Archive for Water

1x1.trans Petition to halt the Canale Contorta Solution

This is one view of what a lagoon looks like, especially when the tide is going out and the clams are just waking up.

This is an unusual step for me, but I think it’s worth it.  Even though I don’t place much trust in the power of petitions, maybe this time it will be different.

In any case, I’d like to inform you of one which has gone from 700 to 20,000 signatures and counting in about ten days.  I think that means something.

“Gruppo 25 aprile” is a new group of Venetians and Venice-lovers which is concentrating its efforts on stopping the digging of the “Canale Contorta.”  Its reasons are shared by many scientific and environmental experts, not to mention a huge percentage of everyday Venetians.

Once the subject of the big cruise ships and their potential to damage Venice became one of the hottest debates and power struggles of the year, the need for finding an alternate route from the Adriatic to Venice obviously became paramount.  My own opinion is that any “cure” they find will be worse than the “disease” (i.e., the ships in the Bacino of San Marco) — or, as the Venetians put it, el tacon xe pezo del buso (the patch is worse than the hole).

Many solutions have been proposed, but only one had the political muscle behind it to get itself officially considered by the “Comitatone” (“Big Committee”) in Rome, which had the power to decide yes or no.  That “solution” is the dredging of the Canale Contorta.

1x1.trans Petition to halt the Canale Contorta Solution

Sorry it’s in Italian. The red line shows the current route by which cruise ships enter and leave Venice.   The solid yellow line is the Petroleum Canal.  The dotted yellow line is the Canale Contorta, which already exists in a simple, primitive, shallow way.  Changing that will change a whole lot besides.  (www.corriere.it).

Thanks to a calculated maneuver by its promoters, the meeting at which the decision was to be made was held in August.  (“August” is Italian for “vacation.”)

As Marco Gasparinetti, the coordinator of Gruppo 25 aprile, explains (translated by me from the Gazzettino):

“The decision of the Comitatone on August 8 was a summer blitz with which they hoped to surprise a city on vacation.  But the city is fed up with being expropriated from the decisions which concern it, and this time is going to make its voice heard.”

The political vacuum in Venice since the government fell on June 4 has at least one positive aspect, and that is that finally there seems to be some possibility that the voices of Venetians might be heard somewhere beyond their living rooms and favorite bars.  Yes, there is chaos in almost every aspect of daily life here now, but the fact that essentially only one man is in charge — Vittorio Zappalorto, the Commissario who is temporary governor — means that the city is less strangled by the political and bureaucratic tentacles of the past 20 years.  It’s as if — to try another metaphor — a colossal dose of drain cleaner has ripped through the city’s emotional and civic pipes.

Back to the Canale Contorta.  It may not be too late to stop it.  Therefore Gruppo 25 aprile has created a petition addressed to Prime Minister Matteo Renzi, as well as all the ministers concerned (Environment, Infrastructure and Transport, Culture, etc.) urging them to withdraw the hasty approval of what it (and I) regard as a catastrophic move, the last nail in the coffin of the lagoon after the drastic effects of the MOSE floodgates, not to mention the Canale dei Petroli (“Petroleum Canal”), dug in 1969.

1x1.trans Petition to halt the Canale Contorta Solution

A drawing from the 1980′s shows the network of canals, or “ghebi,” in the lagoon. In 2002, a NASA satelite shows the same area, pretty much leveled and smoothed out by the terrific suction of the Petroleum Canal over the years. (Umberto Sartory, 6/29/2006, venicexplorer.net).

The page connected to the link above shows a map (left) from the 1980′s which outlines the major and some minor natural channels (ghebi) which used to cross and re-cross the lagoon.  It represents a complex biological realm which the effects caused by the Canale dei Petroli, in 40 years, has done much to destroy, as shown by the NASA satellite image made in 2002 (right).  Do you see ghebi?  I see just a broad, anonymous stretch of bottom.  That’s what the fish see, too.

1x1.trans Petition to halt the Canale Contorta Solution

Lagoons are rich, meaty environments. The sea is also nice, but not like this. I believe the difference is easy to see.

