Curso de Lagunas CosterasAlice Newton
Universidad de Algarve, Portugal
Universidad EAFIT, Abril 8-23, 2008
9 Abril~Importancia en términos hidrológicos~Tiempo de residencia ~Flujo de nutrientes. ~Modelación en ambientes lagunares
litorales.~Análisis de lagunas costeras – Marco
LOICZ.~Eutroficación.
Importancia en términos hidrológicos
Cap 3 Coastal lagoonsI.Ethem Gonenc and J.P. Wolfin (eds) 2005
Changes in the hydrologic cycle coupled with changes in land and water management alter fluxes of materials transmitted from river catchments to the coastal zone having a major effect on coastal ecosystems.
Hydrological cycle and lagoons
Tiempo de residencia
Residence time in Curonian lagoon
A passive tracer released inside the lagoon basin initially with a concentration of 100%. the wind and river action leads to a decay of its concentration. The concentration for each node of the grid is approximated by an exponential decay equation:
/0
teCC
10
0 )0(
efactorabyofCreducetotimetimeresidence
ionconcentratInitialtCC
DECAYING OF THE TRACER CONCENTRATION
RE
SID
EN
CE
TIM
E M
AP
Flujo de nutrientes
Modelación en ambientes lagunares litorales
Cap 6 Coastal lagoonsI.Ethem Gonenc and J.P. Wolfin
(eds) 2005
Modelling Lagoons
Biogeochemical and physical models are useful tools for understanding how lagoons function as natural systems.
Linked to economic models they become important tools for management.
Where do we start when we model lagoons?
~ A hydrodynamic model is useful and necessary to understand exchanges with the sea and also internal circulation
~ The dominant factor is the tidal exchange
~ Important result are residence time and transit times
Modelling Research
~ Hydrodynamic circulation and water levels
~ Salinity/Temperature modeling~ Wave modeling~ Sediment transport~ Ecological processes and water
quality~ Exchanges through the inlets~ Integrated modeling (coastal
zone management)
Managing fresh water in lagoons
River input
The Cabras lagoon in Sardinia: salinity trend
Dealing with residence times~ Residence time is
an indicator for the renewal capability of a basin
~ Residence time is controlled through fresh water fluxes and exchange with the open sea
Residence times and turn over time• Simulate transport processes and dispersion of tracers and pollutants
• Estimate the renewal time of the basin
• Characterize water masses with the help of time dependent parameters
• Correlate physical, biological and chemical characteristics between each other
Residence Time
Trapping Index
Transit Time
Trapping Index
Identifying water masses
Impact of waste water dischargePlan sewage outfall in the sea
Assess impact of the sewage outfall to the surrounding areas Test area:
• Industrial port [IH]
• Possible sewage outlet position [L1, L2, L3]
• Touristic area [TA]
IH
TA
L1
L2
L3
Commercial port of Oristano
Evaluate impact of pollutants
• SW wind with speed of 8 m/s
L1 L3L2
Dealing with Sewage: BIOPRO Project
Daily average concentrations
Area of influence
High resolution areaHigh resolution area
Adriatic Sea – Lagoon
FEM Grid
Interaction with longshore current
Water level forecast
in Venice
Advantages of modelling~Modelling techniques can be efficiently
applied to coastal zones and lagoons~Modelling approach is needed for
coastal zone management and sustainable development
~Some parameters can not be measured and can be quantified only through modeling (residence time)
~Possibility to link environmental coastal monitoring to numerical modelling
We also need a hydrological model… including groundwater
Groundwaterflow
Rivers/lakes
Unsaturatedzone
Overland/floodplains
Traditional groundwater model
Integrated model
Groundwater
Unsaturatedzone
Overland/floodplains
Rivers/ lakes
IRBM and ICZM ~ Integrated River Basin Management and
Integrated Coastal Zone Management are linked science and management areas
~Scientific and a socio-political need to improve knowledge and management of coastal zones by defining common methodological approaches integrating river basins and coastal lagoons
~Monitoring and modelling the interactions between basin and coastal processes is a priority to inform Policy and Decision makers and improve management
Numerical modelling for lagoon and watershed management
~ Monitoring is expensive~ Modelling can integrate (spatially and
