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| Titel |
Water management sustainability in reclaimed coastal areas. The case of the Massaciuccoli lake basin (Tuscany, Italy) |
| VerfasserIn |
Rudy Rossetto, Ilaria Baneschi, Paolo Basile, Massimo Guidi, Chiara Pistocchi, Tiziana Sabbatini, Nicola Silvestri, Enrico Bonari |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250042395
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| Zusammenfassung |
| The lake of Massaciuccoli (7 km2 wide and about 2 m deep) and its palustrine nearby areas
(about 13 km2 wide) constitute a residual coastal lacustrine and marshy area largerly drained
by 1930.
In terms of hydrological boundaries, the lake watershed is bordered by carbonate
to arenaceous reliefs on the east, by a sandy coastal shallow aquifer on the west
(preventing groundwater salinisation), while south and north by the Serchio River and the
Burlamacca-Gora di Stiava channels alignment respectively. Since reclamation of the peaty
soils started, subsidence began (2 to 3 m in 70 years), leaving the lake perched and central
respect the low drained area, now 0 to -3 m below m.s.l., and requiring 16 km embankment
construction.
During the dry summer season, the lake undergoes a severe water stress, that, along with
nutrients input, causes the continuous ecosystem degradation resulting in water
salinisation and eutrophication. Water stress results in a head decrease below m.s.l.,
causing seawater intrusion along the main outlet, and reaching its highest point
at the end of the summer season (common head values between -0.40 and -0.5
a.m.s.l.).
The water budget for an average dry season lasting about 100 days was computed,
considering a 10% error, in order to understand and evaluate all the components leading to
the above mentioned water stress by means of several multidisciplinary activities during the
years 2008-2009. They started with a thoroughly literature review, continued with
hydrological, hydrogeochemical monitoring and testing (both for surface water and the
shallow aquifer) and agronomical investigations (to characterize cropping systems,
evapotranspiration rates and irrigation schemes). All the collected data were then processed
by means of statistical methods, time series analysis, numerical modelling of the shallow
aquifer and hydrological modelling.
The results demonstrate the presence of two interrelated hydrological sub-systems: the
lake and the reclaimed land sub-systems, the first one showing an average 4.2 mm net daily
water loss during the summer season (about 0.975 m3/s) for the years 2000-2009. Lake
inflow is constituted of two main terms: an anthropogenic one related to the drainage
of the reclaimed land of about 1.1 m3/s (ranging 75-81% of the total inflow); a
natural one defined by recharge through rainfall, the western coastal aquifer and the
eastern reliefs, accounting for 0.25 m3/s (varying 19-25% of the total inflow). On the
other hand, lake water loss is mainly due to evaporation from water surface and
evapotranspiration from the palustrine vegetation for around 56-61% (1.31 m3/s on
average), while 13 to 15% (0.325 m3/s) is due to inefficient irrigation schemes
using lake water and, being the lake perched, recharge to the reclaimed land aquifer
(26 to 29%) by means of water infiltrating along the embankments (0.64 m3/s on
average).
Since several springs on the eastern margin, which would flow to the lacustrine system for
about 0.160 m3/s (Autorità di Bacino del Fiume Serchio, 2007), are tapped (for
residential, tourism and industrial users), the anthropogenic impact on the water deficit
constitutes about 50% of the total, being 34% due to irrigation and 16% to other
users.
This demonstrates the naturally induced water deficit, already known by historical
sources, is heavily altered by anthropogenic pressure defining a not sustainable balance
between the socio-economic system and the natural one. It is then clear, that in order to
reduce the water stress, a new water management strategy in the whole basin must be devised
by revising and enhancing the irrigation schemes and the residential, industrial and tourism
water distribution.
Reference
Autorità di Bacino del Fiume Serchio, 2007. Piano di Bacino “Bilancio idrico del bacino
del lago di Massaciuccoli” Relazione di piano. Lucca, Italy. |
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