The sources of the water are a combination of melting snow and the drainage of rain from the surrounding hills and plateaux which have a Mediterranean climate.
The latter's tributaries bring rain water mainly in spring, autumn and winter but little during the summer.
At Serre-Ponçon, its basin of 3,600 square kilometres (1,400 sq mi) can create a flow as low as 18 cubic metres per second (640 cu ft/s) and a maximum flood of 1,700 cubic metres per second (60,000 cu ft/s) (value recorded in 1957).

At the confluence with the Rhône, the average natural flow of the Durance is approximately 190 cubic metres per second (6,700 cu ft/s), with a high annual variability.
It can vary between 40 cubic metres per second (1,400 cu ft/s) (the most severe low water levels) and 6,000 cubic metres per second (210,000 cu ft/s) in catastrophic historic floods, levels reached in 1843, 1882 and 1886.
At the outlet into the Lac de Serre-Ponçon, the medium flow is 81 cubic metres per second (2,900 cu ft/s); at Oraison it is 123 cubic metres per second (4,300 cu ft/s) and after the confluence with the Verdon, flow reaches 174 cubic metres per second (6,100 cu ft/s) (250 to 330 m³/s in spring, 100 m³/s in the summer).
The contribution of water from the downstream tributaries is very low.
The annual maximum flow generally occurs in May or June, but the most violent flash floods occur in autumn.
The lowest water levels occur in winter in the upper valley, and in summer in the middle and lower part of the river.
The sources of the water are a combination of melting snow and the drainage of rain from the surrounding hills and plateaux which have a Mediterranean climate. The latter's tributaries bring rain water mainly in spring, autumn and winter but little during the summer. At Serre-Ponçon, its basin of 3,600 square kilometres (1,400 sq mi) can create a flow as low as 18 cubic metres per second (640 cu ft/s) and a maximum flood of 1,700 cubic metres per second (60,000 cu ft/s) (value recorded in 1957).
At the confluence with the Rhône, the average natural flow of the Durance is approximately 190 cubic metres per second (6,700 cu ft/s), with a high annual variability. It can vary between 40 cubic metres per second (1,400 cu ft/s) (the most severe low water levels) and 6,000 cubic metres per second (210,000 cu ft/s) in catastrophic historic floods, levels reached in 1843, 1882 and 1886. At the outlet into the Lac de Serre-Ponçon, the medium flow is 81 cubic metres per second (2,900 cu ft/s); at Oraison it is 123 cubic metres per second (4,300 cu ft/s) and after the confluence with the Verdon, flow reaches 174 cubic metres per second (6,100 cu ft/s) (250 to 330 m³/s in spring, 100 m³/s in the summer). The contribution of water from the downstream tributaries is very low. The annual maximum flow generally occurs in May or June, but the most violent flash floods occur in autumn. The lowest water levels occur in winter in the upper valley, and in summer in the middle and lower part of the river.
Durance