The Audomarois marsh: history, fauna, flora and traditions

A natural area recognized by Unesco

The marshes of Saint-Omer and Clairmarais: a must-see destination in Audomarois

Located 40 minutes from Calais and Dunkirk and one hour from Lille (Hauts-de-France, Nord-Pas-de-Calais), the Audomarois marsh has many surprises in store for anyone looking for an exotic nature destination steeped in history and authenticity. On the program: cultural outings in the town of Saint-Omer, guided boat tours, rowing or electric motor boat rides, hiking, cycling... A real breath of fresh air between town and nature!

In Saint-Omer and its surroundings, an exceptional natural site is indeed offered to visitors! Indeed, the Audomarois marshes, bordered to the east by the limits of inner Flanders and to the west by the foothills of Artois, are spread over fifteen towns in the Nord and Pas-de-Calais: Saint- Omer, Clairmarais, Serques, Éperlecques, Houlle, Moulle, Salperwick, Tilques, Saint-Martin-lez-Tatinghem, Longuenesse, Arques, Watten, Saint-Momelin, Noordpeene and Nieurlet.

Bacôve excursion in the Audomarois marshes (Credit: Philippe Hudelle)

The Audomarois marsh in a few words

This labyrinth of land and water, stretching over 3700 hectares (37 km2), includes 700 kilometers of waterways, of which 170 kilometers are navigable! In addition to these revealing figures of the size of this natural space recognized as a Biosphere Reserve by UNESCO, let us underline its historical richness as well as its ecological importance.
It was once a peat wetland still affected by high tides via the Aa River in Carolingian times. Then the men appropriated the place little by little: the monks of Sithiu (former name of Saint-Omer) as well as of the abbey of Clairmarais, extracted the peat there, the farmers polderized the places, the drainage canals multiplied in order to evacuate the water towards the sea, the significant arms of water were channeled in order to allow the development of trade and international exchanges in Saint-Omer... In the XNUMXth century, the marsh appears to us almost as we know him today; a space sometimes inhabited, sometimes wild, or sometimes cultivated by Audomarois market gardeners still perpetuating the tradition of summer cauliflower from Saint-Omer as well as winter endive.
A discreet destination but nevertheless full of surprises, the last market gardening marsh in France is a delight for hikers, fishermen and lovers of nature outings by boat in a preserved environment. It is on board the traditional market gardeners' boats, the escutes and the bacôves that the last boat builders in the region offer you trips full of authenticity in "cruise" mode in the heart of this natural environment shaped by man.

Let's discover without further delay the Audomarois marshes, its history, its fauna and its flora!

Summary :
The Audomarois marsh in a few figures
History of the marsh
UNESCO recognition and other labels
Natural heritage of the Audomarois marshes
Cultural heritage of the Audomarois marshes
A walk in the marshes of Saint-Omer and Clairmarais
To conclude

The Audomarois marsh in a few figures

As indicated above, the Audomarois marsh covers an area of ​​3726 hectares, or just over 37 km2, which makes it the largest wetland in the Hauts-de-France region. In comparison, it has almost 12 times more surface area than the hortillonnages of Amiens and 4 times more rivers. This large natural basin has an average altitude of 0 meters and can drop to nearly one meter below sea level. This is why this area is particularly fragile in the event of rising waters. Apart from a few hundred hectares belonging to public bodies (Region Hauts-de-France, Department of Pas-de-Calais, Eden 62, commune of Saint-Omer and Clairmarais, community of communes, PNR, coastal conservatory ...), like the Romelaere nature reserve, the Audomarois marsh is mostly private (90%). It is indeed divided into more than 13 plots belonging to nearly 000 owners. In terms of agriculture, it includes 5000 hectares dedicated to market gardening (cultivation of 450 vegetables including cauliflower), 50 hectares for various crops (cereals) and a thousand hectares of grassland. Among the latter, some are dedicated to the breeding of cows, oxen and sheep.

Eco actor label
The Boat Makers are among the eco-actors of the Audomarois marsh!

History of the Audomarois marshes: 13 centuries of labor

The marsh of Saint-Omer during Antiquity

We have very little information about the Audomarois marshes during Antiquity. Integrated in the territory of the morins, the Morinie, we know that this marshy basin flooded by the Aa allowed the activity of fishing.
After the fall of the Roman Empire, things became clearer: the Aa flooded the marsh between Saint-Omer and the Goulet de Watten-Eperlecques before continuing its way towards the sea through maritime Flanders. This was like a gulf named portus Itius, more or less extensive according to the tides. The marsh, composed of fresh water, could then include brackish water at the level of Watten. It is in this marshy and inhospitable environment that the history of Saint-Omer began.

