Definitions

Durance

Durance

[door-uhns, dyoor-]
Durance, river, c.180 mi (290 km) long, rising in SE France at the foot of Montgenèvre Pass on the Italian border and flowing southwest then northwest before entering the Rhône River at Avignon. The upper Durance is used to generate hydroelectricity; the lower river is used for irrigation and for municipal water supply.
ancient Druentia.

River, southeastern France. The principal river draining the French side of the Alps toward the Mediterranean, its origin is in the Montgenèvre region. To its confluence with the Rhône River below Avignon, it is 189 mi (304 km) long. It is the site of extensive hydroelectric projects that were established after World War II.

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The Durance (Occitan: Durença in classical norm or Durènço in Mistralian norm) is a 324 km long river in south-eastern France, left tributary of the Rhône. Its source is in the south-western Alps, in the ski resort of Montgenèvre near Briançon. It flows south-west through the following départements and cities:

The Durance flows into the river Rhône near Avignon. The main tributaries of the Durance are the rivers Bléone and Verdon.

Etymology

The Durance is documented in the old forms Druentia (1st century), Drouentios potamos (in Ancient Greek), Durantia (854, 1271) or Durentia (1127). The traditional forms are probably derivatives of *Dūrantia, based on the hydronym dur- (French for hard) that one finds in the names of many rivers in the Western Alps (Dora in Italy, Dranse in Haute-Savoie, Drome), Durensola, associated with the rental suffix - antia. All these rivers have their sources in mountains, and have torrential courses.

The Durance is a river much weaker than Clarée and Guisane, which are however in front of it. If the name of the Durance dominates over those two, it is probably because the valley of the Durance is an important and old transportation route, whereas those of Clarée and Guisane are cul-de-sac.

Hydrography

From its source at the foot of Sommet des Anges, at 2.3km, beneath Montgenèvre, to the confluence with the Rhone, the Durance traverses 305km. However, a longer course is traced by the Clarée-Durance system and has a length of 325km. The uniqueness of the course is its slope, 81 m/km in its first 12 km, then 15 m/km to the confluence with the Gyronde, and still nearly 8 m/km to the confluence of Ubaye. This slope remains relatively high in the lower part: approximately 0.33% in its middle part (to the bridge of Mirabeau), then still 0.24% in its lower course. For comparison, at approximately 100km from the source, the Isere is at 330m altitude and the Durance at 700m. This fact contributes partially to the torrential character of the river, including in the lower part of the river. The uneveness of the Durance from its source to Mirabeau is 1847 m, and approximately 2090 m to the confluence with the Rhone.

Departments and main towns crossed

Only the agglomerations of Briançon and Sisteron, built where the banks are very boxed, are actually crossed by the Durance, the other towns quoted being built on a slope close to the river:

As for the catchment area, this extends to 4 other departments: le Var, la Drome as well as les Alpes-Maritimes.

From the source to Serre-Ponçon: the start of the Durance

Until lake Serre-Ponçon, the Durance circulates in a more or less broad valley surrounded by the high mountains of the Pelvoux range. It is an alpine river in the nival mode, with high-water in June and a flow that is sustained even in summer. The torrent of Montgenèvre flows into Clarée, crosses Briançon then the Guisane flows into it. It then moves south where the waters of the Gyronde also flow into it (glacial torrent des Ecrins) in L'Argentière-la-Bessée. Its course inflects towards the south-south-east until the confluence with Guil below Guillestre-Montdauphin, then sets out again towards the south-south-west and flows into the lake of Serre-Ponçon a little downstream of Embrun. The confluence with the Ubaye was drowned during the filling of the lake.

