Arguenon

File:Plancoët - Arguenon.jpg ]]

The length of the watercourse is {{convert|53.4|km}}.{{sfn|Fiche cours d'eau - L'Arguenon}}{{sfn|Observatoire des Poissons Migrateurs en Bretagne}}{{efn|The length is 54 km according to Sandre and 64 km according to the Brittany migratory fish observatory. The length given in this article is that of Sandre since it is the official French reference.}}

The river rises in the commune of Le Gouray in Côtes-d'Armor and flows into the sea near Saint-Jacut-de-la-Mer, in the commune of Créhen, in the Bay of Arguenon.{{sfn|Géoportail (France)}}

The Arguenon is very wide between Jugon-les-Lacs and Plorec-sur-Arguenon.

The Ville-Hatte dam built in 1972 to supply the department with drinking water has created a water reservoir more than {{convert|10|km}} long named Lac d'Arguenon.

The Arguenon runs northeast from its source to Jugon-les-Lacs, north between Jugon-les-Lacs and Plorec-sur-Arguenon, northeast again between Plorec-sur-Arguenon and Plancoët and north-northeast from Plancoët to its mouth.

During high tides a small tidal bore rises up the river, up to the height of the Guildo bridge.

{{Further|Singing Stones of Brittany}}

The Arguenon's course is entirely within the Côtes-d'Armor department.

It crosses twelve communes, from upstream to downstream: Le Gouray (source), Plénée-Jugon, Dolo, Jugon-les-Lacs, Plorec-sur-Arguenon, Plédéliac, Pléven, Bourseul, Pluduno, Plancoët, Saint-Lormel, Créhen and Saint-Cast-le-Guildo (mouth).{{sfn|Fiche cours d'eau - L'Arguenon}}

The managing body is SAGE Arguenon – Baie de la Fresnaye.{{sfn|SAGE Arguenon - Baie de la Fresnaye}}

The Arguenon has four named tributary streams, one river and 10 unnamed tributaries including:{{sfn|Fiche cours d'eau - L'Arguenon}}

• Rosette river, {{convert|31.2|km}}, enlarged by the Rieule, {{convert|13.8|km}}.
• Bos Robert stream, {{convert|5.6|km}}, in the two municipalities of Langourla and Plénée-Jugon.
• Quiloury stream, {{convert|14.7|km}}, in the four municipalities of Le Gouray, Penguily, Plénée-Jugon and Saint-Glen.
• Étang du Guillier stream, {{convert|6.2|km}}, over the four municipalities of Jugon-les-Lacs, Plédéliac, Plestan and Tramain.
• Montafilan stream, {{convert|16.3|km}}, in the six municipalities of Corseul, Créhen, Plancoët, Plélan-le-Petit, Saint-Maudez and Saint-Michel-de-Plélan.

We can also add, according to the National Institute of Geographic and Forest Information or Géoportail, and since the Guébriand is not a river in its own right:

• The Guébriand, {{convert|19.8|km}}, passing through the commune of Landébia and joining the Arguenon between the communes of Saint-Lormel and Saint-Cast-le-Guildo at the entrance to Arguenon bay opposite the town of Créhen.

The Arguenon has been observed in Jugon-les-Lacs since 1972 at station J1103010 L'Arguenon, at an altitude of {{convert|31|m}} with a catchment area of {{convert|104|km|2}}.{{sfn|L'Arguenon à Jugon-les-Lacs, Hydro}}

The annual average of its flow at this point is {{convert|0.829|m3/s}}.{{sfn|L'Arguenon à Jugon-les-Lacs, Hydro}}

{{Vertical bar chart |full_name=Average flow at Jugon-les-Lacs in m3/s |height=250px

|Jan |1.92

|Feb |2.02

|Mar|1.40

|Apr |0.986

|May |0.693

|Jun |0.347

|Jul |0.196

|Aug |0.107

|Sep |0.119

|Oct |0.295

|Nov |0.638

|Dec |1.30

|note=Hydrological station: J1103010 - L'Arguenon in Jugon-les-Lacs
2015-08-08 - data calculated over 44 years from 1972 to 2015

}}

At low water the minimum flow rate of the watercourse recorded for three consecutive days in a month, during a five-year dry period, was {{convert|0.014|m3/s}}.{{sfn|L'Arguenon à Jugon-les-Lacs, Hydro}}

File:L'Arguenon au Gouray.jpg

During the observation period, the maximum daily flow was observed on 28 February 2010 at {{convert|24.80|m3/s}}.

