AU2003268859A1 - Water conservation - Google Patents

Description

P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: "WATER CONSERVATION" The following statement is a full description of this invention, including the best method of performing it known to me/us: 1

TITLE

"WATER CONSERVATION" FIELD OF THE INVENTION This invention is concerned with systems for water conservation.

The invention in one aspect is concerned particularly, although not exclusively, with conservation of water flowing through open drains, ditches or other forms of water course.

In another aspect, the invention is concerned with conservation of water stored in large surface area water storage structures.

BACKGROUND OF THE INVENTION In many parts of Australia in particular, water is conveyed from a source such as an artesian spring or the like to a usage destination via open man made ditches or channels. Similarly, water pumped from a river or bore may also be conveyed to a remote usage destination, such as irrigated crops, via open ditches or channels.

The use of open ditches or channels to convey water over relatively long distances is widespread throughout many regions of Australia as the value of fresh water was never appreciated when these ditches or channels were originally formed.

The greatest shortcoming of these ditches or channels is that, in many cases, over 50% of the water entering one end of a channel is wasted due to evaporation and/or seepage. Other disadvantages include silting and weed growth in the channels, which restricts water flow and is a labour intensive maintenance problem.

Additionally, open drains or channels pose a danger to stock and other animals, and are prone to contamination from dead animals, fertilizer and pesticide run-off from adjacent properties, algae blooms and aerial contamination from airborne pathogens and pesticides distributed by aircraft.

While it has been contemplated that replacement of open bore drains, ditches, channels or the like may be closed with steel or thick walled plastics pipes, the cost and practical limitations have so far proven to present insurmountable barriers.

For example, in order to build a steel pipeline in an existing bore drain or the like, the drain would first have to be emptied to permit construction of the pipeline. Any interruption to water flow for the period required to build the pipeline would be unacceptable to water users.

While a pipeline could be built beside an existing bore drain without affecting water flow, the resultant pipeline, which could be up to two metres in diameter, would create a barrier to stock and other animals as well as vehicles, thus necessitating the construction of overpasses or underpasses at frequent intervals.

Another problem with water conservation is the storage of water in large surface area containment structures such as dams where high evaporation losses are encountered. While there are many floating covers or chemical or structural membranes available to reduce evaporation losses, there are known difficulties in these covers due to high cost, frailty or wind related problems.

Accordingly, it is an aim of the present invention to overcome or alleviate at least some of the problems associated with conveying water in open bore drains or the like, storage of large volumes of water and otherwise to provide a convenient alternative to water users and/or authorities governing the use of water.

SUMMARY OF THE INVENTION According to one aspect of the invention there is provided a method for conserving water flowing through an open water course, said method comprising the steps of:positioning within said water course one or more elongate flexible polymeric tubes; and, guiding a flow of water into respective inlet ends of said one or more tubes whereby, in use, water losses due to seepage and evaporation between an inlet end and respective outlet ends of said one or more tubes are minimized.

Preferably, said one or more tubes are each adapted to form a compact roll for transportation purposes.

Suitably, each said tube is a lay flat type tube.

Preferably, the tube is positioned in a water course in a deflated state in an empty channel or on the surface of a body of water therein, and allowed to inflate in situ as a flow of water progresses therethrough.

Alternatively, said tube is positioned beside said water course 4 with an inlet end located within the water course whereby, in use, as a flow of water progresses through said tube, the water containing portion of said tube is progressively drawn into said water course under the influence of gravity.

According to another aspect of the invention there is provided a flexible conduit system for the conservation of water flowing in an open water course, said flexible conduit system comprising:one or more thin walled tubular members each adapted, in use, to be formed into a compact roll, each said tubular member including a penetration resistant wall portion and/or a weather resistant wall portion.

If required, each said conduit may include a fibre reinforced wall portion.

Suitably, at least the penetration resistant wall portion is tear resistant.

The weather resistant wall portion is preferably resistant to degradation under the influence of solar radiation.

If required, the penetration resistant wall portion may comprise, in use, a lower wall portion of said conduit.

Suitably, the weather resistant wall portion comprises, in use, an upper wall portion of said conduit.

If required, said inlet end of said conduit may include a support member to retain said conduit in an open position at least at said inlet end thereof.