From Serre-Ponçon to the Water gap of Mirabeau: the middle of the Durance

The middle part of the Durance runs in a landscape that changes radically because the mountains draw aside and increasingly vast plains replace them. The bed itself becomes boxed again, digging through the terraces around a furrow of a few meters to a some tens of meters of depth. Here, the mode of the Durance becomes mediterranean: floods caused by the autumnal rains, severe low water levels in summer. Right before the water gap of Sisteron, the Durance joins Buëch, which recovered water of the channel EDF. Many minor affluents with the rain mode also flow close to Sisteron (Sifts, Jabron, Vançon). As upstream, the Durance remains surrounded by hills or plains, but the valley widens in an alluvial plain several kilometers of width (5km in Manosque), recently arranged with the development modern agriculture and the construction of the A51 motorway. The river receives water from Bléone close to Mées, the Adze a few kilometers to the south Oraison. The Verdon flows into the Durance near Cadarache: the place of junction is difficult to see unless placing itself in height. Several stoppings were built along the middle part of the Durance, in addition to Serre-Ponçon: Espinasses, Sisteron, the Stopover and Cadarache. It is in fact more of the hydrants, of which the principal goal is to deviate most of the discharge of river in the channel EDF which feeds from the hydroelectric factories; the lakes which they create cannot be used to control the course of the river. Some of the water is used for irrigation.

The end of the Durance: From Jouques to Avignon

The valley tightens for a few kilometers with the crossing of the Mirabeau water gap (depth 200m), then rewidens into an even broader plain with the confluence of the Rhone. Its orientation passes the North-South one to East-West, as small the provençaux links between which it runs (Alpilles and Luberon). The Durance does not receive a significant affluent during this last part of its course: Coulon, which circumvents the solid mass of Lubéron by the north.

Summary of the affluents

(G) Affluent left bank; (D) Flow Right Bank; (CP) Principal course, announces the name given to part of the course (G) Affluent left bank; (D) Flow Right Bank; (CP) Principal course, announces the name given to part of the course water taken into account in the calculation its length.

Hydrology

River known as “capricious“and formerly dreaded for its flash floods (was called the 3rd plague of Provence) as well as for its low water level, the Durance is at the same time an alpine and mediterranean river with quite particular morphology. The High-Durance was an alpine river (varying flow of 18 with 197m³/s). Its total area catchment is of 14225 km². With confluent with Ubaye, it salmon thrived, and one finds trout until Sisteron before installations of the river.

Flow

With the confluence with the Rhone, the average natural flow of the Durance is approximately 190m³/s, with a strong annual variability. It can vary between {{Unité|40m³/s (the most severe low water levels) and 6000m³/s (floods millénales), levels reached into 1843,1882 and 1886. With the outlet in the lake of Serre-Ponçon, the medium flow is of 81m³/s; on the level of Oraison it is 123m³/s and after reception of the Verdon reached 174m³/s (250 to 330 m³/s in spring, 100m³/s in the summer). The contribution water of the affluents downstream is very weak. The annual maximum generally occurs in May or June, but the most violent flash floods occur in autumn. The low water level takes place in winter in the high valley and summer in the average and lower part of the course.

Mixed formation

The catchment area of the Durance gathers territories going of the eternal snow to the hills and plates with Mediterranean climate. Thus, the river is subjected to a nival mode in its higher course (with Serre-Ponçon), with winter low water levels and floods each year from May to July. With Serre-Ponçon, for a catchment area of 3600 km², a module of 83,3 m³ /s, with one low water level of 18 m³ /s, and a maximum flood of 1700 m³ /s (value recorded in 1957).

Downstream, its many affluents of medium mountains or the plates to the Mediterranean primarily rain mode n' thebring; water qu' in winter, in spring and theoccasion of raw the autumn, with a low and very irregular flow in summer. Its a shift of the natural maximum of spring from June to May follows while descending the course.

Flash floods and low water levels

The river is famous from time immemorial for its unstable course, impetuous and changing. The floods, violent and frequent, increased in number and force from the second half of the 16th century, to attenuate and space themselves in the 20th century. As in all the mediterranean alpine surface, this period of strong increase in the force and the flood frequency is due to the combination of cooling starting from the 14th and until the 19th century (rains and snowfalls more frequent), and to an important clearing of the slopes of the mountains of the basin of the Durance, starting from the 16th century.

Between 1832 and 1890, the Durance knew 188 water rises of more than 3 meters (measured with the bridge of Mirabeau). That of 1843 carried several just built suspended bridges (those of Remollon, going back to 1829, of Mirabeau, built in 1835, of Manosque, unfinished, of Mées, going back to 1838). The flood of 1872 still carries the bridge of Mallemort (1847). These floods millénales (three in the 19th century: 1843, 1856, 1886) reach 5000 with 6000m³/s according to the auteurs; for comparison, the Seine flooding of 1910 reached approximately 2400 m³/s with its more extremely. With the 19th century, the principal floods are those of 1843,1856 (which flooded Avignon) and 1886. And even of raw less important can be devastating: that of 31 May and 1 June 1877 carried the bridge of Tallard.

