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SEAWATER INTRUSION IN THE COASTAT AQUIFERS OF ITALY

tionary processes of saltwater contamination of abandoned altogether within the next ten years.
fresh groundwater. (Cotecchia et al., 1981; Tuli- Coastal pinewoods are also suffering because of
pano & Fidelibus, 1986). Salt water intrusion in high salinity levels. In the delta plains of the
Apulian coastal aquifers is evident in figure 3. rivers Ombrone and Albegna, where more than
4000 irrigation wells are known to exist, values of
The saturation attained by groundwater as a T=10-2 -10-3 m2/s and a storage capacity (coeffi-
consequence of karst processes and fresh/saltwa- cient) S= 1.22 x 10-4 ÷ 6.1 x 10-6 have been eval-
ter mixing processes has been evaluated by uated. The aquifer is recharged by direct rainfall
hydrochemical determinations. Significant values infiltration and lateral inflow from the piedmont
of the characteristic ratios rCa/rMg, rMg/rNa, and deposits. Groundwater table was above sea level
rCa/rNa have been found considered to mark the in 1985 in undisturbed conditions, while there a
limits for the change from over- to undersatura- significant drawdown to below sea level was
tion also determined by a given value of Sr2+ con- observed in 1984 during irrigation. In autumn
centration, at least for the groundwater in the zone 1994 the drawdown appeared to have diminished
under consideration (Tadolini et al., 1982). The considerably as the result of the less intensive
chemical and isotopic features of waters drained aquifer exploitation for irrigation and an increase
from coastal springs, through which groundwater in withdrawals to secure domestic water supplies
of the Apulia karst carbonate and coastal aquifer
flow into the sea, are mostly affected by mixing
phenomena between fresh and intruding seawater.
By analysing certain chemical parameters intrud-
ing seawater could be differentiated, as a func-
tion, above all, of the different residence time of
sea water in the aquifer. By comparing the iso-
topic characteristics of mixed water with the iso-
topic composition of groundwater of marine ori-
gin, it was possible to trace the original isotopic
composition of the supply waters (Fidelibus &
Tulipano, 1986).

Tuscany

In all Recent coastal plains of Tuscany
ground-water is affected to a greater or lesser
extent by saltwater intrusion, as shown in figure 4
(Bencini & Pranzini, 1992). The situation is still
acceptable in the Versilia and Pisa plain, but this
phenomenon is a major cause for concern in the
Corna, Ombrone, and Albegna plains, Castiglione
della Pescaia, and in the Isle of Elba. Saltwater
intrusion is threatening water supply, mainly in
the summer when the influx of tourists swells the
resident population. Groundwater supply has to
be rationed locally, and for agricultural use with
the result that profitable strawberry production
has had to be abandoned in favour of tomatoes Figure 4. Saltwater intrusion in Tuscany. 1:coastalplains;
because of water and soil salinization. In some 2: areas affected by groundwater salinization (After Bencini &
places agricultural activities may well have to be Pranzini, 1992).

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