SYSTEM AND METHOD OF CONTROLLING WATER EVAPORATION

PRIORITY CROSS-REFERENCE

[001 ] The present application claim priority to Australian provisional patent application No. 2022902858 filed 3 October 2022, the contents of which are understood to be incorporated into this specification by this reference.

TECHNICAL FIELD

[002] The present invention relates to a water evaporation mitigation system and method for controlling evaporation from a body of water. The invention is particularly applicable to controlling water evaporation from bodies of waters such as reservoirs and dams and it will be convenient to hereinafter disclose the invention in relation to those exemplary applications. However, it is to be appreciated that the invention is not limited to that application and could be used in a number of other types of water containing bodies and formations.

BACKGROUND OF THE INVENTION

[003] The following discussion of the background to the invention is intended to facilitate an understanding of the invention. However, it should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was published, known or part of the common general knowledge as at the priority date of the application.

[004] The need to conserve water is important in many areas, for example, areas that are generally hot, which receive little annual rainfall or little seasonal rainfall, or which are subject to periodic droughts and water shortages can suffer from a lack of sufficient water. The lack of water can restrict the ability to provide for purposes such as drinking, domestic or industrial use or agricultural use such as crop irrigation and for other needs.

[005] The storage of water in tanks, dams and reservoirs is one way of ensuring that sufficient water reserves are available for domestic, industrial and agricultural use. However, the evaporation of water from these open bodies of water can result in significant losses of critical water resources. This is a global problem impacting water security. In the Australian agricultural industry evaporation causes the potentially avoidable loss of 20 to 40% of water stored on farms, more than 1 ,320 GL/year in total. If this level of water evaporation could be reduced, then farmers would have increased water security. The saved water could be used to irrigate additional land, producing a larger crop, or for additional environmental flows. Similar issues and benefits also apply to urban water storages, recreational storages and industrial reservoirs.

[006] In an attempt to reduce water evaporation, physical covers that float on the surface of a body of water have been used. However, a problem with such covers is that they are not practical or cost effective for large volumes of water such as reservoirs and large dams, and therefore has not been widely adopted.

[007] Another solution to reduce evaporation is to apply a monolayer composition onto the surface of a water body, which forms a thin film on or at the water surface. Such films or monolayers can reduce the rate of water loss to the surrounding atmosphere by creating a barrier between the water body and the atmosphere. A problem with many monolayer structures is their lack of stability against wind disruption. In open water storages in external environments, winds which reach speeds above 1 to 2 m/s can cause failure of the monolayer film and therefore there can be no significant evaporation savings.

[008] It would be desirable to address some or all of the problems of the prior art and to provide an effective method for controlling water evaporation.

SUMMARY OF THE INVENTION

[009] The present invention provides a water evaporation mitigation system configured to control evaporation from a body of water having a water surface, the system comprising: at least one wind barrier that includes at least one wind suppression panel extending outwardly from the water surface and substantially around a perimeter of a selected surface area of the body of water, wherein the at least one wind suppression panel is formed from a mesh material having an optical porosity of from 5 to 65%. [010] The present invention provides a wind barrier that acts to reduce wind shear stress at the water surface. The inventors have surprisingly found that a mesh material can effectively reduce wind shear stress and supress the wave generated by wind. This barrier acts to reduce wind shear stress at the water surface resulting in the reduction of wind driven evaporation directly by mitigating moisture flux across the air-water interface. Accordingly, supressing the formation of waves using mesh materials can result in water evaporation savings.

[01 1 ] It is to be understood that “mesh material” refers to any material formed from a material formed from of a network of wire, thread or other thin elongate members that crossover, interlace, are interwoven or the like to form a grid pattern with a plurality of apertures therein. Examples of mesh material include nets, woven fabrics, unwoven fabric, wire mesh or the like. In embodiments, the mesh material comprises a flexible mesh material, preferably a mesh fabric. In some embodiments wherein the mesh material comprises a knitted or woven fabric, preferably a shade cloth fabric. It should be understood that a shade cloth is a fabric that comprises woven or knitted strands of polymers such as polypropylene, saran, polyethylene and polyester. In some embodiments, the mesh material comprises a woven polymeric fabric.

[012] The degree of porosity (measured and defined herein as optical porosity (P)) can be varied to control the impact. It should be appreciated that optical porosity is a two-dimensional measure of porosity, which is defined as a simple ratio of perforated area of the material to total area of the material. Generally, optical porosity is not equivalent to aerodynamic porosity (p _a ) since it does not take into account the three-dimensional nature of the pores, but for a narrow artificial windbreak material, for example a mesh fabric, p is close to p _a .

[013] For wind resistance, the Inventors have found that wind suppression/ retardation functionality can be achieved using a wind suppression panel formed from a mesh material having an optical porosity of from 5 to 65%. However, for areas with large wind speed variations, a narrower range of optical porosities can provide better wind suppression/ retardation functionality, particularly for high wind speeds. In embodiments, the mesh material comprises a porous material having an optical porosity of 25 to 50%, preferably 30 to 40%, and more preferably about 35%. The Inventors have found that for high wind speeds (greater than 3 m/s) an optical porosity of 30 to 40%, and preferably about 35% provides good wind suppression/ retardation functionality.

[014] It should be understood that body of water in the present invention encompasses any expanse of water having a surface area from which water can be evaporated. Examples of bodies of water in which the present invention can be used include, but are not limited to, at least one of: dams, reservoirs, channels, canals, streams, rivers, creeks, ponds, brooks, pools, lakes, lochs, billabongs or the like. In embodiments, the body of water comprises at least one of a channel, canal, pond, reservoir, or dam. In some embodiments, the body of water comprises water irrigation and/or distribution channels, canals, ponds, reservoirs, or dams. In particular embodiments, the body of water comprises water irrigation and/or distribution channels. In other embodiments, the body of water comprises a reservoir, or a dam.

[015] The wind barrier preferably forms substantially vertical wind suppression/ retarding barriers around the selected surface area of the body of water. To achieve this, the at least one wind suppression panel preferably extends substantially perpendicular to the water surface. That wind suppression panels preferably extend from the surface of the body of water upwardly thereof. Thus, at least a portion of the at least one wind suppression panel is preferably located at or immersed at or below the water surface of the body of water.

[016] The height and separation of the at least one wind suppression panel can be varied to optimise the performance of the wind barrier. In embodiments, the at least one wind suppression panel is configured to have a height (H) to separation (S) ratio of 1 :7.5 to 1 :25, preferably 1 :10 to 1 :20, more preferably 1 :15, wherein height H is the height of the top of the wind suppression panel above the water surface, and separation S is the distance between two parallel spaced apart wind suppression panels. Here, the ratio of the height of the wind suppression panels to separation distance between parallel spaced apart wind suppression panel scales linearly. A larger degree of spacing or separation between wind suppression panels reduce the evaporation due to the wind being able to reengage with the surface and increase evaporation. Smaller spacing between wind suppression panels results in increased turbulence, which reduced savings. During large-scale lab trials (described below) with the wind suppression panels at the optimal separation to height ratio, the monolayer was stable up to a constant wind speed of 6 m/s (21 .6 km/h).

[017] The wind barrier, and particularly the wind suppression panel(s) provides a large surface area onto which significant air pressure can be exerted through wind gusts and the like in external environments. This can be problematic in extreme weather conditions, when substantial wind pressure can be exerted on one or a number of wind suppression panels of the wind barrier, potentially causing damage of the wind barrier. Thus, in some embodiments the at least one wind suppression panel includes at least one biased flap configured to move from a closed position to an open position when a selected wind pressure is exerted on the flap. In preferred embodiments, the biased flap comprises an elastically tensioned barrier flap configured to release the wind force exerted on the at least one wind suppression panel during extreme weather conditions. In some embodiments, at least one section of a wind suppression panels is configured to pivot or move to release the wind force exerted on the at least one wind suppression panel during extreme weather conditions. The pivot point can form part of on which the at least one wind suppression panel is formed and supported (see below). Thus, in some embodiments the wind suppression panel comprises a continuous fabric surface that is mounted to a support frame using a hinge mechanism and the whole wind suppression panel is able to move in response to high wind speeds.

[018] The wind barrier and wind suppression panels thereof are typically formed from an underlying structure that supports the wind barrier in position within the body of water. In many embodiments, the wind barrier is configured as a floating structure that is located in a floating position on the body of water. This advantageously allows the wind barrier to be positioned in a desired location on the body of water away from the water’s edge of that body of water. In embodiments, the at least one wind barrier includes: a framework on which the at least one wind suppression panel is formed and supported; and at least one float on which the framework is supported, the at least one float being buoyant in water thereby enabling the wind barrier to float on the water surface of the body of water.

[019] This framework structure can include a number of interconnecting components which are used to support the at least one wind suppression panel, and also interconnect adjoining wind suppression panels into a desired configuration around the perimeter of the body of water and (if applicable) across the selected area of the body of water bounded by the wind barrier. In embodiments, the framework comprises at least two spaced apart panel mounting poles, each panel mounting pole extending from a float with at least one wind suppression panel extending between each pole. The framework may also include at least one cross-member extending between each spaced apart panel mounting pole. In embodiments, the framework includes supporting crossmembers which extend across the selected surface area.

[020] In other embodiments, the framework comprises at least one cable, preferably at least one tensioned cable, on which the at least one wind suppression panel is supported. In these embodiments, the tensioned cable extends between adjacent floats, and the wind suppression panel hangs or is otherwise supported from that cable.

[021 ] In some embodiments, particularly where the wind suppression panel comprises a flexible material such as a mesh fabric, the wind barrier may further include a strengthening mesh, for example a wire or plastic/polymer based mesh or netting, that extends between spaced apart panel mounting poles configured to add structural support to each of the adjacent wind suppression panel.

[022] The float or floats may comprise any suitable buoyant structure which can support the framework and wind suppression panel. Examples include buoys. In embodiments, the at least one float comprises a self-righting float or buoy, such as a wide low float. However, it should be appreciated that many types of buoyant bodies and structures may equally be used.

