3. Objectives

In the case in point, the two projects described in this article were triggered primarily by the issue of flood protection, but from two significantly different angles:

• for the Petit Rosne, in Sarcelles-village, the challenge of reopening the river is first and foremost to enable surface runoff to re-enter the riverbed under optimum conditions. Indeed, during the catastrophic floods of 1992 (figure 5 ), this area remained under 1.50 m of water for almost three weeks, even though the river, which was underground at the time, had rapidly regained its flow and discharge capacities;

• for the Croult, in Gonesse, the initial objective was to reduce the frequency of flooding in the housing estate known as...