Here is a section of a brief but pointed piece by Tom Spencer, reader in coastal ecology and geomorphology at the University of Cambridge, and director of the Cambridge Coastal Research Unit:

Coastal lagoons are transitional environments between fully terrestrial and fully marine conditions; in the absence of direct human intervention, their long-term tendency is to infill with sediments. Over the centuries, the Venetian Republic was instrumental in maintaining this vital yet delicate land/sea balance, starting with the huge undertaking to divert the main rivers in the 16th century and stop the region from silting up altogether.

Since that time, however, historical and near contemporary records of changing patterns of lagoonal topography and water depth; tidal currents; and sediment transport from the lagoon to the sea all show unequivocally that the current lagoon is moving in the opposite direction, becoming a downward-eroding, sediment-exporting system. It is thus on a trajectory that will turn it into a fully marine bay. That this process is well underway is evidenced by the appearance of plant and animal species in the lagoon that are characteristic of marine environments.

We may argue about the velocity of this trajectory but the evidence for such a trend, clearly related to a whole series of human interventions from the late 18th century to the present, is not in doubt. As wave height and tidal flows are strongly influenced by water depth, such a shift has critical importance for the sustainability of the historic core of Venice itself. If we drill down into the detail behind this general trend, it is clear that the excavation of two large canals (Canale Vittorio Emanuele, around 1925, and Canale Malamocco Marghera, around 1969) produced strong transversal currents across the original tidal network, with consequent siltation of channels and erosion of adjacent shallows.

There is one simple question that needs to be answered. Can we be assured that the large-scale excavation of the Canale Contorta will not have the same effect and not give the Venice lagoon a further shove in the direction of yet more environmental degradation and urban vulnerability?

The petition asks the national government to reconsider all the proposals.  That seems like an extremely modest request.

The petition can be signed online.  Here is the link explaining their position, with the possibility of signing.  (“Firma” means “signature.”)

Or, you can copy and paste:

http://www.change.org/p/stop-the-plan-to-dredge-the-maxi-canal-contorta-in-venice-before-it-s-too-late

If anyone might be tempted to suppose that Venice can be happy and healthy in the middle of a maimed and deformed lagoon, that person should consider this: That the water through the Canale Contorta will enter or leave the lagoon with a force and a quantity that will endanger the city to a degree that the biggest cruise ship could never dream of.

1x1.trans Petition to halt the Canale Contorta Solution

The lagoon is loaded with egrets who might like to be considered in the great scheme of things.

 

Categories : Water
Comments (0)
Nov
12

San Martino blows through

Posted by: | Comments (14)
1x1.trans San Martino blows through

It amuses me to see boats floating up so high. In a really serious acqua alta, they can go high enough to slip off the top of their pilings, though this enterprising/lazy/cheap person has opted to skip buying pilings and tied his destroyer to the barrier instead. This is risky, considering that the force of the tide (either rising or falling) can pull the boat down on one side. Then the boat fills with water.  I have seen this with my own eyes; they say the boat has “hanged” itself, just like a person.  By the way, I notice that this owner is unnaturally concerned with the potential contact between the hull and the fondamenta.  Five fenders?  Are we waiting for a tsunami?

Saint Martin’s day yesterday was a lot more emphatic than it usually is with the banging of pots and pans by kids on a quest for candy.  In addition to the kids, and the traditional cookies, we got acqua alta — the second visitation of the season, and it was noticeable.  The news tonight reported that it had reached 149 cm (4.8 feet)  above sea level, the sixth highest since 1872.  (The highest on record remains November 4, 1966, which was 190 cm/6.2 feet).

Water didn’t enter our hovel, but it didn’t miss by much.

We heard the sirens sound, as expected, two hours before the peak predicted for 8:20 AM.  There were three extra tones, which indicated an anticipated maximum of 120 cm (3.9 feet).  Not long after that, we heard the sirens again, this time with four tones (140 cm/4.5 feet).  At that point we sat up and began to pay attention.

What made this event more interesting than usual wasn’t simply the height of the water, it was the speed of the wind — I mean, the force of the scirocco, which is always a major factor in keeping the lagoon in when it wants to go out.  The wind was blowing around 40 km/hr (24 mph), with gusts of 55 km/hr (34 mph).

All this was part of a major weather system that hit large areas of Italy leaving real drama and destruction in its wake — mudslides, blocked roads, fallen trees, and more mayhem than we could ever manage here, thank God.

