1911 Encyclopædia Britannica/Adour
ADOUR (anc. Aturrus or Adurus, from Celtic dour, water), a river of south-west France, rising in the department of Hautes Pyrenees, and flowing in a wide curve to the Bay of Biscay. It is formed of several streams having their origin in the massif of the Pic d'Arbizon and the Pic du Midi de Bigorre, but during the first half of its course remains an inconsiderable river. In traversing the beautiful valley of Campan it is artificially augmented in summer by the waters of the Lac Bleu, which are drawn off by means of a siphon, and flow down the valley of I esponne. After passing Bagneres de Bigorre the Adour enters the plain of Tarbes, and for the remainder of its course in the department of Hautes Pyrenees is of much less importance as a waterway than as a means of feeding the numerous irrigation canals which cover the plains on each side. Of these the oldest and most important is the Canal d'Alaric, which follows the right bank for 36 m. Entering the department of Gers, the Adour receives the Arros on the right bank and begins to describe the large westward curve which takes it through the department of Landes to the sea. In the last-named department it soon becomes navigable, namely, at St Sever, after passing which it is joined on the left by the Larcis, Gabas, Louts and Luy, and on the right by the Midouze, which is formed by the union of the Douze and the Midour, and is navigable for 27 m.; now taking a south-westerly course it receives on the left the Gave de Pau, which is a more voluminous river than the Adour itself, and flowing past Bayonne enters the sea through a dangerous estuary, in which sandbars are formed, after a total course of 208 m., of which 82 are navigable. The mouth of the Adout has repeatedly shifted. its old bed being represented by the series of etangs and lagoons extending northward as far as the village of Vieux Boucau, 22 1/2 m. north of Bayonne, where it found a new entrance into the sea at the end of the 14th century. Its previous mouth had been 10 m. south of Vieux Boucau. The present channel was constructed by the engineer Louis de Foix in 1579. There is a depth over the bar at the entrance of 10 1/2 to 16 ft. at high tide. The area of the basin of the Adour is 6565 sq. m.