Suitably, said conduit includes coupling members adapted to fluidically couple an outlet end of a length of conduit with an adjacent inlet end of a further length of conduit.

According to yet another aspect of the invention there is provided a water conservation system comprising a plurality of flexible conduit elements each coupled end to end to form one or more elongate conduits of desired length, said one or more elongate conduits, in use, being located in an open water course to direct a water flow through said conduit.

According to a still further aspect of the invention there is provided a tubular liner system for a liquid conduit, said liner system comprising one or more collapsible tubes of polymeric material adapted for installation in said liquid conduit in a deflated state and then selected ones of said system being inflated by allowing liquid in said conduit to enter an inlet end of said liner.

If required, said liner system or said conduit may include one or more additional inlet/outlet ports intermediate the length of the conduit.

The liner system, in use, may comprise a branched conduit system having a plurality of inlet branches and/or a plurality of outlet branches.

If required, the tubular liner may be inserted in said conduit in a longitudinally folded state and allowed to inflate by ingress of a fluid therein.

The fluid may comprise an aqueous liquid.

Alternatively the fluid may comprise a gas such as air.

The tubular liner may be constrained to retain a tubular shape once inflated by a degree of rigidity in at least portion of the liner wall.

Alternatively, at least portion of said tubular liner may include an adhesive compound on an outer surface thereof to adhesively engage an inner wall surface of said conduit.

The tubular liner may be installed in a metal or cementitious conduit as a corrosion resistant lining.

Alternatively the tubular liner may be installed as a temporary or permanent repair to a damaged fluid conduit.

According to an alternative aspect of the invention there is provided a cover system for a high surface area water storage structure, said cover system comprising:a plurality of tensionable polymeric sheets extending substantially parallel to each other over a surface of a body of water in said water storage structure, said plurality of tensionable polymeric sheets each being anchored at opposite ends thereof by respective tensionable anchors located on opposite sides of said water storage structure.

Suitably, said tensionable polymeric sheets comprise a polymeric material having a specific gravity less than water contained in said water storage structure.

If required, said polymeric material may comprise a polyolefinic compound.

Preferably, said polymeric material comprises a polypropylenic compound having a high modulus of elasticity.

The polymeric sheets may be arranged with adjacent edges abutting.

Alternatively, a first array of polymeric sheets may be arranged in spaced parallel relationship with a second array of spaced parallel polymeric sheets interwoven therewith, each of said polymeric sheets comprising said first and second arrays being anchored at respective opposite ends of said sheets at respective opposite sides of said water storage structure.

Preferably, the polymeric sheets are arranged in side by side juxtaposition with overlapping edges, each upper overlapping edge extending in a direction of a prevailing wind for at least part of an annual seasonal environment for said storage structure.

If required, one or more tensionable cables may overly said polymeric sheets.

Suitably, said polymeric sheets are adapted for resistance to weathering.

According to yet another alternative embodiment of the invention there is provided a method for reducing surface evaporation in a high surface area water storage structure, said method comprising the steps of:securing a plurality of tensionable polymeric sheets extending substantially parallel to each other over a surface of a body of water in said storage structure, said plurality of tensionable polymeric sheets being anchored at opposite ends thereof by respective tensionable anchors located on opposite sides of said water storage structure; and, tensioning at least some of said polymeric sheets with said tensionable anchors.

Suitably, said polymeric sheets are arranged with adjacent edges abutting.

Preferably, said polymeric sheets are arranged with adjacent edges overlapping, each upper overlapping edge extending in a direction of a prevailing wind for at least part of an annual seasonal environment for said storage structure.

Alternatively, a first array of polymeric sheets may be arranged in spaced parallel relationship and a second array of spaced parallel polymeric sheets may be interwoven with said first array.

If required, a tensionable cable may extend longitudinally over each or some of said polymeric sheets.

Alternatively, one or more tensionable cables may extend transversely over said plurality of polymeric sheets.

BRIEF DESCRIPTION OF THE DRAWINGS In order that the various aspects of the invention may be more clearly understood and put into practical effect, reference will now be made to preferred embodiments illustrated in the accompanying drawings in which:- FIG. 1 shows a cross-sectional view of a lay flat tube located in a bore drain or channel; FIG. 2 shows a partial plan view of a method of installing the lay flat tube into the bore drain or channet; FIG. 3 shows an enlarged part cross-sectional view of a lower wall portion of the lay flat tube of FIG. 1; 9 FIG. 4 shows an enlarged part cross-sectional view of an upper wall portion of the lay fiat tube of FIG. 1.