In the 20th century, the floods were less frequent and violent thanks to the afforestation of the catchment area, but one still observed important ones in 1957 and 1994 (3000 m³/s). These maxima are raised in Mirabeau; in Sisteron, the floods can have a flow of 2800 m³/s; with the confluence with the Verdon, the flow can reach 500 m³/s.

The importance of these floods is due to a very important streaming: the height of the water blade run out in Cadarache east of 472 mm, for an average of 750 mm precipitations: 63% of the rains stream and lead in Durance.

Previously, the Durance had carried the town of Rama (between Briançon and Embrun, with the confluence of Biaisse) in the 12th century.

At Mirabeau, the low water level is of 45 m³ /s, that is to say a variation from 1 to 133; at the time of the dryness of 1921, which lasts until December, the flow goes down up to 27 m³/s.

Formations of islands in the bed of the Durance

Three types of islands are formed in the bed of the Durance:

  • gravel benches, brought by the floods, and generally without or with little vegetation;
  • the iscles or let us isclons, fertile benches of silts on which can push plants with rapid growth (wicker), and which are swept only by the strong floods;
  • stuffed them, of the accumulations of trunks and wood flottés.

Management of the course of the Durance

Dams and channels

To secure devastating floods (which carried sometimes a whole side of bank, and a city with), of dam the started to be built during the Middle Ages. They are often boxes of wood filled up of stones, which do not resist the floods a long time. In another direction, since the same time, one uses the water of the Durance to irrigate the close grounds, then to feed out of water all Provence. The first known channel is it channel of Saint-Julien, dug in 1171 by the marquis de Forbin. Follow those of Adam de Craponne (50 km dug in nine months into 1554 of Silvacane with Arles), Alpine, of Marseilles, of Carpentras, of Manosque, of Ventavon, and of the hundreds of others more petits for a total of 540 km dug of the end of the 16th century at the end of the 19th century.

The Canal de Marseille

From 1839 to 1854, the engineer Franz Mayor de Montricher built a canal intended to supply the city of Marseilles with drinking water. The canal follows a layout of 80km in length of which 17km is underground and traverses the [[Bouches-du-Rhône]. The canal is made out of concrete, the air works out of stones or stones and bricks. Flow of the work is of 10 m³ /s, the slope of 0.36 m/km. The width at the top is 9.4m, the width of the basin 3m.

The catch initial water was located on the Durance at the level of the bridge of Pertuis, at an altitude of 185 meters, and with 50 kilometers with flight bird of Marseilles. From there the channel left towards thewest under theHolyone. During the construction of the large channel EDF, which doubles the Durance since Serre-Ponçon with Living room-of-Provence and thepond of Berre, the catch water of the channel of Marseilles was deferred on channel EDF itself, after Saint-Estève-Janson. From there the channel of Marseilles continues towards the North-West with the bridge of Cadenet, where it supplies the basin of Saint-Christophe. The Durance still provides today two-thirds of the water resource of the town of Marseilles.

Hydroelectric Installation

In 1955, a law is voted for the installation of the Durance- unit the Verdon. Within this framework, three missions are entrusted at EDF:

  • electrical production;
  • water supply of the cultures (irrigation) and the cities;
  • regulation of the crues.

This program involved, over one 40 years period, the construction of 23 stoppings and hydrants (hydrants upstream of Claux on Argentière with that of Mallemort while passing by the stopping of Serre-Ponçon), channel EDF of the Durance, feeding 33 hydroelectric stations, and several control stations.

