MODIFICATIONS OF DEEP-RELEASE DAM WATER INTAKES FOR IMPROVED DOWNSTREAM FISH HEALTH

Abstract

Dams and methods for modifying deep-release dam water intakes are provided. In an example, a dam for holding back and releasing water comprises: a dam body having a first side and a second side, the dam body configured to hold the water on the first side of the dam body; at least one intake formed in the dam body, the at least one intake having a first opening defined on the first side and a second opening defined on the second side, for releasing the water from the first opening to the second opening; and a dam modification element on the first side of the dam body, and configured to supply to the first opening of the at least one intake the water from a position higher than the first opening.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority from U.S. Provisional Patent Application No. 63/004,607, entitled “MODIFICATIONS OF DEEP-RELEASE DAM WATER INTAKES FOR IMPROVED DOWNSTREAM FISH HEALTH”, filed Apr. 3, 2020, which is incorporated herein by reference in its entirety.

FIELD

The present application relates to water dam, in particular to dams and methods for modifying deep-release dam water intakes.

BACKGROUND

Dammed rivers dramatically change the nature of a watershed as there is a change from moving surface water (lotic systems) to still water lakes (lentic systems) as reservoirs are created above the dam.

The construction of a dam with a deep head pond leads to thermal stratification similar to lakes. Thermally stratified water is comprised of: 1) the shallow upper layer, or epilimnion, featuring warm water and close proximity to the atmosphere which allows for oxygen transfer and total gas pressure similar to atmospheric total gas pressure; 2) the thermocline, a well-defined body of water separating the epilimnion from the hypolimnion and featuring a rapid decrease in temperature with depth below the thermocline; and 3) the hypolimnion, featuring low temperature, low oxygen levels, high biological oxygen demand and the potential for high levels of nitrogen. The low-oxygen and high-nitrogen levels of the hypolimnion are exasperated by virtue of the hypolimnion being a sink for organic material from anthropogenic sources. See Robert Scott Winton, et. al. 2019 Reviews and Syntheses: Dams, Water Quality and Reservoir Stratification, Biogeosciences, 16, p 1657-1671, which is incorporated herein by reference.

Since commercial hydro-electric dams generally obtain and release water from a position well below the surface, the water is typically obtained and released from the hypolimnion. This has substantial adverse consequences for downstream fish health. For watersheds with seasonal migratory upstream fish runs, this means large quantities of fish can be challenged to come upstream because they must traverse through a low-oxygen environment. This, in turn, leads to stress, fatigue, exhaustion, and the build-up of lactic acid in the muscular tissue of the fish. As a result, the fish may not have the necessary energy to navigate dam fish ladders. For the fish that do manage to navigate the ladders, the induced stress on the fish can lead to less productive spawning exercises. Further complications from releasing water downstream from the hypolimnion include gas bubble trauma or gaseous embolism, also known as gas bubble disease or the bends. This potentially lethal condition is caused by ingested/absorbed nitrogen-saturated water releasing the nitrogen as the gasses/water warms inside of a fish. It is important to note that the conditions described here can exist for miles downstream of a large commercial deep-release dam. (See https://ottawacitizen.com/news/local-news/fish-deaths-caused-by-over-gasified-water-atdam-quebec-government-says/(accessed 3/27/2020), https://www.researchgate.net/publication/254326693_Severe_Gas_Bubble_Diseas e_in_a_Warmwater_Fishery_in_the_Midwestern_United_States (accessed 3/27/2020), and https://cedb.asce.org/CEDBsearch/record.jsp?dockey=0047552 (accessed 3/27/2020)).