FIG. 5 shows a multi-tube water conveying system according to the invention; FIG. 6 shows an anchoring mechanism for a tubular conduit according to the invention; FIG. 7 shows an alternative embodiment of the invention; FIGS. 8 and 9 show yet further adaptations of the embodiment of FIG. 7; and FIG. 10 shows another embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS In FIG. 1 there is shown a typical open bore drain profile comprising a fairly shallow trench 1 having sloping side walls 2. A typical water level is represented by broken line 3.

Located within the bore drain trench is a relatively thin walled plastics tube 4 through which a body of water 5 flows thus partially inflating the tube under hydrostatic pressure whereby it adopts a generally elliptical cross-sectional shape.

With the passage of time, small sharp stones or rocks 6 may accumulate on the floor of trench 1, either from the excavated earth walls 2 or due to erosion by the water flowing therethrough.

The polymeric sheet or film material from which tube 4 is made accommodates the shape of stones or rocks 6 but even under the pressure of water contained within the tube 4, the tear resistant nature of the polymeric sheet or film material resists puncture or penetration by objects such as sharp rocks.

FIG. 2 shows a method of positioning tube 4 in trench 1.

Initially a roll of lay flat tubing 4 is laid out in a deflated state beside trench 1 and an inlet end la of tube 4 is located in the trench beside the bore head 7 or other outlet which introduces water into the trench 1.

The inlet end la may be coupled directly to the bore head or inlet 7 by a fabricated coupling (not shown) or otherwise the inlet end 1 a may be supported in an open position by a frame 8. Frame 8 may be anchored in position by pegs and tethers 9, 10 respectively if required.

With water already flowing in trench 1, a quantity of water enters the inlet end la of tube 4 and commences inflating the tube with water. As the tube inflates, the mass of water therein overcomes the frictional engagement between the earth surface and the deflated portion of the tube and causes the tube to slide into the trench where it occupies a generally central position as shown in FIG. 1. Effectively, the tube 4 is drawn into the trench 1 at the same rate as water flowing in tube 4.

In an alternative method, the lay flat tube may be unrolled directly onto the surface of water in the trench and then inflated from an inlet end whereupon the tube will progressively sink as it fills with water.

It readily will be apparent to a person skilled in the art of water conservation that the use of a flexible polymeric lay flat tubing of the type described above will substantially reduce water losses by seepage and/or evaporation.

In a practical sense however, it would be desirable that in addition to offering a relatively inexpensive installation method, the lay flat tubing employed should be sufficiently robust to perform its expected duty over a prolonged period of time, say 10-20 years or even longer, without maintenance or the need to repair easily damaged tubing materials or to replace polymeric tubing damaged by exposure to solar radiation and other weather conditions.

FIGS. 3 and 4 illustrate preferred constructions of lower and upper wall portions of a flexible polymeric lay flat tube according to one aspect of the invention.

The main requirement of a lower wall portion of a flexible polymeric lay flat tube is physical strength including, in particular, resistance to tearing and puncture from sharp stones.

FIG. 3 shows schematically an enlarged partial cross-sectional view of a polypropylene sheet material known as CURV (Trade Mark). This sheet material is believed to comprise a woven fabric 20 of linearly oriented polypropylene tape with a fused layer 21 of polypropylene formed on either side thereof, possibly by lamination and/or subsequently calendaring to form a thin continuous sheet with a thickness in the range of from 0.3 mm to mm. Because the woven central core 20 is comprised of linearly oriented tapes 20a, 20b extending in the warp and weft directions respectively, the resultant sheet material, whilst flexible, has a tensile strength of about 160 N/mm and an extremely high tear resistance.

The polypropylene sheet material may be formed into a lay flat tube by folding the sheet longitudinally in the centre and then fusing together the adjacent free edges of the sheet. Alternatively a lay flat tube may be formed by overlaying two sheets of material and then fusing together the respective free edges along opposite sides of the sheet.

Although generally effective for its intended purpose, even when UV stabilizers are incorporated therein, it is considered that a UV resistant top layer or coating would provide even greater resistance to degradation due to weathering.