This program is an almost complete success:

  • the Durance-Verdon unit produces 6 to 7 billion kWh per annum (10% of the French hydroelectric production);
  • the stoppings tanks provide drinking water to all the area, and irrigate all Provence (a third of the French irrigation);
  • the lakes are a tourist attraction (Serre-Ponçon attracts 10% of the tourists attending Hautes-Alpes);
  • if the flow is regularized, and the weak and average floods perfectly controlled, installation does not have any effect on the major floods, like showed it the flood of 1994 (3000 m³ /s in Cadarache). Indeed the stopping tank of Serre-Ponçon controls only the higher course of the Durance, and does not play any part on the affluents, whose role is important in the formation of the major floods. All the other stoppings are only hydrants. Only the Verdon sees its flow controlled by the stopping of Holy-Cross (so of storage capacities exist at the time of raw).

Impact of the works

The Durance had an average natural flow of 188m³/s and a river mode of Mediterranean type, but hydraulic installations modified its course. Separately a very low reserved flow, the mass of water circulates from now on in a “channel usinier” which skirts the natural bed of the large river in order to make them pass by a series hydro-electric factories. This channel usinier can contain until 250m³/s. So at the time of the great floods, the surplus waters borrow again the natural bed, the tanks being largely insufficient to store similar masses water (it acts especially of Serre-Ponçon, but also of the large tanks of The Verdon, its principal affluent).

Ecology along the river

The valley presents the interest to gather many natural habitats Community interest, regularly altered by the floods, and being subject to at the same time the mediterranean influences and mountain. She plays also a biological big role of corridor, within the framework of green screen national and of ecological network pan european, which explains its classification in zone Natura 2000.

In running water, one counts today from 150 to 200 species of macro-invertébrés, but with few plant species (because of the mode of raw).

Water quality is considered good in the higher valley, in spite of inevitable filling with many reserves, which deprive the Durance of the power necessary to the carrying of the sediments. This quality was obtained thanks to actions of cleansing (including on the affluents of Luye and of Coulon). There remain some black spots in the average valley (downstream from the factory Arkema with Castle-Arnoux, after the junction with Coulon).

The 32 cm depth on average involves strong temperature variations according to the season (from 0 to 28°C) and according to the hour of the day (7,5°C of amplitude the summer, 10°C the winter), which selects the watery organizations adapted to these changes. The installation of the valley and the spacing and reduction in the importance of the floods allowed the colonization of alluvial space by one ripisylve of alder S and of poplar S which constitutes one locally gallery-forest. The bed, although less wet, accommodates 110 more species of birds at the year, plus 82 species of migratory birds which find there zones of rest and nourrissage and sometimes of reproduction. 110 species hibernate there. Avian diversity increased after installations, but it is probable there was formerly a diversity higher than this, the same number individuals higher for certain families of birds.

One also finds in the Durance or with his accesses approximately 75 species of mammals of which it beaver Europe, it amphibious field vole, it crossope (or watery shrew), of many species of bat (barbastelle (Barbastella barbastellus, large murine (Myotis myotis), large rhinolophe (Rhinolophus ferrumequinum), minioptère of Schreibers (Miniopterus schreibersi), small murine (Myotis blythii), small rhinolophe (Rhinolophus hipposideros), vespertilion with indented ears (Myotis emarginatus), vespertilion of Capaccini (Myotis capaccinii)). One finds there also species introduced and become invasive (of which it coypu) and muskrat more recently arrived. Otter could have recently disappeared or its presence would be very relictuelle. The populations of algae and water plants (100 species on average and the low Durance) and water invertebrates (77 species) are varied than before installations (comparison with those of Adze and of Buëch). Jussy, invasive plant, gradually appears (since 1986) in the stagnant water (dead gravel pits, pond, arms).

There are in the same way few fish species (14), but some patrimonial species; in addition to blageon and it toxostome one finds there also it apron of the Rhone (fish very threatened of disappearance and it loach (Cobitis taenia taenia) still very significantly presents. But the silting and the lack; oxygen compromise the reproduction of the truites. The Brook lamprey was still recently seen there. Perhaps it has disappeared.

History

The Durance played a very important part in the history of Provence, and largely contributed to the economic growth and demographic of the Marseilles area, after having been an obstacle with circulation during centuries. Of theAntiquity with the 19th century, the Durance was famous for its difficult crossing, its brutal floods and an inconstant flow. The width of its bed, the force and low depth of its current, and the changes of course after the floods returned there crossing by ford or ferry, as well as the very difficult river navigation (in spite of a height relatively important water in period of high-water). One needed sometimes several ferrys to cross the various arms or channels, to frequently rebuild the cable (“flying bridge” ) support, and the unstable and sometimes abrupt banks returned the establishment of the ferry and its difficult access. The fords were difficult to establish, often carried: the only durable ones are those of Mirabeau and Pertuis, unusable in periods of crues.

