29 October 2013

Introduction to the Midi

Early on Tuesday afternoon, the 8th of October we left Étang de Thau and entered le Canal du Midi. Half an hour later we arrived at the first lock to find it closed for lunch, so we secured to the waiting quai. While Edi prepared a quick lunch for us, I walked up to the lock to look at the bollard arrangement and to plan our passage through it. 

The canal connects the Étang de Thau on the Mediterranean to Toulouse, where it joins Canal de Garonne, which leads past Bordeaux to the Atlantic. 

The canal rises 189.4 metres through 74 locks over a distance of 183.5 kilometres to a 5 kilometre summit pound. From there it descends 57.18 metres through 17 locks in 51.6 kilometres to Toulouse and the junction with the Canal de Garonne. 

Construction of the canal was begun in 1666 and it was completed in 1681. The inspiration and driving force behind its construction was Pierre-Paul Riquet. At the time it was widely praised as one of the great achievements of the seventeenth century. It was initially named Canal royal en Languedoc, but with the Revolution in 1789 it was renamed Canal du Midi. In 1996 it was named as a UNESCO World Heritage Site, described as: “one of the most remarkable feats of civil engineering in modern times”. 

Most of the locks on the canal have curved sided chambers, though a few have been rebuilt with parallel sides. The original dimensions of the chambers are 29.2 metres long with a maximum width of 11 metres at the centres. The entrances past the doors are 5.8 metres wide, the design principal being to allow two 20-metre barges of 5 metres width to easily fit into the lock simultaneously. The average height change of the locks is 2.1 metres.

Shortly after 1330, Madame l’éclusier finished her lunch break and pushed the appropriate buttons on her portable box to open the gates and allow us in. The rise of this lock is only 1.51 metres, so looping the bollards was easy, though with a broken mid-point bollard not replaced, we were rather strung-out with our lines. We made it through our first curved lock unscathed and motored out with a better idea of what to expect.

Very soon out of the lock we passed through a section of canal where all the Plane trees had been cut down. In 2006 the first outbreaks of coloured canker were detected. This disease is caused by a microscopic fungus, now believed to have come to France during WWII in the wood of US Army ammunition boxes.  The number of infected trees reach 83 in 2008 and 153 in 2009. 

Selective tree-felling campaigns have been conducted to try to stop the spread but with no effect. In addition there is no effective treatment against the disease. By 2011, 211 areas and 1,338 diseased trees had been identified.

There is now a fifteen-year program to remove all 42,000 Plane trees along the Canal du Midi and replace them with other species. Costs will run to a quarter billion Euros.

We finally came to a section of canal with seemingly healthy trees; at least they were all standing and all still had leaves.

We passed through Écluse de Garde de Prades and into l’Hérault. The flood gate is open except in times of flooding on the river.

For a short stretch, the river serves as canal, turning after about a kilometre into an arm leading to l’écluse ronde d’Agde. This lock was built in 1680 with a perfectly round chamber to allow barges to enter and choose to be lifted and go straight ahead into the continuation of the Midi, or to be lowered and turn left into the river Hérault below the weir. It was a wonderful piece of seventeenth century ingenuity and engineering. Unfortunately, its beauty and symmetry were destroyed in 1984 when it was modified to allow Freycinet gauge grain barges to use it.

About a kilometre and a half after the lock we came to one of the more famous bridges along the canal. Le Pont des Trois Yeux, the Bridge with Three Eyes. This is one of the 126 stone bridges that had been built across the canal, many of which are still in use today.

The bridge gracefully spans a wider section of the canal, providing one arch for navigation, one for the towpath and one to allow better water flow. 

Four kilometres further along we came to a complex structure, l’ouvrages du Libron, the works of Libron. This unique structure allows the canal to traverse the Libron River. Where the canal and river intersect, the Libron is at sea-level and the Canal du Midi is very slightly above, so a traditional aqueduct was not an option.

