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BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a device for fairways with changing salt concentrations or suspended sediment concentrations in brackish water areas as a result of tidal flows, with a lateral branch or enlargement in the manner of a lock entrance or a harbor basin, to prevent deposits of silt/sand, whereby in the vicinity of the beginning of the branch or enlarged portion, with respect to an incoming flood current, by means of a current deflection wall that is located at some distance from the bank, a channel is realized, the cross section area of which equals a small portion of the inlet cross section area of the branch or enlargement, and the inlet opening of which lies in the fairway in the vicinity of the beginning, and the outlet opening of which lies in the vicinity of the branch or enlargement. 
     In other words, and according to at least one embodiment of the present invention, this invention relates to an arrangement for minimizing the deposit of silt and/or sand in brackish fairways characterized by changing salt concentrations and/or suspended sediment concentrations resulting from tidal flows and having a lateral branch or enlargement, such as a lock entrance or a harbor basin, whereby a current deflection wall is placed offshore in the vicinity and downstream of the entrance to the lateral branch or enlargement so that a channel is formed having an inlet opening lying in the fairway in the vicinity of and downstream of the entrance to the lateral branch or enlargement and an outlet opening lying in the vicinity of the branch or enlargement, the cross sectional area of the channel equaling a small portion of the cross sectional area of the entrance to the branch or enlargement. 
     2. Background of the Invention 
     On lateral branches or enlargements of this type, one problem is that for the major part of the flood tide, the salt concentration or suspended solids contents in the watercourse is greater than in the body of water of the lateral branch or enlargement, and thus a density current originates from the fairway to the branch or expansion, which is active primarily close to the bottom and thereby carries large amounts of silt or sand along with it which, it is well known, can result in large deposits of sediment. As a result of the sediment deposits formed, there are high maintenance costs for dredging and deposition of the dredged material. 
     The density of a tidal fairway can vary both as a function of changes in the salt concentration as well as changes in the suspended sediment concentration. Salt concentrations can change because, during flood tide, the highly salty sea water can penetrate farther into a tidal flow, and during ebb tide, can be kept farther out to sea. The suspended sediment concentration changes during flood and ebb tide as a result of the varying location of the turbidity zone, or by the increase and decrease of the turbulent tidal currents. All these effects are caused by the tide. 
     Because increases in the salt content and also in the suspended sediment concentration in the fairway can be achieved a great deal more rapidly than in lateral branches or expansions, the density differences described above occur over the total length of time involved in a tide, with the result that density currents are realized, by which large amounts of sand or silt are deposited in the lateral branches. 
     German Patent No. 37 07 074 C1 describes a system of the prior art to prevent circulation currents in fairways by installing current deflection walls at harbor entrances, thereby reducing the resulting lenticular sedimentary deposits. 
     These realizations, however, cannot be used to solve the problems described above, because the object of such a system is merely to reduce the eddy currents caused by the tidal flow. 
     Attempts have also been made to prevent density by means of a air bubble curtain or underwater skirts suspended on buoys, thereby preventing the ingress of silt and sand. Both methods have been found to be unsatisfactory. 
     OBJECT OF THE INVENTION 
     The object of the present invention, according to at least one embodiment, is to develop an arrangement and a method for diverting tidal flows in brackish fairways that substantially solves the problems encountered in systems of the known art. 
     SUMMARY OF THE INVENTION 
     The invention teaches that the baffle partition is located in the upper portion with reference to the water depth and an additional deflection wall is located in the lower portion of the water depth in the watercourse. This additional deflection sill diverts a near-bed density current of the fairway toward the middle of the fairway, starts at the bank in the vicinity of the current deflection wall and projects into the fairway. 
     In other words, and according to at least one embodiment of the present invention, the invention teaches that a current deflection wall is located in the fairway at an upper level and an additional deflection sill is located at a lower level, the upper and lower levels having reference to the water depth. The additional deflection sill, which starts at the bank in the vicinity of the current deflection wall and projects into the fairway in the direction of the incoming flow, diverts a near-bed density current of the fairway toward the center of the fairway and away from the lateral branch or enlargement. 
