Boivre

The Boivre is a French river which runs in the departments of the Two-Sevres and the Vienna, in area Poitou-Charentes. Boivre is also called the river with the beavers . Its etymology comes from a Germanic root which gave biber in German and beaver in English.

Geography

Boivre takes its source with Vasles in the Two-Sevres. It runs out of west in east. It crosses Benassay, Lavausseau, the Vault-Montreuil, Montreuil-Bonnin, Béruges, Vouneuil-under-Biard and Biard, before being thrown in the Clain with Poitiers.

Hydrology

Its quiet course protected the medieval city from Poitiers by artificial marshes (two roadways barred its course in its steepsided valley) in the west of the city. Its course from now on is channeled in the crossing of Poitiers. However, its risings can be important and have several times paralyzed line the SNCF Paris-Bordeaux.

Hydrometry - flows

Boivre was observed during one 21 years period (1987-2007), at Vouneuil-under-Biard, locality of the department of the Vienna, was located little upstream of its confluence with the Clain (ref.: ). At this place studied surface is of 185 km ², on 200 for the totality of the catchment area.

The interannual medium flow or module of the river with Vouneuil-under-Biard is of 1,07 m ³ a second.

Boivre present of the seasonal fluctuations of flow important, with high waters of winter-spring carrying the average monthly flow on a level of 1,37 to 2,45 m ³ a second, from December to April included (maximum in January), and of low waters of summer from July to September, with a fall of the monthly medium flow up to the level of 0,261 m ³ in still appreciable level, August, it is true. But these monthly averages hide more important periodic oscillations and are also variable according to the years.

The VCN3 can fall until 0,044 m ³, in the event of dry period quinquennial (44 liters a second), which cannot be described as really severe (see note).

As for the risings, they can be rather important. The QIX 2 and QIX 5 are worth respectively 11 and 20 m ³. The QIX 10 or calculated flow of decennial rising is of 25 m ³ a second and the QIX 20 of 31 m ³. As for the QIX 50 it was not calculated, for lack of duration of sufficient observation to determine it with precision (see note).

The maximum instantaneous flow recorded with Vouneuil-under-Biard was of 54,4 m ³ a second on August 1st, 2004, while the value maximum day laborer had been of 26,5 m ³ a second on January 23rd, 1995. By comparing these data with the scale of the calculated QIX of the river, one notes that the rising of August 2004 was very largely higher than the vicennial rising defined by the QIX 20, and thus completely exceptional.

The Lame of water past in the catchment area of Boivre is of 183 millimetres annually, which is largely lower than the overall average of France all confused basins, thus besides that of the catchment area of the Vienna (319 millimetres) and of the Clain (223 millimetres). The specific Débit (or Qsp) posts the extremely average figure of 5,8 liters a second and per square kilometer of basin.

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