Environmental Engineering Reference
In-Depth Information
At the same time piezometric decline was recorded, together with subsidence
along a leveling line, as shown in Figures 5.5 and 5.6.
Figure 5.2.
Total subsidence in Venice during the period 1908-1996:
contributions of the three different mechanisms are shown
The rate of water withdrawal from wells in the industrial zone since 1930 is
shown in Figure 5.4. Total values are presented, even though different aquifers with
different distributions were used during the exploitation period. Information
regarding distribution between the aquifers can be found in [LEW 98].
In 1969 the maximum withdrawal in Marghera was about 0.46 m
3
per second.
After 1970 the industrial pumping was gradually reduced. A sensible decrease in
active wells occurred in the period between 1972 and 1975, when a new industrial
aqueduct was put into operation. Between 1975 and 1980, the pumping rate was
estimated to be about 0.20 m
3
per second, subsequently being drastically reduced
and eventually stopped completely.
The mean values of the piezometric decline observed from 1920 to 1975 in the
same regions are shown in Figure 5.5. A remarkable recovery of the piezometric
levels can be observed after 1970.
