Gave d\' Oloron

The gave of Oloron (or lo gaver , lo gave of Sauveterre ) is a French Rivière of the the Pyrenees which runs in the departments of the Yrénées-Atlantiques and of the Landes.

The word Gave means torrential River.

Geography

The gave of Oloron is born with Oloron-Holy-Marie in the department from the Yrénées-Atlantiques from the Confluence from the Gave d' Aspe and the Gave d' Ossau.

It is thrown in the Gave of Pau to the upstream of Peyrehorade in the department of the Landes where they form the Gaves joined together before throwing itself in the Adour.

Departments and crossed cities

; Yrénées-Atlantiques ; Moors:

Principal affluents

Both gaves, Gave d' Aspe and Gave d' Ossau, by their meeting form the gave of Oloron. Then join the gave:

left bank: the Green , the Joos, the Lausset, the Season (or gave of Mauléon).
Right Bank: the Escou, the Auronce, the arrèc Heurer, the Saleys.

Shortly after Oloron-Holy-Marie it receives water of the Vert but its principal affluent is the Saison, or Gave de Mauléon, which sprinkles the valley of the Soule. It joined the gave of Oloron, out of left bank, on the commune of Autevielle-Saint-Martin-Bideren.

Hydrology

The flow of the gave of Oloron was observed during one 86 years period (1922-2007), with Escos, locality of the department of the Yrénées-Atlantiques located at little distance from its confluence with the Gave of Pau. Surface thus studied is of 2 456 km ², are it quasi totality of the catchment area of the river.

The interannual medium flow or module of the river with Escos is of 102,00 m ³ a second.

The gave of Oloron presents seasonal fluctuations of flow marked well, like generally in mountain medium. Its mode is mainly nival, with a rather important rain component. The high waters are characterized by a double top, the first in December corresponding to the rains of end of autumn with an average monthly flow of 132 m ³ a second. In January one attends a light fall of the flow which is prolonged until March (109 to 110 m ³ a second for these three months), a more significant part of precipitations being retained in the mountain, in the form of snow. The second top proceeds in spring, in April and especially in May and corresponds above all to the snow melt. It is characterized by average monthly flows of 148 and 161 m ³ a second, respectively for these two months. As of June, the flow drops quickly, to the low waters (low water level) of summer which take place from July to September included, involving a fall of the average flow monthly to the floor of 34 m ³ in August, which remains extremely comfortable besides. But these monthly averages occult more marked fluctuations over short periods or according to the years.

With the low water levels, the VCN3 can fall until 12 m ³ a second, which cannot however be described as severe (see note).

The risings, as for them, can be very important, as it is of rule in mountainous territory. And the basin of the river, just like its module, being important, one attends risings of important volume. The QIX 2 and QIX 5 are worth 1 respectively; 200 and 1 600 m ³ a second. The QIX 10 or calculated flow of decennial rising is of 1 800 m ³ a second, the QIX 20 of 2 100 m ³, while the QIX 50 is assembled to 2 400 m ³ a second (see note).

The recorded maximum instantaneous flow with Escos was of 1 960 m ³ a second on October 6th, 1992, while the value maximum day laborer was of 1 920 m ³ a second on November 29th, 1931. If one compares the first of these values on a QIX scale of the river, one notes that this rising was not even of a vicennial nature, and thus by no means exceptional.

The gave of Oloron is a very abundant river. The Lame of water past in its catchment area is of 1 308 millimetres annually, which is more or less four times superior with the overall average of France all confused basins, but completely normal compared with the various rivers of the Western area of the Pyrenees, generally very abundant. The specific Flow (or Qsp) reached of this fact the very high figure of 41,4 liters a second and per square kilometer of basin.

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