Prehistory

Twelve million years ago, the Durance ran to the Mediterranean, without throwing itself in the Rhône. During glaciation of Riss, the Durance took its source with Sisteron, where the icecap finished recovering Alpes. It is also during this period that the Durance course changed towards the west, between Luberon and Alpilles, and flow into the Rhone.

Antiquity

In pre-Roman times, the Durance was the border between various people celto-Ligurians established along his bed, like Cavares (Cavaillon) and them Salyens (Bouches-du-Rhône).

Strabon (1st century) signaled that a ferry was established in Cavaillon, the great Roman way of Spain in Italy not crossing the Durance between Cavaillon and the Mount-Genèvre. That a bridge existed in Sisteron Other ferrys were allowed to cross it, in particular with the height of Pertuis, city whose name preserves the memory of this function. Difficult to cross (except in Sisteron, where its course is tightened between two rock banks), the Durance is nevertheless navigable. Low-relief the S of Cabrières-in Aigues show it, the river is used for the transport of various liquid food products (wine, olive oil), Gallo-Romans using the boat-towers and wind to go up the current. Several specialized corporations ensured this transport: nautes had to it monopoly transport on large rivers and used boats, them utricular which had it on the small rivers and in the marshes used rafts floating on inflated goatskin bottles. Two corporations the utricular ones were in Sisteron and Riez.

This trade fed the activity of an important port, near to the road crossroads of Sisteron, with the locality Bourguet, the Stopover: the port existed before the Roman conquest, but was arranged with the , knows prosperity until crisis of the 3rd century, before finding an economic activity until the beginning of the 5th century.

The valley of the Durance is a way of penetration of the Alps, borrowed by way domitienne; a statue of Janus is high besides in Montgenèvre, not passage between Gaulle cisalpine and it Gaulle Narbonnese

Middle Ages to today

In the Middle Ages, the county of Forcalquier all in length along the Durance is stretched, of Cavaillon to Rock-of-oar close to Embrun. 12th century with the 19th century, it river was employed with flotation of wood, crossed in the Alps (in particular by the monks of Boscodon, which by privilege of 1191 used the fleuve) and used in the towns of plain and the shipyards.

Other goods were transferred on the river, of which mainly salt, goods which see their price increased by the ten tolls established out of the 300 km of the river. The bridge of Sisteron, set up with the Middle Ages, remained in the middle of the 19th century the only passage into hard a bank with theother of the Durance. After the year Millet, the number of ferrys (already present before) increases however: it is about trail ferries (equipped with a mast which are pressed on a cable, the flying bridge, tended between two banks of the principal course). Oldest known is that active of Castling-d' Anthéron with Cadenet (in Gontard), attested in 1037. In the 16th century, exists still that of Pertuis. Thereafter, the evidence of existence of ferrys multiplies, in particular with Rognonas, La Brillanne (13th century), Noves, Orgon, Le Puy-Sainte-Réparade, Meyrargues, Pertuis, Peyrolles, that of Cante-Perdrix in Mirabeau, Manosque, Giropey, Château-Arnoux, Bourguet, Volonne, Bonpas. The principal ones are those of Cadenet and Mirabeau, which were borrowed by the herds of sheep in transhumance. Other ferrys are installed to supply the mills built at the end of the 18th century in Poët, with Upaix and Claret. Nevertheless, the service road by ferry remains increasingly weaker than that of the Rhone (a ferry all 9 to 11 km on average, against every 5.2 km on the Rhone). Starting from the 12th century, one also builds wood bridges, which last more or less a long time, and are destroyed in various ways:

  • in Maupas (current Bonpa', in Caumont), of the end of the 12th century with its destruction by the count of Toulouse in 1241;
  • in Mirabeau, the beginning of the 13th century, close to Holy-Madeleine-of-Bridge;
  • in Savines, more attended bridges of the High-Durance (15th century). Lastly, the ancient bridge of Sisteron east rebuilt in 1365.

