View source for Isère (river)

{{distinguish|Yser}}
{{Infobox river
| name              = Isère
| native_name       = {{native name list |tag1=frp|name1=Isera |tag2=oc|name2=Isèra}}
| image             = Grenoble Isere.jpg
| image_alt         = The Isère in the center of Grenoble.
| image_caption     = The Isère in the center of [[Grenoble]]
| map               = Isère.png
| map_alt           = 
| map_caption       = Path of the Isère
| source1_location  = Sources de l'Isère Glacier, [[Grande Aiguille Rousse]], [[Graian Alps]]
| source1_coordinates= {{coord|45|26|45|N|7|5|47|E}}
| mouth_location    = [[Rhône]]
| mouth_coordinates = {{coord|44|58|56|N|4|51|8|E|display=inline,title}}
| progression       = {{RRhône}}
| subdivision_type1 = Country
| subdivision_name1 = [[France]]
| subdivision_type2 = [[Regions of France|Region]]
| subdivision_name2 = [[Auvergne-Rhône-Alpes]]
| subdivision_type3 = [[Departments of France|Departments]]
| subdivision_name3 = {{hlist|[[Drôme]]|[[Isère]]|[[Savoie]]}}
| length            = {{convert|286|km|mi|abbr=on}}<ref name=Sandre />
| source1_elevation = ±{{convert|2900|m|ft|abbr=on}}
| mouth_elevation   = ±{{convert|110|m|ft|abbr=on}}
| discharge1_avg    = {{convert|329|m3/s|ft3/s|abbr=on}}<ref name=Eaufrance />
| basin_size        = {{convert|11890|km2|sqmi|abbr=on}}<ref name=Sandre />
| tributaries_left  = [[Arc (Savoie)|Arc]], [[Drac (river)|Drac]]
| tributaries_right = [[Arly]]
| custom_label      = Sources
| custom_data       = [[Sandre]], [[Géoportail]], {{Interlanguage link|Banque Hydro|fr}}, {{Interlanguage link|Symbhi|fr}}
}}

The '''Isère''' ({{IPAc-en|US|iː|ˈ|z|ɛər}} {{respell|ee|ZAIR}},<ref>{{Cite American Heritage Dictionary|Isère|access-date=22 August 2019}}</ref><ref>{{Cite Merriam-Webster|Isère|access-date=22 August 2019}}</ref> {{IPA|fr|izɛʁ|lang|LL-Q150 (fra)-GrandCelinien-Isère.wav}}; {{langx|frp|Isera}}; {{langx|oc|Isèra}}) is a [[river]] in the [[Auvergne-Rhône-Alpes]] [[Regions of France|region]] of southeastern [[France]]. Its source, a [[glacier]] known as the ''Sources de l'Isère'', lies in the [[Vanoise National Park]] in the [[Graian Alps]] of [[Savoie]], near the ski resort in [[Val-d'Isère]] on the border with [[Italy]]. An important left-bank tributary of the [[Rhône]], the Isère merges with it a few kilometers north of [[Valence, Drôme|Valence]].

Many riverside [[Communes of France|communes]] have incorporated the Isère's name into their own, for example, [[Sainte-Hélène-sur-Isère]] and [[Romans-sur-Isère]]. The [[Departments of France|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."<ref>{{cite web |url=http://www.arbre-celtique.com/forum/isar-3997.htm |title=ISARA / ISAROS (ISÈRE) |date=2009 |website=Encyclopédie de l'Arbre Celtique |publisher= Guillaume Roussel|language=fr |access-date=24 March 2015}}</ref> Not originally a [[Celtic languages|Celtic]] word, it was very likely assimilated by the [[Celts]] in ancient times. This word is related to the [[Proto-Indo-European language|Indo-European]] ''*isərós'', meaning "impetuous, quick, vigorous," which is similar to the [[Sanskrit]] ''isiráḥ'' इसिरः อิสิระ with the same definition.<ref name=Delamarre>{{cite book |last=Delamarre |first=Xavier |date=2003 |title=Dictionnaire de la langue gauloise : une approche linguistique du vieux-celtique continental |trans-title= Dictionary of the Gallic Language: A Linguistic Approach to Continental Old Celtic |language=fr |publisher=Errance |location=Paris |edition=Revised and augmented 2nd |series=Collection des Hespérides |isbn=978-2-87772-369-5 |oclc=354152038 |page=191}}</ref> It was probably based on the reconstructed Indo-European root ''*eis(ə)'' (and not ''*is''), which incidentally has not been found in the [[Insular Celtic languages|Celtic languages of the British Isles]].<ref name=Delamarre />

