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CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This patent application claims the benefit of U.S. Provisional Application No. 61/975,421 filed Apr. 4, 2014. The above application is incorporated by reference herein in its entirety. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    The invention described herein was made by an employee of the United States Government and may be manufactured and used by the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefore. 
     
    
     BACKGROUND OF THE INVENTION 
       [0003]    1. Field of Invention 
         [0004]    This invention relates to the field of hydraulic engineering and more specifically to a vertically sliding adjustable fluid control system. 
         [0005]    2. Description of Related Art 
         [0006]    Weir stacks and water control gates are permanent structures known in the art used to maintain desired water levels and to control the stage, discharge, distribution, delivery or direction of water flow. 
         [0007]    A weir stack is a barrier that operates like a small adjustable dam, pooling water behind the stack while also maintaining a maximum water level by allowing it to flow steadily over the top of the stack. Common uses of weir stacks include altering the discharge flow of rivers to prevent downstream flooding, regulating fluid discharge and rendering rivers navigable. Typically, weir stacks consist of a stack of “stop logs” fabricated out of timber or aluminum and held into place with vertical channels. One of problems known in the art is that buoyant stop logs can float, compromising the stack. Additionally, water level control is typically achieved by removing logs from or adding logs to the stack. Adjusting the weir stack places personnel at risk in situations where the flow of water is powerful. 
         [0008]    Water control gates are used as an alternative to weir stacks. A control gate is a single, solid structure held into place with vertical channels, or hinged and employing water pressure to seat the gate. Water is drained from a reservoir by lifting a mechanically actuated gate. Constructing a water control gate is an expensive undertaking, because the structure requires a substantial foundation and complex engineering. Once installed, it is difficult to modify the structure as environmental conditions change. Another problem known in the art is that water released from the reservoir bottom may contain undesired sediment or be under unacceptably high pressure. 
         [0009]    Traditional water control structures in the art offer limited options for adjusting and controlling the flow of water, are difficult to modify and are not capable of achieving incremental release or multiple flow paths. 
       BRIEF SUMMARY OF THE INVENTION 
       [0010]    In one embodiment, an incrementally adjustable fluid control system includes two guide channels, a plurality of stack beams and a picker mechanism. The two guide channels are located in opposition. Each guide channel includes a plurality of guide channel flanges connected by a guide channel web. The plurality of stack beams are constrained between the two guide channels. Each stack beam includes a stack beam channel and a plurality of stack beam flanges operatively connected by a stack beam web. Each stack beam is made of a non-porous, non-buoyant material. The picker mechanism includes a picker beam operatively connected to a picker rod by a picker connector. 
         [0011]    In another embodiment, a method for opening an incrementally adjustable fluid control system includes the step of determining a desired gate opening height within a plurality of stack beams constrained between two guide channels. Each guide channel includes a plurality of guide channel flanges connected by a guide channel web. Each stack beam includes a stack beam channel and a plurality of stack beam flanges operatively connected by a stack beam web. Each stack beam is made of a non-porous, non-buoyant material. Next, the method lowers a picker mechanism including a picker beam operatively connected to a picker rod by a picker connector, until the picker beam reaches a stack beam corresponding to the desired gate opening height. The method then inserts at least one of the picker beam flanges between at least two of the plurality of stack beam flanges and applies a lifting force to the picker beam through the picker rod. Next, the method raises at least one of the plurality of stack beams along the two guide channels. 
         [0012]    In another embodiment, a method for installing an incrementally adjustable fluid control system includes the step of fixing two guide channels in opposition. Each guide channel includes a plurality of guide channel flanges connected by a guide channel web. The method then inserts a plurality of stack beams into the guide channels such that the plurality of stack beams are constrained between the two guide channels and substantially block movement of a fluid through an area located between the guide channels. Each stack beam includes a stack beam channel and a plurality of stack beam flanges operatively connected by a stack beam web. Each stack beam is made of a non-porous, non-buoyant material. Next, the method supplies a picker mechanism including a picker beam operatively connected to a picker rod by a picker connector. 
     
    
     
       BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWING(S) 
         [0013]      FIGS. 1   a - 1   c  are top, back and side views, respectively, illustrating an exemplary embodiment of an incrementally adjustable fluid control system. 
           [0014]      FIG. 2  is a flowchart illustrating an exemplary embodiment of a method for opening an incrementally adjustable fluid control system. 
           [0015]      FIG. 3  is a flowchart illustrating an exemplary embodiment of a method for installing an incrementally adjustable fluid control system. 
       
