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