As well, clinical signs of both acute and chronic Gas Bubble Disease are commonly observed in fish that are downstream of deep-release dams. Acute signs which can lead to mass mortality include hyper inflated swim bladder, cranial swelling, exophthalmos, blindness, moderate gill filament hyperplasia, and emboli in blood/tissues. Chronic signs include hyper inflated swim bladder, emboli in gills/gastrointestinal tract/mouth, severe gill hyperplasia, oedema of 2o gill lamellae, and occlusion of large branchial vessels. Chronic Gas Bubble Disease in fish interferes with gas exchange, cardio-circulation, and osmoregulation. This, in turn, leads to reduced growth and immunosuppression.

Finally, higher dissolved nitrogen levels present a potentially favorable environment for algae blooms which, in turn, causes a further reduction in the dissolved oxygen level which is harmful for aquatic life. In addition, algae blooms can also leave lethal neurotoxins in the water which can kill both aquatic and terrestrial animals if ingested.

SUMMARY

It is an objective of the present application to addresses the damages to aquatic environments caused by deep-release dams.

The present application relates to dams and processes to enable deep-release dam water intakes to be modified such that the water from the low-oxygen, high-nitrogen hypolimnion of the head pond is not released downstream of the dam. Low-oxygen, high-nitrogen water from the hypolimnion presents serious health risks for downstream aquatic life.

In an aspect, a dam for holding back and releasing water comprises: a dam body having a first side and a second side, the dam body configured to hold the water on the first side of the dam body; at least one intake formed in the dam body, the at least one intake having a first opening defined on the first side and a second opening defined on the second side, for releasing the water from the first opening to the second opening; and a dam modification element on the first side of the dam body, and configured to supply to the first opening of the at least one intake the water from a position higher than the first opening.

In another aspect, the dam modification element comprises at least one baffle placed in front of the first opening of the at least one intake, the at least one baffle defines a chamber, the chamber has a top surface higher than the first opening of the at least one intake, and the chamber is configured to prevent the water below the top surface of the chamber from flowing into the chamber for supplying to the first opening of the at least one intake.

In another aspect, each of the at least one baffle covers one intake.

In another aspect, each of the at least one baffle covers two or more intakes.

In another aspect, the at least one baffle comprises an adjustable depth baffle.

In another aspect, the adjustable depth baffle comprises a plurality of baffle supports, a plurality of bottom fixed walls, and a plurality of upper walls for forming the chamber; each bottom fixed wall is placed below an upper wall; each bottom fixed wall and each upper wall are placed between two baffle supports; at least one upper wall is a moveable wall; and the at least one upper moveable wall is configured to moveably adjust a height of the top surface of the chamber.

In another aspect, the dam modification element comprises at least one pipe having a first end and a second end for supplying the water to the first end; the first end of the pipe is connected to the first opening of the at least one intake; and the second end of the pipe is at a position higher than the first end.

In another aspect, the position of the second end of the pipe is adjustable.

In another aspect, the water supplied to the first opening from an epilimnion area or an upper layer of a water body stored by the dam.

In another aspect, the dam of the preceding aspects, further comprises an oxygenation system for oxygenizing the water away from the at least one baffle and supplying oxygenated water to the first opening in the chamber.

In another aspect, the oxygenation system is configured to oxygenize the water away from the at least one baffle from a hyponimnion area and injecting oxygenated water into the hyponimnion.

In another aspect, the dam of the preceding aspects, further comprises an oxygenation system for oxygenizing the water away from the at least one baffle from a hyponimnion and injecting oxygenated water into the hyponimnion area.

In another aspect, the dam of the preceding aspects, further comprises an oxygenation system for oxygenizing at a downstream on the second side of the dam.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference will now be made, by way of example, to the accompanying drawings which show example embodiments of the present application, and in which:

FIG. 1 is a cross-sectional view of a unmodified deep-release dam;

FIG. 2 is a cross-sectional view of an exemplary modified deep-release dam according to an embodiment;

FIGS. 3a, 3b, and 3c are top views of exemplary baffles of the modified deep-release dam in FIG. 2, according to some embodiments;

FIG. 4 is a front view of an exemplary adjustable depth baffle, according to another embodiment;

