GB2285953A

GB2285953A - Regulating the melting of surface ice

Info

Publication number: GB2285953A
Application number: GB9500861A
Authority: GB
Inventors: Vladimir Aizen
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-01-17
Filing date: 1995-01-17
Publication date: 1995-08-02
Also published as: GB9400750D0; GB9500861D0

Abstract

A method for regulating the melting of surface ice by solar radiation comprises covering the surface ice with a sheet (10) comprising a lower insulating layer (12) such as polyurethane and an upper solar radiation reflecting layer (14) such as metallic foil or metallised plastic film. The sheet (10) can be secured to the ice by means of a spike (20) having a resiliently biased transverse bar (28) for urging the sheet (10) against the ice. The sheet (10) can be left in place until water is required from the surface ice. To allow the solar radiation to melt the ice, at least a part of the sheet (10) is removed. <IMAGE>

Description

METHOD AND APPARATUS FOR REGULATING MELTING OF SURFACE ICE The present invention relates to a method of regulating the melting surface ice. In this specification, the term "surface ice" is employed to cover snow, aufeis (naturally or artificially created), and glaciers.

In warmer climates, it is common to provide irrigation systems for the supply of water for agricultural, industrial and civil purposes. However, such systems cannot by themselves cope with seasonal melting of surface ice since under normal conditions this gives rise to a high supply of melt water in the spring but only a relatively low supply in the other seasons.

The present invention seeks to allow regulation of the melting of surface ice and thereby permits both regulation of a surface water supply, where that water supply is governed by the seasonal melting of surface ice, and the preservation of surface ice in situ, for example for the fortification of roads in permafrost areas during summer and support of artificial ice platforms for search and development at oil, gas etc. at sea.

The present invention provides, in its first aspect, a method of regulating the melting of surface ice comprising, removably covering a region of surface ice with a sheet comprising a heat-insulating layer and an outer solar radiation-reflecting layer. Thus, to preserve surface ice, the sheet is left in position. To permit melting of the ice to supply surface water, the sheet is, at a later occasion, at least partly removed to uncover a part of the region of surface ice. This later occasion would normally be during a season of different ambient temperature and/or ambient solar radiation intensity to the season in which the ice is covered. For example, the ice may be covered in spring and at least partly uncovered in summer. The supply of surface water can be regulated by varying the amount of ice uncovered by the sheet.The effect of this is to allow maintenance of a substantial proportion of the surface ice in the frozen state until such time as water is required, which may be some months later. Furthermore, the rate at which water is supplied can be regulated.

It is possible to store surface ice by this method for several months, i.e. throughout the summer season, at least in some climates.

Thus, the supply of melt water can be modulated to correspond more closely to the needs of the water consumer.

In a second aspect, the present invention relates to a sheet for use in such a method, and to the use of such a sheet. A suitable sheet comprises an insulating layer, typically of synthetic plastics insulation material, such as polyurethane, bonded to a layer of solar radiation reflecting material, for example a metallic foil, such as aluminium foil, or aluminised plastic film. A suitable thickness for the plastics layer is 0.5 to 1 cm.

It is preferable that the sheet is anchored to the underlying ground or ice, and in a third aspect the present invention provides an elongate spike for anchoring a sheet with a ground engaging portion at a first end and a second end having at least one transversely projecting member, the transversely projecting member being resiliently biased toward the ground engaging portion. In use, the ground engaging portion of the spike may be pushed through a hole in the sheet, or through a loop or projection attached to the sheet, into the underlying ground sufficiently far for the transversely projecting member to be biased against the top surface of the sheet, or the top or projection as the case may be. Suitably, a plurality of such spikes are used to fasten the sheet firmly to the ground.

The ground or ice engaging portion of the spike is ideally of a form suitable for the underlying material. For example, if it is to engage earth, it may have a generally tapering section, possibly with projecting tines. Where the underlying material is ice, it is preferred that the ground engaging portion is generally cylindrical and has a an external screw thread arrangement to facilitate engagement with the ice. In this case, it is desirable to provide the spike with a handle to facilitate turning, although a separate tool could be used.