     As a result, a simple deflection and filling current control system is created, whereby a near-bed density current in the lower portion of the watercourse at the beginning of the branch or enlargement is diverted by the deflection sill toward the watercourse, In the upper portion of the water area, a channel is formed in the form of a filling current control system with the bank, by means of which the quantities of water at the flood tide to fill the branch or enlargement and create a counter current for an incoming density current, and thus prevents the entry of silt and sand that is carried along near-bed into the lateral branch or enlargement. 
     In other words, and according to at least one embodiment of the present invention, as a result, a simple deflection and filing current control system is created, whereby a near-bed density current in the lower portion of the fairway at the beginning of the branch or enlargement is diverted by the deflection sill toward the center of the fairway while the channel at the upper level of the watercourse foams a filling current control system so that quantities of water with the incoming flood tide to fill the branch or enlargement creating a counter current to the incoming density current with the result that the silt and sand normally carried along near-bed is prevented from entry into the lateral branch or enlargement. 
     In one advantageous embodiment, in particular to control the ebb current, the invention teaches that in the vicinity of the end of the branch or enlargement opposite the area of the current deflection wall, starting from the bank in the fairway, a deflection sill that extends toward the middle of the fairway is located at least in the lower portion with regard to the water depth. 
     In other words, and according to at least one embodiment of the present invention, in one advantageous embodiment, to control in particular an ebb current, the invention teaches that a deflection sill projecting from a bank of the fairway toward the center of the fairway is located offshore in the vicinity and upstream of the entrance to the lateral branch or enlargement and opposite the site of the current deflection wall. Such a sill is located at least in the lower level with regard to the water depth. 
     To prevent the formation of turbulence behind the deflection sills, the invention teaches that an area between the deflection wall and bank is backfilled with material. 
     For this purpose, in a refinement of a realization that has favorable flow conditions, one outer edge of the area of the deflection sill filled with material is rounded 
     The invention also teaches that the current deflection wall is located on columns, at least in the area outside the area filled with material. 
     In one preferred embodiment, each deflection sill is realized in an S-shape to divert the flow without creating turbulence. 
     The invention further teaches that the areas of the current deflection wall and the deflection sill partially overlap. 
     The invention further teaches that the point of the bank that lies in the vicinity of the end of the branch or enlargement opposite the current deflection wall is cut off in the downstream direction. 
     In other words, and according to at least one embodiment of the present invention, the invention additionally teaches that the point of the bank in the vicinity of and upstream of the entrance to the branch or enlargement opposite the baffle partition is cut off in the downstream direction. 
     The above discussed embodiments of the present invention will be described further hereinbelow with reference to the accompanying figures. When the word “invention” is used in this specification, the word “invention” includes “inventions”, that is, the plural of “invention”. By stating “invention”, the Applicants do not in any way admit that the present application does not include more than one patentably and non-obviously distinct invention, and maintains that this application may include more than one patentably and non-obviously distinct invention. The Applicants hereby assert that the disclosure of this application may include more than one invention, and, in the event that there is more than one invention, that these inventions may be patentable and non-obvious one with respect to the other. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is explained in greater detail below with reference to the exemplary embodiments illustrated in the accompanying drawings, in which: 
     FIG. 1 is a schematic diagram of a device in action during flood tide; 
     FIG. 2 is a schematic diagram of a device in action during ebb tide with deflection sills on both sides of a branch; 
     FIG. 3 shows a realization like the one illustrated in FIG. 1 as a detail with backfilling and a rounded edge of the bank as well as a rounded edge of the backfilled area; 
     FIG. 4 is a sectional drawing along Line IV—IV in FIG. 3, on an enlarged scale; 
     FIG. 5 is a sectional drawing along Line V—V in FIG. 3, on an enlarged scale, with a partly elevated filling current control system and rounded edge on the end of the backfilled area behind the deflection system; and 
     FIG. 6 shows a realization of a lateral enlargement with a streamlined shape of the bank point and a backfilled area on the ebb-side end of the branch. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In the illustrated systems, there is a river  1  as the fairway, from which a harbor basin  2  branches off. The river  1 , when there is flood tide, has the tidal current  4 , and also, as a result of the incoming seawater, a near-bed density current  3 . At ebb tide, the arrows show the ebb current  19  and the near-bed density current  18 . The arrows also show the density equalization currents at the flood tide (Arrows  17 ) and ebb tide (Arrows  22 , which are active whenever the salt or suspended sediment concentration in the fairway  1  is greater than in harbor basin  2 . 
