Environmental Engineering Reference
In-Depth Information
Lagoon channels actually represent a 100 km network, partly navigable, connecting the
lagoon to the northern Adriatic Sea, with waterways close to the main industrial and tourist
areas.
4.1 Hydraulic regime
Hydraulic circulation and diffusive processes in lagoon environments exert a pivotal role in
most of the physical and biogeochemical processes. Interannual and interseasonal variations
of hydraulic forcing greatly contribute to biogeochemical processes through dispersion of
nutrients and pollutants (Rigollet et al., 2004) and changing basic physico-chemical
parameters (i.e., turbulence, dissolved oxygen, pH, salinity). During the first half of the last
century some investigations concerning hydrodynamic of the lagoon were conducted;
however, variation in both physical and chemical parameters were firstly described in order
to define water circulation pattern by Dorigo only in 1965. Recently, more sophisticated 2D
models were applied by Bosa & Petti (2004) and Petti & Bosa (2004) for clarifying the
sediment transport and the dispersion of a dissolved pollutant in the lagoon environment.
Ferrarin et al. (2010) employed a finite element modelling system (named SHYFEM,
http://www.ve.ismar.cnr.it/shyfem) developed at ISMAR-CNR (Umgiesser et al., 2003;
2004) to describe the water circulation taking into account different forces such as tides,
wind, rivers and sea-lagoon exchanges. One of the main outputs of this work was the
comparison of the simulation against water levels, salinity and temperature data collected in
several stations inside the lagoons. The lagoon has a strong tidal influence with several
basins separated by the watersheds where exchange of water between neighboring basins
occurs (Umgiesser, 1997). In a simulation proposed following Solidoro et al. (2004)
employing different tracers, the lagoon can be roughly divided in three subbasins. Taking
into consideration areas influenced by riverine inputs, a clear west-east salinity gradient was
found (from ~20 to~ 34 in western and eastern region, respectively) with a narrow band (1-2
km width) where a rapid change from mesohaline to euhaline conditions occur. The eastern
part of the lagoon presents a physical division due to the bridge connecting the main land to
the city of Grado.
4.2 Conflicts in coastal areas
The Marano and Grado Lagoon is one of the most important ecological systems of the North
Adriatic Sea, assuring connectivity with some psammophile and halophile habitats of the
coast. Nowadays, most of the natural areas are included in the Regional System of Protected
Areas (S.A.R.A.), as Communitary Importance Sites (CIS) and Special Protection Zones
(SPZ). The area includes some historical sites designed to protect wildlife migration
submitted to the Ramsar Convention in 1971, and, following the implementation of the
Habitats Directive (92/43/EEC transposed in Italy by DPR Sept. 8, 1997 No 357), concerning
the protection of biodiversity, the entire basin has been identified in the survey sponsored
by the state called "Natura 2000 "as a site to be included among the sites of Community
importance (SCIs - IT3320037). Moreover, the lagoon is an economical important source for
the inhabitants.
Fishing involves actually 245 fishermen and 200 persons in charge of marketing in Marano
Lagunare, whereas in Grado tourism represents the leading sector (over 1,700 persons), and
is almost exclusively carried out from April to October. Aquaculture (lagoon fish farming) is
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