[023] Any number of floats may be needed to ensure the wind barrier is buoyant and thus floats in the body of water. In embodiments, the framework includes a plurality of floats, each float including a panel mounting pole extending therefrom.

[024] The wind suppression panels can be configured in any suitable configuration around, across and within a perimeter of a selected surface area of the body of water. In some embodiments, the wind suppression panels are configured in a grid pattern over and across the selected surface area of the body of water. Any suitable grid pattern or configuration can be used. In some embodiments, each wind barrier comprises at least a two by two polygonal grid of wind suppression panels, preferably a three by two grid of wind suppression panels. In other embodiments, the grid pattern comprises a six by three grid, preferably a nine by three grid. In yet other embodiments, the grid pattern comprises a three by three grid of wind suppression panels. In yet other embodiments, the grid pattern comprises a four by two, preferably four by three grid of wind suppression panels. In other embodiments, the grid pattern comprises a six by six grid of wind suppression panels.

[025] In some embodiments, the wind barrier has a modular configuration, in which the wind barrier preferably comprises at least two interconnectable modules. This modular design allows the wind barrier to move independently hence reduce the potential damage caused by persistent or gusts of high wind speed. Furthermore, the floating wind barriers are preferably configured as independent modules forming a grid pattern and are deployed adjacent to an adjoining module, each module being independently tethered to a ground engaging anchor. This independence enables continued coverage over the body of water even if one or more of the independent modules are damaged or are otherwise removed from service. [026] A floating wind barrier can be tethered or otherwise connected to a ground engaging anchor at near or spaced away from the edge of the body of water to locate that wind barrier in the desired location on the body of water. In embodiments, the wind barrier is anchored to at least one ground engaging anchoring point using at least two spaced apart anchoring members, preferably comprising flexible elongated members such as straps or ropes, and wherein each anchoring member includes a resilient extension device (for example at least one spring) to enable the anchoring member to accommodate wind force that may cause mechanical stress to the device. In embodiments, the resilient extension device comprises spring loaded mounts at each ground engaging anchoring point.

[027] Again, in some embodiments, at least one wind suppression panel includes a biased (for example elastically tensioned) flap which can move from a closed position to an open position when a selected wind pressure is exerted in the flap. The flap can be hinged in some embodiments. The flap is configured to allow a high-speed wind to pass through the flap and escape. In some embodiments, at least one section of a wind suppression panel is configured to pivot or move to release the wind force exerted on the at least one wind suppression panel during extreme weather conditions. The pivot point can form part of the structure on which the at least one wind suppression panel is formed and is supported.

[028] In view of the above, embodiments of the wind barrier of the present invention can be configured to be sustainable for wind speeds of at least 60 km/h.

[029] Finally, it is noted that whilst the wind barrier arrangement of the present invention comprises physical barriers, unlike previous wind barriers, such as shade cloths and floating systems, the wind resistant panels of the present invention are arranged in a perimeter around a large surface area in the body of water, and thus can be sparsely placed (for example 6 m apart between parallel spaced apart wind resistant panels) and thus do not fully cover the water surface area. [030] In a second aspect of the present invention, the water evaporation mitigation system of the present invention can further comprise: at least one monolayer extending as a layer at the surface over at least a portion of the water surface bounded by the at least one wind barrier.

[031 ] Thus in embodiments, the present invention provides a water evaporation mitigation system configured to control evaporation from a body of water having a water surface, the system comprising: at least one wind barrier that includes at least one wind suppression panel extending outwardly from the water surface and substantially around a perimeter of a selected surface area of the body of water; and at least one monolayer extending as a layer at the surface over at least a portion of the water surface bounded by the at least one wind barrier, wherein the at least one wind suppression panel is formed from a mesh material having an optical porosity of from 5 to 65%.

[032] Where additional water evaporation savings are desired, the system can therefore also include at least one monolayer formed over a selected surface area of the body of water bounded by the wind barrier arrangement. Advantageously, the wind suppressant function of the wind barrier reduces the impact of wind on the monolayers or thin-films. This wind barrier acts to reduce wind shear stress at the water surface assisting to prevent failure of monolayers at the water surface. The wind barrier or the first aspect of the present invention and the monolayer of this second aspect of the present invention therefore cooperatively reduce evaporation of water from the body of water.

[033] In addition, the Inventors have found that a porous mesh helps to improve the wind speed tolerance before failure of the monolayer compared to a solid (non-porous) barrier. In this second aspect of the present invention, the wind barrier also acts to reduce wind shear stress at the water surface and protect the monolayer. The wind barrier provides a physical (mechanical) barrier which acts to reduce the impact of wind (wind shear stress) at the water surface mitigating the failure (breakup/ dispersement) of the monolayers at the water surface. The present invention typically increases the ability of the monolayer to resist wind speeds of >3 m/s, preserving the monolayer and thus mitigating water loss to evaporation.

[034] It should be appreciated that the use of wind barriers and a monolayer combine the benefits from both techniques. When using a monolayer, the evaporation mitigation performance of the monolayer can be improved by using wind barriers to shield the water surface and therefore reduce the surface movement that can disrupt and/or reduce continuous surface coverage of the monolayer. The wind barriers also allowed the film to reform when wind speeds were reduced to below this threshold, this was tested using wind speeds of 4 m/s (14.4 km/h) as the lower wind speed. This result was a significant increase when compared with trials without barriers, where the monolayer failed at constant wind speeds of 1 m/s (3.6 km/h). Furthermore, by using the monolayer, the amount of wind barrier material required can be reduced, compared with other existing water covering commercial solutions.

[035] Any suitable monolayer composition can be used in this second aspect of the present invention. It should be appreciated that layer structures such as monolayers can be formed from molecules that possess a polar hydrophilic head group and a non-polar hydrophobic tail. These molecules can align themselves at an air-water interface and self-assemble to ideally form a one-molecule thick layer on the surface of a body of water (approximately 2 nm). This structure enables the molecules to sit at the water surface and pack closely together forming a film. It is the close packing of these molecules that provides the resistance to water evaporation.

[036] Traditionally, the monolayer materials have been the higher alcohols, that is, linear hydrocarbon chains with 16 or 18 carbons and with an alcohol (-OH) group at one end (hexadecanol or cetyl alcohol and octadecanol or stearyl alcohol respectively). The longer the carbon chain, the more effective the monolayer is at suppressing water loss, but at the same time a longer chain decreases the affinity of the monolayer for water, suppressing the rate at which the monolayer will spread on a water surface, and increasing the brittleness of the monolayer. C16-18 alcohols can be used because they offer high resistance to water evaporation and small flakes of the solid alcohol spread spontaneously to form monolayers with a high molecular packing density. Monolayers based on cetyl or stearyl alcohol are permeable to oxygen and need only be present in a layer one molecule thick; enabling large surface areas to be covered with minimal environmental disturbance. Furthermore, monolayers of cetyl alcohol (a mixture of C16 and C18 alcohols) are biodegradable and have been cleared for use on drinking water storages by national regulatory agencies. They have a minimal effect on the transport of oxygen through the air/water interface, hence a minimal impact on aquatic biota, but can significantly suppress the loss of water by evaporation.

[037] In embodiments, the monolayer comprises a composition comprising amphiphilic molecules, preferably a C16 or C18 alcohol, more preferably selected from hexadecanol (cetyl alcohol) or octadecanol (stearyl alcohol). In some embodiments, the monolayer composition comprises ethylene glycol monooctadecyl ether (E1 ), cetyl alcohol, or a mixture of cetyl alcohol and polyvinyl pyrrolidone (PVP).

[038] A monolayer may be used together with a polymer which interacts with the monolayer. For example in some embodiments, the present invention includes a monolayer taught in International Patent Publication No. WO2010/071931 , the contents of which should be understood to be incorporated herein by this reference. In these embodiments, the monolayer is formed by applying a water insoluble compound and a water soluble polymer to the body of water, wherein the water insoluble compound assembles to form a layer at the surface of the body of water, and wherein the water soluble polymer interacts with the water insoluble compound by non-covalent bonding interactions. One preferred form of this embodiment is where the monolayer comprises a water insoluble compound and a water soluble polymer including at least one polymer selected from the group consisting of (i) carbonyl polymers including at least one functional group having a carbonyl moiety and (ii) non-carbonyl polymers having a molecular weight of at least about 5000 to the body of water. [039] Other commercially available monolayer compositions that can be used in this second aspect of the present invention include WaterGuard™, produced by Aqutain (see for example https://www.aquatain.com/WaterGuard.html) which is a liquid siloxane that forms a thick surface layer to reduce water evaporation.

[040] A third aspect of the present invention provides a method of controlling evaporation from a body of water comprising: providing a wind barrier around the perimeter of a selected surface area of the body of water, the wind barrier comprising: at least one wind suppression panel extending outwardly from the water surface and substantially around a perimeter of a selected surface area of the body of water, the at least one wind suppression panel being formed from a mesh material having an optical porosity of from 5 to 65%.

[041 ] As with the first aspect of the present invention, the barrier acts to reduce wind shear stress at the water surface resulting in the reduction of wind driven evaporation directly by mitigating moisture flux across the air-water interface. Again, the use of a mesh material has been found to be effective in reducing wind shear stress and supress the wave generated by wind.

[042] It should be appreciated that the wind barrier is preferably configured in accordance with the water evaporation mitigation system according to the first aspect of the present invention. The above described features of the wind barrier and comprising wind suppression panel in relation to the first aspect of the present invention therefore equally apply to this third aspect of the present invention.

[043] Again, the wind barriers can be configured in any suitable configuration and/or arrangement on the body of water. In embodiments, the floating wind barriers are configured as independent modules forming a grid pattern and are deployed adjacent to an adjoining module, each module being independently tethered to a ground engaging anchor. This independence enables continued coverage over the body of water even if one or more of the independent modules are damaged or are otherwise removed from service. [044] Again, where additional water evaporation savings is desired, the method of the present invention can also include the addition of at least one monolayer formed over a selected surface area of the body of water bounded by the wind barrier arrangement. In these embodiments, the method of the third aspect of the present invention comprises: applying a monolayer forming composition on the selected surface area within the perimeter bounded by the wind barrier, wherein the monolayer forming composition assembles to form a layer at the surface of the body of water over at least a portion of the water surface bounded by the at least one wind barrier.