     In other words, and according to at least one embodiment of the present invention, in the illustrated systems of FIGS. 1 and 2, river  1  is shown as the fairway from which a harbor basin  2  branches off. When there is flood tide, river  1  has the tidal current  4 , and also, as a result of the incoming seawater or turbidity zone, a density current  3  near the bottom. At ebb tide, the illustrated arrows represent the ebb current  19  and the density current  18  flowing in the downstream direction The arrows  17  and  22  also show the density equalization currents during flood tide and ebb tide, respectively, which are active whenever the salt or suspended sediment concentration in fairway  1  is greater than in harbor basin  2 . 
     In the vicinity of the beginning  20  of the branch  2 , there is a filling current control system with a current deflection wall  6  in the upper portion, and a deflection sill  5  in the lower portion. With the bank  23 , with the current deflection wall  6 , a channel  24  is formed in the upper portion of the water depth. As a result of channel  24  with the inlet opening  8  in the river area  1  and the outlet opening  9  in the transitional area between the fairway  1  and the harbor basin  2 , at flood tide, a quantity of water is guided in the current direction  7 . This quantity of water is split into the tidal filling volume  11  for the harbor basin  2  and a return flow portion  10  which flows back into the fairway  1 , and displaces a density equalization current  17  back into the fairway  1 . 
     In the area  20 , a deflection sill  5  is also located in the lower portion of the water depth behind which, up to the bank  23 , a space  13  is backfilled up to an approximately vertical closing wall  26  with material, e.g. with sand or rocks. During flood tide, the S-shaped deflection sill  5  that begins at the bank  23  and extends in the fairway  1  in the vicinity of the beginning  20  of the branch  2  displaces the density current  3  close to the bottom as shown by the arrows  12  away from the harbor entrance  2 . 
     The density current  12  that is diverted in this manner, in connection with the partial outflow  10 , causes a density equalization current  17  during flood tide to be displaced so far from the harbor entrance  2  that it remains in the fairway  1 . As a result of this displacement, the deposits of sand and silt that would otherwise be carried along by the density equalization current in the vicinity of the bottom of the fairway, and the resulting high sedimentation in the harbor basin  2 , can be prevented. At the end of he branch  2 , beginning at the bank  25 , there is a deflection sill  14  which is located in the lower portion of the water depth, and extends in an S-shaped curve into the fairway  1 . The area  15  between the deflection wall  14  and the bank  25 , like the area  13 , is backfilled with material up to the vertical closing wall  16 . 
     The purpose of the deflection sill  14 , during ebb tide, with the tidal current  19  and the density current  18 , is to deflect this density current  18  as shown by the arrows  27 , so that in combination with an outflow  28  from the harbor basin  2 , the penetration of a density equalization current  22  is prevented, and in this manner a deposit of silt or sand in the harbor basin  2  that would otherwise occur during ebb tide can be prevented. 
     Steel, reinforced concrete or wood are suitable materials for the construction of the deflection systems. 
     The closure wall  26  of the backfilled area  13  for the deflection sill  5  is realized in a streamlined rounded shape  29 . 
     FIG. 6 illustrates a streamlined variant of a bank point  21  in connection with the deflection sill  14  and a streamlined closure wall  16  of a backfilled area  15  and a likewise =streamlined, cut-off bank point  21 ′, which work together at flood tide to improve the outflow of a partial current  10 . 
     In the exemplary embodiment illustrated in FIG. 5, the current deflection wall  6  is located outside the backfilled area  13  of the deflection sill  5  on elevated pilings in the form of columns  30 . 