The word ''Isara'' figures in the etymology of many other river names, from ancient [[Gaul]] and its neighboring lands. Examples of this are the [[Ésera]] in [[Spain]], the [[Isar]] in [[Germany]], the small Franco-Belgian [[Yser]], or even the ancient name of the [[Oise (river)|Oise]], ''Isara'' (the [[French language|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]],<ref name=Delamarre /> ''[[Jizera (river)|Jizera]]'' in the [[Czech Republic]] and ''[[Usora (river)|Usora]]'' in [[Bosnia and Herzegovina]].

== Geography ==
The Isère's course measures {{convert|286|km|mi|abbr=off|sp=us}}<ref name=Sandre>{{Sandre |id=W---0000 |nom=Isère |consulté le=24 March 2015}}</ref> 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]], cuts between the [[Chartreuse Mountains|Chartreuse]] and [[Belledonne]] mountain ranges, follows the [[Vercors Massif]], passes through the [[Dauphiné]] [[Provinces of France|province]], and finally meets with the Rhône at the foot of the [[Vivarais]].

=== Valleys ===
[[Image:Unités de paysage du Valentinois.JPG|thumb|left|Lower Isère valley (''basse vallée de l'Isère'') in the north of the Plain of Valence]]
The upper valley of the Isère is called the [[Tarentaise Valley|Tarentaise]], and its middle valley the [[Grésivaudan]].

The lower valley constitutes a section of the {{Interlanguage link|Plain of Valence|fr|3=Valentinois}} (also called the ''Valentinois'')<ref>Ravit, Philippe (2007). ''Le paysage valentinois, de la fondation de la colonie de ''Valentia'' (Valence) au IIIème siècle ap. J.-C.'' (Dissertation) (in French). Université Jean Moulin Lyon 3. p. 202.</ref> and is characterized by the river's deep, winding channel. Instead of widening its banks over time, the Isère has dug deeper into its [[Stream bed|bed]], forming stepped [[fluvial terrace]]s. The valley has clearly defined borders and is relatively narrow, not exceeding {{convert|2|km|mi|abbr=on}} in breadth.

The repetition of [[Alluvium|alluvial deposition]] (during periods of [[Quaternary glaciation]]) and [[overdeepening]] (during [[interglacial]] periods), known as a [[Fluvioglacial landform|fluvioglacial system]], led to the formation of several stepped [[Terrace (geology)|terraces]] in the lower Isère valley, like the one on which [[Saint-Marcel-lès-Valence]] is built.<ref>{{Cite thesis |last=Delahaye |first=Emmanuelle |title=Les espaces fluvio-urbains rhodaniens à l'aval de Lyon, Vienne, Valence, Avignon, Tarascon, Beaucaire et Arles : des territoires à la dérive ? |trans-title=Urban river spaces along the Rhône downstream of Lyon, Vienne, Valence, Avignon, Tarascon, Beaucaire and Arles: territories left to drift? |language=fr |chapter=Chapter 2.1.2., page 'Caractéristiques topographiques : au-dessus du fleuve' |chapter-url=http://theses.univ-lyon2.fr/documents/lyon2/2009/delahaye_e#p=74&a=TH.3.1.2.1.1 |date=23 January 2009 |publisher=Université Lumière Lyon&nbsp;2 |access-date=25 March 2015}}</ref> This occurred through the massive accumulation of alluvium from the Isère on top of a bed of [[Miocene]] [[molasse]]. Today, these terraces still define the geography of the Plain of Valence.<ref>{{cite journal |last=Faucher |first=Daniel |year=1914 |title=La plaine de Valence (Bas-Dauphiné) |url=http://www.persee.fr/web/revues/home/prescript/article/geo_0003-4010_1914_num_23_128_8134 |journal=[[Annales de Géographie]] |language=fr |trans-title=The Plain of Valence (Lower Dauphiné) |publisher=Armand Colin |volume=23 |issue=128 |pages=127–128 |doi=10.3406/geo.1914.8134 |issn=0003-4010 |access-date=20 March 2015 |via=Persée}}</ref>