FIG. 4 shows an enlarged partial cross-sectional view of a high strength sheet material incorporating a laminate 22 of ethylene propylene rubber (EPR) such as ethylene propylene diene polymer fused to a high strength polypropylene sheet of the type described above. Alternatively, the high strength sheet may be formed from a knitted or woven fabric of polymeric fibres or of linearly oriented polypropylene strips 23 co-extruded with a polypropylene outer skin, the woven or knitted fabric then being calendared or the like to fuse the outer skins surrounding adjacent fibres to form a smooth outer skin 24 encapsulating the woven or knitted linearly oriented "fabric" in a manner similar to the "CURV" product described above.

The lay flat tube suitable for the invention may be formed by laminating an EPDM layer onto one side of a reinforced flexible polymeric lay flat tube utilizing a material of the type described in FIG. 3 or FIG. 4.

Alternatively, the tube may be formed by laminating a single sheet of reinforced polypropylene with EPDM or other UV resistant polymers, and then fusing or otherwise securing along opposite edges a further sheet of reinforced polypropylene.

It readily will be apparent to a person skilled in the art that many variations and modifications may be made to the present invention without departing from the spirit and scope thereof.

As shown in FIG. 5, the system may comprise a plurality of separate flexible walled tubes 30 lying side by side in a ditch or channel 31.

In this manner, the capacity of the "aquaduct" system may be varied by adding additional tubular conduits 32 as required or simply selectively directing water flow down one or more of tubes 30 as required.

Where considerable additional capacity is required to compensate for additional flow due to seasonal variations, further layflat tubes 32 may be supported on base tubes when all tubes 30,32 are inflated by a water flow therein.

When available water flow diminishes, all or selective ones of said tubes 30 may be allowed to share water flow as required and adjacent tubes may be allowed simply to deflate to flat bands or ribbons lining channel 31. Where one or more of tubes 30,32 are allowed to deflate completely to form generally planar strips or bands of polymeric material, a series of spaced retaining strips 33 are anchored on both sides of channel 31 by pegs 34 to resist the effects of wind gusts tending to remove the flat uninflated tubes from channel 31.

To accommodate seasonal variations and water flow through the system, the apparatus may include a timing device to signal that the device system as a whole works satisfactorily according to predetermined criteria.

In FIG. 6, there is shown an anchoring system for a layflat tube according to another aspect of the invention.

Mounting members 36 in the form of inwardly facing channels 37 are located in spaced pairs along the path of a prepared conduit, whether located in a channel or otherwise.

Mounting members 36 receivably locate tube adaptors 38 comprising a generally circular body 39 with a central aperture 40 and outwardly extending mounting ears 41 locatable, in use, in the channel-like apertures 37 offered by mounting members 36.

Tube adaptors 38 may comprise a spigot-like extension 42 such as a short length of metal pipe having a free end extending from each side of tube adaptors 38 for attachment of layflat tubes on the upstream and downstream sides of the mounting members 36.

Alternatively, tube adaptors 38 in the form of concrete yokes may be employed as tube retaining or anchoring members intermediate the length of layflat tubes to captively retain the tube against the effects of wind when the tubes are deflated.

In another variation, a composite layflat tube may be fabricated by forming an inner tubular portion by extrusion of a layflat tube from a thin walled high density or high molecular weight polyethylene, polypropytene, polyethylene terephthalate or other suitable polymer or copolymeric combination or even a co-extrusion of compatible polymeric compounds. A sheet of high strength puncture or penetration resistant material such as the linearly oriented polypropylene fabric/polypropylene laminates described above or another tough polymer such as PET may be laminated or adhered to one side of the inner tubular portion, and a weather resistant sheet may be adhered to an opposite side to form a structure having similar physical and weather resistant properties of the composite lay flat tubes hereinbefore described.

Various forms of layflat tube or collapsible tube structures according to the invention may also be used as liners for liquid conduits such as storm water drains, sewer lines and the like. Storm water drains can be damaged and/or partially blocked by the ingress of tree roots, and concrete sewer pipes are subject to gaseous corrosion in that part of the wall surface above the liquid level.

Layflat tubing according to certain aspects of the invention can be employed to permit an in-situ repair to such liquid conduits.