19th century

In 1856, the millénale floods all the basin of the Durance, of Sisteron to its confluence in Avignon. It carries the cultivated alluvial terraces, breaks the dams, destroys the channels.

The trade unions of sprinkling (which replaced the pareries) and the local services of the Bridges and Chaussées request an exceptional intervention from the State. The first service of observation of a river is created, the Special service of Durance, in order to study the hydrology of the river, follow-up of the kilometric demarcation of the river as from 1868, the confluence with the Verdon with that with the Rhone. This demarcation allows one levelling and to chart the grounds inondables.

The construction of Marseilles canal in the middle of the 19th century allowed the Marseilles agglomeration to develop very quickly.

20th century: hydroelectric installations

The use of the Durance as loader-gate decrease with the competition of the road, and ceases definitively with that of railroad. There remain only 10 raftmen in 1896, one in 1908.

Hydroelectric installations, with the construction of the chain of stoppings on the Durance, the Verdon like on Buëch and Bléone, had the most important economic impacts and most visible in the landscape. The major part of the flow was diverted in channels downstream from Serre-Ponçon, and only in the natural bed a reserved flow of 2 with circulates 5m³/s, corresponding to 1/40 of the natural flow. The bed is gradually fixed and vegetation starts to push there, where thewater does not run any more. Thanks to the tanks of Serre-Ponçon and Holy-Crosses, which can retain a total of more than 2 billion tons water, theirrigation remains possible in summer during the driest years, and around the plans; water theeconomy could develop around [[tourism] the] estival one.

Economic

From the 1950s, the bed of the Durance provided very hard aggregate used for road surfacing and resistant concretes. The majority of the quarries are being closed. In the same way, the few factories using the energy of the river have closed (an aluminium factory at Argentière-la-Bessée) or are being closed (Arkema at Saint-Auban).

The Durance in the Arts

The Durance is represented in the form of a majestic group carved with Longchamp palate, with Marseilles, built between 1862 and 1869 by thearchitect Espérandieu in order to celebrate thearrival of water of the Durance in the city, via Canal of Marseille.

It is also carved under the features of a woman to the fertile belly, with Charleval (Rhone delta).

It is present in the literature:

  • poets Adolphe Dumas (1806-1861), félibre, republican and traditionalist, Paul Arena, Clovis Hugues in the Time of cherries and Élémir Bourges evoked this river;
  • the best known writer to be inspired by the Durance is however Jean Giono, who makes use of it in his imaginary geography of Provence, transforming it into river (it speaks about it with the masculin, making him cross the cluse of Sisteron without evoking the city, then the Rebeillard highland completely imaginaire. Horseman on the Roof he also sets along the course of the Durance.) Among the painters to have represented it, Guigou and Monticelli, friendly close relations, settle with the Saint-Paul-the-Durance and carry out many tables where it appears, either like decoration, or like subject (86 of the 421 tables of Guigou). The painter surrealist of origin Rumanian Victor Brauner, taken refuge in 1942 with Remollon, makes several tables of them on materials of fortune.

Notes and references

Bibliography

  • Direction of theenvironment, of sustainable development and theagriculture, The Durance: bond of life of the territory régional, District council PACA, 106 p
  • Claude Gouron, photographer, Helene Vesian, author of the texts, Pierre Magnan, preface writer, The Durance: photographic voyage from the Alps in Provence, Avignon: Alain Barthélemy, 2002
  • Henri Julien, and Jean-Marie Gibelin, You, Durance, Barred, ED. Terradou, 1991, ISBN 978-2-907389-36-5
  • Cecile Miramont, Denis Furestier, Guy Barruol, Catherine Lonchambon, The Durance length into broad: ferrys, boats and rafts in thehistory a river capricieuse, Forcalquier: the Alps of light, 2005, Collection: The Alps of light, ISSN 0182-4643, num. 149,120 p, ISBN 978-2-906162-71-6
  • Jean-Paul Clébert and Jean-Pierre Rouyer, Durance, Privat, Toulouse, 1991, in the collection Rivers and valleys of France, ISBN 2-70899503-0

Video

  • Jacques Sapiega, The Durance, course & regard', District council PACA, 2004

External links

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