FIG. 5a is a cross-sectional view of an exemplary modified deep-release dam according to another embodiment;

FIG. 5b is a top view of the modified deep-release dam of FIG. 4a;

FIG. 6 is a cross-sectional view of an exemplary adjustable-height piping, according to another embodiment;

FIG. 7 is a cross-sectional view of an exemplary modified deep-release dam, according to another embodiment;

FIG. 8 is a cross-sectional view of an exemplary modified deep-release dam, according to another embodiment; and

FIG. 9 is a cross-sectional view of an exemplary an exemplary oxygenation system of a downstream of a dam, according to an embodiment.

Similar reference numerals may have been used in different figures to denote similar components.

DESCRIPTION OF EXAMPLE EMBODIMENTS

As illustrated in FIG. 1, a dam 10 may be used for holding back a water body 11 and releasing water. the water body 11 includes a head pond surface or an epilimnion area, which is an upper layer of a water body 11, a head pond bottom or a hyponimnion area, which is a bottom layer of a water body 11, and a middle layer or the thermocline between the epilimnion area and hyponimnion area.

The dam includes a dam body 12 having a first side 14 and a second side 16. The dam body 12 is configured to hold the water on the first side 14 to form the water body 11. The same body 12 includes at least one intake 18 formed in the dam body 12. The at least one intake 18 having a first opening 18a defined on the first side 14 and a second opening 18b defined on the second side 16, for releasing the water from the first opening 18a to the second opening 18b.

As will be described in greater detail below, the present application mitigates or substantially addresses the damage to aquatic environments caused by deep-release dams through dam modification to draw water from a point closer to the water surface, the epilimnion 11, or through modification of the gas-environment associated with the water to provide improved oxygen and lower nitrogen gas levels.

As illustrated in the examples of FIGS. 2 to 5b, the dam 10 may include a dam modification element on the first side 14 of the dam body 12. The dam modification element may be configured to supply to the first opening 18a of the at least one intake 18 the water of the water body 11 from a position higher than the first opening 18a.

Modification of the dam water intake may be accomplished through either the construction of a baffle around the water intakes or the connection of piping to the existing water intakes of a dam where the piping extends upwards towards the epilimnion.

For example, as illustrated in FIG. 2, the dam modification element comprises at least one baffle 22 placed in front of the first opening 18a of the at least one intake 18. As illustrated in FIGS. 3a-3c, the at least one baffle 18 defines a chamber 32, 34 or 36. The chamber 32, 34 or 36 for formed by the a portion of the first side 14 and a plurality walls formed the baffle 22 to form a space from the bottom surface of the water body 11. The chamber 32, 34 or 36 has a top surface configured to be higher than the first opening 18a of the at least one intake 18, and the chamber 32, 34 or 36 is configured to prevent the water below the top surface 22a of the chamber 32, 34 or 36 from flowing into the chamber. The water flowed into the chamber from the top surface is then supplied to the first opening 18a of the at least one intake 18 and released from the second opening 18b.

For example, a baffle 22 may be constructed using the concrete prefabrication construction system for dams developed by French Development Enterprises (see http://www.fdepower.com).

As illustrated in FIG. 3a, each baffle 22 may cover one intake 18.

As illustrated in FIGS. 3b and 3c, one baffle 22 may cover two or more intakes 18.

The baffle 22 may use of a variable depth intake to accommodate dam systems where the head pond depth is subject to significant variability. A control system may be used to adjust the depth of the opening of the baffle. As illustrated in FIG. 4, the baffle 22 may be an adjustable depth baffle 40. The adjustable depth baffle 40 comprises a plurality of baffle supports 42, a plurality of bottom fixed walls 44, and a plurality of upper walls 46 for forming the chamber 32, 34 or 36; each bottom fixed wall 44 is placed on the head pond bottom and below an upper wall 46; each bottom fixed wall 44 and each upper wall 46 are placed between two baffle supports 42 which are secured place on the head pond bottom; at least one upper wall 46 is a moveable wall, and the at least one upper moveable wall is configured to moveably adjust a height of the top surface 40a of the chamber 32, 34 or 36. The height of the upper moveable wall may be adjusted manually or automatically to below the top surface of the water body at a predetermined depth, for example, as the surface level of the water body changes.

