DURANCE (anc. Druentia), one of the principal rivers draining the French slope of the Alps towards the Mediterranean. Its total length from its source in the High Alps of Dauphine to its junction with the Rhone, a little below Avignon, is 2171 miles. It is commonly said to take its origin in some small lakes a little south of the Mont Genevre pass, but has two other head streams of much greater length and volume. These are the Clairee, flow ing in from the north, through the smiling Nevache glen, at the head of which, not far from the foot of the Mont Thabor ft.) it rises in some small lakes, on the east side of the Col des Rochilles ; and the Guisane (flowing in from the north-west and rising near the Col du Lautaret, 6,8o8 ft.). Between its junc tion with the Cerveyrette and the Gyronde the Durance passes through fine deeply-cut gorges. It then runs through a stony plain, where it frequently overflows and causes great damage, this being indeed the main characteristic of the Durance through out its course. At the foot of the fortress of Mont Dauphin and some distance above the town of Embrun, it receives (left) the Guil, which flows through the Queyras valley from near the foot of Monte Viso. It becomes the boundary for a while between the departments of the Hautes-Alpes and of the Basses-Alpes, and receives the considerable Ubaye river, flowing from near the foot of Monte Viso past Barcelonnette (left) .
Flowing through the Basses-Alpes it is joined above Sisteron (right) by the wild torrent of the Buech, flowing from the deso late region of the Devoluy, the Bleone (left) (on which Digne, the capital of the department, is situated) and the Asse (left). The Verdon, flowing past the town of Castellane, joins it from the lower summits of the Maritime Alps. After passing through some narrow gorges near Sisteron the bed of the river becomes wide and liable to flood, the frequent overflows being kept within bounds by numerous dykes and embankments. These features are especially marked when the river, after leaving the Basses-Alpes, bends north-west and, always serving as the boundary between the departments of Vaucluse (north) and of the Bouches-du-Rhone (south), passes Cavaillon above its junction with the Rhone. The drainage area of the Durance is about 5,166 sq.m., while the height it descends is 6,55o ft., if reckoned from the lakes on the Mont Genevre, or 7,85o ft. if we take those at the head of the Nevache valley as the true source of the river.