Naturally we went out to buy the newspaper and look around the neighborhood.  I don’t usually take pictures of acqua alta anymore, as they have long since become repetitive.  But this was toward the unusual side of the daily scale of nuisances.

Of course I’m glad the water didn’t exceed our top step, but if it had, I’d still be alive.  This is the first of my annual pleas to the world to  ignore the wailing and gnashing and published or broadcast claims that the city has been driven to its knees.  I do not consider the fact that a tourist has had wade across the Piazza San Marco carrying her suitcase on her head an indication of anything larger than a temporary annoyance — it certainly does not make  even the tiniest wail begin to form anywhere in my thorax. Anyone who has been dealing with Hurricane Sandy and its aftermath — not to mention people in stricken areas of Tuscany and Umbria — would find the suggestion that a large but temporary inconvenience could be compared to life-threatening catastrophe not only ridiculous, but offensive.  By noon the water was all gone and the streets were drying off.

1x1.trans San Martino blows through

We hadn’t even reached the end of the fondamenta before we got inconfutable evidence that in spite of the blasting wind and rain and water up to our thighs that the tide had turned: Under the boats, the  anguele (Atherina boyeri)  were all facing upstream, against the tide.

1x1.trans San Martino blows through

As usual, somebody had left a bag of garbage out on the street. You can’t pick them all up as they float around and away, but this was the first one we came across and Lino decided he had to do something about it. Nobody would have noticed, or cared, but I was impressed and I know he felt better.

1x1.trans San Martino blows through

The owner of our favorite cafe didn’t even try to keep the water out, though she did take all the boxes of panettone out of the window display and stacked them up on the counter along the wall. As she told us later, there’s no point in putting a barrier across the door — the water just comes in some other way. In the case of the cafe across the street, jets of water were coming in through fissures in the wall even as he was pumping the water out. Meanwhile, this lady is here every day, reading. Why let a little water ruin a perfectly fine routine?

1x1.trans San Martino blows through

Many of the shops along via Garibaldi were being pumped out — it was like walking around the gardens of the Villa d’Este with all the fountains.

1x1.trans San Martino blows through
I was struck by yet another illustration of the fact that Venice is not perfectly flat. We were sloshing along in our hipwaders, while just beyond the gate there was high ground. When the acqua isn’t alta, you’d think it was all level.
1x1.trans San Martino blows through

As you see, not everybody got the memo that the city was afflicted with a desperate situation. This is Venice with acqua alta: People waist-deep in the Piazza San Marco carrying their suitcases on their heads, people sitting in cafes as the water laps at their chairs, and some people (they were French, for the record) who think it’s all more fun than watching elephants ride a roller-coaster. So take your pick. Tragedy? Comedy? Farce?

1x1.trans San Martino blows through

As we got closer to the Riva dei Sette Martiri facing the lagoon, the reality of the tide going out began to really mean something. The combined power of the water channeling out of the Grand Canal and the Giudecca Canal toward the sea hit the embankment approximately at the end of via Garibaldi. Lino said he’d never seen anything like this, and he’s seen every acqua alta in the past 70 years. Walking against this was like walking against an Alpine torrent. (Apologies for the blur — the wind and rain were also picking up force here.)
1x1.trans San Martino blows through

Someone pauses to assess the situation as we near the edge of the Riva. As you can tell, there’s relatively little to assess. If you’re still standing up, you’re okay.

1x1.trans San Martino blows through

The only yacht moored near the Arsenal was in a fairly unpleasant situation. Perhaps the waves wouldn’t have lifted it up onto the pavement, but it was making progress to having its expensive hull  well and truly bashed and dented. The only two people on board were working like madmen to push the fenders between the stone and the metal. But it was a doomed endeavor. Why? Because the wind and water were pushing against them, and for some incomprehensible reason they had not slackened one of the lines attaching the boat to the fondamenta. Even if these two were Samson and Hercules, they couldn’t have pushed the boat out further than the rope would let them. And yet they kept trying. I wanted to go say “Untie the line!” but Lino said “Don’t even think of getting yourself involved, for the sake of the souls of all my dead relatives.”

1x1.trans San Martino blows through

I have the utmost respect for the fact that they were giving it all they had to protect the boat (though then again, why it took them so long to remember the fenders is a mystery. The high-water siren sounded at 6:00 AM and it’s now 9:30.) Instinct clearly has taken over, because two people with a combined weight of perhaps 300 pounds couldn’t possibly shift an object weighing at least a ton being pushed by the combined strength of Poseidon and Aeolus. I hope they’re okay today. I hope they didn’t get fined, or fired, when the boss called in to check on his boat.