For example, a layflat tube having a diameter complementary to the inside diameter of a sewer line may be folded one or more times along a longitudinal axis and then rolled into a compact roll for handling. The folded tube may be unrolled and extended over the surface of a layer of liquid in the sewer line over a predetermined distance extending, for example, between adjacent manhole access points in the line. A collapsible coupling member is then erected at an inlet end of the layflat tube to force the tube into engagement with the inner wall of the sewer line and otherwise to form a fluid tight coupling with an outlet end of an adjacent length of tubing in the sewer line upstream of the manhole access.

The tough penetration resistant nature of the layflat tubing according to one or more aspects of the invention permits temporary or semipermanent lining of damaged liquid conduits. As the layflat tube liner is not exposed to solar radiation, no UV resistant properties are necessary.

FIG. 7 shows an alternative embodiment of the invention dealing with another aspect of water conservation.

To prevent evaporation from the surface of a body of water in a dam or like water storage facility, a tensionable cover 50 is proposed to lie on or near the water surface in a dam structure 51.

Tensionable cover 50 comprises a woven array of polymeric sheets 52,53 extending respectively in warp and weft directions. Polymeric sheets 52,53 are preferably comprised of CURV (Trade Mark) sheet material fabricated from woven strips of linearly oriented polypropylene tape with a fused layer of polypropylene formed on either side thereof as described with reference to FIG. 3. The upper surface of the sheets 52,53 is coated with a UV resistant coating such as a paint or the like or a laminate of a UV resistant material such as ethylene propylene rubber (EPR) or even a metallic foil or foil/plastics laminate.

The sheets 52,53 may be woven into a regular weave pattern with alternate warp sheets passing over respective adjacent weft sheets and vice versa as shown in the region of the intersections of sheets 52a,53a.

Alternatively, the weave pattern may be irregular with say, the warp sheets 53b passing over groups of four adjacent weft sheets before passing under one or more weft sheets 52b or over groups of two adjacent weft sheets as shown by warp sheet 53c.

Starting from one corner of dam structure 51 alternate warp and weft sheets 53,52 are connected at one end to a cable 54 extending between pulleys 55 located on anchoring posts (not shown) at each corner of the dam structure. Each warp and weft sheet is then progressively extended across the surface of water in the dam in a desired weave pattern and connected at its opposite end to the cable 54 on the opposite side of the dam.

When the surface of the water is covered by the woven structure, cable 54 is tensioned by one or more tensioning devices 56 to form a taught woven mat extending over the surface of the water.

As the specific gravity of the polypropylene sheeting is about 0.9 gm/cc it will float on the water surface during the installation process.

Once installed, the bidirectionally tensioned mat has a high modulus of elasticity which prevents stretching even in high wind conditions and prevents the mat from being lifted off the surface of the water with a potential for damage under certain wind conditions.

The woven structure allows ingress of rainwater collected on the surface of the mat without ponding but generally prevents ingress of dry airborne contaminants such as dust, leaves, microorganisms or airborne herbicides or pesticides from nearby crop spraying activities.

FIG. 8 shows another embodiment of the water conservation aspect of the invention.

As shown, elongate parallel strips of polypropylene film 60 are 18 anchored to an earth bank 61 surrounding a water storage facility 62 by pegs 63 and tensionable cords or the like 64 secured to fastener mounts attached adjacent the ends of strips To resist the effects of wind lifting the strips 60, tensionable steel cables 66 are anchored to the earth bank 61 by anchors 67 to lie substantially along the longitudinal axes of the strips 60. When tensioned, cables 66 resist lifting of the strips 60 under windy conditions.

FIG. 9 shows an alternative embodiment of that illustrated in FIG. 8. For the sake of simplicity, like reference numerals are employed for like features.

In this embodiment, the spaced tensionable steel cables 66 extend transversely of the longitudinal axes of the strips 60 and, like the embodiment of FIG. 8, serve to resist lifting of the strips 60 under windy conditions.

In yet another embodiment (not shown) an array of adjacent tensionable plastics strips may be secured against lifting under windy conditions by a grid comprising both longitudinally extending and transversely extending tensionable steel cables as shown in FIGS. 8 and 9 respectively.

FIG. 10 shows a still further embodiment of the invention.