[045] As described above for the second aspect of the presentation, any suitable polymer monolayer composition can be used in the system and method of the present invention. In embodiments, the monolayer forming composition comprises amphiphilic molecules, preferably a C16 or C18 alcohol, more preferably selected from hexadecanol (cetyl alcohol) or octadecanol (stearyl alcohol). In some embodiments, the monolayer forming composition comprises ethylene glycol monooctadecyl ether (E1 ), cetyl alcohol, or a mixture of cetyl alcohol and polyvinyl pyrrolidone (PVP).

[046] Again, the present invention may include a monolayer forming composition taught in International Patent Publication No. WO2010/071931 , the contents of which should be understood to be incorporated herein by this reference. Additionally, commercially available polymeric compositions can also be used as discussed above.

[047] The monolayer forming composition can be provided in/onto the surface of the body of water in any suitable form. In embodiments, the monolayer forming composition is provided as a powder, a tablet, a pellet, or as a composition within a water-soluble capsule. Similarly, the monolayer forming composition can be applied in/ onto the surface of the body of water in any suitable manner. In embodiments, the monolayer forming composition is applied to the the surface of the body of water by hand, a dispenser device from a specific position at the edge of or within the body of water, or by a dispensing machine, preferably a flying drone.

[048] In view of the above, the advantages of the water evaporation mitigation system and method of the present invention are as follows:

• Reduce the waves and moisture flux across the air-water interface caused by wind or other sources.

• Cause the suppression of water evaporation.

And, where a monolayer is also used, the wind barrier in the system of the present invention has the following further advantages:

• Reduces wind damage to monolayer.

• Allow monolayer to spread across entire water storage surfaces.

• Allowed the film to reform when wind speeds were reduced to below this threshold, this was tested using wind speeds of 4 m/s (14.4 km/h) as the lower wind speed. This result was a significant increase when compared with trials without barriers, where the monolayer failed at constant wind speeds of 1 m/s (3.6 km/h).

[049] Finally, the Inventors have found that embodiments of the wind barrier that can save 25 to 35 % water evaporation from the water storage. The addition of monolayer to the system can further save additional 12 to 25 % water loss from evaporations. The system (wind barrier plus monolayer) may therefore save combined water evaporation from water storage surface by 15 to 50 %.

BRIEF DESCRIPTION OF THE DRAWINGS

[050] The present invention will now be described with reference to the figures of the accompanying drawings, which illustrate particular preferred embodiments of the present invention, wherein:

[051 ] Figure 1 provides an arial/ top view image of an embodiment of the wind barrier of present invention showing four adjacent wind barrier modules arranged in a dam. [052] Figure 2 provides an further top view image of one section of a module of the wind barrier shown in Figure 1 showing the floats and wind suppression panels therein.

[053] Figure 3 provides a front view image of one module of the wind barrier shown in Figure 1 .

[054] Figure 4 provides an image showing the framework construction of part of a wind suppression panel used to form a wind barrier according to embodiments of the present invention.

[055] Figure 5 provides a schematic of the grid pattern comprising the four adjacent wind barrier modules shown in Figure 1 .

[056] Figure 6 provides a schematic drawing of a wind suppression panel in which the barrier material is pivotably attached to the top cross-member that can be used to form a wind barrier according to embodiments of the present invention.

[057] Figures 7A and 7B provide tethering and anchoring detail of one module of the wind barrier shown in Figure 1 .

[058] Figures 8A and 8B provide a schematic drawing of a second embodiment of a wind barrier of present invention showing (8A) a front view of a wind suppression panel used to form the wind barrier; and (8B) a top view showing the arrangement of four wind suppression panels spaced around a perimeter that are used to form the wind barrier.

[059] Figure 9A provides a schematic and setup used in a larger scale wind wave facility (SIWWI) to investigate the evaporation rate with barriers and monolayer under the influence of constant wind stress.

[060] Figure 9B shows the channel setup of a) the control case (channel 2), b) 0.3 m barriers (channel 3), and c) 0.9 m barriers (channel 5).

[061 ] Figure 10 shows the outline of the barrier configuration used during the different stages of channel trials [062] Figure 11 shows the channel setup of channel 3 showing wire mesh added to the wind barriers.

[063] Figure 12 shows the evaporation reduction of mixtures of cetyl alcohol (CeOH) and polyvinylpyrrolidone (PVP) on deionised water under wind comparing a) the impact of amount of cetyl alcohol added, and b) the impact of CeOH:PVP ratio holding the mass of CeOH at 4 mg.

[064] Figure 13 shows the evaporation experiments investigating a) the impact of commercial materials (WaterSavr and WaterGuard) on evaporation compared with cetyl alcohol over 12 hours, and b) the impact of WaterSavr addition on evaporation reduction.

[065] Figure 14 shows a) the medium porous material and b) the evaporation reduction performance as a function of optical porosity of the new barrier materials in small scale trials

[066] Figure 15 shows the evaporation trials in the large wind-wave tank (SIWWI facility) investigating the impact of fence porosity on a) evaporation over time comparing several materials, and b) evaporation savings as a function of fence porosity. Fence porosities of 35% and 65% were trialled in the SIWWI facility and compared with the no fence case.

[067] Figure 16 shows the total water evaporation as a function of time for various configurations at wind speed = 5 m/s. Cetyl alcohol is used as the monolayer in these trials.

[068] Figure 16A shows a plot of the maximum wind speed before monolayer failure of the barriers vs barrier separation (AS)/bamer height (Ah).

[069] Figure 17 shows the change in water height in sections of channel to measure test for differences between water loss, trials were conducted between 2 March 2021 to 9 March 2021 . [070] Figure 18 shows the cumulative change in water height of the channels during barrier trials that were conducted over 28 days from 21 March 2021 to 17 April 2021 . Data is for channel sections 2 to 5. Results were calculated by taking an average of the results from the two sensors on each channel.

[071 ] Figure 19 shows a) The day to day evaporation savings on channels 3 and 4 compared with channel 2 as the control over the barrier only trials, b) the average wind speed during the day between 9 am to 9 pm, c) the average temperature between 9 am to 9 pm, and d) predominant daily wind direction.

[072] Figure 20 shows the impact of environmental conditions on the water evaporation rate during barrier trials. Data represented is the impact of daily average temperature on a) the control evaporation rate, b) daily evaporation reduction (%), the impact of daily average wind speed on c) the control evaporation rate, d) daily evaporation reduction (%). Also represented is e) the correlation between average wind speed and temperature, as well as f) the correlation between daily evaporation reduction (mm) and control evaporation. Data represented was collected over the period from 21 March 2021 to 17 April 2021.

[073] Figure 21 shows the change in water height in channels during combined monolayer trials over 34 days from 21 April 2021 to 24 May 2021. Data is for channel sections 2 to 5. Results were calculated by taking an average of the results from the two sensors on each channel.

[074] Figure 22 shows a) The day to day evaporation savings on channels 3 and 4 compared with channel 2 as the control over the combined barrier and monolayer trials, b) the average wind speed during the day between 9 am to 9 pm, c) the average temperature between 9 am to 9 pm, and d) predominant daily wind direction.

[075] Figure 23 shows the impact of environmental conditions on the water evaporation rate during combined barrier and monolayer trials. Data represented is the impact of daily average temperature on a) the control evaporation rate, b) daily evaporation reduction (%), the impact of daily average wind speed on c) the control evaporation rate, d) daily evaporation reduction (%). Also represented is e) the correlation between average wind speed and temperature, as well as f) the correlation between daily evaporation reduction (mm) and control evaporation. Data represented was collected over the period from 21 April 2021 to 24 May 2021.

[076] Figure 24 shows the change in water height in channels during barrier only and combined barrier and monolayer trials over 52 days from 04 February 2022 to 27 March 2022. Data is for channel sections 2 to 4. Results were calculated by taking an average of the results from the two sensors on each channel. Red shaded region indicates the period when monolayer was added to channel 3 with the barriers.

[077] Figure 25 provides a photo of the original large scale installation (9x3 cells) prior to the storms with high winds, taken on 09 December 2021 .

[078] Figure 26 shows the change in water height of the barrier dam (dam 1 ), control dam (dam 2), and monolayer (ML) only dam (dam 3) over the period from 17 February 2022 until 24 March 2022. The red box indicates the period when the combined barrier and monolayer trial was performed (8 March 2022 to 24 March 2022).

[079] Figure 27 shows a) Average daily water evaporation savings in the barrier dam (dam 1 ) compared to the control dam over the period 17 February 2022 until 24 March 2022, and b) the weather conditions (maximum temperature and maximum wind speed) over this period. The red box indicates the period when the combined barrier and monolayer trial was performed.

[080] Figure 28 provides a summary of range of variation in evaporation savings over the barrier and combined monolayer trials. Data was calculated by using the sensor data on dams 1 , 2, and 3 over a period from 17 February 2022 until 24 March 2022. A seepage rate of 2.3 mm/day was taken into account. [081 ] Figure 29 provides plots showing Figure: Impact of environmental conditions on the water evaporation rate during barrier and monolayer trials. Data represented is the impact of; daily average temperature on a) the control evaporation rate and b) daily evaporation reduction (%); the impact of daily average wind speed on c) the control evaporation rate and d) daily evaporation reduction (%). Also represented is e) the correlation between average wind speed and temperature, as well as f) the correlation between daily evaporation reduction (mm) and control evaporation. Data represented was collected over the period from 17 February 2022 until 24 March 2022.

DETAILED DESCRIPTION

[082] The present invention provides a system configured to control evaporation from a body of water which includes: a wind barrier arrangement that forms a mechanical barrier which acts to reduce the impact of wind on water evaporation. This wind barrier arrangement acts to reduce wind shear stress at the water surface resulting in the reduction of wind driven evaporation directly by mitigating moisture flux across the air-water interface.

