A flood barrier for protecting the environment having a venturi type effect pumping means not requiring external power, the flood barrier comprising a wall and a pump for drawing water across the barrier from a first side to a second side. The wall configured to provide a barrier preventing movement of water from the first, drain, side to the second, tributary, side, of that wall. The barrier further comprising a pipe traversing the wall for transferring water between the two sides of the wall the pipe being terminated in the first side of the wall at a venturi effect pump, the pump being feedable with water from the drain through a conduit inlet so as to create suction in the pipe for drawing water through the pipe from the second side of the wall to drain water from the second to the first side of the wall.