The Ozanne is a 46.0 km long French

river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of wat ...

, a

tributary A tributary, or affluent, is a stream or river that flows into a larger stream or main stem (or parent) river or a lake. A tributary does not flow directly into a sea or ocean. Tributaries and the main stem river drain the surrounding drainage ...

of the

Loir The Loir () is a long river in western France. It is a left tributary of the Sarthe. Its source is in the Eure-et-Loir department, north of Illiers-Combray. It joins the river Sarthe in Briollay, north of the city of Angers. It is indirectly a ...

, which is a tributary of the

Loire The Loire (, also ; ; oc, Léger, ; la, Liger) is the longest river in France and the 171st longest in the world. With a length of , it drains , more than a fifth of France's land, while its average discharge is only half that of the Rhôn ...

Geography

The river spring is located at Perche-Gouët, Béthonvilliers at 222 m high at le Burail locality in le Bois de Beaumont. 2 offshoots: la Suzanne ou Sainte-Suzanne et l'Ozanne de Dampierre ou Moranne ou Mozanne which join near Brou. It flows into le Loir, right bank, 1 km north of Bonneval at 129 m high at Ouzenain (locality).

Tributaries

The Ozanne has 7 official affluents (14 including sub-affluents) : * ?(source secondaire), (rg), 3 km, sur les deux communes de Vicheres et Beaumont-les-Autels. * ?, (rg), 0.9 km, sur les deux communes de

Miermaigne Miermaigne () is a commune in the Eure-et-Loir department in northern France. Population See also *Communes of the Eure-et-Loir department The following is a list of the 365 communes of the Eure-et-Loir department of France. The communes c ...

et Beaumont-les-Autels. * sept bras de l'Ozanne, pour un total de 8.3 km sur les six communes de Unverre, Brou,

Yèvres Yèvres () is a commune in the Eure-et-Loir department in northern France. Population See also *Communes of the Eure-et-Loir department The following is a list of the 365 communes of the Eure-et-Loir department of France. The communes coope ...

, Dangeau, Moulhard et Luigny. * le Sainte Suzanne, (rd), 19.2 km sur les cinq communes de Unverre, Authon-du-Perche, Charbonnières, Beaumont-les-Autels et Les Autels-Villevillon avec deux affluents : ** ?, 4 km ?un bras? sur Unverre. ** la Sonnette, (rd), 13.5 km sur les cinq communes de Unverre, Charbonnières, Soize,

La Bazoche-Gouet La Bazoche-Gouet () is a commune in the Eure-et-Loir department in northern France. Population See also *Communes of the Eure-et-Loir department The following is a list of the 365 communes of the Eure-et-Loir department of France. The commu ...

, Les Autels-Villevillon. * la Vallée d'Esse, (rd), 10.1 km sur les deux communes de Unverre et

. * la Vallée de Tronchet, (rd), 8.8 km sur la seule commune de

. * la vallée de Montparentière, (rg), 3.1 km sur la seule commune de

. * la vallée des Vollars, (rd), 6.3 km sur les trois communes de

, Dangeau, Gohory.

Strahler number In mathematics, the Strahler number or Horton–Strahler number of a mathematical tree is a numerical measure of its branching complexity. These numbers were first developed in hydrology by and ; in this application, they are referred to as the ...

of 3

Watershed

The hydrological area of the Ozanne and its affluents is 278 km² wide, which is composed of farming land (91.52%), of forests and semi-natural areas (6.55%), artificial areas (1.76%) and damp areas (0.12%).

Hydrology

The Ozanne debit was studied from 1973 to 2014 at Prémoteux, near Trizay-lès-Bonneval at 126 m high, very close to its meeting point with the

. The river

watershed Watershed is a hydrological term, which has been adopted in other fields in a more or less figurative sense. It may refer to: Hydrology * Drainage divide, the line that separates neighbouring drainage basins * Drainage basin, called a "watershe ...

is of 268 km² (96% of the 278 km²). The river module at Trizay-lès-Bonneval is of 1.46 m³/s. The river presents impotent seasonal debital fluctuations, with high waters in Winter: mean monthly debit of 2,71 and 3.61 m³/s, from December to March (peak in January) and low waters in Summer, end of May to beginning of October, with a mean monthly debit drop of up to 0.235 m³ in August (235 L/s).

Low waters

However, the 3-day low-water volume can drop to a severe 0.044 m³ during a dry five-year period (or 44 L/s).

Floods

Floods can also be important. The maximal debit recorded was 65.2 m³/s on January 22, 1995, while the maximal daily worth was of 52.6 m³/s on April 10, 1983, which is expected to happen every 10 to 15 years on average. The maximal height was of 1920 mm (or 1.92 m) on January 14, 2004.

Water slide and debit

The yearly

precipitation In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, Rain and snow mixed, sleet, snow, ice pellets, ...

in the Ozanne basin is of a modest 173 mm, far below the national average, but also to that of la Loire (244 mm yearly), closer to its neighboring river Yerre (176 mm), with an average debit of 5.5 L/s and km².

Mill localities

Géoportail records 11 "mill" localities : le moulin de Vinet, le moulin de l'Orme, le moulin Foulon, le moulin Vieux et un gué, le moulin Brière, le moulin de Forçonnerie, le moulin d'Epasses, le moulin de Georges, le moulin de la Varenne, le moulin de Patry, un gué, le moulin de Frécot.

ZNIEFF

The river Ozanne marks the northern limit of a little ZNIEFF Chenaie-charmaie de la Poupelière.

References

{{Reflist Rivers of France Rivers of Centre-Val de Loire Rivers of Eure-et-Loir