[083] In some embodiments, the system also includes at least one monolayer formed over a selected surface area of the body of water bounded by the wind barrier arrangement. Advantageously, the wind barrier arrangement’s wind suppressant function reduces the impact of wind on the integrity of the monolayer or thin-film on the surface of the water. This barrier acts to reduce wind shear stress at the water surface assisting to prevent failure of monolayers at the water surface. The wind barrier arrangement and monolayer therefore cooperative reduce evaporation of water from the body of water.

[084] Again, it should be appreciated that body of water that the wind barrier arrangement and at least one monolayer can be used encompasses any expanse of water having a surface area from which water can be evaporated. Examples of bodies of water in which the present invention can be used include, but are not limited to at least one of: dams, reservoirs, channels, canals, streams, rivers, creeks, ponds, brooks, pools, lakes, lochs, billabongs or the like. [085] Figures 1 to 7 illustrate one embodiment of the wind barrier of the present invention. As best shown in Figures 1 and 5, the exemplified wind barrier arrangement 100 comprises four adjacent floating modules 110 floating as buoyant structures on the surface 135 of a body of water 132, in this case water 130 in a dam.

[086] Starting firstly with an overall ariel view of the wind barrier arrangement 100 illustrated in Figure 1 , it can be seen that the wind barrier arrangement 100 comprises four adjacent floating modules 1 10 each comprising a three by two grid arrangement of wind suppression panels 120. Each module 1 10 is independent, and is tethered to ground engaging anchor points 140 in the ground 145 surrounding the water 130 of the dam through tether ropes 142 which are located at various points around the perimeter each module 1 10. This independence enables continued coverage over the body of water 132 even if one or more of the independent modules 1 10 are damaged or are otherwise removed from service.

[087] The wind suppression panels 120 are configured in a grid pattern over and across the selected surface area of the body of water 132 enclosed or bounded by each module 1 10. Again, the illustrated modules 1 10 of wind barrier 100 comprises a three by two grid of wind suppression panels 120 (see Figures 1 and 5). As will be described below in more detail, that grid also encloses a number of intersecting supporting cross-members 122 to help add structural stability and strength to the spaced apart wind suppression panels. Whilst the illustrated modules 110 shown in Figures 1 , 2 and 3 comprise a three by two grid, it should be appreciated that any suitable grid pattern or structure could be used to suit the particular application and size/ shape/ configuration of the body of water 132 on which the wind barrier 100 is installed. Similarly, any number of modules 1 10 can be used to suit the particular application and size/ shape/ configuration of the body of water 132 on which the wind barrier 100 is installed.

[088] As shown in Figure 2, 3 and 4, each wind suppression panel 120 comprises a substantially planar body that extends outwardly and substantially perpendicularly upwardly from the water surface 135, and using the grid structure, extends substantially around a perimeter of a selected surface area of that body of water 132. As shown in Figure 3, each wind suppression panel 120 extends from the surface 135 of the body of water upwardly thereof with the base of the one wind suppression panel 120 touching or being immersed in the water 130 at the water’s surface 135.

[089] As best shown in Figure 4, each wind suppression panel 120 is formed from a mesh material 121 , in the illustrated case, a knitted or woven shade cloth fabric having an optical porosity of from 5 to 65%. In experimental trials (see example section below), the Inventors tested a number of mesh fabrics with different optical porosities. Mesh fabric materials with an optical porosity of between 25 and 50% showed at least some evaporation mitigation/ reduction results. Mesh fabric materials with an optical porosity of between 25 and 50% showed good evaporation mitigation/ reduction results for higher wind speeds. However, mesh fabric material with a 35% optical porosity showed the best results evaporation mitigation/ reduction results with a 31 % reduction in evaporation using a wind suppression panel constructed with that material alone. In this regard, the Inventors have found that for high wind speeds (greater than 3 m/s) an optical porosity of 30 to 40%, and preferably about 35% provides good wind suppression/ retardation functionality. Barriers with these porosities showed savings above 20% in absence of the monolayer as shown in Figure 14, and above 10% in larger tank trials as shown in Figure 15.

[090] As shown in Figures 2, 3 and 4, the wind barrier 100 and wind suppression panels 120 include an underlying floating and support structure that is located in a floating position on the body of water 132. This supporting structure comprises:

A. a framework 150 on which each wind suppression panel 120 is supported and configured into the desired grid pattern; and

B. a plurality of floats 160 on which the framework 150 is supported. The floats 160 comprise buoyant bodies, for example air filled containers, that enable the wind barrier to float on the water surface 135 of the body of water 132. [091 ] As illustrated in Figures 2, 3, 4, the framework 150 comprises a number of interconnected components comprising PVC piping in the illustrated embodiment, but as can be appreciated could be formed from any suitable lightweight elongate member or material. As shown best in Figure 4, each wind suppression panel 120 is supported between two spaced apart panel mounting poles 152, with each panel mounting pole 124 extending from a float 160. The framework 150 may also include two cross-members - a top cross-member 154 and a lower cross-member 156 - which extend between each spaced apart panel mounting pole 124, maintaining the spacing between the panel mounting pole 124 and providing horizontal structure and stability to the overall wind suppression panel 120. Whilst not illustrated in Figures 2, 3 and 4, each wind suppression panel 120 may further include a wire or plastic/polymer based mesh or netting extending between spaced apart panel mounting poles 152 configured to add structural support to each of the adjacent wind suppression panel (the use of wire mesh is shown and described below in the example section in relation to Figure 1 1 for an experimental prototype). It should be noted that each wind suppression panel 120 is arranged in a perimeter around a large surface area in the body of water, spaced apart a relatively large distance, for example 6 m apart between wind suppression panel 120. This grid structure therefore does not fully cover the water surface area of the body of water 132 of the dam.

[092] As best shown in Figure 2 and 3, each wind suppression panel 120 is constructed to form either a horizontal or vertical wall in a three by two grid of wind suppression panel 120 that form each module 1 10. Each spaced apart wind suppression panel 120 also includes a middle supporting cross-member 122. These supporting cross-members 122 comprise elongate members, typically pipes (again PVC pipes in the illustrated embodiment) that extend across the bounded water surface spaces of the grids, and intersect at a center 170 of that space at a floating support member 172 (best illustrated in Figure 2) that comprises a float 160 and vertical support pole 174. These supporting crossmembers 122 and floating support members 172 provide lateral support between the center point of the spaced apart wind suppression panels 120. [093] As detailed previously, the height H (Figures 4 and 6) and separation S (Figures 2, 5) between parallel spaced apart wind suppression panels 120 can be varied to optimise the performance of the wind barrier 100. However, experimental studies (see example section below) have found that a height H to separation S ratio of 1 :7.5 to 1 :25, preferably 1 :10 to 1 :20, more preferably 1 :15 provides a good design for controlling evaporation. It was found that above the 1 :15 ratio (larger separation) the savings will decrease evaporation savings of the barrier alone. Decreasing the ratio (reducing separation) also reduces the savings (this is due to increased turbulence behind the barrier) until a ratio of 1 :2/1 :4 where there is an increase in savings (possibly because the system starts to mimic a cover on the surface). During large-scale lab trials (described below) with the wind suppression panels at the optimal separation to height ratio, the polymer monolayer was stable up to a constant wind speed of 6 m/s (21 .6 km/h).

[094] Each wind suppression panel 120 need not be mounded to the framework as a solid continuous fabric surface. As illustrated in Figure 6, the mesh fabric 121 may be pivotably or hingedly attached to the top cross-member 154 to enable the wind suppression panel 120 to form a biased flap 180 configured to open when a selected wind pressure is exerted on the flap 180. The bias in the flap 180 can be provided by any suitable means. In the illustrated arrangement, the bias is provided by an elastic member 182 attached to lower cross-member 156 attached to the wind suppression panel 120 which provides a designed tension configured to release the wind force exerted on the wind suppression panel 120 during extreme weather conditions. The wind suppression panel 120 is a continuous fabric surface that is joined at the top (as a hinge mechanism) and the whole side is able to move in response to high wind speeds. Thus, in this structure, the whole panel 120 pivots about the top cross-member 154 during extreme weather conditions. The wind suppression panel 120 is mounted on a wire mesh, plastic/ polymer based mesh or netting, or other supporting structure to provide a mounting platform for the mesh material of the panel 120.

[095] As noted above, each floating module 110 of the wind barrier 100 is tethered to a ground engaging anchor 140 using tether lines 142 (ropes or straps) positioned at various points around the perimeter of the module. As shown in Figures 7A and 7B, that anchor 140 and tether 142 arrangement may include a resilient extension device, such as a tension spring 190 (see Figure 7B) to enable the anchoring member to accommodate wind forcing that cause mechanical stress to be transferred to the module 1 10.

[096] Where additional water evaporation savings are required, the wind barrier arrangement 100 can also include at least one monolayer formed over a selected surface area 133 of the body of water 132 bounded by the wind barrier arrangement 100. Here, each module 1 10 of the wind barrier 100 acts to reduce wind shear stress at the water surface 135 and protect the monolayer therein.

[097] As previously discussed, any suitable monolayer composition can be used. The monolayer forming composition can be provided in/ onto the surface 135 of the body of water 132 in any suitable form such as a powder, a tablet, a pellet, or as a composition within a water-soluble capsule. Similarly, the monolayer forming composition can be applied in/ onto the surface 135 of the body of water 132 in any suitable manner, for example by hand, a dispenser device from a specific position at the edge of or within the body of water 132, or by a dispensing machine, preferably a flying drone.

[098] Figures 8A and 8B illustrate a second embodiment of a wind barrier of present invention. Similar to the first embodiment described above, the exemplified wind barrier arrangement 100A can be arranged as a floating modules 1 10A floating as buoyant structures on the surface 135A of a body of water 132A. Figure 8B illustrates only four wind suppression panels 120A are configured in a square over and across the selected surface area of the body of water 132A. As indicated by the broken lines, further wind suppression panels 120A can be arranged in a grid pattern similar as shown in Figure 1 to provide a larger module 110A.