1x1.trans San Martino blows through

Despite the surging water and lashing waves and all, here is undeniable proof that the tide is falling: Detritus left behind on the steps of the bridges. I don’t usually find trash appealing, but this was a beautiful thing to see.

 

 

 

Categories : Acqua Alta, Water
Comments (14)

So the Costa Concordia ran aground (January 13) and the administration here instantly went into several varieties of fits to show how eager it was to ensure that no such catastrophe could ever be inflicted on the most-beautiful-city-in-the-world by one of these leviathans, whose number is increasing at a Biblical rate.

1x1.trans The latest big fat idea for the big fat ships

Passengers see a ship. The anti-ship cadre sees a potential disaster. The city government sees a floating Brink's truck loaded with money, without which Venice can no longer survive. You decide.

Mission: Banish the Big Ships from the Bacino of San Marco where they might well run into a section of historic and irreplaceable real estate. I haven’t seen any calculations on the odds of this risk, but they may be similar to the odds of winning the lottery.

Lots of people who buy a lottery ticket think/hope that the probability of winning could be pretty good.  In the same way, lots of people who see the big ships passing think/fear that the probability of a huge catastrophe could be pretty good.  The distance between “could” and “might” is hard to measure when emotions run high.

The mayor, of course, promised rapid solutions, to be followed, naturally, by immediate results (hence the use of the word “solution”).  As expected, “rapid” is morphing into “eventual” on its way to “maybe” and then — who knows? — “never.”

1x1.trans The latest big fat idea for the big fat ships

The Petroleum Canal, which has already done so much damage, is the right angle on the left of the frame. The proposed new extension to the cruise port is the slightly sagging line connecting it to Venice. The idea would be to assign either the arrival or departure of a big ship via this route,thereby halving the number of transits of the bacino of San Marco.

The first proposal launched — and so quickly as to have barely resulted from first thoughts, much less second thoughts — was to dig a new canal. The environmental damage this would cause is so vast and so obvious that it’s hard to believe it was even discussed.  A large amount of information demonstrating what a terrible idea it is was instantly thrown in front of this notion to prevent its going any further (latest detail: deepening the Canale di Sant’ Angelo would mean having to tear out and reposition somewhere else a certain quantity of important cables buried there, not to mention the high-tension-wire pylons flanking it).  Even the cost of this undertaking hasn’t caused this notion to be officially abandoned, but its momentum seems to have slowed.

But if a new canal makes no sense, the proposal made a few days ago obliterates the line between creative and cuckoo. I wouldn’t even have mentioned it, but I wanted to show how really hard it is to come up with an alternative to the present system.

Ferruccio Falconi, a retired port pilot (who you might think would be more familiar with the lagoon and its behavior than most), has pulled the pin on the following idea and tossed it at the groin of common sense.

He proposes gouging out the mudbanks between the island of Sant’ Erasmo and the inlet at San Nicolo’, an area known as bacan’ (bah-KAHN).  On the map, it looks like useless empty space longing for a purpose in life.  But it already has a purpose — two of them.

1x1.trans The latest big fat idea for the big fat ships

This view shows the lagoon inlet at San Nicolo' on the left; in the middle is the island created for the MOSE project, which has already affected tidal behavior. "Bacan'" is the beige area in the big channel to the right, a swath of mudbanks with a temporarily exposed islet fronting the lower edge of the island of Sant' Erasmo. (Photo: Chris 73, Wikimedia Commons).

Its first purpose is the same as that of similar areas which compose the bloody-but-unbowed natural lagoon ecosystem. Mudbanks and barene, the remnants of marshy wetlands scattered around, are an essential component of the lagoon environment.  You may not care about clams and herons and glasswort, but these formations also slow the speed of the tide, something that ought to interest people ashore in the most-beautiful-city at least as much as the vision of a ship heading toward the fondamenta.

Its second purpose is as one of the all-time favorite places for thousands of pleasure-boaters to spend long summer days swimming and clamming and picnicking.