In FIG. 10 a plurality of parallel strips 60 of polypropylene sheet or film are arranged side by side with overlapped edges 70 all facing in the same direction. To counter the effects of wind lift, the parallel strips 60 are oriented say, north/south, in the direction of a primary prevailing northerly 19 wind. The overlapped edges 70 face in an easterly direction in the same direction of, say, a secondary prevailing westerly wind. The ends of the adjacent strips 60 are secured to a metal bar 71 which is treated with a corrosion resistant coating to resist corrosion of the metal bar. The free end 72 of each strip is folded over the bar 71 and secured thereto by bolts 73 and large washers 74 on opposite sides. Preferably metal bar 71 is coated with a resilient rubber paint which not only acts as a corrosion proof coating but also serves to enhance the grip between the bar 71 and the polypropylene strip The strips 60 are tensioned along their longitudinal axes by a perimeter cable 75 supported on anchor posts 76. A free running connector cable 76 having eyes 77 at both ends enables tension to be transferred in a self-aligning manner from perimeter cable 75 to an attachment cable 78 secured to bar 71 via apertures 79.

By aligning the sheets with adjacent overlapped edges facing in the same direction as a secondary prevailing wind, the risk of damage from wind lift forces is reduced, installation costs are minimized and any rainfall accumulating on the cover system is able to drain via the underlapped edges Throughout this specification, unless the context requires otherwise, the word "comprise", and variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers or steps but not the exclusion of any other integer or group of integers.

Claims (30)

1. A method for conserving water flowing through an open water course, said method comprising the steps of:- positioning within said water course one or more elongate flexible polymeric tubes; and, guiding a flow of water into respective inlet ends of said one or more tubes whereby, in use, water losses due to seepage and evaporation between an inlet end and respective outlet ends of said one or more tubes are minimized.

2. A method as claimed in claim 1 wherein said one or more tubes are each adapted to form a compact roll for transportation purposes.

3. A method as claimed in claim 1 or claim 2 wherein each said tube is a layflat type tube.

4. A method as claimed in any preceding claim wherein the tube is positioned in a water course in a deflated state in an empty channel or on the surface of a body of water therein, and allowed to inflate in situ as a flow of water progresses therethrough. A method as claimed in any one of claims 1 to 3 wherein said tube is positioned beside said water course with an inlet end located within the water course whereby, in use, as a flow of water progresses through said tube, the water containing portion of said tube is progressively drawn into said water course under the influence of gravity.

6. A flexible conduit system for the conservation of water flowing in an open water course, said flexible conduit system comprising:- one or more thin walled tubular members each adapted, in use, to be formed into a compact roll, each said tubular member including a penetration resistant wall portion and/or a weather resistant wall portion.

7. A system as claimed in claim 6 wherein said conduit includes a fibre reinforced wall portion.

8. A system as claimed in claim 6 or claim 7 wherein at least the penetration resistant wall portion is tear resistant.

9. A system as claimed in any one of claims 6 to 8 wherein the weather resistant wall portion is resistant to degradation under the influence of solar radiation. A system as claimed in any one of claims 6 to 9 wherein the penetration resistant wall portion comprises, in use, a lower wall portion of said conduit.

11. A system as claimed in any one of claims 6 to 9 wherein the weather resistant wall portion comprises, in use, an upperwall portion of said conduit.

12. A system as claimed in any one of claims 6 to 11 wherein said inlet end of said conduit includes a support member to retain said conduit in an open position at least at an inlet end thereof.

13. A system as claimed in any one of claims 6 to 12 wherein said conduit includes coupling members adapted to fluidically couple an outlet end of a length of conduit with an adjacent inlet end of a further length of conduit. A water conservation system comprising a plurality of flexible 22 conduit elements each coupled end to end to form one or more elongate conduits of desired length, said one or more elongate conduits, in use, being located in an open water course to direct a water flow through said conduit. A tubular liner system for a liquid conduit, said liner system comprising one or more collapsible tubes of polymeric material adapted for installation in said liquid conduit in a deflated state and then selected ones of said system being inflated by allowing liquid in said conduit to enter an inlet end of said liner.

16. A liner system as claimed in claim 15 wherein said liner system or said conduit includes one or more additional inlet/outlet ports intermediate the length of the conduit.