As illustrated in the example of FIG. 5a, the dam modification element may be at least one pipe 52 having a first end 52a and a second end 52b for supplying the water from the second end 52b to the first end 52a; the first end 52a of the pipe 52 is connected to the first opening 18a of the at least one intake 18; and the second end 52b of the pipe 52 is at a position higher than the first end 52a. The first end 52 may be secured mounted on the first side 14 of the dam body 12, for example by fasteners, and covers the first opening 18a.

The pipe 52 may use of a variable depth intake to accommodate dam systems where the head pond depth is subject to significant variability. A control system may be used to adjust the depth of the second end 52b of the pipe 52. For example, as illustrated in FIG. 6, the pipe 52 may include a first portion 51(1) have the first end 52a, and the a second portion 52(2) having the second end 52b. The second portion 52(2) is configured to be moveably adjusted in relation to the first portion 52(1). For example, the inner surface of second portion 52(2) may have thread that can be rotatable with respect to an flange 52(3) secured on the top end of first portion 52(1) and thus the position of the second end 52b can be adjusted.

The height of the pipe 52 may be adjusted manually or automatically to below the top surface of the water body at a predetermined depth, for example, as the surface level of the water body changes.

In some examples, the water supplied to the first opening 18a may be from an epilimnion area or an upper layer 11 of a water body stored by the dam 10.

With the water intake process being brought closer to the surface, it may put certain unintended upper pelagic fish stocks at risk for passing through the dam water intakes. Standard mitigation approaches, such as porous curtains, nets, screens, etc. may be used such as on the top surface 22a of the baffle 22, or on the second end 52b of the pipe 52. This allows water to pass through but stop targeted fish from entering a dam water intake.

In some examples, by virtue of drawing water for the dam intakes from a more shallow depth (epilimnion), the dissolved oxygen levels under normal conditions will be much higher than in the hypolimnion, and dissolved nitrogen levels will be much lower than in the hypolimnion. Due to various environmental conditions such as agricultural runoff and algae blooms, oxygen levels could still be somewhat diminished and nitrogen levels can still be somewhat elevated. This condition can be remediated by injecting dissolved oxygen into the water which, in turn, will force the net release of dissolved nitrogen based on Henry's Law.

As illustrated in FIG. 7, the dam 10 may include an oxygenation system 72 for oxygenizing the water away from the baffle 22 and supplying oxygenated water to the first opening in the chamber.

As such, water can be broadly oxygenated in the epilimnion region near the dam. A standard barrier system may also be used to keep fish away from a water intake 72a of the oxygenation system 72.

In some examples, a stream of water may be taken via piping away for concentrated oxygenation and then release that stream directly into the modified water intake system where it will extensively mix through turbulence with the surrounding low-oxygen, high-nitrogen water to remediate that condition. As will be apparent to those who are skilled in the art, the oxygenation of water can be achieved through a variety of techniques and is conceptually the same as injecting carbon dioxide to carbonize soft drinks.

As well, twice a year the epilimnion and hypolimnion flip positions. In the Fall, this is caused by the epilimnion cooling and therefore increasing in density. The high density epilimnion water sinks and displaces the hypolimnion water. Throughout the winter, the colder atmospheric surface temperatures and the formation of ice force cooler water to remain in the epilimnion. However, with the arrival of warmer atmospheric surface temperatures in late-Winter and into Spring the epilimnion and hypolimnion again flip positions (turnover).