The unsanitary marsh at the beginning of the Middle Ages

Under Dagobert 1st, in the XNUMXth century, three monks from Luxeuil (Mommelin, Bertin and Ebertram), came to settle in the territory of Morinie in order to convert the pagan people of Morins to Christianity. The three monks were then headed by Audomar, the bishop of Thérouanne (powerful bishopric at the time). The first monastery was established at the level of the current village of Saint-Mommelin. However, this location proved to be very vulnerable to flooding and attacks. Legend has it that the three monks boarded a boat and let themselves drift in order to find a new place with more amenities. This is how God guided them to the shore of Sithiu. Another legend has it that these lands belonged to a pirate named Aldroad, who, once converted by Bishop Audomar, left him all of his lands including, among others, the territories of the current communes of Saint-Omer, Clairmarais and d'Arques.

Contrary to Saint-Mommelin bordered by the marsh and adjoining the gulf of Portus itius, Sithiu presented more comfort. Mount Sithiu, 12 meters high, made it possible to see the enemies arriving from afar. In addition, the marsh surrounding three-quarters of it formed an excellent natural rampart. It was good for them, moreover, Saint-Omer having had to undergo the Viking invasions in the XNUMXth century (see our article Saint-Omer and the Viking invasions). Very quickly, successive developments and the construction of the abbey below (the Benedictine abbey of Saint-Bertin, formerly dedicated to Saint-Pierre) and the church above (which would become the cathedral of Saint -Omer), allowed Sithiu to become a small fishing village, then a small town before experiencing a much more fabulous history. It will become a market place in Flanders and Artois from the XNUMXth century, an important stronghold, a commercial port from the XNUMXth century, an administrative and religious power, a bastion of the counter-reformation during the Renaissance... ).

Saint-Omer developed from the XNUMXth century

Let's go back to the XNUMXth century: some improvements were organized by the monks with the diversion of the Aa towards Arques by the creation of the Basse-Meldyck canal in order to allow the operation of a mill (Meldyck means "flour" in Flemish). Then was dug the Haute-Meldyck arriving at the foot of the Abbey of Saint-Bertin.
The polders also began to bloom around the 1866th century in the Audomarois marshes. Their purpose is to dry out the marsh: the furrows left by the Aa in the marshy basin are widened and deepened in order to promote the flow of water. The mud extracted was used to raise the land dedicated to livestock and agriculture. This technique will be used in successive stages in a logical order (from the high marshes on the outskirts of towns to the low marshes located in the center of the basin), and this until the end of the XNUMXth century. This allowed, little by little, the creation of new lands. We will then adopt the technique of the Dutch polders until the XNUMXth century. One then speaks of "binding" of the low marsh for its cultivation, thanks to the constitution of marshes closed by dikes, whose water management was ensured by water gates and windmills. . Since XNUMX, there are no more lands to conquer.

Pipeline works and international trade era

In addition to the creation of agricultural land and small drainage ditches called watergangs, it was necessary to fight against floods and promote maritime trade. It is with this in mind that the river "Nova A", known as the "Grand Large" was dug in 1100 (crossing the marshes of Salperwick, Tilques, Serques, Houlle and Moulle). This allowed the navigation of larger boats while promoting the flow of water from the Aa to the sea. In 1165, it was the turn of the so-called Grande Rivière to experience a major transformation. It became a canal serving the ports of Saint-Omer (the Quai du Haut-Pont, the Vain Quai and the Quai des Salines) and connecting them to that of Gravelines. This maritime outport was created on the initiative of Count Philippe of Alsace. Developments facilitating the flow of water made it possible to reduce the water level of the marsh and facilitate polderization. This campaign of works was carried out under the impetus of the Count of Flanders Baudoin VII after his predecessor Baudouin VI had linked the basin of the Lys to that of the Aa by a wide defensive ditch which would later become the Neuffossé canal. At the same time, the installation of a dyke on the Flemish coast made it possible to retain the high tides.