The maximum instantaneous flow (QIX: quantité instantanée maximale) was observed at 14:21 on 28 February 2010 was {{convert|36.10|m3/s}}, and at the same time the instantaneous maximum height was {{convert|217|cm}}.{{sfn|L'Arguenon à Jugon-les-Lacs, Hydro}}

The 10-year QIX is {{convert|23|m3/s}}, the 20-year QIX is {{convert|28|m3/s}} and the 50-year QIX is {{convert|34|m3/s}} while the 2-year QIX is {{convert|11|m3/s}} and the 5-year QIX is {{convert|18|m3/s}}.{{sfn|L'Arguenon à Jugon-les-Lacs, Hydro}}

The Arguenon has experienced several significant floods.

The first took place in 1974.

The water overflowed {{convert|1|m}} on the Plancoët quay, causing major and widespread damage.

The second took place in 2010, this time with {{convert|50|cm}} on the quayside.

The floodwater affected a lot of businesses.

The last took place in February 2014, with {{convert|1.45|m}} on the quays.

Shops were closed permanently and a park was completely flooded.

The depth of runoff in this part of the river's catchment area is {{convert|253|mm}} annually, which is a little lower than the average in France.

The specific flow rate reaches {{convert|8.0|litre/second}} per {{convert|1|km2}} of basin.{{sfn|L'Arguenon à Jugon-les-Lacs, Hydro}}

The Arguenon is crossed by Route nationale 176 and Route nationale 12.

The Arguenon estuary is protected by a {{convert|381|hectare}} Zone naturelle d'intérêt écologique, faunistique et floristique.{{sfn|INPN, ZNIEFF 530030026}}

Arguenon Bay is part of the Natura 2000 zone Lancieux Bay, Arguenon Bay, Saint Malo and Dinard Archipelago.{{sfn|INPN - FSD Natura 2000 - FR5300012}}

{{notes}}

{{reflist|30em}}

{{refbegin}}

• {{citation |publisher=Sandre; Service d'administration nationale des données et référentiels sur l'eau |ref={{harvid|Fiche cours d'eau - L'Arguenon}}

|title=Fiche cours d'eau - L'Arguenon (J11-0300) |url=http://www.sandre.eaufrance.fr/geo/CoursEau/J11-0300 |accessdate=2021-09-15}}

• {{citation |url=http://www.geoportail.fr/ |title=Géoportail

|author=Géoportail (France) |publisher=Institut national de l'information géographique et forestière |accessdate=15 August 2015}}

• {{citation |ref={{harvid|INPN - FSD Natura 2000 - FR5300012}}

|title=INPN - FSD Natura 2000 - FR5300012 - Baie de Lancieux, Baie de l'Arguenon, Archipel de Saint Malo et Dinard - Description

|url=https://inpn.mnhn.fr/site/natura2000/FR5300012 |work=inpn.mnhn.fr |accessdate=2020-11-11}}

• {{citation |ref={{harvid|INPN, ZNIEFF 530030026}}

|title=INPN, ZNIEFF 530030026 - ESTUAIRE DE L'ARGUENON - Description

|url=https://inpn.mnhn.fr/zone/znieff/530030026.pdf |work=inpn.mnhn.fr |accessdate=2020-11-11}}

• {{citation |url=http://www.hydro.eaufrance.fr/stations/J1103010&procedure=synthese |accessdate=2021-09-15 |language=fr

|title=L'Arguenon à Jugon-les-Lacs |ref={{harvid|L'Arguenon à Jugon-les-Lacs, Hydro}} |work=Banque Hydro |publisher=Ministry of the Ecological Transition (France)}}

• {{citation |url=http://www.observatoire-poissons-migrateurs-bretagne.fr/bretagne/arguenon-montafilan-guebriand |title=L'Arguenon, le Montafilan et le Guébriand

|author=Observatoire des Poissons Migrateurs en Bretagne |accessdate=15 September 2021}}

• {{citation |ref={{harvid|SAGE Arguenon - Baie de la Fresnaye}}

|title=SAGE Arguenon - Baie de la Fresnaye |url=https://www.smap22.fr/index.php?option=com_content&view=category&id=28&Itemid=246 |work=www.smap22.fr |accessdate=2020-11-11}}

{{refend}}

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Category:Rivers of Côtes-d'Armor

Category:Rivers of Brittany

Category:Rivers of France