To prepare for this transition and mitigate the adverse oxygen and nitrogen levels of the hypolimnion, a stream of water is pumped out of the hypolimnion near the dam and oxygenated and then returned to the hypolimnion. Since the water in the hypolimnion tends to stay in this region prior to the seasonal exchange or turnover, then the aqueous gas environment can be improved to minimize the downstream post-turnover impact of water formerly in the hypolimnion being released.

As illustrated in the example of FIG. 8, the oxygenation system 82 is configured to oxygenize the water near but away from the baffle 22 from a hyponimnion area 82a and injecting oxygenated water into the hyponimnion 82b.

In some examples, rather than having two oxygenation systems 72 and 82 individually addressing the gas environment issues described above, a control system is used to either have the oxygenation system 72 or 82 draw water from the epilimnion and release it to the chamber, or have the oxygenation system draw water from the hypolimnion and return it to the hypolimnion.

In another example, the aqueous gas-environment can be modified: oxygenation may be strategically used at a location downstream of the dam 10 in areas where fish specifically are known to gather such as eddies prior to entering the dam's fish ladder system. Through the strategic use of oxygenation, fish can metabolically recover from the consequences of a low-oxygen/high-nitrogen environment prior to entering the fish ladder or lift.

In the example of FIG. 9, the dam 10 may further comprises an oxygenation system 92 for oxygenizing at a downstream on the second side of the dam 10.

Certain adaptations and modifications of the described embodiments can be made. Therefore, the above discussed embodiments are considered to be illustrative and not restrictive.

Claims

1. A dam for holding back and releasing water, comprising:

a dam body having a first side and a second side, the dam body configured to hold the water on the first side of the dam body;

at least one intake formed in the dam body, the at least one intake having a first opening defined on the first side and a second opening defined on the second side, for releasing the water from the first opening to the second opening; and

a dam modification element on the first side of the dam body, and configured to supply to the first opening of the at least one intake the water from a position higher than the first opening.

2. The dam of claim 1, wherein the dam modification element comprises at least one baffle placed in front of the first opening of the at least one intake, the at least one baffle defines a chamber, the chamber has a top surface higher than the first opening of the at least one intake, and the chamber is configured to prevent the water below the top surface of the chamber from flowing into the chamber for supplying to the first opening of the at least one intake.

3. The dam of claim 2, wherein each of the at least one baffle covers one intake.

4. The dam of claim 2, wherein each of the at least one baffle covers two or more intakes.

5. The dam of claim 2, wherein the at least one baffle comprises an adjustable depth baffle.

6. The dam of claim 5, wherein:

the adjustable depth baffle comprises a plurality of baffle supports, a plurality of bottom fixed walls, and a plurality of upper walls for forming the chamber;

each bottom fixed wall is placed below an upper wall;

each bottom fixed wall and each upper wall are placed between two baffle supports;

at least one upper wall is a moveable wall; and

the at least one upper moveable wall is configured to moveably adjust a height of the top surface of the chamber.

7. The dam of claim 1, wherein the dam modification element comprises at least one pipe having a first end and a second end for supplying the water to the first end;

the first end of the pipe is connected to the first opening of the at least one intake; and the second end of the pipe is at a position higher than the first end.

8. The dam of claim 7, wherein the position of the second end of the pipe is adjustable.

9. The dam of claim 1, where the water supplied to the first opening from an epilimnion area or an upper layer of a water body stored by the dam.

10. The dam of claim 2, further comprising an oxygenation system for oxygenizing the water away from the at least one baffle and suppling oxygenated water to the first opening in the chamber.

11. The dam of claim 10, wherein the oxygenation system is configured to oxygenize the water away from the at least one baffle from a hyponimnion area and injecting oxygenated water into the hyponimnion are.

12. The dam of claim 10, further comprising an oxygenation system for oxygenizing the water away from the at least one baffle from a hyponimnion and injecting oxygenated water into the hyponimnion.

13. The dam of claim 1, further comprising an oxygenation system for oxygenizing at a downstream on the second side of the dam.