[099] Again, each module 110A can be tethered to ground engaging anchor points 140A in the ground 145A surrounding the water 130A through tether ropes 142A which are located at various points around the perimeter each module 1 10A. The tether or cable can be anchored using a cable anchor in Geotech bearing areas which is designed for the surrounding soil conditions. This tethering system (tether ropes 142A etc) may include an elastic buffering system to respond to water level change.

[100] The wind suppression panels 120A are configured in a grid pattern (of which only one square is illustrated in Figure 8B) over and across the selected surface area 133A of the body of water enclosed or bounded by each module 1 10A. It should be appreciated that any suitable grid pattern or structure could be used to suit the particular application and size/ shape/ configuration of the body of water 132A (not illustrated in full) on which the wind barrier 100A is installed. Similarly, any number of modules 1 10A can be used to suit the particular application and size/ shape/ configuration of the body of water 132A (not illustrated in full) on which the wind barrier 100A is installed.

[101 ] As shown in Figure 8A, each wind suppression panel 120A comprises a substantially planar body that extends outwardly and substantially perpendicularly upwardly from the water surface 135A, and using the grid structure, extends substantially around a perimeter of a selected surface area of that body of water 132A. Each wind suppression panel 120A extends from the surface 135A of the body of water upwardly thereof with the base of the one wind suppression panel 120A touching or being immersed in the water 130A at the water’s surface 135A.

[102] Similar to the first embodiment, each wind suppression panel 120A of this second embodiment is formed from a porous mesh material 121 A, in the illustrated case, a knitted or woven shade cloth fabric having an optical porosity of from 5 to 65% - as detailed for the first embodiment.

[103] As shown in Figures 8A, the wind barrier 100A and wind suppression panels 120A include an underlying floating and support structure that is located in a floating position on the body of water 132A. This supporting structure comprises:

A. A tensioned cable 150A on which each wind suppression panel 120A and comprising porous mesh material 121 A is supported and configured into the desired grid pattern; and B. a plurality of floats 160A on which the tensioned cable 150A is supported. The floats 160A comprise buoyant bodies, for example air filled containers, that enable the wind barrier to float on the water surface 135A of the body of water 132A.

[104] As illustrated in Figures 8A, the tensioned cable 150A extends between adjacent but spaced apart floats 160A. The porous mesh material 121 A (porous barrier material) extends and is supported along and downwardly from that tensioned cable 150A, with the porous mesh material 121 A also extending between the floats 160A. In some embodiments, the porous mesh material 121 A may also be attached or otherwise connected to the floats 160A. The porous mesh material 121 A hangs downwardly from the tensioned cable 150A to the water’s surface 135A. The porous mesh material 121 A may be weighted or elastically restrained to maintain its position between the floats 160A, and handing substantially perpendicularly down from the tensioned cable 150A. It should be noted that the tension requirements of the tensioned cable 150A may be relatively low due to the use of the floats 160A.

[105] The illustrated floats 160A comprises self-righting floats, self-righting buoys, or wide low floats. These types of floats or buoys typically include a large buoyant base. It should be appreciated that a variety of float designs can be used, which typically comprise a polymeric buoyant structure designed to include an upright structure 152A such as a pole or other structure which extends upwardly from the water’s surface 135 designed to support the tensioned cable 150A thereover, and the porous mesh material 121 A therebetween.

[106] Whilst not illustrated in Figures 8A and 8B, each wind suppression panel 120 may further include a wire or plastic/ polymer based mesh or netting extending between the upright structure 152A of each float 160A configured to add structural support to each of the adjacent wind suppression panel.

[107] As detailed previously for the first embodiment, the height H and separation S between parallel spaced apart wind suppression panels 120A can be varied to optimise the performance of the wind barrier 100A. However, experimental studies (see example section below) have found that a height H to separation S ratio of 1 :7.5 to 1 :25, preferably 1 :10 to 1 :20, more preferably 1 :15 provides a good design for controlling evaporation.

[108] Where additional water evaporation savings are required, the wind barrier arrangement 100A can also include at least one monolayer formed over a selected surface area 133A of the body of water 132A bounded by the wind barrier arrangement 100A, as discussed above for the first embodiment. The same considerations and advantages are also applicable for this embodiment. Here, each module 110A of the wind barrier 100A acts to reduce wind shear stress at the water surface 135A and protect the monolayer therein.

EXAMPLES

[109] Experimental trials covering the development and testing of prototypes of the water evaporation mitigation system of the present invention will now be discussed in the following examples:

1 . Methodology and Field Trial Site Set-Up

Small-Scale Evaporation Trials

[110] Small tray experiments conducted to measure the evaporation reduction performance of monolayers. A small container (1094 cm ² ) placed on a weighing balance was first filled with water (1 L) before applying monolayer in powder form (1 -4 mg). A wind turbine was then used to blow wind over the water surface (4.5 m/s, 16 km/h) and the mass of water was measured once a minute over 20 hr.

Small-Scale Long Tank Evaporation Trials

[111] Small scale long tank trials done with monolayer and barriers to investigating the performance of barriers alone and in combination with a monolayer. A Perspex tank (10 cm x 1 m) was filled with water and an ultrasonic sensor used to measure the change in water height. To test the performance of the barrier material, small barriers were made up (10 cm wide, 2.5 cm high) and places at intervals of 10 cm along the tank. Wind was then applied using a wind turbine (4.5 m/s, 16 km/h). In combined monolayer and barrier experiments, the monolayer was applied in powder form at various amounts. Large Scale Tank Trails

[1 12] Larger scale trials were conducted in the Simulated Ice Wing-Wave Interaction (SIWWI) tank with dimensions of 15 m x 0.75 m under a temperature and humidity-controlled environment. Figure 9A shows a schematic of the experimental setup. Barriers, with the dimensions of 0.3 x 0.7 m, were made using a Perspex frame and shade cloth with a range of porosities (5%, 35%, 65%). These mechanical devices with different porous materials were used to investigate the relationship between the material porosity and the evaporation reduction obtained. The choice of these materials considered reducing initial costs (including material and installation costs) and self-sustaining mechanism under the various environmental conditions. Six of these devices were installed partly submerged to have a height above the water surface of 0.1 m. These were placed along the channel every 1 .5 m to maintain the ratio of 15 between height of barriers above the water and the separation, covering the entire length of the wave tank. A range of porosities were used to investigate and the optimal material to maximise the effectiveness of the monolayer and barrier on water evaporation reduction. The freestream velocity of over 5 m/s unidirectional wind was used with a range of various control configurations to measure the amount of water evaporation and multiple ultrasonic sensors (HollyKell UE3002) were used to measure the change in water height over a long period of time, acquiring converged statistics. During the trials, the temperature was maintained at 28 to 30°C and a relative humidity of 31 to 35%.

[1 13] For trials combining barriers and monolayer, cetyl alcohol (382 mg), was added to the water surface at one end of the tank while the barriers were installed and allowed to spread along the tank. The wind was then turned on at the same conditions as the barrier only trials (5 m/s) and the changes of the water height was measured to monitor water loss due to the evaporation.

Field Trial Site - Channel Trials

[1 14] The trial site for the channel trials was the Yanco Agricultural Institute, Yamco, New South Wales, Australia. This site contains five identical sections of channel having following dimensions: • Surface area when filled = 42 m x 5 m

• Surface area at the base = 40 m x 2.5 m

• Water depth = 0.85 m to 0.9 m

• Divisions between the channels = 1 m at the top (2 m at the base)

• Volume = 0.105 ML

Water Level Monitoring Devices and Weather Station - Channel Trials

[115] Ten ultrasonic (US) sensors were used during the trial to measure the change in the water height across all five channels. The ultrasonic sensors (UE3002, Holykell) were chosen as they are highly accurate and also cost effective. Two sensors were installed on each channel. The sensors had a measurement resolution of 1 mm with a sampling rate of 10 minutes. Data from the sensors were measured and stored using the in-situ EMS data acquisition boards (EMS-solar powered, Ontoto) and the data was transmitted telemetrically every 24 hours. These datasets from all the sensors have been stored in online database repository which can be remotely access to monitor and acquire data during the measurement campaign.

[116] Weather data (temperature, wind speed, wind direction, and humidity) were collected using an onsite weather station. The data from this sensor is publicly available on Weather Underground (see https://www.wunderground.com/dashboard/pws/INARRA2).

Evaporation Suppressing Film - Channel Trials

[117] The evaporation supressing material used in this trial was Cetyl alcohol (>95% pure, milled and sieved to less than 250 pm) which was purchased from P&G Chemicals. The material (7.64 g) was added as a solid powder daily throughout the trials, to test the monolayer performance, with the materials being added to the water surface between the barriers. The location of addition was varied throughout the trials to eliminate the potential of monolayer being contained in one section of the channel. a. Wind Suppression Device - Channel Trials 2020/21

[1 18] Barriers were installed on channels 3, 4, and 5 during the trials. Channels 1 and 2 were used as controls for throughout the trials. Shade cloth with an optical porosity of 35% were used as the barrier material and were attached to pickets along the length of the channel. The barriers were installed across the width of the channels as well as along the sides. Concrete weights were attached at the bottom of the barrier to hold down the barrier material within the channels against strong wind, while tent pegs were used to pin down the barrier material along the sides of the channel as illustrated in Figure 9B. The dimensions of the barriers on specific channels are below.

• Channel 3/4 design: Barrier height above water:0.3 m; Barrier separation :4.5 m

• Channel 5 design: Barrier height: 0.9 m; Barrier separation - Across the channel: 5 m; Along the channel: 13.5 m

Evaporation Trial Plan - Channel Trials 2020/21

[1 19] The evaporation trials were conducted in three stages to measure the performance of the barriers and monolayer films, Figure 10. The three stages were:

Stage 1 : Control trials

Stage 2: Barriers trials

Stage 3: Combined barrier/monolayer trials

Wind Suppression Device - Channel Trials 2021/22

[120] For the 2021/22 Summer trials, the barriers on channel 3 were modified by combining wire mesh with the shade cloth to improve stability of the barriers, Figure 1 1 . The wire mesh was added to the cross channel barriers on Channel 3. The barriers on channel 4 were removed and this was used as a control along with channel 2. Channels 1 and 5 were not used during these trials as the depth sensors on these sections were brought to the dam trial site for background testing. The same shade cloth was used as the previous year (with an optical porosity of 35%) and were attached to pickets along the length of the channel as before. The barriers were installed across the width of the channels as well as along the sides. The wire mesh was able to keep the mesh in place so the cement weights were not required during these trials. The dimensions of the barriers on specific channels are - Channel 3 design: Barrier height above water: 0.3 m; Barrier separation: 4.5 m

Evaporation Trial Plan - Channel Trials 2021/22

[121 ] The evaporation trials were conducted in three stages to measure the performance of the barriers and monolayer films using channels 2, 3 and 4 shown in Figure 10.

