Acolin
The Acolin is a French river , affluent of the the Loire out of left bank. It crosses the oriental party of the Département Allier, in area Auvergne and the south of that of the Nievre in Burgundy.
The course of Acolin
Acolin takes its source in Combining it, with a score kilometers in the south-east of Moulins, the south of the locality of Mercy, in a covered wooded area of many ponds, and takes from the start the direction of north. Its basin drains the area located between the courses lower Allier than the west and of Besbre than the east. Just like its neighbors, it maintains her orientation towards north, throughout its course of more than 60 kilometers and ends up being thrown in the the Loire with the April-on-Loire, a little downstream from the town of Decize.
Common crossings
Acolin does not bathe important localities.
Hydrology
Acolin is a river fairly abundant, but very irregular, like almost all the small rivers of the department Allier. Its flow was observed over one 33 years period (1970-2003), with Saint-Germain-Chassenay, locality of the department of the Nievre located at little distance from its confluence with the the Loire. The catchment area of the river there is of 384 km ², that is to say more than 80% of its totality and does not include/understand the basin of its affluent, the Abron.
The interannual medium flow or module of the river with Saint-Germain-Chassenay is of 2,5 m ³ a second.
Acolin presents seasonal fluctuations of flow marked enough, like very often in the basin of the Loire, with high waters of winter carrying the average monthly flow on a level located between 3,4 and 4,8 m ³ a second, from December to March included (with a maximum Net in January). It follows one intermediate period of progressive fall of the flows, crossed by a serious rebound in May. The low waters are held at the end of June with the beginning of October with one minimum of the monthly medium flow of 0,81 m ³ in September, which remains extremely comfortable for this small river. But the fluctuations of flow are much more marked over moreover short periods or according to the years.
With the low water level, the VCN3 can fall until 0,360 m ³, in the event of dry period quinquennial, that is to say 360 liters a second, which is far from being severe compared with good of other rivers of plain of the basin of the Loire. Let us recall that the VCN3 is the past minimal quantity or minimal flow over three days consecutive.
As for the risings, they can be very important relative with the modest size of the river and its catchment area. The QIX 2 and QIX 5 are worth respectively 35 and 52 m ³ a second. The QIX 10 or calculated flow of decennial rising is of 64 m ³ a second, the QIX 20 of 75 m ³, while the QIX 50 was not calculated being given the insufficiency of the duration of observation of the flows (see note).
The recorded maximum instantaneous flow with Saint-Germain-Chassenay during this 33 years period, was of 103 m ³ a second on May 1st, 1977, while the value maximum day laborer was of 71 m ³ a second on May 27th of the same year. By comparing the first of these values with the scale of the QIX of the river, one can note that this rising was largely higher than the vicennial rising calculated according to the QIX 20 and probably much more than cinquantennale, and thus extremely exceptional.
Acolin is a river not very abundant. The Lame of water past in its catchment area is of 206 millimetres annually, which is definitely lower than the overall average of France all confused basins, like to the average of the basin of the the Loire. The specific Débit of the river (or Qsp) does not reach of this poor fact that one 6,5 liters a second and per square kilometer of basin.