Sainte Aldegonde church in Saint-Omer, destroyed during the Revolution. Its fountain symbolized the link between the Lys and the Aa. The latter still adorns Place Victor Hugo

Some key dates

The history of the Audomarois marshes also retains a few other additional key dates: the creation of the Calais canal in 1681, the creation of the Vauban lock at Gravelines in 1699 (it closes to prevent the large marshes from invading the Aa and opened to facilitate the flow of the Aa river) and the creation of the Neuffossé canal in 1753 to connect the Aa to the Lys. It became possible, in the midst of the Industrial Revolution, to link Dunkirk to Lille by serving Saint-Omer by taking the Colme canal, the Aa canal, the Neufossé canal, the Lys and the Deule. In 1958, a last campaign of work will upset the appearance of the Audomarois marshes: the closure of the reach of the Haut-Pont and the diversion of the Neuffossé canal by the creation of a Grand Gabarit canal. The barges, much larger now than the small Freycinet barges of the end of the XNUMXth century, required the design of such an infrastructure. Thus, from now on, heavy boats are banned from the city and cross the natural space.

A space recognized by UNESCO as well as other prestigious labels

The Audomarois marsh, fed in particular by the Aa, rainwater and runoff as well as by two groundwater tables, is one of the two wetlands of national or international importance in the Nord-Pas-de-Calais region (with the Scarpe-Escaut area). It is thus classified under the Ramsar Convention and includes an important national natural park (The PNR of the Romelaere ponds).

Finally, it has been recognized as a Biosphere Reserve by UNESCO since 2013. This MAB (Man and Biosphere) recognition is perfectly suited to the Audomarois marshes. Indeed, the environment has been and still is shaped by Man, which makes Man and nature more interdependent: without clearing or weeding, the Audomarois marsh would regain its inhospitable aspect of the High Middle Ages. Biodiversity would be less flourishing there and human activity would be impossible.
The upkeep of the marsh now falls to the seventh section of the wateringues, which, depending on the season, cleans the rivers, cuts the algae and even reinforces certain banks using the technique of fascination. To help them in their work, suitable machines are mobilized, such as cranes, barges and a mower. In the past, some of these tasks were carried out using traditional manual tools such as the troupa (used to redo the banks), the edrack (used to dig ditches), the grepe (a kind of shovel allowing the extraction of peat) and the baguette (sturdy landing net used to pull out the mud).

Today, inhabitants, market gardeners, breeders, hunters, fishermen, walkers, tourists and sportsmen rub shoulders, each imposing rules in order to respect and not endanger the fragile balance allowing the good health of this exceptional natural environment.

Note that the Audomarois marsh is today the twelfth French biosphere reserve with the Dordogne basin, the Camargue, the Cévennes national park, the forest of Fontainebleau and Gâtinais, the Gorges du Gardon, the Islands and the Iroise sea , the Luberon-Lure Regional Nature Park, Mont Ventoux, the Fango Valley (Corsica), the Vosges du Nord-Pfälzerwald cross-border biosphere reserve, Fakarava (French Polynesia and the Guadeloupe Archipelago.

It is part of the prestigious global MAB network aimed in particular at reducing the loss of biodiversity, improving the means of subsistence of populations, fostering the social, economic and cultural conditions essential to the viability of sustainable development as well as improving knowledge through exchanges of experience and expertise organized at regional and global level.

Natural heritage: the fauna and flora of the Audomarois marshes

The favorable climate, the presence of water and the peat land are conducive to agriculture, and are all factors allowing the marsh to benefit from an extraordinary floristic richness.

We find in the Audomarois marshes a high ecological richness, with a hundred exceptional plants including more than 25 protected species and more than sixty plant communities, some of which are very rare and threatened. In addition, 50% of the regional aquatic flora flourishes in the Audomarois marsh! A true island of biodiversity in the heart of the region!

As far as fauna is concerned, the last censuses were able to count, among others, more than 200 species of birds (including the least bittern, the bittern, the marsh harrier, the great crested grebe, the kingfisher, etc.) and 26 species of fish (pike, zander, common European eel, etc.). Of course, we find in the watergangs, ponds and rivers many amphibians (green and red frogs), dragonflies, grass snakes...

Some species are currently threatened, such as European common eels. Others are proliferating to the great displeasure of market gardeners, such as the muskrat having the annoying habit of digging tunnels in the banks and nibbling the plants.

The gray heron

Cultural heritage of the Audomarois marshes and old memories

The visitor in love with old stones cannot cross the Audomarois without visiting the old town of Saint-Omer and its cathedral, or without crossing the surrounding towns and villages with a certain heritage. Beyond the old market gardening suburbs, everyone enjoys a short trip to Clairmarais, to admire the old medieval farmhouse and the ruins of the Cistercian abbey, to venture into the Romelaere ponds reserve as well as into the forest of Rihoult Clairmarais. On foot, by bike or by boat, the destination is full of charm. It is not for nothing that the bourgeois of the 1677th century appreciated the "water walks" in Saint-Omer and Clairmarais and that the writings of this period stipulated that any good self-respecting visitor should, passing through the Audomarois , linger to contemplate the “floating islands”. This is what Louis XIV did once he had taken the city in XNUMX. It was once a matter of heaps of earth and vegetation forming real islands drifting on the water spaces. These gradually disappeared, dragged down by the bottom due to their settling, but also following various developments.