Water Level Sensor Data Processing - Channel Trials

[122] The data from the ultrasound sensors was processed before being presented in this report. Data from the ten ultrasound sensors (two sensors for each channel) were processed and analysed using programmable software MATLAB and associated in-built functions. Two sensors per channel were installed to minimise the impact of any data loss due to unforeseen issues during the trials, while also providing an additional dataset to cross-check the acquired data and detect any spurious data in the measurements. The data from the sensors was first cross-checked for all the channels. The data was then processed using the following steps to investigate the water evaporations during the trials.

[123] The water height measurement from two sensors were averaged to get more converged data. The data was acquired every 10 minutes during the entire trials. Outliers in the data due to water fluctuation, sensor blockage or any other ambient condition related issues were marked and removed if the measurement error was larger than 3 standard deviations of its averaged value (MATLAB function “filloutliers” was used during this process).

[124] Daily water evaporation was calculated by computing the changes of water height over 24 hours period. Calculated water loss amount was cross-checked between two sensor pairs to identify any outliers. Daily water loss values were stored across the full measurement periods. Change in water height between two consecutive days indicated the total water loss for each channel. The total water loss was compared with the “control case” to calculate the evaporation savings for the various evaporation mitigation techniques. Water height data was measured each day to track the overall water evaporation trend during the trials in addition to measuring daily variation of different experimental configuration.

Field Trial Site - Dam Trials 2021/22

[125] The trial site for the channel trials was the University of Melbourne - Dookie Campus. An analysis of the historical evaporation in the area was done (Shepparton is near Dookie) and compared with the evaporation data from the location from the channel trials (Yanco) and a location for previous field trials (St George). Shepparton shows similar daily evaporation rates over January as the other locations considered, Table 1. The location is also ideal due to the high average wind speeds and relatively high maximum daily temperature in January, Table 2. Three Dams were used in the experiment. Dam 1 was chosen as the location for the barrier instillation and had an approximate area of 0.173 ha. Dam 2 had an approximate area of 0.17 ha when full and was chosen as the control. Dam 3 was chosen as the experimental dam to trial the monolayer without the barrier intervention and had an approximate area of 0.056 ha.

[126] T able 1 : Summary of the last 10 years of evaporation (January data) at the proposed site for field trials (Dookie College, near Shepparton, Vic), the location for channels trials (Yanco, NSW), two locations in NSW (Narrabri) and Qld (St George).

St

Shepparton Yanco Narrabri

Year George

(mm) (mm) (mm)

(mm)

................. ........................................ __ ................................... _ ..................................... _ .................................... _

2019 I 275 288 314 314 2020 235 248 292 280

2021 | 222 231 229 239

10-vear ]

] 239 245 266 264 average ]

[127] Table 2: Summary of the average weather conditions in January over the last 10 years of evaporation at the proposed site for field trials (Dookie College, near Shepparton, Vic), the location for channels trials (Yanco), two possible locations in NSW (Narrabri) and Qld (St George).

Min

Max T Min T Max RH 10 m Wind speed

Location RH

°C °C % m/s

%

32.4 15.9 78.2 23.3 4.6 34.6 19.3 68.1 22.1 3.9 35.4 20.9 71.2 23.9 4.7 36.0 23.0 64.6 23.4 4.3

Water Level Monitoring Devices - Dam Trials 2021/22

[128] Nine ultrasonic (US) sensors were used during the trial to measure the change in the water height across all 3 dams. Five sensors were installed in Dam1 (barrier) and the other two dams had two sensors each to measure the change of water height. The ultrasonic sensors (UE3002, Holykell) were chosen as they are highly accurate and also cost effective. The sensors had a measurement resolution of 1 mm with a sampling rate of 10 minutes. Data from the sensors were measured and stored using the in-situ EMS data acquisition boards (EMS-solar powered, Ontoto) and the data was transmitted telemetrically every 24 hours. These datasets from all the sensors have been stored in online database repository which can be remotely accessed to monitor and acquire data during the measurement campaign. Wind Suppression Devices - Dam Trials 2021/22

[129] Barriers were installed in dam 1 . Dams 2 and 3 were used as controls and monolayer only cases to investigate the effect of the barriers throughout the trial period. The floating barrier device consist of a grid pattern (modular design) of small fences made from a porous material with 35% porosity. These barriers were supported by a solid frame made with PVC pipe and stainless wire mesh. Individual vertical poles were mounted to buoyant contains to float on water. Four of 2 by 3 barrier grids were successfully installed (shown in Figures 3 and 5) to keep the surface area of the dam within the sheltering regions created by the barriers. High-strength 10 mm rope and high-tensile strength spring were attached to the outer poles of the barriers and star pickets to place the grid in position.

Channel 5 design:

Barrier height: 0.6 m

Barrier separation: 6m between barriers

Evaporation Trial Plan - Dam Trials 2021/22

[130] The evaporation dam trials were conducted over three stages.

Stage 1 : Seepage/control evaporation measurements

Stage 2: Barrier trials

Stage 3: Combined barrier/monolayer trials

[131 ] The Seepage experiments were conducted over two periods due to the different times sensors were installed. The Seepage experiments were conducted comparing Dam 1 to Dam 2 from 8 February until 15 February 2022. Seepage experiments comparing Dam 3 with Dam 2 were conducted from 24 February until 5 March 2022. Barrier trials were started 17 February until the 7 March 2022. Monolayer plus barrier trials were conducted from 8 March to 6 April 2022 (with a short gap between the 22 March to 24 March). Monolayer addition to dam 3 (monolayer only trial) went until the 30 March 2022. 2. Results and Discussion

Monolayer Formulation Trials - Channel Trials

[132] Optimisation of the monolayer concept was done through exploring the impact of monolayer addition method and composition on formation properties and evaporation reduction. A range of alternative monolayers were investigated to find one which is cheap on a large scale and shows good reduction performance. Cetyl alcohol is economical ($2 per kg as of March 2022) and is also naturally present in the environment so bio-degradation pathways exist to prevent accumulation.

[133] In addition to this monolayer, polyvinyl pyrrolidone (PVP) was investigated in small scale laboratory trials as a way of increasing film viscosity, which will help improve resistance to wind further. However, these trials demonstrated that the addition of polymer reduced the performance of cetyl alcohol and was not considered further - see Figure 12.

Monolayer Formulation Trials - Dam Trials

[134] For the dam trials, commercial products were investigated that are available and approved for use on drinking water and for use around livestock, as the trial dams at the University of Melbourne - Dookie campus are used as a water source for sheep. Two main materials were investigated for their evaporation reduction performance; WaterSavr which is a mixture of cetyl alcohol and stearyl alcohol mixed with lime (calcium carbonate), and WaterGuard, which is a silicon oil based liquid. For the dam trials, 244 g (183 mg/m ² ) of each monolayer material was added to the dam with barriers.

[135] WaterGuard showed the best performance with an average evaporation reduction of 83% when 0.1 ml of liquid was applied to an area of 1094 cm ² (0.91 ml/m ² ) as shown in Figure 13a. WaterSavr showed an average savings of 58% when 20 mg was added to an area of 1094 cm ² (183 mg/m ² ). Increasing the loading of WaterSavr showed a large increase in performance from 10 mg to 20 mg loading however this levelled off with further increases reaching 68.8% savings at 40 mg (366 mg/m ² ) and 79% with 60 mg (549 mg/m ² ) as shown in Figure 13b. The results of WaterSavr showed similar reductions to the cetyl alcohol used in the channel trials. For the dam trials 20 mg (183 mg/m ² ) was used as this was below the recommended maximum usage indicated by the manufacturer of WaterSavr.

Small Scale Monolayer and Barrier Trials

[136] Trials of the monolayer in conjunction were conducted in a small tank (1 m long) with wind speeds of between 2.5 and 6.5 m/s were conducted to determine the optimal spacing between the barriers prior to conducting experiments with both the monolayer and barriers in the long tank. Initial experiments showed that the optimal increment of spacing was 37 cm with a barrier height of 2.5 cm.

[137] In developing the barrier prototype for large scale trials, a new material was chosen which would be more cost effective and potentially show improved evaporation reduction results. A range of materials with different optical porosities was tested in small scale trials for their evaporation reduction performance as shown in Figure 14b. Material with 35% optical porosity showed the best results with a 31 % reduction in evaporation using barriers alone.

[138] Additional trials combining the monolayer and the wind barriers were performed with the new materials tested. These materials were trialled to find the optimal porosity for reducing the impact of wind (optical porosity of 35%). These barriers showed good savings alone (31 %), while in conjunction with cetyl alcohol they demonstrated 49% reductions as shown in Table 3.

[139] Table 3: Evaporation rates from long tank trials containing barriers (35% porosity) in combination with monolayers Large Scale Monolayer and Barrier Lab Trials

[140] The trials investigating barrier porosity were scaled up to larger tank trials in the 16 m long SIWWI facility. These trials tested the evaporation performance with barriers with 35% and 65% porosity and compared with the control case, Figure 15. These trials also demonstrated that the 35% porous barriers showed the greatest evaporation reductions with a reduction of 29%, similar to the smaller scale trials.

[141 ] Trials with Cetyl alcohol in combination with the barriers (35% porosity) were then conducted to investigate the evaporation performance. The results from the subsequent trials would provide direct comparison to the previous small- scale experiments for the verification purpose.

