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Another cause of the difference between western and underground conditions of Favignana are not so easy Research & development
eastern sector is that the former is almost uninhabited, to describe: well FA22, for instance, in the middle
with few rural buildings dispersed over the country of the town, one hundred meters from the quays,
areas and no urban centers; conversely, the latter hosts water with the lowest electrical conductivity
sector is the real vital center of the Island, from the (i.e. the lowest content in salts): 676 µS/cm as annual
town of Favignana in the center of the island to the average. In the western sector, wells FA02 and FA03,
tourist facilities on the more eastern coast. excavated in a calcareous outcrop, although situated
As for the wet and the dry seasons, there are some some 100-200 meters from the rocky northern
differences indeed, nevertheless they are the seashore, give water that is quite salty indeed (3200
most various and apparently accidental variations: µS/cm and 2435 µS/cm, respectively), but not so
somewhere they are positive, somewhere negative. salty as the other wells situated slightly above sea
No correlation has been found with the seasonal level (where electrical conductivity rises as high as
variation of the water table either. 6000, 7000, even almost 12000 µS/cm).
Comparing the average electrical conductivity
values with the ground elevations above sea level Conclusions
at the sites of the wells (Figure 13), instead, it is
easy to see that higher electrical conductivity On the sole Favignana Island (with its area of less
values are more common in shallower wells (even than 20 km2) 520 wells are officially registered at
with conspicuous exceptions): it could be easy present: even if many of them are out of service, and
to conclude that this occurs since these wells are others belong to houses inhabited only for limited
nearer to the seashore than the deeper ones. In holiday periods during the year, it is still a huge
fact electrical conductivity is function of the salt number of points from which the groundwater can
content, and this latter is, in turn, function of the be tapped.
mixing with the sea water surrounding the island. In addition to this anthropogenic potential
The cited exceptions, however, demonstrate that the
consumption of groundwater,
FIGURE 13 Conductivity vs. ground elevation another way water is wasted
due to the cited characteristic
quarries and caves located
everywhere in the eastern
sector of Favignana: most if
not all of them reach the water
table, so their floor, and even
their walls, act as evaporation
surfaces contributing to the loss
of the available groundwater.
All this could pose a serious
threat to the survival of the
natural groundwater resource,
if people do not manage it with
responsibility: according to
the results of this survey, it can
be said that there is no real
danger, because water tapped
from the island wells is not used
extensively but only for limited
27EAI Energia, Ambiente e Innovazione 4/2015
