Acqua alta
Venice is an artificial island in the
middle of an natural lagoon in the northern Adria. The lagoon is
separated by an offshore island chain from the open Mediterranean
Sea. To a lagoon belongs a natural influx which is given here by
the river Po which transports constantly depositions and sediments
from the Alps right in to the waters of the lagoon. These sediments
are lowering the natural ground by its masses. The mud is the the
reason for continuos decline of the ground. There after the
artificial islands are threatened to sink in the mud.
The water of the lagoon is a mixture of
freshwater and sea water, the so-called brackish water. Due to
permanent changing water levels of the Mediterranean sea there is a
water exchange.The regular high water which causes this water
exchange and a "cleaning" of the lagoon counteracts against a rapid
aggradation. On the other way the high water levels are a bane. The
city is sinking in the mud and the high waters rise into the
streets and places. This very high water or the "Acqua alta" is not
only cleaning, but also a load for the inhabitants of the
lagoon.
The main island Venice is established
on oaken posts which were done partially already in the 9-th
century in the morass. Afterwards the respectable houses were
established on these posts.
The ways between the houses are
uneven and interfused with numerous stairs. A bicycle is an unknown
object in Venice. The ways as well as the houses lie partial only
about 1 metre about the natural sea level. Indeed, by the
protection of the offshore islands no danger threatens by storm or
swell, probably, however,by high water that the city floods several
times in the year almost during winter.
While the inhabitants see in the
floods nothing unusual this high water is a spectacle for the
tourists who visit the city every year to millions.
Shortly before rising of the sea
level a highwater warning signal is given by horns. The tone
signals have three escalation steps. While for the lowest step only
wellingtons and suitable clothes are needed for the protection, the
third step requires the construction of an omnipresent footbridge
system. The necessary materials are to be found in the townscape
everywhere.
The establishment of a dam project
called moses was begun in 2003. The project protects in spite of
numerous doubts of environmentalists the water exchange and should
prevent another dropping of the lagoon.
To log this Cache you must answer at
first two questions. At the given coordinates you will only find
one necessary information. The questions can be solved by homework
and attentive observing in the city, e.g., with the use of a
Vaporetto, the watercoach.
Question 1:
How many increasing tones are
included in the warning signal of the highest high water
step?
Question 2:
In which year was the highest water
level ever?
Send an email with your team name and answer
through my profil.
You will not have to wait for a log
permission. If your answers are not right I will get into contact
with you. However, before logging you must still visit the
coordinates. There you will find two gigantic anchors. Place
yourself on an anchor with your GPS in the hand. Take a photo of
this scene and load the picture to your logbook entry. Logs without
picture will be extinguished by me regularly.
Have a lot of fun in the
serenissima.