These stakes were made from alder wood which is water-resistant and, luckily, there was a layer of hard clay at the bottom of the canals on which it all rested. Atop those sat wooden platforms on which stone was placed and this served as the foundation for the buildings which would eventually make up the city. In order to get all of these materials to the soon to be Venice, however, wood needed to be imported via boat from Montenegro, Croatia, and Slovenia.
The incredible thing about the foundation on which Venice sits on is that while wood normally rots - especially when exposed to water - but even the water in Venice was conducive to its building.
The saltwater prohibits microorganisms from growing but also allows salt and additional minerals to harden the wood further, making it nearly as strong as stone.
While it can be a challenge to decipher exactly how deep those trenches are while drifting by on a gondola , there's truly no exact answer for this. Many would assume that the canals in Venice are fairly shallow since an entire city sits atop them but this is simply not the case.
Rather, every canal varies in its depth depending on location and condition, and can't all be measured with one yardstick. Most of the canals in Venice measure no more than six and a half feet deep, but there are others that do exceed that. In fact, the Grand Canal is more than twice as deep as the others, measuring to a depth of just over 16 feet deep.
It's expected that this waterway would be deeper due to its increased traffic and the fact that it's a main route, not unlike the Canale della Giudecca, which serves as a separation channel between Venice and the mainland, and reaches a depth of 30 to 55 feet. Of course, these depths are also subject to change with the tides as much of the world saw with the recent flooding in Venice and also change according to the season and time of year.
Recently, another idea has been discussed. Just as withdrawing groundwater can cause subsidence, injecting water can reverse it.
Injection was used successfully in Long Beach, California in the late s to halt subsidence caused by oil and gas extraction as well as groundwater usage. After the land surface dropped nearly 30 feet, injection stabilized the subsidence and a slight rebound in land surface elevation a little over 30cm was even seen in some spots. Early research indicated that a similar amount of uplift could be achieved in Venice, which could make a big difference for a city on the edge.
The precision of those predictions was limited, however, by the lack of detailed knowledge about the layers of sediment beneath the city. A new paper, published in Water Resources Research , adds that information and uses it to show that the idea really could work in Venice.
Without boreholes around the city to provide observations of the stratigraphy, researchers have relied on data gathered by seismic surveys. Like the familiar sonar systems used by submarines, seismic surveys require a much more powerful signal to be generated so its return can be analyzed as it bounces off sediment in the subsurface. And, attempts to use potent air and water guns as seismic signal sources caused problems by kicking up large amounts of sediment.
The Italian National Research Council acquired a large amount of old, raw seismic data from an Italian oil company, and the researchers were able to use it to construct a high-quality, three-dimensional model of the stratigraphy below Venice.
This allowed them to confirm the presence of a continuous layer of impermeable clay below which injected water could increase pore pressure, rather than simply bubble up to the surface. It also allowed them to determine the thickness and extent of the various layers proposed to be used for the injection. The group simulated the effects of 12 injection wells in a ring around the city. The results showed that, after 10 years of continuous seawater injection a total of almost million cubic meters of water , the city could be lifted centimeters.
That would greatly cut down on the frequency with which the MOSE floodgate system would have to be activated each year. As the wooden support in Venice is submerged underwater, they are not exposed to oxygen, one of the elements needed by microorganisms to survive. In addition, the constant flow of salt water around and through the wood petrifies the wood over time, turning the wood into a hardened stone-like structure.
As a city surrounded by water, Venice had a distinct advantage over her land-based neighbours. For a start, Venice was secure from enemy invasions. For instance, Pepin, the son of Charlemagne, attempted to invade Venice, but failed as he was unable to reach the islands on which the city was built. Venice eventually became a great maritime power in the Mediterranean.
For instance, in , Venice allied itself with the Crusaders and succeeded in capturing the Byzantine capital, Constantinople. Nevertheless, Venice started to decline in the 15 th century, and was eventually captured by Napoleon in when he invaded Italy.
As of today, the lagoon that has protected Venice from countless foreign invaders is the biggest threat to its survival. To the local Venetians, the flooding of the city seems to be a normal phenomenon, as the water level rises about a dozen times a year. These floodings are known as aqua alta high water , and are generally caused by unusually high tides due to strong winds, storm surges, and severe inland rains. However, this is happening more frequently in recent years due to the rising sea level caused by climate change, which is starting to alarm the city.
Thus, a number of solutions have been proposed to rescue Venice from sinking. One of these measures is the Mo. This involves the construction of 79 mobile floodgates which will separate the lagoon from the Adriatic when the tide exceeds one meter above the usual high-water mark. Nevertheless, some pessimistic observers doubt that such measures will be sufficient to preserve Venice forever, and that the city will eventually sink, just like the fabled city of Atlantis.
Featured image: Beautiful Water Street Venice. Photo source: BigStockPhoto. Lansing, M. The Story of Venice. Merali, Z. Saving Venice. Och, M. Schlamp, H. Simmons, B. Tee, P. Venice and its Lagoon.
Webb, B. Venice: Rising Water, Sinking Land. Wikipedia, Although his primary interest is in the ancient civilizations of the Near East, he is also interested in other geographical regions, as well as other time periods Read More. There is no edit function here that i could find.
I meant to say, the rise was at first very rapid, but since has been slow small and consistent. You are correct that that the flooding has nothing to do with "climate change" this being the fake-science short hand for Man Caused Global Warming.
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