Patent Publication Number: US-6988853-B1

Title: Muted tidal regulator

Description:
BACKGROUND OF THE INVENTION 
   Estuaries and connected tidal marshes play a critical role in aiding the survival of juvenile salmonid and other aquatic creatures by providing a productive feeding area that is protected from marine predators and a transitional zone for gradual acclimation to salt water. Unfortunately, a tide gate is likely to be installed at the mouth of an estuary to prevent tidal flooding of low lying coastal areas. A tide gate, which prevents the flow of ocean water into the estuary or tidal marsh, destroys the habitat&#39;s value to salmonids &amp; other auquatic life by decreasing salinity and dissolved oxygen and increasing the temperature range of the remaining water. In addition, a tide gate disrupts the movement of fish from the ocean into the estuary or other inland water body. 
   If one were to simply remove the tide gates, however, many structures that had been built since the tide gates&#39; installation would be destroyed. Moreover, agricultural and other developed areas would face a harmful intrusion of salt water. Nevertheless, entry of ocean water into a coastal area could be permitted if the entry was restricted to a level that avoided harm to structures and farms. Unfortunately, heretofore there has been no practical way of accomplishing this goal. 
   SUMMARY OF THE INVENTION 
   In a first separate aspect, the present invention is a muted tidal regulator adapted to be interposed between a tidal body of water and an inland area at least partially isolated from the tidal body of water by a physical barrier. The assembly includes a tide gate that is made up of a conduit connecting the tidal body of water to the inland area and a closure operable to selectively prevent water flow through the conduit. The assembly also includes an inland water level sensing device and a closure control assembly responsive to the sensing device and adapted to affirmatively permit water flow through the conduit when the sensing device senses an inland water level below a threshold. 
   In a second separate aspect, the present invention is a method of restoring the intertidal quality of a coastal inland area that has been blocked from the ocean by a barrier. The method includes permitting water to flow from the ocean to the coastal inland area whenever the water level in the coastal inland area falls below a threshold. Water is also permitted to flow from the coastal inland area to the ocean whenever the water level of the coastal inland area exceeds the water level of the ocean immediately adjacent to the coastal inland area. 
   The foregoing and other objectives, features and advantages of the invention will be more readily understood upon consideration of the following detailed description of the preferred embodiment(s), taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side sectional view of a muted tidal regulator according to the present invention, in a closed state. 
       FIG. 2  is a side sectional view of the muted tidal regulator of  FIG. 1 , in an open state. 
       FIG. 3  is a side sectional view of a muted tidal regulator according to an alternative embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) 
   In one preferred embodiment a muted tidal regulator  10  is placed between an ocean  6 , or other tidal water body, and an estuary  8 , or other inland water body, that are separated by a levee  4 . Muted tidal regulator  10  includes a conduit  12 , connecting water bodies  6  and  8 . At the tidal or ocean side of conduit  12  there is a closure  14  seated on an outer rim  16  of conduit  12 . 
   As closure  14  is generally top mounted, it will have the tendency, similar to the closure of a standard tide gate, to swing shut to prevent ocean water from entering the estuary  8 . Unlike other tide gates, however, closure  14  can be prevented from closing by a further mechanism as will be explained. Closure  14  is mounted by a hinge  20  that is rotatably mounted to the top of the conduit  12 . Hinge  20  is also flexibly mounted to closure  14 , so that some rotation is permitted, to facilitate the proper seating of closure  14  on rim  16 . Taken together, closure  14 , rim  16  and hinge  20  form a tide gate. 
   Hinge  20  is shaped with an upward portion that is rotatably mounted to a gate rod  22 . As will be explained below, gate rod  22  pulls closure  14  open when the water level in the estuary  8  is below a threshold level. This permits the water of ocean  6  to pour through conduit  12  (given that the tide is high enough in ocean  6 ) until the level of estuary  8  is above a threshold level, at which point gate rod  22  is permitted to travel downwardly, permitting closure  14  to close. 
   To achieve this object, gate rod  22  is hinged to a gate rocker arm  30  that can be pulled backwardly (toward estuary  8 ) by a pull rod  32 . Pull rod  32  extends through an opening  31  in rocker arm  30  and is retained there by an enlarged end  33 . Accordingly, pull rod  32  can pull, but cannot push, rocker arm  30 . Pull rod  32  is in turn connected to a float rocker arm  34  by extending in an aperture  35 . As a result, pull rod  32  is pulled by rocker arm  34 , when arm  34  is pulled toward estuary  8  by a float rod  36  that is hinged to a float  38 . Float  38  pulls float rod  36  toward estuary  8  when the water level of estuary  8  is low. This, in turn, pulls float rocker arm  34 , which pulls pull rod  32 , which pulls gate rocker arm  30 , thereby pulling gate rod  22 , which pulls hinge  20 , which pulls open closure  14 , allowing water from ocean  6  to pour through conduit  12 , if the tide is high enough. When the level of estuary  8  is high, closure  14  is unrestrained, because as noted, pull rod  32  only pulls and cannot push rocker arm  30 . Accordingly, at any time the level of estuary  8  is higher than the level of ocean  6 , water can drain from the estuary  8  into the ocean  6 . 
   The advantages of assembly  10  should now be apparent. Fresh water is permitted to empty out of estuary  8 , whenever the water level in estuary  8  is higher than the water level of ocean  6 . In this manner, assembly  10  performs the normal, draining function of a tide gate. Controlled tidal flooding of inland areas around estuary  8  is also allowed, more closely approximating the natural state of estuary  8 . This controlled tidal flooding helps to prevent water temperature from rising to a level that is deadly to young fish and maintains the salinity and other water quality parameters of estuary  8  in a range that can be tolerated by juvenile salmonids and other aquatic life. Moreover, the adjustment mechanism  40  permits the maximum tidal flooding level to be set at a level that will not damage buildings or farm or pasture land. 
   The maximum distance between the float rocker arm  34  and the gate rocker arm  30  can be set by a length adjustment mechanism  40  on pull rod  32 . This, in turn, sets the threshold below which, if the water in body  8  descends, closure  14  will be pulled open. 
   Referring to  FIG. 3 , in an alternative preferred embodiment of a muted tidal regulator  110  (partial view) a hydraulic linkage is used, rather than a purely mechanical linkage. The parts of assembly  110  that are not shown may be exactly the same as the like portions of assembly  10 . In assembly  110 , the pull rod  32  of assembly  10  is replaced by a hydraulic assembly  132 , which includes a pair of hydraulic cylinders  150  and  154 , connected by a hydraulic tube  152 . Pistons  156  and  158 , which cooperate with cylinders  150  and  154  respectively, are engaged with rocker arms  134  and  130 , respectively, in the same manner that pull rod  32  is engaged with rocker arms  34  and  30 . An adjustment  140  may be used in the same manner as adjustment element  40 . In another alternative preferred embodiment piston  158  links as a pull rod directly to the top of closure  14 . 
   The terms and expressions that have been employed in the foregoing specification are used as terms of description and not of limitation. There is no intention, in the use of such terms and expressions, of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow. Specifically, although the tide gate or closure  14  shown is top hinged, it would also be possible to use, for example, a side hinged closure.