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ITALIA
Sardinia’s largest coastal aquifers are hosted Total stream-flow into the alluvial aquifer is esti-
in the Jurassic karstic limestone formations of the mated at about 100 m3/s. In the intermediate hilly
Bays of Orosei and Nurra, on the East and North- zone this water reappears at the surface and forms
West coasts respectively, and in the karstic lime- a continuous line of springs with an aggregate
stones of the Cambrian series of the Iglesiente flow rate of over 150 m3/s. Downstream ground-
region, in the south-west of the island. Most Sar- water is abstracted through thousands of dug and
dinian coasts consist of imposing cliffs of Palae- drilled wells to meet the increasing water demand
zoic-Quaternary metamorphic, crystalline, vol- for municipal, agricultural and industrial uses.
canic and sedimentary rocks, where groundwater Both the volume and outflow of the aquifer are
occurs locally in large bedrock fractures and in considerable. In the Venice area there are more
porous weathered zones of the overburden. than 13,000 wells and groundwater overexploita-
Recent alluvial and sedimentary deposits with tion has been found responsible for the increasing
their numerous coastal ponds interrupt the cliffs subsidence of the area to the extent that many
at the mouth of the deep valleys incised by the wells have had to be closed. In Romagna, and
most important rivers and at the margins of the likewise upstream in Emilia and the lower Plain of
graben stretching from the Bay of Oristano in the Lombardy, flow lines tend towards the Po River
West to the Bay of Cagliari in the South. with a piezometric gradient of 1-2% in the hilly
zones and 0.1-0.2% in the lower zones. Aquifer
COASTAL AQUIFERS recharge by the river system in the outer hilly zone
is calculated at about 10 m3/s, whereas average
The Carso plateau, the region near Trieste in drainage from the same rivers in the valley zone is
the far north-east of Italy which gave its name to estimated to be 7 m3/s. In this part of the plain,
the karst phenomenon, represents one of the most transmissivity varies between 5x10-2 and 10-3 m2/s.
important aquifer systems in the Mediterranean. The storage coefficient ranges from 10-2 for the
Surface waters disappear, infiltrating into sink- surface strata to 10-4 for the deep zones, where the
holes and grottoes, to reappear as groundwater stratum is under pressure.
drained by streams such as the Timavo, deeply
carved out of the rough morphology, and flowing Along the Adriatic coast there are more than
out from subaerial and submarine high-yield 20 valleys with major local alluvial deposits, all
springs. lying parallel in a SW-NE direction. As they are
no more than 60 metres thick, only their large
The unconfined, semiconfined and confined areal extent makes these aquifers valuable for sat-
aquifers bordering the northern Adriatic sea are isfying local water needs. Analysis of the alluvi-
largely supplied by lateral inflow of groundwater um indicates a steady increase in grain size with
formed in the Friuli, Venetia, and Po alluvial depth. Further to the south, in Apulia, in the sandy
plains for direct recharge and upstream infiltra- deposits of the Tavoliere plateau, the piezometric
tion into the mountain and piedmont deposit areas surface indicates downward flow into the sea with
at the foot of the Alps and Apennines. Stream dis- a gradient of 0.5 per cent with several thousands
charge from the upper part of the plain is substan- of wells under exploitation (Cotecchia et al.
tial and causes the piezometric surface to rise 1981).
noticeably. In the Venetia part of the plain the
average piezometric slope drops from 0.5-1.1% in Calcareous outcrops appear in three distinct
the piedmont deposit zones to 0.01-0.04% in the sectors of Apulia: on the Gargano promontory, the
coastal area (Zuppi, 2003). Murgia uplands and Salento Peninsula. The promi-
nent elevation of the Gargano promontory hosts an
That aquifer system, divided into distinct aquifer supplying a number of peripheral springs
sectors, is certainly the most productive in Italy. flowing out into the sea. There are 27 known
springs with a flow rate higher than 30 l/s, 14 with
210
