The Isère ( , ; frp, Isera; oc, Isèra) is a

river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of w ...

in the Auvergne-Rhône-Alpes

region In geography, regions, otherwise referred to as zones, lands or territories, are areas that are broadly divided by physical characteristics ( physical geography), human impact characteristics ( human geography), and the interaction of humanity an ...

of southeastern

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of overseas regions and territories in the Americas and the Atlantic, Pacific and Indian Oceans. Its metropolitan area ...

. Its source, a

glacier A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such as ...

known as the ''Sources de l'Isère'', lies in the Vanoise National Park in the

Graian Alps , it, Alpi Graie , photo = , photo_caption = , country_type = Countries , country = , subdivision1_type = Provinces/Regions , subdivision1 = , parent = Alps , borders_on = ...

Savoie Savoie (; Arpitan: ''Savouè'' or ''Savouè-d'Avâl''; English: ''Savoy'' ) is a department in the Auvergne-Rhône-Alpes region, Southeastern France. Located in the French Alps, its prefecture is Chambéry. In 2019, Savoie had a population ...

, near the ski resort in

Val-d'Isère Val-d'Isère (, literally ''Valley of Isère'') is a commune of the Tarentaise Valley, in the Savoie department ( Auvergne-Rhône-Alpes region) in southeastern France. It lies from the border with Italy. It is on the border of the Vanoise Na ...

on the border with

Italy Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical ...

. An important left-bank tributary of the

Rhône The Rhône ( , ; wae, Rotten ; frp, Rôno ; oc, Ròse ) is a major river in France and Switzerland, rising in the Alps and flowing west and south through Lake Geneva and southeastern France before discharging into the Mediterranean Sea. At Ar ...

, the Isère merges with it a few kilometers north of Valence. Many riverside

communes An intentional community is a voluntary residential community which is designed to have a high degree of social cohesion and teamwork from the start. The members of an intentional community typically hold a common social, political, relig ...

have incorporated the Isère's name into their own, for example, Sainte-Hélène-sur-Isère and

Romans-sur-Isère Romans-sur-Isère (; Occitan: ''Rumans d'Isèra''; Old Occitan: ''Romans'') is a commune in the Drôme department in southeastern France. Geography Romans-sur-Isère is located on the Isère, northeast of Valence. There are more than 50,00 ...

. The department of Isère is likewise named after the river.

Etymology

The name ''Isère'' was first recorded under the form ''Isara'', which means "the impetuous one, the swift one." Not originally a Celtic word, it was very likely assimilated by the

Celts The Celts (, see pronunciation for different usages) or Celtic peoples () are. "CELTS location: Greater Europe time period: Second millennium B.C.E. to present ancestry: Celtic a collection of Indo-European peoples. "The Celts, an ancien ...

in ancient times. This word is related to the

Indo-European The Indo-European languages are a language family native to the overwhelming majority of Europe, the Iranian plateau, and the northern Indian subcontinent. Some European languages of this family, English, French, Portuguese, Russian, Dutc ...

''*isərós'', meaning "impetuous, quick, vigorous," which is similar to the

Sanskrit Sanskrit (; attributively , ; nominally , , ) is a classical language belonging to the Indo-Aryan branch of the Indo-European languages. It arose in South Asia after its predecessor languages had diffused there from the northwest in the late ...

''isiráḥ'' इसिरः อิสิระ with the same definition. It was probably based on the reconstructed Indo-European root ''*eis(ə)'' (and not ''*is''), which incidentally has not been found in the Celtic languages of the British Isles. The word ''Isara'' figures in the etymology of many other river names, from ancient

Gaul Gaul ( la, Gallia) was a region of Western Europe first described by the Romans. It was inhabited by Celtic and Aquitani tribes, encompassing present-day France, Belgium, Luxembourg, most of Switzerland, parts of Northern Italy (only during ...

and its neighboring lands. Examples of this are the Ésera in

Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = ''Plus ultra'' (Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , i ...

, the Isar in

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...

, the small Franco-Belgian Yser, or even the ancient name of the

Oise Oise ( ; ; pcd, Oése) is a department in the north of France. It is named after the river Oise. Inhabitants of the department are called ''Oisiens'' () or ''Isariens'', after the Latin name for the river, Isara. It had a population of 829,41 ...