     One feature of the invention resides broadly in the device for a fairway that has changing salt concentrations and/or suspended sediment concentrations in brackish water as a result of tidal flows, with a lateral branch or expansion in the manner of a lock entrance or a harbor basin, for the prevention of silt and/or sand deposits, whereby in the vicinity of the beginning of the branch of expansion, with respect to a flood tide current; by means of a current deflection wall that is located at some distance from the bank, a channel is formed, the cross sectional area of which represents a small portion of the inlet cross sectional area of the-branch or expansion, and the inlet opening of which lies in the fairway in the vicinity of the beginning and the outlet opening of which lies in the vicinity of the branch or expansion, characterized by the fact that the current deflection wall  6  is located in the upper area with respect to the water depth, and in the lower area with respect to the water depth in the fairway there is an additional deflection sill  5 , which diverts a near-bed density current toward the center of the river, runs outward from the bank  23  in the vicinity of,the current deflection wall  6  and projects into the fairway  1 . 
     Another feature of the invention resides broadly in the device characterized by the fact that in the vicinity  21  of the end of the branch or enlargement  2  opposite the current deflection wall  6 , starting from the bank  25  in the fairway  1  there is a deflection sill  14  that extends toward the middle of the river, at least in the lower portion with respect to the water depth. 
     Yet another feature of the invention resides broadly in the device characterized by the fact that an area  13 ,  15  between the deflection wall  5 ,  14  and the bank  23 ,  25  is filled with material. 
     Still another feature of the invention resides broadly in the device characterized by the fact that one edge  16 ,  26  of the area  13 ,  15  of the deflection sill  5 ,  14  backfilled with material is rounded on top. 
     A further feature of the invention resides broadly in the device characterized by the fact that the current deflection wall  6  is located on columns  30  at least in the vicinity outside the area  13  that is backfilled with material. 
     Another feature of the invention resides broadly in the device characterized by the fact that each deflection sill  5 ,  14  is realized in an S-shape to divert the current without forming turbulence. 
     Yet another feature of the invention resides broadly in the device characterized by the fact that the areas of the current deflection wall  6  and the deflection sill  5  partly overlap . 
     Still another feature of the invention resides broadly in the device characterized by the fact that the bank point  21 ′ that lies in the vicinity  22  of the end of the branch or expansion  2  opposite the current deflection wall  6  is cut off in the downstream direction. 
     Some examples of rounded or streamlined structures in tidal streams and the may be found in the following U.S. Pat. Nos.: 4,330,224, 4,498,806, 4,665,578, 4,846,004, 4,881,848, 4,887,361, 4,923,335, 5,067,851, 5,165,357, 5,707,265 and 5,725,326. 
     The components disclosed in the various publications, disclosed or incorporated by reference herein, may be used in the embodiments of the present invention, as well as, as equivalents thereof. 
     The appended drawings in their entirety, including all dimensions, proportions and/or shapes in at least one embodiment of the invention, are accurate and to scale and are hereby included by reference into this specification. 
     All, or substantially all, of the components and methods of the various embodiments may be used with at least one embodiment or all of the embodiments, if more than one embodiment is described herein. 
     Although only a few exemplary embodiments of this invention have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the following claims. In the claims, means-plus-function clauses, if any, are intended to cover the structure described herein as performing the recited function and not only structural equivalents but also equivalent structures. 
     The invention as described hereinabove in the context of the preferred embodiments is not to be taken as limited to all of the provided details thereof, since modifications and variations thereof may be made without departing from the spirit and scope of the intention.

Summary:
Arrangement for fairways in brackish water tidal zones to prevent or minimize deposits of silt and/or sand in a branch or enlargement of such fairways. The invention is realized by the installation of a flow wall system. At the entrance to the branch or expansion, a current deflection wall is submerged in the fairway at an upper level some distance from the bank so that a channel is formed near the entrance to the branch or enlargement to direct an flood tide into the branch or enlargement and a deflection sill is juxtaposed with the partition at a lower level to divert an incoming near-bed current of the fairway away from the entrance to the branch or enlargement. The cross sectional area of the channel is small when compared with the cross sectional area of the entrance to the branch or enlargement.