Indrois

The Indrois is a French river , affluent out of Right Bank of the lower course of the Indre, and thus tributary of a tributary of the the Loire.

Geography

The river is born in north from the Département from Indre with five kilometers in south-east from the locality from Préaux and takes the direction of the North-West. It enters quickly the department of Indre-et-Loire, and bathes Montrésor. It is thrown in the Indre with Azay-on-Indre in the department of Indre-et-Loire, after having run in the sympathetic nerve and re-elected valley of Indrois.

Affluents

the Storm of which it receives water close to Villeloin
the Olivet

Hydrology

Indrois is a fairly abundant river. Its flow was observed during one 31 years period (1977-2007), with Genillé, locality of the department of Indre-et-Loire, located at about fifteen kilometers of its confluence with the Indre (ref.: and). The catchment area of the river is there of 396 km ², i.e. more than 85% of this last which counts 450 of them on the whole.

The interannual medium flow or module of the river with Genillé is of 2,29 m ³ a second.

Indrois presents seasonal fluctuations of flow very marked, like very often the rivers of plain of the basin of the Loire. The high waters are held in winter and carry the average monthly flow on a level located between 3,73 and 4,86 m ³ a second, from January to March included (with an in January maximum). As of at the end of March, the flow falls gradually to the low waters of summer which take place from June to October, involving a fall of the monthly medium flow going up to 0,52 m ³ in August, which remains rather consistent. But the fluctuations are much more marked over moreover short periods.

With the low water level, the VCN3 can fall until 0,18 m ³, in the event of dry period quinquennial, that is to say 180 liters a second, which cannot be regarded as severe, especially for a small river. Let us recall that the VCN3 is a measurement of the severity of the low water levels which gives the past minimal quantity or minimal flow over three days consecutive.

As for the risings, they can be extremely important taking into account the rather reduced size of the basin. The QIX 2 and QIX 5 are worth indeed respectively 53 and 85 m ³. The QIX 10 or calculated flow of decennial rising is of 110 m ³ a second, the QIX 20 of 130 m ³. As for the QIX 50, it is assembled to 150 m ³ a second (see note).

The recorded maximum instantaneous flow with Genillé was of 127 m ³ a second on May 12th, 1985, while the value maximum day laborer was of 82,1 m ³ a second the same day. If one compares the first of these values on a QIX scale exposed higher, one notes that this rising was hardly of a vicennial nature, and thus by no means exceptional. On the whole, Indrois is an irregular and fairly abundant river in the context of the rivers of plain of the basin of the Loire. The Lame of water past in its basin is of 180 millimetres annually, which is lower than the overall average of France all confused basins, but also to the average of the basin of the the Loire (more or less 244 millimetres). The specific Débit of the river (or Qsp) is assembled consequently at weak 5,7 liters a second and per square kilometer of basin.

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