, ''Isara'' (the French adjective ''isarien'' still exists in the language and continues to describe anything related to the Oise). In non-Celtic countries, we find the ''Isarco'', a river in Northern Italy, the ''Éisra'' and ''Istrà'' in Lithuania,,'' Jizera'' in the

Czech Republic The Czech Republic, or simply Czechia, is a landlocked country in Central Europe. Historically known as Bohemia, it is bordered by Austria to the south, Germany to the west, Poland to the northeast, and Slovakia to the southeast. The ...

and '' Usora'' in

Bosnia and Herzegovina Bosnia and Herzegovina ( sh, / , ), abbreviated BiH () or B&H, sometimes called Bosnia–Herzegovina and often known informally as Bosnia, is a country at the crossroads of south and southeast Europe, located in the Balkans. Bosnia and H ...

Geography

The Isère's course measures and runs through a wide variety of landscapes: from its source near the Italian border in the western Alps, it crosses the Pays de Savoie and the

Tarentaise Valley The Tarentaise Valley (french: Vallée de la Tarentaise, ; frp, Tarentèsa) is a valley of the Isère River in the heart of the French Alps, located in the Savoy region of France. The valley is named for the ancient town of ''Darantasia'', the ...

, cuts between the Chartreuse and Belledonne mountain ranges, follows the Vercors Massif, passes through the

Dauphiné The Dauphiné (, ) is a former province in Southeastern France, whose area roughly corresponded to that of the present departments of Isère, Drôme and Hautes-Alpes. The Dauphiné was originally the Dauphiné of Viennois. In the 12th centu ...

province A province is almost always an administrative division within a country or state. The term derives from the ancient Roman '' provincia'', which was the major territorial and administrative unit of the Roman Empire's territorial possessions ou ...

, and finally meets with the Rhône at the foot of the

Vivarais Vivarais (; oc, Vivarés; la, Vivariensis provincia{{cite web , url=http://www.columbia.edu/acis/ets/Graesse/orblatv.html , title = ORBIS LATINUS - Letter V) is a traditional region in the south-east of France, covering the ''département'' of A ...

Valleys

The upper valley of the Isère is called the Tarentaise, and its middle valley the Grésivaudan. The lower valley constitutes a section of the (also called the ''Valentinois'') and is characterized by the river's deep, winding channel. Instead of widening its banks over time, the Isère has dug deeper into its

bed A bed is an item of furniture that is used as a place to sleep, rest, and relax. Most modern beds consist of a soft, cushioned mattress on a bed frame. The mattress rests either on a solid base, often wood slats, or a sprung base. Many beds ...

, forming stepped

fluvial terrace Fluvial terraces are elongated terraces that flank the sides of floodplains and fluvial valleys all over the world. They consist of a relatively level strip of land, called a "tread", separated from either an adjacent floodplain, other fluvial t ...

s. The valley has clearly defined borders and is relatively narrow, not exceeding in breadth. The repetition of alluvial deposition (during periods of

Quaternary glaciation The Quaternary glaciation, also known as the Pleistocene glaciation, is an alternating series of glacial and interglacial periods during the Quaternary period that began 2.58 Ma (million years ago) and is ongoing. Although geologists describ ...

) and

overdeepening Overdeepening is a characteristic of basins and valleys eroded by glaciers. An overdeepened valley profile is often eroded to depths which are hundreds of metres below the deepest continuous line (the thalweg) along a valley or watercourse. This p ...

(during interglacial periods), known as a fluvioglacial system, led to the formation of several stepped terraces in the lower Isère valley, like the one on which Saint-Marcel-lès-Valence is built. This occurred through the massive accumulation of alluvium from the Isère on top of a bed of

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

molasse __NOTOC__ The term "molasse" () refers to sandstones, shales and conglomerates that form as terrestrial or shallow marine deposits in front of rising mountain chains. The molasse deposits accumulate in a foreland basin, especially on top of flysc ...

. Today, these terraces still define the geography of the Plain of Valence.

Confluence

The Isère initially merges with one of the Rhône's diversion canals, built for navigational purposes, at Pont-de-l'Isère. At the southern tip of La Roche-de-Glun (a commune on an island formed by the canal), the Isère Dam drains part of the water back into the Rhône and permits the Isère to continue its course alone until it passes through the Bourg-lès-Valence Dam and reaches its final junction with the Rhône.

Main Tributaries

(L) ''Left-bank tributary''; (R) ''Right-bank tributary''. * (L) , ** (R) Doron de Champagny, ** (L) , ** (L) , * (R) Arly, ** (L)

Chaise A one-horse chaise A three-wheeled "Handchaise", Germany, around 1900, designed to be pushed by a person A chaise, sometimes called chay or shay, is a light two- or four-wheeled traveling or pleasure carriage for one or two people with a folding ...