1x1.trans The latest big fat idea for the big fat ships

Doesn't this look neat and tidy? Eight ships all snugged up together. While constant dredging would undoubtedly be required to keep the area from refilling with sand and mud, that effort would be helped by the vortexes created by cruise-ship propellers. (Photo: Il Gazzettino)

But according to Falconi, the creation of a basin where nature never put, or wanted, or intends to keep one, would be the perfect place to park the cruise ships. Ergo, there would also have to be the construction of a huge jetty.

As simple geometry, it looks okay, though I failed geometry. But apart from the problems the size, weight, and propeller-power those eight little rectangles represent, there is also the inconvenient fact that Sant’ Erasmo is an island, raising the issue of by what means the floating Alps of the sea would be provisioned, and how the passengers would arrive and depart.

Simple: By boat. Thereby increasing by several powers of ten the amount of waves (motondoso) caused by the multiplied number of motorized craft running around the area (barges, taxis, launches, and scows carrying trucks). Motondoso has already damaged a lot of the lagoon, so this new activity would eradicate a new chunk of what’s left. The summer motorboats are already sufficiently destructive — why would even more be seen as a good thing?

This idea is yet another example of the point where Feasibility and Desirability break up, despite the best efforts of people with assorted motives to make them get married and have children.

1x1.trans The latest big fat idea for the big fat ships

The "Ruby Princess" backing out of its berth at Tronchetto, like its companions, scours up a lot of sediment, not all of which settles back where it came from.

The following letter to the Gazzettino (March 29, 2012) gives an excellent analysis of this suggestion (translated by me):

LAGUNA CROCIERE E GRANDI NAVI  (Lagoon, cruises, and big ships)

I read in the Gazzettino of the new proposal to “save” the cruises.

One appreciates the fantasy that unfortunately is right in step with the temerity of certain choices which we see at all institutional levels in the management of this problem.

To excavate bacan’ at Sant’ Erasmo to make it feasible for the big ships to maneuver and moor, ships which are tending to get bigger, would signify changing the hydrodynamics of the North Lagoon.

The creation of the new island in front of the inlet (at San Nicolo’) has already caused an increase in the velocity of the incoming tide, creating hydrodynamic imbalances with important consequent damage to the city.

To create a basin of 12 meters (40 feet) deep, at the least, to move and accommodate ships would make even that piece of lagoon into a piece of the sea.

Perhaps the fanciful pilot who has come up with this “loveliness” has forgotten about the abyss in front of San Nicolo’ with the resulting collapse of the bastions of the Fort of Sant’ Andrea a few years ago.

One understands that unfortunately the mentality still hasn’t changed: One tries to resolve a problem creating others. Or to put it this way: the application of the theory that has created MOSE: one creates a “solution” which, to talk about it, resolves the effects but not the cause.

The question arises spontaneously: Is the port worth the city?

(signed) Manuel Vecchina, Venezia

Excellent question, but don’t put it to Falconi.  He’s already got the answer.

1x1.trans The latest big fat idea for the big fat ships

Here's a view of the area where the eight ships would park, with Sant' Erasmo in the background. Low tide reveals how much mud and sand there is, and how far below the surface it is. Guess Vittorio Orio will have to find another place to work on his mascareta, to make room for the Queen Victoria, the Norwegian Gem, and so on.

1x1.trans The latest big fat idea for the big fat ships

A winter view of the same area, seen from the shore of Sant' Erasmo. It may look empty, but you should just see how much life there is bustling around in there.

1x1.trans The latest big fat idea for the big fat ships

And here's a glimpse of how much life is bustling around the surface on a typical summer day here. Actually, this is nothing -- there are boats anchored all over bacan'.

1x1.trans The latest big fat idea for the big fat ships

Egrets like to eat too, but if the big ships move in, all this will wash out to sea and the birds will have to bring their lunch with them.

1x1.trans The latest big fat idea for the big fat ships

By "big ships" I mean something like this.

The Venetian lagoon is one of the most important coastal ecosystems in the entire Mediterranean.  A century ago there were 35 square miles of salt-marsh wetlands in the lagoon; due to erosion by motondoso and the tidal force increased by the Petroleum Canal, by 1990 there were only 18 square miles left. Now we have MOSE, the floodgates whose installation required extreme deepening of the inlets, creating even stronger tidal flows.