The problem was further exacerbated by the Libron's propensity to flash flood up to twenty times a year. The problem was originally solved by the building of a pontoon aqueduct known as the Libron Raft which utilised a flush-decked barge to fill and protect the canal channel in times of flooding, allowing the river and its debris to flow over the barge. 

Because the raft blocked the canal, navigation was closed until the flooding subsided and the barge could be removed. To replace the barge, in 1855 the works were built to better allow the two streams to coexist. The structure was designed to allow the river to be directed to allow a canal boat to safely pass and to limit the mud and debris being deposited into the canal by the flooding river.

The works allowed the river path nearest an approaching boat to be stopped for sufficient time to allow the boat to cross through that area and rest for a time in the "protected area" between the two paths. The river path behind the boat is then returned to flow and the path in front of the boat is halted, allowing the boat to cross this second path without interference.

This “new” solution, barely over a hundred fifty years old, elegantly solves the problem.

We uneventfully passed through Écluse Portiragnes and under another graceful stone bridge.

At 1640 we secured to bollards on a quai just downstream from the lock in Villeneuve-lès-Béziers. We had come 49.9 kilometres and had passed through three locks since we left Frontignan midmorning.

At 0855 on Wednesday morning we slipped and headed up toward the next lock a hundred metres along. There was no delay in passing through it, nor with the next one a kilometre further up canal. Four kilometres further along we pulled over and secured to bollards to wait for three boats to be cycled down in Écluse Béziers.

While we were waiting we were entertained by the manoeuvring antics of a bangy boat attempting to moor on the canal bank astern of us. We watched as it somehow got perpendicular to the Left Bank. There was no wind and with negligible current in the canal, we could not figure out how the skipper managed to do it.

Then, as if to reverse the error, the boat somehow managed to do a 180º turn and ended up with its bow on the Right Bank.

The boat was sufficiently far away from us that we thought it safe to divert our attention and watch the parade of boats coming out of the lock. They were all rentals, and offered a more immediate threat.

By the time they were safely past us, the bangy astern had finally managed to secure parallel to the bank.

Écluse Béziers is a modern parallel-sided lock built to replace the original curved-sided double lock. Because it replaces two locks, it is double height. At 4.24 metres, it would be nearly impossible for an up-bound boat to loop the bollards at the top, so the chamber has mooring rods set in indents in the walls. The looped mooring lines slide up these as the water rises. The next lock, Écluse Orb is only 375 metres further along and appears to replace an original multiple set of locks that brought traffic back up from the River Orb. It has parallel sides, is 6.19 metres high and has the same system of mooring rods. Locking through both of these was easy.

From Écluse Orb we motored across le pont-canal de Béziers. This superb bridge was built in 1856 to finally end the need for barges to descend to the Orb, cross it and lock back up the other side. It is 198 metres long supported on arches of 17 metre span and it is considered to be by far the most attractive of the nineteenth century stone canal bridges. 

A kilometre further along we came to the traffic light controlling the entrance to l’échelle de Fonserannes. We were delighted that it was green as we approached; passage is tightly scheduled. Up-bound traffic this time of year is between 1000 and 1215 and then 1600 and 1815 and the passage takes 30 to 45 minutes. L’écluse de Fonserannes, which is also called les neuf écluses, is a staircase lock that consists of eight interconnected ovoid lock chambers and nine sets of gates. There were originally two additional locks that connected the bottom of the staircase to the river, but since the 1856 opening of the aqueduct over the river, these are no longer used and the entrance to the system is now in the side of the seventh chamber.

I dropped Edi off on the quai at the entrance and then continued into the chamber, while she climbed the stone steps to the top of the first lock to take the lines. We settled into place, the gates closed behind us and the sluices were opened to flood our chamber from the next one up the ladder. 

When the next chamber above us had drained into our chamber, our upstream doors were opened and the sluices in the next set of doors were opened to continue filling the two chambers. The initial surge of water was a bit frightening to see coming down the chamber toward our bows like a tidal bore. However, Zonder Zorg was well-positioned and the brunt of the wall of water passed down our port side making it rather easy tending the bow line to keep us against the wall.

