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SEAWATER INTRUSION IN THE COASTAT AQUIFERS OF ITALY
iments are currently under way on a variety of wedges have also been studied by combining
soil types cultivated with different crops. A com- geophysical investigations with groundwater
parative analysis of different irrigation techniques physical-chemical parameters, namely electrical
is in progress with a view to convincing and conductivity and temperature.
advising farmers to adopt the best practices. The
results are encouraging and farmers are much less The extent of seawater encroachment is
sceptical about wastewater reuse for irrigation. only known to the south of Chioggia, where the
Long distance water transfer has long been prac- ground elevation of the littoral sector is up to
tised in southern Italy for securing both drinking three m above sea level. Dune belt and palaeo-lit-
and irrigation water supplies; suffice it to mention toral strip sand formations constitute a well-
the Roman aqueducts, which are still in operation developed phreatic aquifer with a fresh water
today. To alleviate the effects of drought, a num- body, up to 10 m deep, floating on salt water. Sea-
ber of reservoir systems have recently been inter- water contamination af-fects aquifers and
connected in southern Italy and particularly in aquitards below the fresh water body down to a
Sardinia, despite its rugged topography. depth of 70 m. Inland there is an area of reclaimed
land at an elevation of -2 to -3 m below sea level,
So far, water rationing is the most common thus groundwater has to be pumped away to keep
measure for mitigating water scarcity problems. the water table below land surface. The critical
Wastage and losses from leaking aqueducts are ground elevation, drawdown and seawater inflow
significant, especially in southern Italy, and the into the rivers during high tides all contribute to
cost of water is partially subsidized. seriously diminishing the fresh water body and
salination of agricultural land. Conversely, sever-
CASE STUDIES al piezometric depressions caused by groundwa-
ter overexploitation in the past (1950’s, 60’s and
Venetia 70’s) are evident in the northern portion of the
above-mentioned tectonic line, like for instance
Sand layers bounded by silt and clay strata around Marghera, Venice. Though close to the
constitute the Venice multi-aquifer system, with Venice lagoon, these depressions do not cause
depth down to 1000 m (Quaternary basement). inland saltwater encroachment because of the
Moving northwest, towards the foothills of the high hydraulic head of the groundwater flowing
Alps, the sedimentary structure tends to change. from the Alps and the significant lateral
Materials become increasingly coarser, while the recharge from the streams in the Venetian plain.
aquitards become shallower, eventually petering In this case, saline intrusion is related to the dif-
out. The unconsolidated deposits in the foothills ferent geomorphology of the littoral and inland
belt form a homogeneous system of sand and sectors.
gravel. For the hydrologist, the system constitutes
the reservoir supplying the aquifer-aquitard sys- Apulia
tem extending beneath Venice and even further
below the Adriatic Sea (Conti et al. 2000; Zuppi In Apulia groundwater exploitation has
& Sacchi, 2003). resulted in extensive water quality degradation
due to salt-water intrusion and contamination
The Venetian aquifer system consists of six caused by major industries and the widespread
aquifers, four of which are extensively exploited use of chemicals in agriculture. The territory has
(2nd, 4th, 5th and 6th). Hydrogeological maps of been divided up into four hydrogeological units:
the phreatic and confined aquifers show a general Gargano, Tavoliere, Murgia and Salento, as
southward flow direction. Water heads at sea lev- shown in figure 2 along with their water balance
el or below are found in the southern sector of the parameters referred to a climatic time serie up to
Schio-Vicenza tectonic line extension. Saltwater 1980.
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