 Complete the following phrase:  The Schwingesperrwerk is a man-made movable barrier located on the Schwinge at its confluence with the Elbe near Stade, Germany. It is part of the flood control program for the Lower Elbe tidewater region, from the weir in Geesthacht to the mouth of the Elbe where it flows into the North Sea. Engineers constructed the Schwingesperrwerk after a 