    
    
     TERMS OF ART 
       [0016]    As used herein, the term “horizontal tolerance” means a physical, horizontal distance between two parts. 
         [0017]    As used herein, the term “non-buoyant material” means a material having an average density greater than that of a fluid in which the material is immersed. 
         [0018]    As used herein, the term “non-porous material” means a material that does not gain more than 5% weight when immersed in fluid for a period of time of at least one week. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0019]      FIGS. 1   a - 1   c  are top, back and side views, respectively, illustrating an exemplary embodiment of an incrementally adjustable fluid control system  100 . Incrementally adjustable fluid control system  100  includes two guide channels  10 , a plurality of stack beams  20  and a picker mechanism  30 . 
         [0020]    Guide channels  10  are substantially vertically oriented channels located opposite each other. Each guide channel  10  includes two guide channel flanges  11   a  and  11   b  connected by a guide channel web  12 . In the exemplary embodiment, guide channels  10  are spaced apart according to the width of the fluid channel bracketed. In other embodiments, multiple guide channels  10  may be attached along their respective guide channel webs  12  to connect multiple incrementally adjustable fluid control systems  100 . In still other embodiments, guide channels  10  may be attached along their respective guide channel webs  12  to posts or other structures within a fluid channel or reservoir to enable fluid guidance. Guide channels  10  may be attached along their respective guide channel webs  12  using means including, but not limited to, an adhesive, at least one mechanical fastener or a combination thereof. 
         [0021]    Guide channels  10  partially enclose first and second ends of the plurality of stack beams  20 . Guide channel flanges  11   a  and  11   b  have a width greater than twice the horizontal tolerance of stack beams  20 . This width ensures guide channel flanges  11   a  and  11   b  are wide enough to securely hold stack beams  20 , while not so wide as to impede fluid flow. Guide channel flange  11   b  provides a smooth mating surface with stack beams  20 . A length of guide channel web  12  is approximately 5% to approximately 15% longer than a length of stack beams  20 . This tolerance allows for substantially frictionless raising of stack beams  20  but is not enough to allow stack beams  20  to become slanted and/or wedged 
         [0022]    The plurality of stack beams  20  are vertically stacked atop each other between guide channels  10  to lie in a substantially horizontal orientation. Stack beam flanges  22   a  and  22   b  and stack beam web  23  surround stack beam channel  21 . In the exemplary embodiment, each of the plurality of stack beams  20  has a C-shape formed by connecting stack beam flanges  22   a  and  22   b  with stack beam web  23 . In the exemplary embodiment, stack beam channel  21  faces upstream while stack beam web  23  faces downstream. In an alternate embodiment, stack beam channel  21  faces downstream while stack beam web  23  faces upstream. In this embodiment, the ends of stack beams  20  are sealed. 
         [0023]    In the exemplary embodiment, the plurality of stack beams  20  with stack beam channels  21  facing upstream provides a large flat sealing surface between beam web  23  and guide channel flange  11   b , forming a wall spanning the horizontal distance between guide channel flanges  11   a  and  11   b . Another embodiment of stack beam  20  closes stack beam channel  21  with an additional stack beam web  23  to create a hollow core stack beam  20 . In another embodiment, the plurality of stack beams  20  is a combination of C-shaped stack beams  20  and hollow core stack beams  20 . In one embodiment, certain individual stack beams  20  may be attached to other stack beams  20  to limit potential openings. Stacks beams  20  may attach to each other through adhesive or welding, or may be integrally formed. 
         [0024]    Each of the plurality of stack beams  20  is a non-porous, non-buoyant material. This material may be, but is not limited to, composite material, stainless steel and marine grade aluminum. In one embodiment, the stack beams are fiberglass reinforced, UV resistant polymer resin. Calculation of the density and resultant buoyancy of the material takes into account the specific gravity of the surrounding fluid and any air pockets contained within stack beam  20  in embodiments using hollow core stack beams  20 . 
         [0025]    In the exemplary embodiment, the easily accessible stack beam flanges  22   a  and  22   b  allow for insertion of a lifting mechanism such as, but not limited to, picker mechanism  30  into stack beam channel  21  to lift the plurality of stack beams  20 . In another embodiment, part of picker mechanism  30  inserts between two stack beams  20 . Because lifting the plurality of stack beams  20  can occur at any point along the plurality of stack beams  20 , system  100  may create a window anywhere in the plurality of stack beams  20  and function interchangeably as a sluice, a weir or a suspended orifice. This can allow for the bypassing of sediment to maintain reservoir capacity or controlled drainage of a reservoir to a given level. 
         [0026]    Picker mechanism  30  includes picker beam  31 , picker rod  37  and picker connector  38 . Picker beam  31  has a width of approximately 50% to less than 100% of the width of stack beam  20 . This width prevents stack beam  20  from rising in a non-level manner when raising the plurality of stack beams  20  if uneven weighting occurs in stack beam channel  21  due to settled sediment or unequal fluid or slurry drainage. This also reduces the likelihood of stack beam  20  tilting and becoming wedged in guide channel  10 . 