In little more than 30 years, some 25,000,000 cubic meters of sediment have been flushed out to sea.  At the current rate of erosion, the World Wildlife Fund has estimated that by 2050 there will be no wetlands left. So Venice is spending masses of money to rebuild a batch of them where they’ve been eroded away. Where they will be eroded away again. Now we want a fantasy port to speed up the process which is turning the lagoon into a bay of the sea?

I sometimes think that if these people want to change the lagoon so much, why don’t they just drop a bomb on it, and get it over with?

1x1.trans The latest big fat idea for the big fat ships

The fort of Sant' Andrea was built in the mid-1500's to defend the approach to Venice from enemies entering at San Nicolo'. The cannon were placed at the waterline in order to blast out the hulls of any approaching enemy ships. At low tide the cement apron is easy to see.

The reference to the Fort of Sant’ Andrea in Vecchini’s letter recalls the fact that some years ago (even before MOSE) the force of the tide was eroding the island beneath this historic structure, and the walls of the entrance were beginning to sag and open up. Solution: Throw masses of cement on the shallow lagoon bottom in front of it to stop the slow-motion collapse.  When we row past there, we have to avoid what is essentially a broad cement shelf reaching outward from the fort.  Of course I’m glad it’s there.  I’m just saying.

Venice wanted the ships, but playing with them and their effects is beginning to look a lot like getting into a game of strip poker with no cards at all.

And no clothes, either.

 

 

Categories : Motondoso, Water
Comments (6)
1x1.trans The Befana was here and she took the lagoon with her

One of the squillion Befanas that swarmed the stores. Snaggly teeth: check. Broomstick: check. Stockings crammed with candy: check. She's good to go.

January 6, as all the world knows, is the Feast of the Epiphany in the non-Orthodox Christian calendar.  Here in Venice, as most of the world by now must know (if it’s been following my bulletins), the day is personified by a grizzled old woman with a broomstick. This cheerful hag is known as the Befana.

Her arrival and swift departure bring joy to overstimulated and overfed children, even if the joy is tarnished by the fact that she signals the official end of the holiday period — back to school, the party’s over.

Anyone walking around Venice will have noticed, even with only one eye open (not recommended, unless that eye is dedicated to scanning the pavement ahead where the remnants of canine overfeeding may well be waiting), that her distinguishing characteristic is candy — specifically, a stocking full of it known as the calza caena (KAL-tzah kah-EH-na).

But anyone who has foregone the city for an afternoon ramble in the lagoon during this period will have noticed that her distinguishing characteristic is exceptional low tide.  This phenomenon is known as the “secche de la marantega barola,” or the exposed-sandbanks-of-the-ugly-old-lady.

1x1.trans The Befana was here and she took the lagoon with her

Our favorite patch of lagoon, between Sant' Erasmo and the Vignole, at a classic late-December/early-January low tide. Here the vegetation is of the non-green variety, but it still reveals plenty of snacks for the birds.

1x1.trans The Befana was here and she took the lagoon with her

The tide is still going out but the egrets have already started noshing. Among other wonders in this scene are what looks like scattered rocks: they're the half-submerged scallops known as pinna nobilis, or "noble pen shell." They are returning after not having been seen here for years.

1x1.trans The Befana was here and she took the lagoon with her

A pinna nobile as we normally see them.

High tide, of course, is the star around here, inspiring in transient visitors (fancy term for tourists) a mixture of fear, loathing, terror, pity, catharsis, and whatever other epic emotions a couple of inches of water on the ground can stimulate.  High water also makes for interesting pictures, even if they are all pretty much the same.

But every year I feel much greater emotions inspired instead by the absence of water.  When the tide really, seriously goes out, as it always does in this little window of time, a concealed world emerges, to the joy of the foraging wildfowl and the marveling eyes of your correspondent.  I know it’s not magic — it just feels like it.

1x1.trans The Befana was here and she took the lagoon with her

The same stretch of water on a summer afternoon. Not only is the water higher, the area is also swarming with trippers from the mainland who come in their motorboats and like to crawl around digging for clams. By the end of the summer they have left nothing behind, except the pinna nobiles. I think these mollusks must have a way of burying themselves, otherwise these savages would be taking them too.

