Abstract: A flood control barrier for separating water in a wet area from an area to be maintained substantially dry comprises a flexible exterior membrane made of liquid impervious material and including elongated upper and lower membrane sections joined at a closed longitudinal downstream end of the exterior membrane opposed to an open longitudinal upstream end thereof. The upper and lower membrane sections are connected by internal partition walls and are displaceable between expanded and collapsed positions, wherein in the collapsed position, the upper membrane section overlies the lower membrane section, whereas in the expanded position, the upper membrane section is spaced from the lower membrane section at the open end of the exterior membrane such that water may flow through the open end and be received between the upper and lower membrane sections such as to be trapped therein, i.e. by the closed downstream end thereof which prevents the water from flowing past the barrier.