From Sisteron (Alpes-de-Haute-Provence) to Avignon (Vaucluse), the middle and lower Durance forms an arc of 112 miles (180 km), the bed of which has been cluttered for anthropogenic reasons. The installation of industrial or agricultural areas, two highways, and a high-speed rail line in the flood expansion zone has slowed the flow of the river, which no longer carries materials during regular floods. They, therefore, clutter the bed of the Durance and contribute to its increasing vegetation.