Embodiments of the present invention will now be described, by way of non-limitative example, with reference to the accompanying drawings, in which: Fig. 1 is a perspective view of a sheet suitable for use with the method of the present invention; Figs 2 and 3 are perspective views of spikes suitable for anchoring the sheet of Fig. 1; Fig. 4 is a diagrammatic perspective view of the sheet of the present invention in use on a non-glacial area; Fig. 5 is a diagrammatic perspective view of a sheet according to the present invention in use in a glacial region; Fig. 6 is a graph of a daily variation in average values of total short wave radiation (Q), radiation reflected from a snow surface (B1) compared with radiation reflected from the surface of a light reflecting film (B2), measured in the valley of R.Susamir;; Figs. 7a-7d is a series of graphs of the daily variation in snow temperature at various depths; depicting the temperature respectively on the surface, at 10 cm depth, at 35 cm depth, on the underlying ground.

T1, the dashed line represents the exposed surface temperature, and T2 the temperature under the film.

Fig. 1 shows a sheet 10 suitable for use in the above described method, comprising a polyurethane layer 12 overlayed with an aluminium foil layer 14. An array of holes 16 are provided, reinforced with metal eyelets.

A plurality of such sheets 10 may be placed in a butting relationship to form a single larger sheet, the joins being covered by a strip of self-adhesive foil 18. The sheet or sheets 10 are secured to the ground using spikes 20.

Figs. 2 and 3 show spikes 20 suitable for securing the above-described sheet. Each spike consists of a generally tubular portion 22 connected atone end to a ground engaging portion 24. Each tubular portion 22 has a pair of diametrically opposed longitudinal slots 26 through which projects a transverse bar 28 within the tubular portion is a spring abutting against a top stop 30 and acting on the transverse bar 28 to urge it towards the ground engaging portion 24. Thus, in use, the spike is pushed through an opening 16, ground engaging portion foremost, until the transverse bar 28 has contacted the sheet 10 and been pushed a distance against the spring 27. The sheet 10 is then held firmly against the ground.

Furthermore, even if some of the underlying ice melts, so that the surface level lowers, the resilient biasing means may maintain the sheet pressed against the ground.

In Fig. 2 the ground engaging portion is a tapering section having a plurality of back-projecting spurs 32. This makes it suitable for driving into earth.

In Fig. 3, the ground engaging portion is a tubular section having an external helical screw thread 34, and a series of openings 36 within the pitch of the helix. This makes the spike of Fig. 3 suitable for engagement in an ice surface. To facilitate insertion, a handle 38 is provided at the top end of the spike 20, projecting transversely from the screw thread axis and thus enabling rotation of the spike 20.

According to the present invention, water supply regulation is carried out by covering the snow and ice surface with a heat insulating material which can reflect up to 90 or more of short wave solar radiation. Those areas covered with material where snow, ice of aufeis and glaciers accumulate during one or more winters can become a natural water storage reserve avoiding crop productivity dependence on drought in the spring-summer vegetation period. The method can be used to smooth flood peaks throughout the spring. The water (as snow and ice) can be preserved for several years if necessary and then used by opening the accumulated mass for melting and run-off strengthening against a background of the natural climate. The variations in some experimental glaciers in any mountain glacier basin allow regulation of the annual run-off without sacrificing of the general hydrological cycle.

The theoretical calculations of energy quantity which is necessary for snow-ice melting are represented by the equation: Qo = Qs + Q1 + Qt + Qc + Or + Qg (Equation 1) where Qo is the heat flow spend for melting, Os is the balance of short wave radiation, Q1 is the balance of long wave radiation, Qt is the atmosphere turbulent heat flow, Q is heat flow connected with evaporation or condensation or sublimation, Qg is heat flow from the surface divided by ground-snow or ground-ice, Or is the heat flow brought by rain.

Experimental investigations were carried out in Tien Shan on glacial and non glacial surfaces and gave the following results: On a non glacial surface at an altitude of 200 m above sea level, two similar areas (about 20 m2, with an average surface inclination from North to South of 1.5 ) were chosen. For the maximum snow accumulation in this region and at this altitude (end of April) one of the chosen areas was covered with a light reflecting material. With the help of electronic sensors connected to a computer simultaneous measurements of radiation, heat balance components and run-off were carried out.