, ** (L) , * (L) Arc, * (L) Drac, ** (R) , ** (L) , ** (R) , ** (L) , ** (R)

Romanche The Romanche () is a long mountain river in southeastern France. It is a right tributary of the Drac, which is itself a tributary of the Isère. Its drainage basin is .Morge, ** , , via the Morge Canal * (L) , ** (L) , * (R) ,

Cities on the Isère

Bourg-Saint-Maurice Bourg-Saint-Maurice (; Arpitan: ''Bôrg-Sant-Mori'' or simply ''Le Bôrg''), popularly known as Bourg, is a commune in the Savoie department in the Auvergne-Rhône-Alpes region in Southeastern France. Located on the Italian border south of Cham ...

, Aime, Moûtiers,

Albertville Albertville (; Arpitan: ''Arbèrtvile'') is a subprefecture of the Savoie department in the Auvergne-Rhône-Alpes region in Southeastern France. It is best known for hosting the 1992 Winter Olympics and Paralympics. In 2018, the commune had ...

, Montmélian * Isère: Pontcharra,

Grenoble lat, Gratianopolis , commune status = Prefecture and commune , image = Panorama grenoble.png , image size = , caption = From upper left: Panorama of the city, Grenoble’s cable cars, place Saint- ...

Voreppe Voreppe () is a commune in the Isère department in southeastern France. It is part of the Grenoble urban unit (agglomeration).Drôme Drôme (; Occitan: ''Droma''; Arpitan: ''Drôma'') is the southernmost department in the Auvergne-Rhône-Alpes region of Southeastern France. Named after the river Drôme, it had a population of 516,762 as of 2019.

, Pont-de-l'Isère, La Roche-de-Glun

Hydrology

The length of the Isère is , and its

drainage basin A drainage basin is an area of land where all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. A basin is separated from adjacent basins by a perimeter, ...

covers . The vertical profile of the river is made up of several zones: * From its sources to Sainte-Foy-Tarentaise (except for those sources having a slope of around 25%), the average slope of the Isère is 5.1%, in a more or less confined valley (forests, gorges, and higher up, grasslands). * As far as Moûtiers, the slope measures 1.18%. * Before the river's confluence with the Arly, its slope is only 0.53%. * The slope decreases to 0.136% until

. * Downstream from Grenoble, it measures 0.1%. The flow of the Isère was observed over a period of 58 years (between 1956 and 2015) at Beaumont-Monteux in the

Drôme Drôme (; Occitan: ''Droma''; Arpitan: ''Drôma'') is the southernmost department in the Auvergne-Rhône-Alpes region of Southeastern France. Named after the river Drôme, it had a population of 516,762 as of 2019.

department, situated near the river's confluence with the Rhône. The discharge of the river at Beaumont-Monteux measured . The Isère's large seasonal fluctuations are typical of rivers fed in large part by snowmelt, with springtime flooding raising the average monthly discharge between and from April to July (peaking in May and June), and low water levels in autumn and winter, from August to February, with a minimum average monthly discharge of in September. Generally speaking, this makes the Isère a very plentiful watercourse throughout the year. However, the can drop to during a five-year dry spell, which is very low. On the other hand, severe flooding can result from rapid thaw or torrential autumn rain. In fact, and QIX 5 are and , respectively. QIX 10 is . QIX 20 reaches , while QIX 50 rises to , which is still moderate compared to other rivers in the south of France, like the Tarn. The highest instantaneous discharge on record was on September 16, 1960, while the highest daily value was on October 7 of the same year. The depth of runoff for the Isère's drainage basin is annually, which is quite high above France's average and clearly superior to that of the Rhône's drainage basin ( in Valence for a surface area of ). The specific dischargeEaufrance Glossary on Water - Specific Flow
/ref> is 27.9

liters The litre (international spelling) or liter (American English spelling) (SI symbols L and l, other symbol used: ℓ) is a metric unit of volume. It is equal to 1 cubic decimetre (dm3), 1000 cubic centimetres (cm3) or 0.001 cubic metre (m3). ...

per second per square kilometer of drainage basin.

Gallery

Image:Isere à Daille.jpg, The Isère from La Daille, near

Image:Moutiers.jpg, Moûtiers: the Isère and the cathedral Image:200604 - Montmelian Pont Isere.JPG, The bridge on the Isère at Montmélian Image:Pont Marius Gontard à Grenoble.JPG, The Isère leaving

Image:Romansvg.jpg, The Isère at

Image:Antoine Guindrand - Paysage de l'Isère - 1836.JPG, Antoine Guindrand
''Paysage de l'Isère'' sère landscape(1836)

References

External links

* {{DEFAULTSORT:Isere (river) Rivers of France Rivers of Drôme Rivers of Isère Rivers of Savoie Rivers of Auvergne-Rhône-Alpes Rivers of the Alps