=== Confluence ===
[[Image:Confluence de L'Isère et du Rhône sur la commune de La Roche de Glun,la commune de Châteaubourg se trouve au niveau du Rhône et en face.JPG|thumb|Confluence of the Isère (left) and the Rhône (right) near [[La Roche-de-Glun]]]]
The Isère initially merges with one of the Rhône's diversion canals, built for [[Inland navigation|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 [[Confluence|junction]] with the Rhône.

=== Main Tributaries ===
<small>(L) ''Left-bank tributary''; (R) ''Right-bank tributary''.</small>
* (L) {{Interlanguage link|Doron de Bozel|fr}}, {{convert|38.7|km|mi|abbr=on}}
** (R) [[Doron de Champagny]], {{convert|15.9|km|mi|abbr=on}}
** (L) {{Interlanguage link|Doron des Allues|fr}}, {{convert|20.9|km|mi|abbr=on}}
** (L) {{Interlanguage link|Doron de Belleville|fr}}, {{convert|28.6|km|mi|abbr=on}}
* (R) [[Arly]], {{convert|34.5|km|mi|abbr=on}}
** (L) [[Chaise (river)|Chaise]], {{convert|24|km|mi|abbr=on}}
** (L) {{Interlanguage link|Doron de Beaufort|fr}}, {{convert|24.1|km|mi|abbr=on}}
* (L) [[Arc (Savoie)|Arc]], {{convert|127.5|km|mi|abbr=on}}
* (L) [[Drac (river)|Drac]], {{convert|130.3|km|mi|abbr=on}}
** (R) {{Interlanguage link|Séveraisse|fr}}, {{convert|32.9|km|mi|abbr=on}}
** (L) {{Interlanguage link|Souloise|fr}}, {{convert|25.6|km|mi|abbr=on}}
** (R) {{Interlanguage link|Bonne (river)|fr|3=Bonne (rivière)|lt=Bonne}}, {{convert|40.1|km|mi|abbr=on}}
** (L) {{Interlanguage link|Ébron (river)|fr|3=Ébron|lt=Ébron}}, {{convert|32.1|km|mi|abbr=on}}
** (R) [[Romanche]], {{convert|78.4|km|mi|abbr=on}}
** (L) {{Interlanguage link|Gresse (river)|fr|3=Gresse|lt=Gresse}}, {{convert|34.6|km|mi|abbr=on}}
* (R) {{Interlanguage link|Vence (river)|fr|3=Ruisseau de la Vence|lt=Vence}}, {{convert|17.2|km|mi|abbr=on}}
* (R) [[Morge (Isère)|Morge]], {{convert|27.2|km|mi|abbr=on}}
** {{Interlanguage link|Fure (river)|fr|3=Fure|lt=Fure}}, {{convert|25.3|km|mi|abbr=on}}, via the Morge Canal
* (L) {{Interlanguage link|Bourne (Isère)|fr|3=Bourne (rivière)|lt=Bourne}}, {{convert|43.1|km|mi|abbr=on}}
** (L) {{Interlanguage link|Vernaison (river)|fr|3=Vernaison (rivière)|lt=Vernaison}}, {{convert|32|km|mi|abbr=on}}
* (R) {{Interlanguage link|Herbasse|fr}}, {{convert|40|km|mi|abbr=on}}