All measurements were carried out from the beginning of snow melting till its dissipation on the natural non shaded surface. The snow thickness at the beginning of the experiment was 80-85 cm. The same experiment on the two areas of glacial surface was carried out on the Golubin glacier North Tien Shan basin R.Chu.

The main heat income to the snow cover and ice melting is through the radiation component (Qs and Q1) between 70 % and 90% of the total, depending on current local climatic conditions. In this case its value was 86%. This suggests that the present invention is most effective in mountain regions with continental and subcontinental climates, where melting due to incoming radiation composes more than 80%. For snow and ice surfaces covered according to the present invention, the value of Qs is near zero. The average time period is represented in Fig. 6, here the ability of material to reflect the solar radiation up to 30-40% more than melting snow and ice surface is shown.The decrease in incoming short wave radiation by the present method supposes the effective possibility of its use on slopes of southern exposure, but does not, however, deny slopes with northern exposure.

The exchange of long wave radiation (Q1) is limited beyond several millimetres of snow thickness.

Therefore the long wave radiation absorption results from the heat insulating properties of covered materials, i.e.

it is possible to approximate this component to zero by the selection of insulating material. During the experiment the snow cover and ice were covered by just the light reflecting film; the heat insulating material was not used. However the use of this film decreased surface melting. For example, on the area covered by this material zero temperatures and melting on the snow or ice surface were observed just in day time. At the same time on the opened area the snow and ice surface had zero temperatures all day and night (Fig. 2a).

The turbulent heat component (out) equalled about 14% of total heat balance for the exposed snow surface during the melting period. The turbulent heat flows and long wave radiation flows influence just the surface layer of snow and it is possible to see from Fig. 7b that these values are minimal. At a depth of 10 cm from the snow surface covered by light reflecting film the amplitude of daily snow temperature variation decreases and there are no cases of zero temperature, i.e. the process of melting does not occur. At the same time under the open surface zero temperatures are observed most of day. At a depth of 35 cm the snow temperatures practically do not change under the light reflecting film in spite of open surface of snow (Fig. 7c).

In insulating from the outside atmosphere, heat exchange from evaporation and condensation (Qc) of snow cover is reduced to zero, because sublimation and crystallisation is compensated by the evaporation of snow cover. The temperature distribution of snow under the film is the result of this compensation; zero values of temperature are observed on the surface during some hours of day but at 10 cm depth melting water is not observed.

During the melting period snow cover cools the ground.

Thus the heat flow from the ground is also close to zero.

The data regarding temperature distribution close to the ground is shown in Fig. 7d, where negative temperatures are observed continuously under the snow covered by the film, according to the present invention. The influence of heat brought by rain is limited by this material and the surface ice layer formed under it through sublimation.

Thus the temperature of the sheet is close to zero or below zero (through the cooling influence of snow and ice) and melting under the reflecting film is minimal, taking place only in a few millimetres of surface layer. By the time total dissipation of exposed snow cover in the R.Susamir basin was complete, the water resources in the snow pack under the sheet of the present invention were 70 of their initial state, and on the glacier correspondingly 90%. In the second case the flow of coldness from the glacial surface plays an important role throughout the summer period.

Thus in the first case (snow preservation on ground surface) the suggested method can be used to prolong the snow cover melting period, water accumulation and to smooth flood peaks. In the second case the (water preservation on glaciers) the method can preserve ice for some years. The variation in different experimental glaciers in one mountain glacial basin can regulate the annual run-off without influencing the general water exchange. This method can alternate the mass accumulation on some glaciers with simultaneous receiving of supplementary water from others. Thus the natural water reservation storage from snow-patches and aufeis can be created in nival zones of a river's head, where glaciers are absent. At the same time these methods can be effective simply on condition that previous preparation and direction of receiving water application are carried out.

Fig. 4 shows a non-glacial area covered with a sheet as previously described, anchored using spikes 20.

The sheet 10 has been partially rolled back to uncover an area 40 which is to be allowed to melt. Melt water flows into drainage ditch 42 and is collected by pipe 44.

