Aubance

The Aubance is a French river which runs in the Département of Maine-et-Loire (49). It is a direct affluent of the the Loire out of left bank.

Geography

Aubance takes its source with Louerre locality of the Département of Maine-et-Loire located at the Western edge of the forest of Milly. Its course which includes/understands many meanders directs initially towards the North-West then curves gently towards the west. It is thrown finally in an arm of the the Loire called Louër on the level of the locality of Denée, with ten kilometers in the south-west of Angers.

Its average slope is of 0,134%.

Common crossings

The common crossings by Aubance, all in Maine-et-Loire, are the following ones (of upstream downstream):

Hydrology

The flow of Aubance was observed for one 26 years period (1982-2007), with Soulaines-on-Aubance, locality of the Département of Maine-et-Loire, located very close to the confluence with the the Loire (ref.: ). The catchment area of the river is there of 172 km ², i.e. nearly 85% of its totality.

The interannual medium flow or module of the river with Soulaines-on-Aubance is of 0,622 m ³ a second.

The seasonal fluctuations of flow of Aubance are rather important. The high waters are presented in winter and carry the average monthly flow on a level oscillating from 0,971 to 1,52 m ³ a second, from December to March included (with a maximum very Net in January). As of March, the flow drops gradually throughout spring, to lead to low waters. Those take place in summer and at the beginning of the autumn, from June to October, accompanied by a fall of the monthly medium flow going up to 0,116 m ³ in 0,126 and August (116 liters a second) in September, which is still acceptable for such a small river.

However, the VCN3 can fall until 0,001 m ³, in the event of dry period quinquennial, that is to say 1 small liter a second, which is very severe, the river being thus quasi dry. The VCN3 is the past minimal quantity or minimal flow over three days consecutive.

In addition the risings can be important taking into account the exiguity of the catchment area and the weakness of the medium flow. The QIX 2 and QIX 5 or calculated flows of biennial and quinquennial rising are worth respectively 12 and 20 m ³. The QIX 10 or calculated flow of decennial rising is worth 26 m ³ a second, while the QIX 20 is assembled to 31 m ³. Finally the QIX 50 is of 38 m ³ a second. (see note). That means that, for example, every five years on average, rising of about 20 m ³ a second can occur. The maximum instantaneous flow recorded with Soulaines-on-Aubance was of 30,3 m ³ a second on January 5th, 1994, while the value maximum day laborer was of 26 m ³ a second on January 22nd, 1995. By comparing the first of these figures with the values of the various QIX of the river, it appears that this rising even 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 Aubance is of 114 millimetres annually, which is frankly poor, very definitely lower than the overall average of France, but also than that of the whole of the catchment area of the Loire (244 millimetres). The specific Débit (or Qsp) is assembled consequently at small 3,6 liters a second and per square kilometer of basin.

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