[142] These trials showed that the combined effect of monolayer and the devices is capable of achieving around 34 to 38% evaporation reduction compared to no intervention, while the device by itself achieved around 26 to 28% evaporation reduction. The water evaporation as a function of time for the barrier with 35% porosity and the case for the barrier with monolayer is shown in Figure 16. The results demonstrate the barriers were able to improve the performance of the monolayer, however the results were lower than the small scale trials. Potential reasons for this are the difference in barrier configuration and wind profile.

[143] Further results looking at the maximum wind speed before failure of the barriers found that an optimum of height to spacing/ separation of the barriers was 1 :15 where height is the height of the top of the barrier panel above the water surface, and separation is the distance between two parallel spaced apart barrier panels. The workable ration range was found to be 1 :7.5 to 1 :25. The results of the trials are illustrated in Figure 16A.

[144] The important consideration is the ratio of height to spacing/ separation as this ratio scales linearly. Larger degrees of spacing reduce the evaporation due to the wind being able to reengage with the surface. Smaller spacing resulted in increased turbulence, which reduced savings, while longer spacings enable wind speeds behind the barriers to recover reducing evaporation savings. Thus, as shown in Figure 16A, above the 1 :15 ratio (larger separation) the savings will decrease evaporation savings of the barrier alone. Decreasing the ratio (reducing separation) also reduces the savings (this is due to increased turbulence behind the barrier) until a ratio of 1 :2/1 :4 where there is an increase in savings (possibly because the system starts to mimic a cover on the surface).

Channel Trials 2020/21

[145] The first round of channel trails was conducted at the Yanco Agricultural Institute over the 2020/21 Summer and into the 2021 Autumn.

Establishment of Channel Trial Site

[146] The Yanco Agricultural Institute, Yanco, New South Wales, Australia was identified as the location for small scale trials on channel segments. The site has five sections of channel (5 m x 42 m) which will be used for evaporation trials of the barrier material in conjunction with the monolayer.

[147] Environmental data for the Yanco Agriculture Institute channel was investigated to determine if this site was suitable for the channel trials. Wind data such as wind speed and dominant wind direction nearby the site was collected and investigated to design experimental setup and parameters for the field trials. Annual wind rose data including the wind direction information near the trial site. This result is compared with the data collected by a weather station installed next to the Yanco channel. Based on the available data, the barrier configuration was designed to have optimal impact on reducing wind driven shear stress on near water surface during the planned trial period.

Control Trials

[148] Control trials were conducted to monitor changes in the water height were monitored on all 5 sections of the channel to test for leakage prior to conducting further trials. Figure 17 shows the results over the period from 02 March 2021 to 8 March 2021 . The water loss results due to the evaporation from channels 2 to 5 were consistent over the period, however channel 1 showed a higher rate of water loss. Based on these results, channel 2 was designated the control channel while channels 3 to 5 were to be used for testing the technology. Throughout these trials the performance of channel 1 was monitored with rates of water loss varying between that of channel 2 and showed higher evaporation rates compared to channel 2.

Barrier Trials

[149] Barriers were installed on the channel sections following the control trials on 1 1 March 2021 . The barriers were installed as outlined previously. Following the instillation there was a noticeable difference in the surface of the water in channels with the barriers. During low wind conditions, the water surface was calm as the wind speed was not high enough to form capillary waves. However, at higher wind speeds, there was noticeable wave action on the sections of channel without barriers. Channels 3 and 4 with barriers installed showed a significant reduction in the surface action on the channels which demonstrated the effectiveness of the porous barrier material in mitigating the wind shear stress on the water surface. This qualitatively indicates that the barriers were successful at reducing the wind speeds at the water surface.

[150] The cumulative change in water height was measured over a 28 day period from 21 March 2021 to 17 April 2021. The results for channels 2 to channels 5 are shown in Figure 18. The data shows that the presence of the 0.3 m barriers reduced the overall evaporation in these channels. The 0.3 m barriers reduced evaporation by an average of 10.3% over this period (1 1.1 % in channel 3 and 9.5% in channel 4).

[151 ] The data from channel five showed a similar cumulative loss as the control channel (channel 2). This was due to significant damage caused to the barriers in channel 5 during the first week following installation, and hence there was minimal effect on reducing wind stress, leading to nominally negligible evaporation saving. The large barrier area acted like a wind sail which placed a large amount of force onto the joints along the barrier which caused tares in the material. The barrier materials on channel 5 were removed for the subsequent trials. [152] Although the overall reduction in evaporation was 10.3% for the channels with barriers, the day to day evaporation savings varied throughout the trial with some days showing savings above 40% to 50% for certain conditions such as presence of strong winds. Figure 19 shows the day to day evaporation savings for channels 3 and 4 (a). The figure also shows the average wind speed (b), the average temperature (c), and the predominant wind direction (d). Looking at the day to day evaporation savings shows that there are periods of time where the savings exceed 20 % (10 out of 30 days and 7 out of 30 days for channel 3 and 4, respectively).

[153] Often these increases in savings are associated with higher average wind speeds. This corresponds well with the method that barriers reduce wind effect at the water surface leading to reductions to the water evaporation rate. Data on the wind direction shows that the predominant wind directions through the trial are from the South and West (Figure 19d). The direction of the channels is from North to South, which means that the wind was split between blowing along the channels and across the channels.

[154] The environmental data was further studied to better understand the impact of environmental conditions on the evaporation rates and savings. Figure 20 presents the results of correlations between the evaporation rates and environmental factors. Overall environmental conditions did not show a strong correlation on the evaporation rates and barrier savings during the trials which is possibly due to the multiple variables that impact evaporation. However, analysis of the data showed some weak correlations. Data from the barrier trials showed a mild correlation between wind speed and evaporation rates (see Figure 20c). Higher wind speeds show a negative correlation (-0.24) with raw evaporation (increase in wind speed leads to lower evaporation). This is potentially due to the negative correlation with temperature (-0.36), as temperature increases the wind speed decreases which results in there being lower temperatures at times of higher wind speeds as shown in Figure 20e. There was a larger correlation between evaporation and savings. Although wind speed showed a weak positive correlation with evaporation reduction amount (0.23 for channel 3, 0.01 for channel 4). There was a stronger correlation for percentage reduction (0.34 for channel 3, and 0.13 for channel 4) as shown in Figure 20d. Percent evaporation reduction better reflects the impact of the barriers as it is a percent of evaporation and accounts for days with higher evaporation.

[155] Temperature did not show a strong correlation with evaporation and results were mixed, for evaporation reduction amount (0.02 for channel 3, -0.22 for channel 4) as shown in Figure 20a. Evaporation percent reduction was also mixed (0.06 for channel 3, -0.17 for channel 4) as shown in Figure 20b. These results were potentially impacted by the stronger correlation with wind. These relatively weak correlations between the ambient environmental conditions and the evaporation rates from the experimental data could be due to the multiple parameters affecting evaporation. The weak correlation could be due to the duration of the experiment. Hence, future measurements during the next irrigation period will be carried out for a longer duration to improve the correlation analysis.

[156] Table 4: Correlation coefficients between different weather conditions and evaporation/ evaporation reduction from data collected during the barrier trials.

Combined Barrier and Monolayer Trials

[157] Combined monolayer and barrier trials were conducted following the barrier trials. These trials were conducted from 21 April 2021 to 24 May 2021. During these trials the cumulative change in water height was measured over 34 days, shown in Figure 21 . During these trials the 0.9 m barriers were not replaced on channel 5 and this channel was instead used for monolayer alone trials. Monolayer was applied daily to channels 3, 4 and 5 throughout the trials. Channels with barriers demonstrates overall evaporation savings throughout the trials. Overall, there was a 9.9% reduction in evaporation with 1 1 .0% savings in channel 3 and 8.8% reductions in channel 4. Channel 5 with the monolayer alone also showed slight savings with 2.2% lower evaporation over the trials. Overall, these trials have a lower level of evaporation comparing the change in water height in control channels which is due to the changing seasons and the lower average temperature (14.6 °C in the monolayer trials compared with 17.8 °C in barrier trials).

[158] Throughout the trials, the monolayer was applied to alternating sections of the channel to prevent potential issues with monolayer spreading through the barriers. During the trials, there was a build-up of algae along the water surface where the barriers contact the water surface. Addition of the monolayer to different spaces between the barrier showed that the monolayer was present, which was observed through the monolayer powder not spreading when added to these spaces. This algae build-up was removed by using a broom to clean the barriers.

[159] Analysis of the day to day evaporation data showed that there was significant variation in the results as shown in Figure 22. Although the overall savings were 9.9%, there were many days where these savings passed 20%, with some days showing savings above 40%. There was also a wider range in the day to day variation compared with the barrier only trials, which may be partly due to the lower overall evaporation rates through these trials, which is because of the lower temperatures during the trials. There were also lower average wind speeds during the monolayer trials (3.35 m/s compared with 4.66 m/s during the barrier only trials).

[160] Further investigation of the environmental data did not show any strong correlations between evaporation savings and environmental conditions, Figure 23. Part of this is due to the lower evaporation rates and a smaller range of conditions such as temperature and wind speeds. Longer trials which cover more environmental conditions could potentially help to identify stronger correlations. Analysis of the data from Channel 5 which only had monolayer showed no correlation between temperature and evaporation reduction, however there was a small correlation with wind speed (-0.19). Although a small correlation, it indicated lower evaporation savings at higher wind speeds, which fits with results from previous trials where wind speed impacts monolayer performance.

[161 ] Table 5: Correlation coefficients between different weather conditions and evaporation/ evaporation reduction from data collected during the combined barrier and monolayer trials.

[162] Analysis of the overall savings from both barrier only and combined trials showed similar performances over these trials however there was variation in the spread of the resulting water evaporation savings. The average daily savings of the combined monolayer trials was 15.6%, which is slightly higher than the barrier only trials, 12.1 %. There was a difference in evaporation savings when considering 75 percentile results, with the monolayer trials showing a 29.0% evaporation reduction compared with 22.9% for the barrier only trials. This data suggests that the addition of monolayer had a positive impact on the days with higher evaporation savings. The 25 percentile savings for the two trials were similar with -1 .9% for the barrier only case and -1.1 % for the combined monolayer trials.

