Curso de Lagunas Costeras Alice Newton Universidad de Algarve, Portugal Universidad EAFIT, Abril 8-23, 2008

9Abril ~ 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 lagoons I.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: DECAYING OF THE TRACER CONCENTRATION RESIDENCE TIME MAP

Flujo de nutrientes

Modelación en ambientes lagunares litorales Cap 6 Coastal lagoons I.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 discharge Plan 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 L1L3L3L2L2

Dealing with Sewage: BIOPRO Project Daily average concentrations Area of influence

High 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

Groundwater flow Rivers/ lakes Unsaturated zone Overland/ floodplains Traditional groundwater model Integrated model Groundwater Unsaturated zone 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…

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Application of simple LOICZ Biogeochemical Budgets has been widespread and successful

Biogeochemical budgets, changes in nutrient supply 22 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 loadDIN loadΔDIPΔDIN n° sitesmol m -2 y -1 mmol m -2 y -1 LOICZ(s) depth<10m Area<2500km 2 94 median min max mean LOICZ(s-E) As above without large estuaries 61 median min max mean LaguNet17 median min max mean

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…

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Integrated modelling approach Integrated approach to coastal lagoon modelling