=== Cities on the Isère ===
* [[Savoie]]: [[Val-d'Isère]], [[Bourg-Saint-Maurice]], [[Aime]], [[Moûtiers]], [[Albertville]], [[Montmélian]]
* [[Isère]]: [[Pontcharra]], [[Grenoble]], [[Voreppe]]
* [[Drôme]]: [[Romans-sur-Isère]], [[Pont-de-l'Isère]], [[La Roche-de-Glun]]

== Hydrology ==
[[File:Isere profil long.svg|thumb|upright=3.2|center|Lengthwise profile of the Isère. Vertical: [[General levelling of France|NGF]] elevation (m). Horizontal: distance from the [[River mouth|mouth]] of the river (km).]]
The length of the Isère is {{convert|286|km|mi|abbr=on}}, and its [[drainage basin]] covers {{convert|11890|km2|sqmi|abbr=on}}.<ref name=Sandre />

The [[Grade (slope)|vertical profile]] of the river is made up of several zones:<ref>[http://www.geoportail.gouv.fr/ Géoportail Maps]</ref>
* From its sources to [[Sainte-Foy-Tarentaise]] (except for those sources having a slope of around 25%),<ref>The starting point is at 2,341 m, near the Prariond Refuge. The ending point is situated just downstream of [[Villaroger]].</ref> 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 [[Grenoble]].
* 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]] department, situated near the river's confluence with the Rhône. The [[Discharge (hydrology)|discharge]] of the river at Beaumont-Monteux measured {{convert|329|m3/s|ft3/s|abbr=off|sp=us}}.<ref name=Eaufrance>{{cite web |url=http://www.hydro.eaufrance.fr/stations/W3540010%26procedure%3Dsynthese |title=Synthèse : L'Isère à Beaumont-Monteux |website={{Interlanguage link|Banque Hydro|fr|3=Banque nationale de donnée pour l'hydrométrie et l'hydrologie}} |publisher=Eaufrance |language=fr |access-date=25 March 2015 |archive-date=1 September 2018 |archive-url=https://web.archive.org/web/20180901215810/http://www.hydro.eaufrance.fr/stations/W3540010%26procedure%3Dsynthese |url-status=dead }}</ref>

The Isère's large seasonal fluctuations are typical of rivers fed in large part by [[snowmelt]], with springtime flooding raising the average monthly [[Discharge (hydrology)|discharge]] between {{convert|382|m3/s|ft3/s|abbr=values}} and {{convert|500|m3/s|ft3/s|abbr=on}} 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 {{convert|246|m3/s|ft3/s|abbr=on}} in September.<ref name=Eaufrance /> Generally speaking, this makes the Isère a very plentiful watercourse throughout the year.

{{River discharge
|station=Beaumont-Monteux
|date=data calculated over 58 years
|unit=m<sup>3</sup>/s
|source = [http://www.hydro.eaufrance.fr/stations/W3540010&procedure=synthese Banque Hydro] - [[Ministry of Ecology, Sustainable Development and Energy]]
|max discharge = 500
|main scale = 100
|secondary scale = 25
|jan1=263
|feb1=291
|mar1=323
|apr1=382
|may1=472
|jun1=500
|jul1=387
|aug1=265
|sep1=246
|oct1=270
|nov1=285
|dec1=268
}}

However, the {{Interlanguage link|VCN3|fr}}<ref>VCN3 is an acronym used by French hydrologists to represent the mean flow of a river recorded over three consecutive days in order to characterize the severity of a drought. [http://www.glossaire.eaufrance.fr/en/concept/minimum-annual-mean-flow Eaufrance Glossary on Water - Minimum Annual Mean Flow]</ref> can drop to {{convert|110|m3/s|ft3/s|abbr=on}} during a five-year dry spell,<ref name=Eaufrance /> which is very low.