Fig. 5 shows a similar arrangement in a glacial region.

Thus, through the present invention, surface ice can be preserved and allowed to melt when required. This enables the smoothing of a water supply in a method that is ecologically sound and does not require major engineering works harmful to the environment.

Various modifications of the invention will apparent to those skilled in the art, within the scope of the general teachings herein, and all such modifications are to be construed as included in the present invention.

Claims

Claims:

1. A method of regulating the melting of surface ice by solar radiation comprising covering the surface ice with a sheet having a lower insulating layer and an upper solar-radiation reflecting layer.

2. A method of regulating the melting of surface ice by solar radiation the ice having a frozen state and a molten state, the molten state providing surface water, the method comprising the steps of covering the surface ice with a sheet having a lower insulating layer and an upper solar-radiation-reflecting layer, retaining the sheet above the surface ice for a period of time substantially to maintain the ice in the frozen state, and at least partly uncovering the surface ice at a later time to allow melting of the ice by said solar radiation from said frozen state to said molten state to provide surface water.

3. A method of regulating the melting of surface ice by solar radiation according to claim 1 or claim 2 wherein said retaining step includes releasably securing the sheet to the ice surface by means of removable spikes.

4. A method of regulating the melting of surface ice by solar radiation according to any one of the preceding claims wherein the ice is covered with two of said sheets, to define a join therebetween, and a solar radiation reflecting strip is positioned over said join.

5. An ice preservation system for regulating the melting of surface ice by solar radiation comprising a surface ice layer having an upper surface, at least one sheet having a lower insulating layer and a upper solar radiation reflecting layer, the sheet being positionable on the upper surface of the surface ice layer substantially to inhibit melting of the surface ice by solar radiation and being at least partly removable from the surface ice layer to allow melting of the surface ice by solar radiation.

6. A sheet, for use in the ice preservation system of claim 5, for regulating the melting of surface ice by solar radiation, the sheet having a lower insulating layer and an upper solar radiation reflecting layer.

7. A sheet according to claim 6 wherein said lower insulating layer comprises synthetic plastics material.

8. A sheet according to claim 7 wherein said lower insulating layer comprises polyurethane.

9. A sheet according to any one of claims 6 to 8 wherein said upper solar radiation reflecting layer comprises a material selected from the group consisting of metallic foil and metallised plastic film.

10. A sheet according to any one of claims 6 to 9 wherein said lower insulating layer has a thickness of between 0.5 and 1 cm.

11. A sheet according to any one of claims 6 to 10 wherein said lower layer is bonded to said upper layer.

12. A sheet according to any one of claims 6 to 11 wherein the upper solar radiation reflecting layer reflects at least about 30t more solar radiation than surface ice.

13. A system for regulating the melting of surface ice by solar radiation, comprising a layer of surface ice, first and second sheets and a solar radiation reflecting strip, each of said first and second sheets having a lower insulating layer and an upper solar radiation reflecting layer, said first and second sheets being arranged on the surface ice layer adjacent each other to define a join therebetween, the solar radiation reflecting strip being positioned above said join.

14. A system for regulating the melting of surface ice by solar radiation according to claim 13 wherein said solar radiation reflecting strip comprises a strip of foil having a self-adhesive surface.

15. A sheet according to any one of claims 6 to 12 comprising means for removably securing the sheet to the surface ice.

16. A sheet for regulating the melting of surface ice by solar radiation according to claim 15 wherein the means for removably securing the sheet to the surface ice comprises means for defining a hole through which a spike can be inserted, and a spike for insertion through said hole.

17. A spike for securing a sheet to surface ice the spike having an elongate body with first and second ends and comprising a ground engaging portion at the first end thereof, a transversely projecting member adjacent the second end thereof, and resilient biasing means connected to said elongate body and to said transversely projecting member to bias said member towards said ground engaging portion.

18. A spike for securing a sheet to surface ice according to claim 17 wherein the ground engaging portion is provided with an external screw thread to be screwed into said surface ice.

19. A method substantially as herein described, with reference to the accompanying drawings.

20. An ice preservation system substantially as herein described, with reference to the accompanying drawings.