the proximity of
estuaries
Validation of the model
In situ measures
Ocean color satellite data
Chlorophyll climatology by SEA-WIFS
Open ocean optical remote sensing of the Mediterranean Sea
by R. Santoleri, G. Volpe, S. Marullo, B. Buongiorno Nardelli
to appear on the book "Remote sensing of the European Seas"
April 22 2004
Seasonal and year to
year variability can be
studied using time
series of ocean color
satellite data.
SeaWiFS data permit
to investigate the
variability of the
Chlorophyll field (or
other ocean color
derived parameters)
in the Adriatic Sea for
the period from 1998
to today.
Courtesy of ADRICOSM NERES
project and ENEA