Hydraulic and earth engineering – Fluid control – treatment – or containment – Flow control
Reexamination Certificate
2002-08-20
2004-04-27
Lee, Jong-Suk (Department: 3673)
Hydraulic and earth engineering
Fluid control, treatment, or containment
Flow control
C405S080000, C119S219000
Reexamination Certificate
active
06726404
ABSTRACT:
FIELD OF THE INVENTION
The field is that hydraulic engineering needed to guide, regulate, and modify fluid flow. In particular, a preferred embodiment of the present invention assists waterborne fauna, such as fish, in avoiding contact with a manmade obstruction.
BACKGROUND
Water resources development typically includes the construction of dams across rivers to impound and regulate flows for power production, flood control, water supply, irrigation and other economically beneficial uses of water. In many rivers, adult fish typically migrate upstream through the river to spawn and rear in upstream areas. Once young, or juvenile, fish reach a certain size they instinctively migrate downstream to the adult habitat areas in downstream reaches of the river, in lakes, or in the ocean where they mature into adults and complete their life cycle. Juvenile salmon and many other juvenile fishes are spawned in upstream fresh water systems where early life stages are completed but reach adulthood in downstream areas.
Unfortunately, dams block the migration of fish and thereby interfere with the completion of their natural life cycles. Sustainable water resources development is often facilitated by the use of hydraulic structures to pass these juvenile fish around the dam and other channel obstructions.
Systems and methods for assisting fish in circumventing man-made barriers in streams have been tried for many years, e.g., U.S. Pat. No. 3,338,056, Fingerling Saving System, issued to Roscoe, Aug. 29, 1967, details a complex arrangement of recesses using vertically oriented entrances for permitting the transport of fingerlings around a dam. Quoting from the '056 patent: “The difficulty (of getting fingerlings downstream) arises due to the tendency of the fingerlings to follow flowing currents of water, and ordinarily such flowing currents go through the turbines of the associated power station. The fingerlings suffer high mortality in passing through the turbines. . . .”
A later patent, U.S. Pat. No. 4,437,431, Method and Apparatus of Diversion of Downstream Migrating Anadromous Fish, issued to Koch, Mar. 20, 1984, uses an “artificial stream” generated by water jets within the natural stream together with long tubes having funnel-shaped entrances located on the sides of the stream at some distance from the upstream side of the dam. Another solution that offers an “attracting” artificial current based on an active source include a propeller generated current as described in U.S. Pat. No. 6,102,619, Flow Inducer Fish Guide and Method of Using Same, issued to Truebe et al., Aug. 15, 2000. A related technique involving a series of opening and closing valves, fish passing actuators and conduits is detailed in U.S. Pat. No. 6,273,639 B1, Method and Apparatus for Facilitating Migration of Fish Past Dams and Other Barriers in Waterways, issued to Eikrem et al., Aug. 14, 2001.
To comply with government regulations, other solutions have involved configurations of barrier screens and bypass conduits such as that envisioned by U.S. Pat. No. 4,481,904, Fish Conservation Device, issued to Fletcher, Nov. 13, 1984; U.S. Pat. No. 4,526,494, Penstock Fish Diversion System, issued to Eicher, Jul. 2, 1985; and U.S. Pat. No. 4,740,105, issued to Wollander, Apr. 26, 1988. One such screen barrier uses a number of like modules in a ladder arrangement affixed to the bottom of the channel as described in U.S. Pat. No. 4,929,122, Fish Protection System for Dams, issued to Yoas, May 29, 1990. An underwater “screen house” located adjacent a dam is described in U.S. Pat. No. 5,385,428, Water Intake Fish Diversion Apparatus, issued to Taft et al., Jan. 31, 1995. A buoyant screen that may be sunk and raised at appropriate fish migrations times is described in U.S. Pat. No. 5,558,462, Flat Plate Fish Screen System, issued to O'Haver, Sep. 24, 1996.
Still other solutions provide for a buoyant arrangement of vertically oriented slats located some distance upstream from a barrier such as described in U.S. Pat. No. 5,263,833, Fish Guiding Assembly and Method Utilizing Same, issued to Robinson et al., Nov. 23, 1993. This arrangement, and others like it, consumes a considerable amount of the surface area immediately upstream from the dam.
Active solutions are also proposed as exemplified in U.S. Pat. No. 5,445,111, Electrified Fish Barriers, issued to Smith, Aug. 29, 1995, describing linear curtain arrays characterized by pulsed driving signals that may use varying voltages. Other active solutions include complex electronic detectors and control systems to alter the operation of a hydroelectric powerhouse in the presence of migrating fish as described in U.S. Pat. No. 6,038,494, Control System for Enhancing Fish Survivability in a Hydroelectric Power Generation Installation, issued to Fisher et al., Mar. 14, 2000.
Fish ladders have been used to help returning anadromous fish get to spawning beds and are also proposed to help the juveniles return to the sea as described in U.S. Pat. No. 6,155,746, Fish Ladder and Its Construction, to Peters, Dec. 5, 2000. This details a complex series of basins having vertical inflow and outflow slots for transporting fish around a barrier.
The above solutions involve a configuration that is either much more complex and costly than a preferred embodiment of the present invention, uses much more “geography” to effect the desired result, uses energy or large quantities of water to effect the desired result, is unable to be used to modify an existing barrier, or a combination of these undesirable factors.
Juvenile outmigrating fish instinctively seek passage through the dam when their downstream journey is blocked. For a detailed discussion, refer to U.S. Pat. No. 6,160,759, Method for Determining Probable Response of Aquatic Species to Selected Components of Water Flow Fields, issued to Nestler et al., Dec. 12, 2000, and incorporated herein by reference. In the Columbia River, conventional surface bypass collectors (SBC's) are a preferred passage design used at dams for passing outmigrating juvenile fish.
A conventional SBC employs a water intake plume to attract fish to its entrance. Using conventional engineering concepts, the SBC's attract and concentrate fish for conveyance around the dam in a manner that helps prevent their entry into turbines or other high-energy hydraulic conditions where they may be injured or killed. An SBC uses an attracting intake plume of sufficient flow magnitude to overcome the attracting flow of competing inflows such as are present at hydroturbines, sluicegates or spillways. Once juvenile fish enter the SBC they are conveyed to a bypass channel where they continue the migration downstream of the dam. Design of the entrance hydraulic conditions used in conventional SBCs does not incorporate knowledge of the behavior of the juvenile fish in natural streams and rivers. As a consequence, the performance of conventional SBCs varies, with some working well and others not. Poor performance most commonly results from uncertainty about the flow conditions required to attract juvenile fish to the entrance of the SBC. A preferred embodiment of the present invention provides a method that employs natural hydraulic cues.
Refer to
FIGS. 1
,
2
, and
3
. To protect fishes that are not intercepted by an SBC, or if an SBC is not available, the present state-of-the-art for fish protection uses diversion screens
206
,
300
such as ones shown in
FIGS. 2 and 3
, to intercept fish and prevent them from entering intakes of turbines or diversion canals. For example,
FIG. 1
illustrates typical structures commonly encountered by fish as they attempt to move from the forebay on the upstream side of a dam to downstream river reaches. The dam depicted consists of a powerhouse
101
and a spillway
102
with water flow indicated by arrows
103
. Once the water passes the dam, it and its contents are dumped into the tailrace
104
.
FIG. 2
shows design features (through cut 1-1 of
FIG. 1
) of a conventional system used to intercept outmigrating fish. A portion of the f
Baugher Jr. Earl H.
Lee Jong-Suk
The United States of America as represented by the Secretary of
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