Arize

Arize is a Rivière south-west of the France which runs in the departments of the Ariège and of the Haute-Garonne. It is a direct affluent of the the Garonne out of Right Bank.

Geography

Arize takes its source in the the Pyrenees (Massif of Arize) in Ariège (09) with the peak of Fontfrède (of 1617 meters). Actually Arize with its source is called Péguère upstream, on 4 to 5 km, since the fountain of Nogué to 1355 meters. It is thrown in the the Garonne with the height of Carbonne in Haute-Garonne (31).

Natural curiosity

It forms a natural Grotte on the level of the Farmhouse-with Azil (Ariège).

See: Cave of the Farmhouse of Azil

Principal affluents

Camedon: 16.7 km
lazaou: 13 km
Pujol: 9.6 km
Artillac: 14.2 km
Argain: 11.8 km

Departments and cities crossed

Ariège: Farmhouse-with Azil, Them Border-on-Arize, Countryside-on-Arize, Daumazan-on-Arize, Country house-with-Besplas

Haute-Garonne: Montesquieu-Volvestre, Rieux-Volvestre and Carbon

Hydrology

The food of Arize is rain, which explains the changes of its flow, the brutal Crue S at the time of Orage S which can take, sometimes, a catastrophic character.

The flow of Arize was observed for one 40 years period (1968-2007), with Rieux-Volvestre, locality of the department of the Haute-Garonne, located very close to the confluence with the the Garonne (ref.: ). Studied surface is of 476 km ², i.e. it quasi totality of the catchment area of the river.

The interannual medium flow or module of the river with Rieux-Volvestre is of 5,46 m ³ a second.

Arize presents seasonal fluctuations of flow rather important. The high waters take place in winter and in spring and carry the average monthly flow on a level located between 6,56 and 9,30 m ³ a second, from December to May included with maximum of 9,3 m ³ in February and 9,04 in April. The low waters occur in summer, from July to the beginning of October, with a fall of the monthly medium flow until 1,47 m ³ in August (247 liters a second), which is still extremely consistent.

However, the VCN3 can fall until 0,150 m ³, in the event of dry period quinquennial, that is to say 150 liters a second, which becomes relatively severe (see note).

In addition, the risings can be very important, even devastators. The QIX 2 and QIX 5 or calculated flows of biennial and quinquennial rising are worth respectively 130 and 180 m ³. The QIX 10 or calculated flow of decennial rising is worth 220 m ³ a second, while the QIX 20 is assembled to 250 m ³, and that the QIX 50 is of 300 m ³ a second. (see note). That means, for example, that one has to expect every five years a rising of about 180 m ³ a second The recorded maximum instantaneous flow with Rieux-Volvestre was of 259 m ³ a second on May 19th, 1977, while the value maximum day laborer was of 210 m ³ a second the same day. By comparing the first of these figures with the values of the various QIX of the river, it appears that this rising was of a vicennial nature and thus by no means exceptional. One can consider that it is intended to repeat itself every 20 years on average.

The Lame of water past in the basin of Arize is of 363 millimetres annually, which is high for a river of the area nonresulting from the Pyrenean high summits. It is definitely higher than the average overall of France all confused basins, but slightly lower than the whole of the catchment area of the Garonne (384 millimetres with the Farmhouse-with Agenais). The specific Débit (or Qsp) is assembled consequently at 11,5 liters a second and per square kilometer of basin.

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