On the other hand, severe flooding can result from rapid thaw or torrential autumn rain. In fact, {{Interlanguage link|QIX 2|fr|3=QIX (hydrologie)}}<ref>QIX is an acronym used by French hydrologists to represent the likely return interval of a flood with a given severity. For example, QIX&nbsp;2 = once in two years, while QIX&nbsp;10 = once in 10 years. [http://www.glossaire.eaufrance.fr/en/concept/flood-flow Eaufrance Glossary on Water - Flood Flow]</ref> and QIX&nbsp;5 are {{convert|1200|m3/s|ft3/s|abbr=values}} and {{convert|1500|m3/s|ft3/s|abbr=on}}, respectively. QIX&nbsp;10 is {{convert|1700|m3/s|ft3/s|abbr=on}}. QIX&nbsp;20 reaches {{convert|1900|m3/s|ft3/s|abbr=on}}, while QIX&nbsp;50 rises to {{convert|2200|m3/s|ft3/s|abbr=on}},<ref name=Eaufrance /> which is still moderate compared to other rivers in the south of France, like the [[Tarn (river)|Tarn]].

The highest instantaneous discharge on record was {{convert|2050|m3/s|ft3/s|abbr=on}} on September 16, 1960, while the highest daily value was {{convert|1510|m3/s|ft3/s|abbr=on}} on October 7 of the same year.<ref name=Eaufrance />

The depth of runoff for the Isère's drainage basin is {{convert|882|mm|in|sp=us|abbr=off}} annually, which is quite high above France's average and clearly superior to that of the Rhône's drainage basin ({{convert|666|mm|in|abbr=on}} in [[Valence, Drôme|Valence]] for a surface area of {{convert|66450|km2|sqmi|abbr=on}}<ref>{{cite web |url=http://www.hydro.eaufrance.fr/hydroweb1/Traitement/genere_pdf_synthese.php?ss_StaCdCode=V4010010&unite=m3/s |title=Le Rhône à Valence |date=8 March 2015 |website=Banque Hydro |publisher=Eaufrance |language=fr |trans-title=The Rhône at Valence |format=PDF |access-date=25 March 2015 |archive-url=https://web.archive.org/web/20150402231532/http://www.hydro.eaufrance.fr/hydroweb1/Traitement/genere_pdf_synthese.php?ss_StaCdCode=V4010010&unite=m3%2Fs |archive-date=2 April 2015 |url-status=dead }}</ref>). The specific discharge<ref>[http://www.glossaire.eaufrance.fr/en/concept/specific-flow Eaufrance Glossary on Water - Specific Flow]</ref> is 27.9 [[liters]] per second per square kilometer of drainage basin.<ref name=Eaufrance />

[[Image:Isère-panorama.jpg|thumb|center|500px|The Isère in the [[Grésivaudan|Grésivaudan Valley]], seen from the [[Chartreuse Mountains]]]]

== Gallery ==
<gallery mode="packed">
Image:Isere à Daille.jpg|The Isère from La Daille, near [[Val-d'Isère]]
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 [[Grenoble]]
Image:Romansvg.jpg|The Isère at [[Romans-sur-Isère]]
Image:Antoine Guindrand - Paysage de l'Isère - 1836.JPG|Antoine Guindrand <br/> ''Paysage de l'Isère'' [Isère landscape] (1836)
</gallery>

== See also ==
* [[List of rivers of France]]

==References==
{{reflist}}

== External links ==
{{commons category|Isère River}}
*{{Cite EB1911|wstitle= Isère (river) | volume= 14 |last= Coolidge |first= William Augustus Brevoort |author-link= W. A. B. Coolidge|  page = 867 |short= 1}}

{{Authority control}}

{{DEFAULTSORT:Isere (river)}}
[[Category:Rivers of France]]
[[Category:Isère basin| ]]
[[Category:Rivers of Drôme]]
[[Category:Rivers of Isère]]
[[Category:Rivers of Savoie]]
[[Category:Rivers of Auvergne-Rhône-Alpes]]
[[Category:Rivers of the Alps]]