We had the stern line led aft to a bollard as a spring and I was motoring forward on it with the tiller lashed to keep the stern in. I monitored this from the bow and had to tie-off the bow line and go aft only once or twice per lock to adjust the stern line or the tiller.

Once the water level in our chamber had reached the proper depth above the gate cill, l’éclusier motioned us to move forward into the next chamber. As we waited for the next buttons to be pressed by l’éclusier, we had the entertainment of watching the bangy boat bounce its way in and bumble alongside the other wall. Finally the gates were closed astern of us and the process repeated. 

Les neuf écluses, was built to take barges 21.5 metres up and down the steep sidehill above the valley of the Orb. It was one of the major engineering accomplishments on the canal. Pierre-Paul Riquet had planned and engineered and lobbied for thirty years before King Louis XIV approved the construction of the canal in 1666. 

Among his planning was a visit to the Canal de Briare, where he studied les Septs Écluses, the flight of seven locks there. 

The Briare had been completed in 1642 to connect the Loire to the Seine. Its 57 kilometre length and 36 locks take barge traffic up 41 metres from the Loire Valley and then down 85 metres on the other side toward the Seine. It was the first summit level canal in Europe and Riquet gathered ideas from it for the Canal du Midi. 

The building of a canal to link the Atlantic to the Mediterranean was an old idea with many projects being previously devised. Leaders such as Augustus, Nero, Charlemagne, François I, Charles IX and Henry IV had dreamed of it for its political and economic benefits. François I even brought Leonardo da Vinci to France in 1516 and commissioned him to survey a route from Toulouse to Carcassonne. 

We quickly progressed up the lock staircase and a little over 25 minutes after we had entered the first chamber, we were looking into the final one.

Then a couple of minutes later we were in it and rising to its top. L’échelle de Fonserannes is one of the three most popular tourist destinations in the Midi, along with Pont de Gard and Carcassonne and we were closely watched all the way up. The tourists obliviously interfered with our attempts to get mooring lines onto bollards and dangerously stood in line loops.

The view back down the flight is superb, and made all the more so by having just spent half an hour getting to know it intimately.

At 1211, thirty-one minutes after we had entered the first chamber, we exited the final one. L’éclusier could take an extra four minutes for lunch. From the top of l’échelle de Fonserannes begins the longest bief of the canal. For 54.2 kilometres there are no locks as the canal winds around the sides of low hills and ridges at 33 metres above sea level.

We motored out and soon came upon a logging scene, as crews worked at removing infected Plane trees from the canal banks.

At 1303 we came to the spud pole and a pin pounded in the bank just upstream of Pont de Colombiers. We had initially stopped for lunch, but found the place so pleasant and restful that we decided to stop for the day. We had come 14.2 kilometres and up 11 locks. 

Astern of us was a bangy boat flying a huge Canadian flag. We chatted for a while with the two couples from Vancouver who were aboard.

In the late afternoon, a prime candidate for the ugliest boat design award motored past.

At 1055 on Thursday we raised the spud pole, retrieved our mooring pin and continued up the canal. Within a kilometre and a half we came to the entrance to le tunnel de Malpas, the first canal tunnel in Europe. As we approached we acknowledged the signage by blowing our air horn, hoping that any oncoming bangy boat skipper knew the meaning of our signal and knew to blow his own horn.

We received no response from our signal, so we proceeded into the one-way tunnel. The interior is lined with a vault of cut stone and there is a narrow towpath along the Left Bank side.

About midway through, the cut stone vaulting gives way to a coarse spongelike surface, which some sources call sprayed concrete and others eroded limestone. It looks like a combination of the two.

At 1252 we secured to pins pounded into the bank about 100 metres short of the new bridge in Capestang. We had come only 11.8 kilometres and it was still early, but this looked to be a very pleasant place, so we decided to pause for a while.

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