ADOUR, a river of south-west France, rising in the depart ment of Hautes Pyrenees, south of the Pic du Midi de Bigorre, and flowing in a wide curve to the Bay of Biscay. It traverses the beautiful valley of Campan and, after passing Bagneres de Bigorre, enters the plain of Tarbes. Beyond Tarbes numerous canals are drawn from the river for irrigation purposes; the most important is the Canal d'Alaric, which follows the right bank for 36m. Within the department of Landes it flows west and later south-west, becoming navigable at St. Sever, beyond which it is joined on the left by the Larcis, Gabas, Louts and Luy, and on the right by the Midouze. After Bayonne the river enters the sea through a dangerous estuary, after a total course of 208m. The mouth of the Adour has repeatedly shifted, its old bed being represented by the series of etangs and lagoons extending north wards as far as the village of Vieux Boucau (221m.), where it de bouched in the 14th century. The present channel was constructed by the engineer Louis de Foix in 1579. The area of the basin of the Adour is 6,565sq.m.