         [0027]    In the exemplary embodiment, picker beam  31  includes picker beam channel  32 , picker beam flanges  33   a  and  33   b , picker beam web  34 , optional picker beam apertures  35  and optional picker beam spacer pads  36 . In the exemplary embodiment, picker beam channel  32  faces downstream, allowing picker beam flanges  33   a  and  33   b  to slide between stack beam flanges  22   a  and  22   b . Because picker beam web  34  is located upstream of picker beam flanges  33   a  and  33   b , hydraulic pressure more firmly seats picker beam flanges  33   a  and  33   b  between stack beam flanges  22   a  and  22   b  and reduces the likelihood of accidental disengagement. In one embodiment, picker beam flanges  22   a  and  22   b  are spaced at a height less than or equal to a height of stack beam web  23 . In another embodiment, picker beam flanges  22   a  and  22   b  are spaced at a height greater than a height of stack beam web  23 . This configuration allows picker beam flanges  33   a  and  33   b  to surround at least one stack beam  20 . 
         [0028]    Optional picker beam apertures  35  in picker beam flanges  33   a  and  33   b  allow picker beam  31  to sink through fluids and allow for improved drainage when picker beam  31  rises above the fluid surface. Optional picker beam spacer pads  36  attach to picker beam flanges  33   a  and  33   b . Picker beam spacer pads  36  can provide increased friction between picker beam flanges  33   a  and  33   b  and stack beam flanges  22   a  and  22   b , making stack beam  20  less likely to dislodge from picker beam  31 . In the exemplary embodiment, picker beam spacer pads  36  are a high-friction material, such as a rubberized material attached to picker beam flanges  33   a  and  33   b  with an adhesive or fastened with mechanical fasteners. In other embodiments, picker beam spacer pads  36  may be texturized regions of picker beam flanges  33   a  and  33   b.    
         [0029]    A proximal end of picker rod  37  connects to picker beam  31  via picker connector  38 . Because a downstream side of picker beam  31  engages an upstream side or sides of stack beams  20 , picker rod  37  must connect to an upstream side of picker beam  31 . Picker rod  37  may connect through picker beam flanges  33   a  and/or  33   b , or along picker beam web  34 . A distal end of picker rod  37  extends above the maximum height of the plurality of stacker beams  20 , allowing application of a lifting force to picker mechanism  30 . In one embodiment, a mechanical device operatively attached to the distal end of picker rod  37  provides the lifting force when actuated. In another embodiment, the lifting force is manual. 
         [0030]      FIG. 2  is a flowchart illustrating an exemplary embodiment of a method  200  for opening an incrementally adjustable fluid control system  100 . 
         [0031]    In step  202 , method  200  determines a desired gate opening height within stack beams  20  constrained by two guide channels  10  in opposition. 
         [0032]    In step  204 , method  200  lowers picker mechanism  30  until picker beam  31  reaches a stack beam  20  corresponding to the desired gate opening height. 
         [0033]    In step  206 , method  200  inserts a portion of picker beam  31  between stack beam flanges  22   a  and  22   b  of at least one of the plurality of stack beams  20 . In one embodiment, method  200  inserts at least one of picker beam flanges  33   a  and  33   b  between stack beam flanges  22   a  and  22   b.    
         [0034]    In step  208 , method  200  applies a lifting force to picker beam  31  through picker rod  37 . In one embodiment, application of the lifting force includes actuating a mechanical device providing the lifting force. 
         [0035]    In step  210 , method  200  raises at least one of the plurality of stack beams  20  along guide channels  10 . 
         [0036]      FIG. 3  is a flowchart illustrating an exemplary embodiment of a method  300  for installing an incrementally adjustable fluid control system  100 . 
         [0037]    In step  302 , method  300  fixes two guide channels  10  in opposition. In certain embodiments, guide channels  10  bracket a fluid channel. In other embodiments, multiple guide channels  10  may be attached along their respective guide channel webs  12  to connect multiple incrementally adjustable fluid control systems  100 . In still other embodiments, guide channels  10  may be attached along their respective guide channel webs  12  to posts or other structures within a fluid channel or reservoir to enable fluid guidance. 
         [0038]    In step  304 , method  200  inserts a plurality of stack beams  20  into and between guide channels  10 . In such a configuration, the plurality of stack beams  20  are constrained between guide channels  10  and substantially block movement of a fluid through an area located between guide channels  10 . 
         [0039]    In step  306 , method  200  supplies picker mechanism  30 . 
         [0040]    It will be understood that many additional changes in the details, materials, procedures and arrangement of parts, which have been herein described and illustrated to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims. 
         [0041]    It should be further understood that the drawings are not necessarily to scale; instead, emphasis has been placed upon illustrating the principles of the invention. Moreover, the terms “substantially” or “approximately” as used herein may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related.

Summary:
The present invention provides a water control system with the reservoir level versatility of a weir stack and the relatively easy drainage of a water control gate. Multiple stack beams constrained between two opposed guide channels create a fluid reservoir having an incrementally adjustable fluid level. Increasing or decreasing the reservoir level is a matter of adding or removing one or more stack beams. To create an opening for draining fluid from any level of the reservoir, a picker mechanism captures at least one of the stack beams. By lifting the captured stack beam, and any stack beams atop the captured stack beam, the picker mechanism opens a gate at any level of the reservoir through which fluid may flow.