Flemish origins

Everyone can be struck by the toponymy of Dutch-sounding places. Some rivers have funny names, such as Stackelwaert, Hongarwaert, Bogarwaert, Petite et Grande Meer, le Westbrouck, le petit et le grand Leeck… We mainly find this type of name in the marshes of Saint-Omer and Clairmarais, even in the marshes of Saint-Martin at Laert, Salperwick, Tilques and Serques (with the Ketestrom, the Nardstrom, the Lansbergue). These names bear witness to the Flemish origins of the Audomarois and the age of these rivers. In order to better understand these names, it is useful to know that Meer means "lake" (the small and large meer are large rivers and polders designed on an ancient lake of several hundred hectares), Leeck means "the leak" (or the outlet of a polder), “waert” means channel, “brouck” swamp and “strom” the current. Other rivers, sounding French, show that their origin is rather recent (this is the case with the new polders) or that they have undergone some transformations or development subsequent to the resumption of Saint-Omer by the French in the XNUMXth century. century. This is the case with the floating islands, the Redoute, the Canarderie, the river, the mussent...

A specific rural habitat

In terms of habitat, the Audomarois marsh still has beautiful traditional Flemish-style houses. Some farmhouses have a simple roof, others a "Mansard" roof made up of 4 sides. Some old market garden houses still have an old wooden barn next to them, a greenhouse, a vegetable kitchen, an agricultural shed, a forcing room for endives as well as river access via a "pucheau", a kind of small quay. used to dock the boat and to "puchoir" (draw water for the needs of everyday life).

Here and there, we find vestiges of pumping mills, old metal Archimedes' screws, cofferdams, valves as well as water gates... So many facilities that are no longer used today and tend to to disappear, like, alas, the old market garden houses made of cob or yellow brick. Postcard landscapes such as the suburb of Lyzel (the "little Venice of the North"), fortunately still bear witness to this rural life of our ancestors... But for how much longer?

We also find the charm of the market gardening and inhabited marsh in the suburb of Haut-Pont and the place called Doulac: the market garden houses face the road and a semi-urban environment. At the back, the garden opens onto the marsh and the endless rivers.

In the western marsh, in the Salperwick sector, the inhabited marsh gives way to an environment more dedicated to vacationing. Small holiday homes and campsites line the canals in which fishermen find their happiness.

Once upon a time, the market gardeners of Saint-Omer

The marsh was cultivated as soon as it was first drained. The first so-called highlands appeared on the outskirts of the city from the XNUMXth century before gradually reaching the old muddy marsh crossed by the Aa.

The market gardening population experienced a certain growth in the 1751th century. We can think that the end of the feudal system allowed a better division of the territory. It was at this time, and more precisely in XNUMX, that the summer cauliflower was planted for the first time in our extremely fertile soils.

Then came the Industrial Revolution. The first station was established in 1848 and very quickly, market gardening found new outlets outside the territory thanks to this innovative means of transporting vegetables. It is said that in Paris, the merchants of the four seasons praised the qualities of the "First Saint-Omer" in the streets in May-June.

Between 1850 and 1870, 400 families came to cultivate the land of Saint-Omer, Clairmarais and the surrounding area as the exploitation of the peat extracted by the peat bogs we called greppeurs was coming to an end. Indeed, the coal, extracted en masse in the coal mines of Artois, made this old fuel fall into disuse, which was then only used during episodes of war. In 1920, market gardeners in Audomarois began growing winter endive, which was used to provide welcome income in the low season.

After the war, due to international competition, technical progress and new production methods, market gardeners began to disappear, as did the traditional boats of the Audomarois marshes. In the past, the plots were only accessible by boat. The market gardener then used the bacôve maneuvered with a pole to transport his products (up to 3,5 tons of cauliflower per trip) as well as his horse which assisted him in his task. After the war, some did not hesitate to pair two or three bacôves side by side in order to transport their tractor!

The escute served as a utility: it was very useful for transporting the family and tools and knew how to thread its way through narrow rivers. She maneuvered with a ruie, a tool resembling a long flat oar. Before the arrival of thermal and then electric boat engines, some wealthy market gardeners propelled their boat using a motor scull.