Channel Trials 2021/22

[163] A second round of channel trials were conducted at the Yanco Agricultural Institute, NSW, over the 2021/22 summer. Prior to the trials minor repairs and adjustments were made to the barriers from the previous year. Notably, wire mesh was added to the shade cloth to improve the barrier stability.

[164] The trials with barrier only cases were conducted from 4 February 2022 to 20 February 2022 and the combined barrier and monolayer trials were performed from 21 February 2022 to 18 March 2022. The cumulative change in water height measurements were obtained over 52 days period and the results are shown in Figure 24. The red shade highlights the period when monolayer was added to channel 3 which already had the barrier installed. The results shows that both barrier only and combined barrier and monolayer cases reduced the overall water evaporation amount in channel 3 compared to the control channels. Similar day to day analysis (as discussed above for the preceding trials) was carried out to quantify the daily evaporation saving amount for the two different trials. From the analysis, the results showed that the average daily savings for the barrier only case is 22.2% compared to the control channel and the addition of monolayer increased the average daily evaporation savings to 39.7%. The addition of monolayer to the channel 3 with the barriers reduced water evaporation significantly further (from 22.2% to 39.7%). This improvement in the water savings compared to the last year Yanco channel trials (2020/21 ) could be due to the further changes made to the barriers such that the barriers were upholding its position against strong wind and also the average temperature during 2021/22 trials was higher (32.3 Celsius) compared to the previous trial.

Large Scale Field Trials on Dams

[165] The barrier technology was tested in conjunction with the monolayer over the 2021/22 Summer at the University of Melbourne - Dookie Campus, Dookie College, Victoria 3647, Australia.

Control Trials and Seepage Experiments

[166] Before the floating barriers were installed in the barrier dam, control trials were conducted to estimate leakage and reference evaporation rates for all three trial dams relative to the control dam (dam 3) prior to conducting further trials with the barriers and monolayer. The trials demonstrated that differences in the water loss rate during barrier and monolayer trials would be directly associated with the efficacy of the barriers and the addition of monolayer.

Barrier Installation and Design Modifications

[167] Following the secure deployment of the two by two prototype floating barriers, the floating barrier designed was confirmed and scaled up to construct three by nine grid (27 cells) to cover the barrier dam (dam 3) which had dimensions of 30 m by 60 m. The Individual cell design was a barrier height of 0.4 m with 35% porous barrier materials combined with stainless steel mesh wire for additional support. These barrier walls were supported by solid rectangle frame made out of PVC pipe. The individual walls were connected using PVC pipe joints with cement glue and multiple screws to form a square cell. These cells consist of four barrier walls which are 6 m by 6 m (length by width). The next cell was built as an extension of the cell adjacent to it to make the three by nine grid consist of 27 cells. Hence the overall dimension of this three by nine grid was 54 m by 18 m (length by width) to cover the barrier dam (dam 3) as shown in Figure 25. This large-scale grid was built next to the barrier dam and deployed. Once the floating barriers were in position, it was securely mounted with high- strength ropes (breaking strength of 120 kg) attached to the multiple star pickets mounted around the bank. It was observed that this three by nine grid of floating barriers withstood wind gusts up to 50 km/h. However, there was an unexpected severely weather condition with a windstorm near the site causing wind gusts up to 80 km/h which damaged a third of the grid structure. Further design work was undertaken to enhance the structural integrity of the floating barriers. Additionally, a smart way to release or navigate extreme wind forcing to avoid any unexpected damage caused by extreme weather conditions were implemented.

[168] Some of the main design changes included:

• segmenting the grid into a smaller grid size (modular structure).

• using high-strength (breaking strength of 1 100 kg).

• high-tensile strength spring to absorb impact loading from strong wind gust (see Figure 7B).

• flapping barrier walls which open up the barrier walls at high wind speed to release the wind forcing.

• Additional PVC crossbeam pipe (122) and floating device (170) within the cells (the centre cross structure).

[169] For the modular grid, instead of constructing a three by nine grid which connects all 27 cells, multiple of smaller grid size of two by three configurations were built. Four of the two by three grids were built and with this modular structure, it could avoid potential collateral damage when one grid fail since these grids are independent to each other (floating and anchored separately). The aerial shot of the modular structure of each module 1 10 of the floating barriers 100 is shown in Figure 1 which shows an arial shot of the segmented barrier design, taken on 17 February 2022. This design is the final version of the barriers and was used in the barrier only and barrier plus monolayer trials. These latest implementations enhanced the stability and strength of the floating barrier grids and allowed it to withstand wind gust up to 60 km/h. Hence, the trials for the barrier case and combined barriers and monolayer were conducted with the current design. Barrier Trials

[170] The trial with the latest floating barrier set up started on 19 February 2022. Following the installation of the floating barriers, the barrier had significant impact on suppressing the wave formation by reducing wind shear stress on the water surface. This clearly demonstrated a reduction in the surface wave formation on the barrier dam which further demonstrated that the porous barrier materials effectively mitigated the wind shear stress and hence the wave formation. In comparison, the control dam was found to have active surface wave formation caused by wind forcing. Further to this, floating tracer particles were used to qualitatively observe the water surface motion inside and outside the barriers, simultaneously. Although the wave suppression within the barrier was clearly observed, those surface motion following tracer particles were often employed to study the surface draft velocity due to the wind forcing. In this case, the particles within the barriers were nominally stationary which indicated the wind shear stress was significantly reduced through the barrier while the particles outside barriers were drifting along the length of the dam with the winds. Similar results were observed in the control dam where those tracer particles were constantly drifted away with the surface waves generated by the wind inputs. This further demonstrated the effectiveness of the floating barriers on mitigating wind shear stress on the water surface.

[171 ] The cumulative change in water height was monitored over a 19 day period from 17 February 2022 to 07 March 2022. The resulting change water heights for the barrier dam and the control dam are shown in Figure 35. The blue shaded regions indicate the days when there was heavy rainfall. The data clearly indicate that the presence of the floating barriers reduced the overall water evaporation compared to the control dam. The barriers reduced water evaporation by 23.8% over the 19 days measurement period (accounting for the rain).

Combined Barrier and Monolayer Trials

[172] Combined monolayer and barrier trials were performed following the barrier trials. These trials were conducted from 8 March 2022 to 24 March 2022. Again, during this period the total water height changes for both the control dam and the barrier dam with monolayer was measured and shown in Figure 26 (highlighted by red box). Throughout the trials, the monolayer was applied at the one end of the barrier dam and monolayer was spreading across the entire water surface through installed floating barriers. From the cumulative change in water height data, the barrier dam with monolayer showed overall evaporation saving during the trials and the average water saving was 26.9% compared to the control dam (accounting for the rain). This water saving of 26.9% from the combined barrier and monolayer case is slightly better than the water saving of 23.8% which was obtained from the barrier only trials. Also, the green solid line shows the cumulative water height changes for the monolayer only case in dam 3. There was no barrier installed on dam 3 to protect monolayer from the wind shear stress and the monolayer was added at the same time as the barrier dam. The result indicated that there was no water saving from the monolayer only case relative to the control dam and this was mainly because the monolayer was constantly disturbed by the presence of wind forcing even at a low wind speed (~ 1 m/s).

[173] To further investigate the effect of monolayer addition and the barriers on the water saving, the day to day evaporation rate and corresponding water height changes were analysed from the datasets and shown in Figure 27. Although there was variation in the averaged daily evaporation reduction relative to the control dam, there were 13 days which showed evaporation reduction over 40 % over the 34 days measurement period. A comparison of water depth change between the control dam and the barrier dam for each day (24 hours period) was used to compute the daily water evaporation reduction. It is worth highlighting that relatively lower water evaporation saving was observed after the rainfall. This could be partly due to the lower temperature and running water went into the open dam after the rainfall. The results from the analysis of day to day water evaporation were used to plot a boxplot showing the range of daily water saving compared to the control dam for three different trials provided in Figure 28. The plot shows that the barrier along and barrier with monolayer trials achieved significant evaporation reductions. Meanwhile, monolayer alone case shows nominally negligible evaporation changes. The average daily water evaporation saving for the barrier with monolayer is 39.4% while the barrier only case is 31 .5%. The increase in water saving with the addition of monolayer is consistent with the previous laboratory testing and Yanco channel trials. Hence the water evaporation results obtained from the dam trials indicated that the addition of monolayer had a positive impact on the days with higher evaporation savings and the barriers were providing sheltered regions within the cells to protect monolayer from the wind shear stress.

Dam trials

[174] Data on the impact of environmental conditions on the water evaporation rate during barrier and monolayer trials on dams at Dookie Campus - The University of Melbourne. Data represented in Figure 29 is the impact of; daily average temperature on a) the control evaporation rate and b) daily evaporation reduction (%); the impact of daily average wind speed on c) the control evaporation rate and d) daily evaporation reduction (%). Also represented is e) the correlation between average wind speed and temperature, as well as f) the correlation between daily evaporation reduction (mm) and control evaporation. Data represented was collected over the period from 17 February 2022 until 24 March 2022.

[175] Figure 29 indicates that implementation of the barriers and barriers in combination with monolayer have a strong positive correlation with between evaporation reduction (mm) and daily evaporation on the control dam (mm). In addition, the evaporation savings with the barriers in combination with the monolayer showed a more positive correlation indicating the increase in evaporation reduction.

Conclusions

[176] These trials have demonstrated the technology from the lab scale to a field trial on a dam site with positive results at all scales. During these trials the device alone showed an average daily reduction of 31.5%. When used in combination with a monolayer these savings increased to 39.4%. With further research, these results could be improved to potentially achieve reductions over 50%.

[177] Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. It is understood that the invention includes all such variations and modifications which fall within the spirit and scope of the present invention.

[178] Where the terms "comprise", "comprises", "comprised" or "comprising" are used in this specification (including the claims) they are to be interpreted as specifying the presence of the stated features, integers, steps or components, but not precluding the presence of one or more other feature, integer, step, component or group thereof.