The first time I saw this phenomenon I was taken completely  by surprise. Looking from the Lido across the lagoon toward Venice, I saw, instead of the usual expanse of grayish-greenish-blueish water, a vast swath of brilliant emerald green, dazzling marine vegetation gleaming in the sunshine.  It was like seeing Nebraska with bell-towers.  Of course I knew that the lagoon bottom wasn’t as empty and flat as the high-school swimming pool, but seeing it was astonishing.  I was hooked.

Why does January (or this year, also late December) always favor us with this phenomenon?  Myself, I’d just give the credit to the Befana and move on, but curiosity has nagged me into looking for a real answer.

After more research than I anticipated, most of which only led me dangerously deeper into the astronomical wilds, I will hazard a summary of the situation.

1x1.trans The Befana was here and she took the lagoon with her

The high atmospheric pressure not only conduces to the lower tide, it also brings weather which is little short of celestial. Yes, it's still chilly, but could anyone want to stay indoors when it's like this out here?

1x1.trans The Befana was here and she took the lagoon with her

The outgoing tide creates a sort of lagoon within the lagoon, dedicated exclusively to the birds.

It’s all based on the indestructible link between the sun, the moon, the earth’s orbit, gravity, centrifugal force,and probably other things as well.  (There is also a correlation between high pressure and low tide — the higher the first, the lower the second.)  But this only tells us what, not why.

One source explains:  ”The gravitational forces of the Moon and the Sun both contribute to the tides. The sun’s gravitational force is greatest when the earth is closest to the sun (perihelion – early January) and least when the sun is furthest from earth (aphelion – early July).”

Basically, the sun’s pull can heighten the moon’s effects or counteract them, depending on where the moon is in relation to the sun.

The Moon follows an elliptical path around the Earth which has a perigee distance of 356,400 kilometers, which is about 92.7 percent of its mean distance. Because tidal forces vary as the third power of distance, this little 8 percent change translates into 25 percent increase in the tide- producing ability of the Moon upon the Earth. If the lunar perigee occurs when the Moon is between the Sun and the Earth, it produces unusually high Spring  (not the season Spring) high tides. When it occurs on the opposite side from the Earth that where the Sun is located (during full moon) it produces unusually low, Neap Tides.

Neap: from the Anglo-Saxon hnep, meaning scanty. I knew you were wondering.

It so happened that the day I took the most dramatic photographs was December 23, when the waning moon was one millimeter from being completely new, which it was on the following day. I maintain that the new moon has the same effect as the full moon, as described above.

To sum up: In January, therefore, I deduce that the relative positions of the sun (low) and moon (high) combine with other factors — such as the aforementioned high pressure — to produce the unusually low tide.

You can have your Bay of Fundy, and I’ll throw in Mont-St. Michel as well.  I wait all year for this moment to see the lagoon revealed in its spectacular variety and richness.

Postscript: Low tide in the city is also diverting, revealing banks of mud lining the canal walls which were churned up by months, even years, of passing motorboats. It also, may I point out, creates at least as many problems as high water — if not more — for normal life here.  If the ambulance or the fireboat doesn’t have enough water to get to your house, it’s arguably worse for the quality of life than whatever happens in acqua alta — for example, having to put on boots for a few hours. This aspect of the secche de la marantega  deserves a chapter of its own, but not today.

1x1.trans The Befana was here and she took the lagoon with her

Between Sant' Erasmo and Murano, the bottom is revealed to be of yet another sort, mounds of hard mud covered with something green. The boat belongs to an old fisherman who is off in the distance digging clams where nobody ever goes. The brown flat fuzzy tableland behind the boat is all that anyone usually sees here, just inches above the water.

1x1.trans The Befana was here and she took the lagoon with her

More of the same area, at sunset. The tide is still going out.

 

1x1.trans The Befana was here and she took the lagoon with her

If the barometer has gone up to this extreme, you don't even have to look outside to know that the water's going to be amazingly low.

1x1.trans The Befana was here and she took the lagoon with her

People sometimes ask me, "How deep are the canals?" And I have to ask them, "When?" This canal at Sant' Erasmo clearly reveals the mark of the normal water level. And, as you see, we've only got inches to row on.

 

1x1.trans The Befana was here and she took the lagoon with her

Most people think the lagoon must be at its most beautiful in the summer. I beg to differ.

 

 

 

 

 

 

 

 

 

1x1.trans The Befana was here and she took the lagoon with her
Categories : Nature, Water
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