temporally) between measurements~ Modeling allows for testing several
hypothesis and projects~ Forecasting is impossible with
monitoring~ Modelling gives faster answers
Next consider the drainage basin…
Ringkøbing Fjord and associated river basin
Mean nitrate leakage for Ringkoebing Fjord basin (kgN/ha/day)
Where are the pollution sources?(Ringkøbing Fjord and associated river basin)
Wastewater discharge
points
Identify the point sources of effluent
For diffuse sources, it is important to understand the catchment
Corine land cover
map
Are there any wetlands? These are key to management (Ringkøbing Fjord and associated river basin)
Análisis de lagunas costeras – Marco LOICZ
Just a biogeochemical model can be complex…
PrecipitationEvaporation
Sea
RunoffGroundwaterOtherResidual
Flux
Exchange
System
PrecipitationEvaporation
Sea
RunoffGroundwaterOther
RunoffGroundwaterOtherResidual
Flux
Exchange
SystemInternal transformations
PrecipitationEvaporation
Sea
RunoffGroundwaterOtherResidual
Flux
Exchange
System
PrecipitationEvaporation
Sea
RunoffGroundwaterOther
RunoffGroundwaterOtherResidual
Flux
Exchange
SystemInternal transformations
PrecipitationEvaporation
Sea
RunoffGroundwaterOtherResidual
Flux
Exchange
System
PrecipitationEvaporation
Sea
RunoffGroundwaterOther
RunoffGroundwaterOtherResidual
Flux
Exchange
SystemInternal transformations
PrecipitationEvaporation
Sea
RunoffGroundwaterOtherResidual
Flux
Exchange
System
PrecipitationEvaporation
Sea
RunoffGroundwaterOther
RunoffGroundwaterOtherResidual
Flux
Exchange
SystemInternal transformations
Application of simple LOICZ Biogeochemical Budgets has been widespread and successful
Biogeochemical budgets, changes in nutrient supply22 LaguNet Budget Sites
Results•Collect all relevant information about water and inorganic nutrient loads in the 22 Italian LaguNet sites
•Compare with the LOICZ global database
Comparison among LaguNet and comparable sites from the LOICZ global database
DIP load DIN load ΔDIP ΔDIN
n° sites mol m-2 y-1 mol m-2 y-1 mmol m-2 y-1 mmol m-2 y-1
LOICZ(s)depth<10m
Area<2500km2
94
median 0.06 1.2 -3.7 -130
min 0.00 0.0 -876 -49640
max 6.84 82.1 9125 242700
mean 0.30 5.3 146 2423
LOICZ(s-E)As above
without large estuaries
61
median 0.05 0.6 -7.3 -146
min 0.00 0.0 -525 -49640
max 1.17 57.0 3042 10220
mean 0.11 2.4 35 -813
LaguNet 17
median 0.01 0.3 -3.2 -175
min 0.00 0.0 -111 -6435
max 0.29 6.9 9 1239
mean 0.04 1.2 -13.7 -761
y = -0.65x
R2 = 0.79
-0.12
-0.10
-0.08
-0.06
-0.04
-0.02
0.00
0.02
0.00 0.05 0.10 0.15 0.20 0.25 0.30
DIP input
DD
IP
y = -0.75x + 0.13
R2 = 0.83
-7
-6
-5
-4
-3
-2
-1
0
1
2
0 1 2 3 4 5 6 7 8
DIN input
DD
IN
Relationships between nutrient inputs and internal fluxes (ΔDIP and ΔDIN) in the LaguNet shallow sites
Not considered in the calculations
•At high loads the systems act mainly as nutrient sinks
•This seems related mainly to the benthic vegetation
Once you understand the physics and the geochemistry…
You can model the primary production, e.g. chlorophyll
yield from nitrogen
Oder Lagoon: a simple box model
When primary production (pp) is dominated by phytoplankton, simple Vollenweider type relationships can be found between input rate of nutrients and mean Chl-a concentrations and/or pp.
HIGH NUTRIENT REGIME
LOW NUTRIENT REGIME
Zaldívar et al. (2007)
Regime shift between
Zostera and Ulva
However, in estuaries and coastal lagoons pp is carried out by angiosperms, epiphytic
algae, drift and attached macroalgae and epibenthic
microalgae. In this case “simple correlations” does not exist,
(Nixon et al., 2001).
…once you have modelled the primary producers,
you can add in the consumers or grazers…
~
Fo rc ing va ria b le s Wind
Te m p e ra tureWa te rshe dinp uts
Ra in
Se d im e nt
O 2
O 2
Wa te r c o lum n
Dia to m s
Fla g e lla te s
Phyto p la nkto n
M ic ro
M e so
Zo o p la nkto n
M a c ro p hyte s
NO 3- NH4
+
C la m s
N itrific a tio nd e nitrific a tio n
N O RG PO 4-3 P a d sAd so rp tio nd e so rp tio nM ine ra liza tio n M ine ra liza tio n
NO 3- NH4
+
N itrific a tio n
G ra zing
Filtra tio nDO M
PO M
Ba c te ria
PO 4-3
Exc re tio n
M o rta lity
O p e nSe a
Diffusio n
Se d im e nta tio n
Se e d ing
Ha rve sting
1
2
3
4
5
6
Integrated modelling approachIntegrated approach to coastal lagoon modelling