At the end of the 1970s, the marsh was adorned with agricultural roads and bridges following the land consolidation operation. More than 500 hectares became accessible by land. The boats soon proved useless and the boat makers closed the doors of their workshops one by one. The opening up of mechanization enabled market gardening in Audomarois to survive in the face of increasingly fierce competition. Nevertheless, the number of families living from this activity decreased further: we counted 200 in the 1970s, 110 at the end of the 1990s, 60 at the end of the 2000s and about thirty today.

Nowadays, some market gardeners work in monoculture and cultivate cauliflower in summer and endive in winter, others perpetuate diversified agriculture, sometimes organically. In all, 50 vegetables continue to be grown in the marshes, including cauliflower and winter endive, cabbage, celery root, Gros Vert de Laon artichoke, Tilques carrots, etc.

In the cultivated marshes, it is not rare to meet a farmer or a seasonal worker, up since 4 am and working “fresh” to cut the cauliflowers before delivering them to the cooperative shortly before noon. This is particularly the case between July and August during the “full” period, when summer cauliflower is abundant.

Saint-Omer market gardeners

Peat extraction, hemp cultivation and fishing in the Audomarois marsh

In addition to the market gardening activities which were in charge of the brouckaillers, the marsh allowed other economic activities, such as the extraction of peat for heating (many of the current ponds, such as that of Romelaere, are the vestiges) as well as the cultivation of hemp used for the manufacture of boat ropes. The inhabitants of the swamp were also excellent fishermen. If today, only angling is authorized for holders of a valid fishing license, it was not the same in the past. In the past, we competed in ingenuity to catch as many fish as possible. Among these techniques prohibited nowadays, we can cite fishing with a net or drum, fishing with a fouenne (a kind of trident), fishing with a blot and a fagot (eel traps), with a puchette or poisenette. (traditional landing nets)… Before the eel was protected, the Audomarois used to fish with tussocks. It involved waving a ball of earthworms weighted with lead in the water until an eel bit. It was then necessary to “shoe” suddenly (before the eel opened its mouth by reflex) and catch it in an upturned umbrella.

The traditional festivals of the Audomarois marshes

Despite the disappearance of some festivals and ducasses like the procession of Lyzel (parade of floats rolling along the road from Clairmarais and rue Saint-Martin to Saint-Omer), two festivals still unleash the enthusiasm of the audomarois: the nautical procession organized in the Faubourg du Haut-Pont on the last Sunday of July as well as the pilgrimage by boat on August 15, to a statue of the Virgin at the intersection of the Grand Large and the Ecou river in Tilques.

Saint-Omer has two giants of the North carried: Batistin, representing a gardener from the Bachelin marshes and his companion Belle-Lyze.

Batistin, the Bachelin giant, Saint-Omer marshes

A walk in the marshes of Saint-Omer and Clairmarais

The best way to discover the Saint-Omer and Clairmarais marshes is still by boat. On board a escute or a traditional bacôve, the last boat builders invite you to take a stroll along the water, rich in exotic discoveries.

Some agricultural paths allow you to discover the marsh on foot or by bike, as well as the walking or hiking trails crisscrossing the natural area, such as the Lansbergue trail between Tilques and Serques or the basin trail between Clairmarais, Nieurlet and Noordpeene (see here the Audomarois hiking trails: ).

The Romelaere nature reserve also offers just over 2km of marked paths accessible to visitors with disabilities. These paths, dotted with ornithological observation posts, allow you to discover the pollard willows, the wet meadows, the old peat bogs that are the ponds as well as the colonies of birds. At the entrance to the park, the Grange Nature allows you to equip yourself with an audio-guide.

Stroll along the water in the marsh of Saint-Omer

To conclude

Let us conclude with two quotations signed by Jean Vaudois, taken from the book "Promenade dans le marsh audomarois" published by the Regional Natural Park of Nord-Pas-de-Calais in 1983: "The finesse of the division of the land, the general organization large sectors, bear witness to the variety of efforts and techniques used over the centuries to create today's marshes. (…) “Rare are the landscapes that leave you really indifferent in the marsh. But beyond the simple aesthetic dimension, it is the socio-economic and cultural dimension that must be reached to fully understand and appreciate this exceptional site. »

It is certain that the Audomarois marshes, which some call the Saint-Omer marshes, the Clairmarais marshes or the Saint-Omer hortillonnages, is full of promise for those who love calm, nature and exotic destinations full of authenticity.