A flap gate includes a door body and a flap ancillary part. When the door body is in its down position, a movable end portion of the door body is located forward of a supported end portion. The door body changes its position between the down position and a maximum up position. The flap ancillary part applies tilt-up moment to the door body only when the door body is located in a position between the down position and a first position. The flap ancillary part also applies tilt-down moment to the door body only when the door body is located in a position between the maximum up position and a second position.

A gate, leaf, and method for controlling water levels in a body of water. The gate comprises a moveable barrier (which may be a leaf), a restoring device such as a spring, and a profile. The barrier automatically opens or closes an amount to allow less or more water through as a result of changes in the water pressure in the upstream body of water. This helps maintain a water level in the upstream body of water. The profile disturbs the flow of water through the gate to influence the water pressure on the barrier. The profile may help provide a more linear curve for the water moment on the barrier across the range of barrier positions. A more linear curve for the water moment may help maintain equilibrium with the restoring moment across the range of barrier positions. The method comprises disturbing the flow of water over a barrier to redistribute the pressures of the water on the barrier.

Methods, systems and computer program products for determining an accurate flow rate based on limited observations are provided. Aspects include receiving a limited sample of flow rate data associated with a test site of a test river. Aspects also include determining topographical characteristics of the test site. Aspects also include determining a plurality of similar tested sites and generating a test site rating curve based on a combination of the limited sample of flow rate data and sufficient flow rate data associated with one or more of the plurality of similar tested sites. Aspects also include obtaining a stage reading associated with the test site from a sensor disposed at the test site. Aspects also include determining a flow rate of the test site based on the stage reading and the test site rating curve.

An axis positioning mechanism serving as a rotation bearing of a flap gate includes a housing disposed at the bottom of an opening, a first rotating plate rotationally supported by the housing via a first shaft, a second rotating plate rotationally supported by the housing via a second shaft having a different axis from the first shaft, and a synchronizing rod rotationally connected to the rotating plates so as to synchronize the rotations of the rotating plates. The axis positioning mechanism further includes connecting members rotationally connecting a door base and the rotating plates with different axes. The door is laid flat with a pivot at a higher position than the axes.

A dynamic fluid flow control structure is provided that allows precise control over fluid flow using a series of two or more orifices, at least one of which may be reconfigured to change its flow characteristics. A flood control system and a flood control process are provided that emulate a preset discharge profile over time. Some versions of the structure, process, and system can be used to provide controlled storm discharge patterns in a developed area that emulate the natural pre-development discharge patterns.

A wall resident in a subterranean chamber and not obscuring a horizontal ground level view is situated between buoyant panels flanking the chamber and is configured to be passively rotationally raised out of the chamber to an upright position by one or both of the flanking panels when the panels rotationally buoy upward to form a barrier against water invading the position that the wall, chamber and panels occupy. When flood waters recede, the wall passively lowers so the horizontal ground level view is again not obscured. Provision is made for cleaning flood laden debris from the subterranean chamber to allow the wall to be operated repeatedly after recurring floods.

A flap gate includes a door body and a flap ancillary part. When the door body is in its down position, a movable end portion of the door body is located forward of a supported end portion. The door body changes its position between the down position and a maximum up position. The flap ancillary part applies tilt-up moment to the door body only when the door body is located in a position between the down position and a first position. The flap ancillary part also applies tilt-down moment to the door body only when the door body is located in a position between the maximum up position and a second position. This simplifies the structure of the flap gate that can speedily start to tilt up when water flows in and that can early start to tilt down when the water level has started to drop.

A tidal barrage comprising: a plurality of spaced towers, a plurality of barriers for controlling water flow through the barrage between the towers, and one or more turbine devices, wherein the towers comprise at least first, second and third towers, wherein the first tower is located between the second and third towers and houses one or more of the turbines, wherein one or more first barriers are provided between the first and second towers, and one or more second barriers are provided between the first and third towers, wherein the barriers are configured so that when the one or more first barriers and the one or more second barriers are in a first configuration, a first flow path through the barrage is defined from a first side of the barrage to a second side of the barrage, and when the one or more first barriers and the one or more second barriers are in a second configuration, a second flow path through the barrage is defined from the second side of the barrage to the first side of the barrage, and water flowing through the first and second flow paths flows through the one or more turbines housed in the first tower in the same direction, wherein one or more of the barriers comprises a water impervious flexible membrane, a buoyancy member; and one or more tethers.

A liquid retaining barrier comprises a plurality of vertically stacked members, each member having first and second ends, a length between the first and second ends, first and second sides, and top and bottom faces. An outer shell extends around a perimeter formed by the first and second sides and first and second faces of the member, and defines an inner core space. A conduit comprising a compression reinforcement material is positioned in the inner core space and forms an approximately parabolic curve extending between the first and second ends. A side of the outer shell is tangent to the curve of the conduit at about the mid-point of the length of the member.

An axis positioning mechanism serving as a rotation bearing of a flap gate includes a housing disposed at the bottom of an opening, a first rotating plate rotationally supported by the housing via a first shaft, a second rotating plate rotationally supported by the housing via a second shaft having a different axis from the first shaft, and a synchronizing rod rotationally connected to the rotating plates so as to synchronize the rotations of the rotating plates. The axis positioning mechanism further includes connecting members rotationally connecting a door base and the rotating plates with different axes. The door is laid flat with a pivot at a higher position than the axes.