17. A liner system as claimed in claim 15 or claim 16 wherein the liner system, in use, comprises a branched conduit system having a plurality of inlet branches and/or a plurality of outlet branches.

18. A method of installation of a liner system of any one of claims to 17 wherein the tubular liner is inserted in said conduit in a longitudinally folded state and allowed to inflate by ingress of a fluid therein.

19. A method as claimed in claim 18 wherein the fluid is an aqueous liquid

20. A method as claimed in claim 18 wherein the fluid is gaseous.

21. A method as claimed in any one of claims 15 to 20 wherein the tubular liner is constrained to retain a tubular shape once inflated by a degree of rigidity in at least portion of the liner wall.

22. A method as claimed in any one of claims 15 to 21 wherein at 23 least portion of said tubular liner includes an adhesive compound on an outer surface thereof to adhesively engage an inner wall surface of said conduit.

23. A cover system for a high surface area water storage structure, said cover system comprising:- a plurality of tensionable polymeric sheets extending substantially parallel to each other over a surface of a body of water in said water storage structure, said plurality of tensionable polymeric sheets each being anchored at opposite ends thereof by respective tensionable anchors located on opposite sides of said water storage structure.

24. A cover system as claimed in claim 23 wherein said tensionable polymeric sheets comprise a polymeric material having a specific gravity less than water contained in said water storage structure. A cover system as claimed in claim 23 or claim 24 wherein said polymeric material comprises a polyolefinic compound.

26. A cover system as claimed in claim 25 wherein said polymeric material comprises a polypropylenic compound having a high modulus of elasticity.

27. A cover system as claimed in any one of claims 23 to 26 wherein the polymeric sheets are arranged with adjacent edges abutting.

28. A cover system as claimed in any one of claims 23 to 26 wherein a first array of polymeric sheets is arranged in spaced parallel relationship with a second array of spaced parallel polymeric sheets interwoven therewith, each of said polymeric sheets comprising said first and second arrays being anchored at respective opposite ends of said sheets at respective opposite sides of said water storage structure.

29. A cover system as claimed in any one of claims 23 to 26 wherein the polymeric sheets are arranged in side by side juxtaposition with overlapping edges, each upper overlapping edge extending in a direction of a prevailing wind for at least part of an annual seasonal environment for said storage structure. A cover system as claimed in any one of claims 23 to 29 wherein one or more tensionable cables overly said polymeric sheets.

31. A cover system as claimed in any one of claims 23 to wherein said polymeric sheets are adapted for resistance to weathering.

32. A method for reducing surface evaporation in a high surface area water storage structure, said method comprising the steps of:- securing a plurality of tensionable polymeric sheets extending substantially parallel to each other over a surface of a body of water in said storage structure, said plurality of tensionable polymeric sheets being anchored at opposite ends thereof by respective tensionable anchors located on opposite sides of said water storage structure; and, tensioning at least some of said polymeric sheets with said tensionable anchors.

33. A method as claimed in claim 32 wherein said polymeric sheets are arranged with adjacent edges abutting.

34. A method as claimed in claim 32 wherein said polymeric sheets are arranged with adjacent edges overlapping, each upper overlapping edge extending in a direction of a prevailing wind for at least part of an annual seasonal environment for said storage structure. A method as claimed in claim 32 wherein a first array of polymeric sheets are arranged in spaced parallel relationship and a second array of spaced parallel polymeric sheets are interwoven with said first array. 36 A method as claimed in any one of claims 32 to 35 wherein a tensionable cable is extended longitudinally over each or some of said polymeric sheets.

37. A method as claimed in any one of claims 32 to 35 wherein one or more tensionable cables is extended transversely over said plurality of polymeric sheets. 38, A method and/or system for conserving water flowing through an open water course substantially as hereinbefore described with reference to FIGS. 1 to 6 of the accompanying drawings.

39. A cover system for a high surface area water storage structure substantially as hereinbefore described with reference to FIGS. 7 to 10 of the accompanying drawings. A method for reducing surface evaporation from a high surface area water storage structure substantially as hereinbefore described with reference to FIGS. 7 to 10 of the accompanying drawings. DATED this Sixteenth day of December 2003. ROBIN KEITH DOWNING By his Patent Attorneys FISHER ADAMS KELLY