US1928473A - Art of forming protective beaches - Google Patents

Description

sept. 26, 1933. s M' WOQD ART OF FORMING PROTECTIVE BEACHES Filed Aug. 20. 1932 awnings ai Hwa A Bbw@ INVENTOR.

ATTORNEY.

' Patented Sept. 26, `1933 a `Arlt/ll? OFFORIVHNG PROTECTIVEBEACHES Sydney M. Wood, Lake Blu, Ill.

Application August 20, 1932. Serial No. Y629,565

y 6 claims.

l*This inventionrelates to improvements in the art, of forming protective beaches.

The problem of` protecting lake front property is one which haspresented innumerable difl` culties On the shores of the Great Lakes, landslideszhaveoccurred from time to time causing the destruction of thousands of dollars worth of property. The majork cause of these landslides, in ^mostV sections, Vis the accumulation of seepage Vl0 water underneath the ground. This seepage Wa- There is, however, another important factor which contributes with `the seepage water in causing a Vreceding shore line, and that is the erosive action" of thek lakes forces.. Necessarily,

Nthis erosive action is most damaging during a` lperiodwhe'n-'the` lake level ishigh, and in view of the-fact-that statistics showl. that high levels occ'ur in regular cycles, there is always a period ofA transition between alow level" and a high level during which most property owners are in- `-adequately. protected. f

Heretofore, it has been attempted to check this erosive action by building retaining walls which parallellthe, edge' of the hillside. There is, however, no wall strong enough to permanently withstand the action of .the lakes forces, and this type ofv protection'is .therefore eiiicacious for a short tim'ebnly; 'A long, gradually sloping beach well supplied withsandand gravel, is the best pro-y tection against ero'sive action, as it has the ability .'Oto rob 1a" storm of its destructive power, Vand it is'toy the formation of a'beach iofithis type that.

is blowing" at an oblique angle'toitheshore, and MWhen-.thisV is the case the Sand vandlother par-L to travel along the shore line.

water itself, Vand the two movements set up by the n ticles held in suspension in the`.water are caused With this fact in mind, it may be seen that the particles'can be accumulated by the construction of an ob-` stacle across their path, that is, by the construction of a jetty or groin extending into the lake at right angles to the bank. The formation of a suitable type of protective beach by .this method, however, cannot be accomplished with the ordinary type of groin, as it is found that Awhiledeposits may form on. the storm side of the jetty, they will tend to concentrate to provide a relatively steep slope adjacentthev jettyy on this side, f and on the lee side objectionable scouring will take place. It is also `found that with most types of jetties, scouring Will take place at the outer end of the jetty due to the accelerated velocity ofthe littoral currents around said end. It is, therefore, one of the objects of the present inventionto provide an improved method of` forming protectivebeaches which results in the formation of a long, gradually slopingbeach on both sidesof the jetty, and in the elimination of scouring action at the outer end'.y

A further object of the invention is to provide an improved jetty'for effecting commercial eX- ploitation of the above method `Other objects of the invention are to provide a jetty which greatly accelerates the deposit of beach building material, which nulliiies the Wave action and reducesthe energy of littoral currents, and which causesl the deposit of a greater per` centage of fine sand. A further object of the invention is to provide a jetty adapted to produce a beach which is advantageous, not only in that it protects the shore so f.'

line,` but also in that itv renders the shore unusu-j ally suitable forbathing purposes. f With the above and other objects in View, the invention consists of the art of forming protective beaches, and all its parts and combinations as set forth in the claims, and all equivalents thereof."

In theaccompanying drawing yillustrating one complete embodiment of the preferred form of the invention, in which the same reference numerals designate the same parts in .all of the views:

Fig. 1 is aside elevational View of the improved jetty; Y n Fig. 2is an enlarged cross sectional View taken,v on linea- 2 oficial; 1 u Fig. 3 is an enlarged cross sectional View taken on line 3-3' of Fig. 1;.and i r v f Fig; 4 is a plan view on a reduced scale of a lake shore showing a plurality of parallel jetties installed.

Referring more particularly to the drawing, the numeral 5 designates a hillside leading down to a 5 beach bordering a lake. In cases where there is an articial barrier such as a retaining wall paralleling a hillside, the jetty will be laid in the same relation with respect thereto as it is with respect to the hillside 5. The numeral 6 designates the sand beach,.and the numeral 7 the water level of the lake. I

With the present invention, in order to obstruct the littoral currents to cause the deposit of particles of sand in proper formation to provide a long, gradually sloping beach, one or more jetties must be extended from the hillside or wall 5 outwardly into the lake at approximately right angles to the hillside. permeability is unimportant on the portion of the beach close to the hillside which is not reached by the water of the lake, it is preferred to construct the rstsection ofthe jetty of concrete or other impermeable materiaLas at 7'. At the outer end 8 of the section '7 theeconstruction is continued `^A by the use of a rockll. These rocks are preferably approximately rectangular in shape and are preferably laid in the manner indicated by cross section in Fig. 2 to provide a jetty with sloping sides 9. Z'I'he rocks are also so laid that there is a permeability in the wall of approximately per cent produced by spaces 10 formed between adjacent corners of the rocks. In the portion of the wall adjacent the section line 2-2 of Fig. 1, the `rocks are preferably laid with a certain degree of f regularity in the manner shown in Fig. 2. As the jetty extends outwardly intoA thelake, however, it is very advantageous to increase the permeability, and this feature is one of extreme importance in A the present invention. This increase in permea- 5 bility is accomplished; by laying the rocks in less regular formation, as the jetty extends outwardly as indicated in Fig. 3, wherein it may be seen that Ythe rocks are less regular in form and are laidin a more haphazard manner to provide larger spaces 11 between ythe individual rocks for the purpose of increasing the permeability.

aIt may be seen that the major portion of the length of the jetty projects above'the water' line. At the outer end, however, it is desirable to have a partial submergenoe below the water level, as indicated at 12. This is for the purpose of allowing the shore currents to pass at reduced speeds through and over the submerged ends, and to cause the retardation of currents passing inward or outward along the sides to prevent scouring at the end and along the'sides.

It is found that the character of the beach may be still Vfurther improved by laying a plurality of jetties of the type described in connection with spaced apart a substantial distance, as indicated in Fig. ,4, wherein the jetties are designated generally by the numeral 13.

Where a solid or impermeable jetty has been used, the littoral currents carryingthe sand and otherne particles in suspension are obstructed by the sides of thev jetty, but the velocity of the currentsis accelerated. to Cause a rather abrupt turning of the'ow of 'the littoral currents'from a direction parallel to the shore line to a direction parallel to the sides of the jetty, the currents therefore flowing around the end of the jetty with accelerated velocity.l When the littoral currents strike the sides of an impermeable jetty, there is likely`tc befa momentary andV rather yabrupt In view of the fact that Fig. 1, in parallelrelationito one another andv change in the direction of travel of the currents which causes a deposit in a rather abrupt manner close to the Windward side of the jetty, and inas-I much as this deposit will be concentrated adjacent the jetty, any beach developed will have an abrupt slope and will not be desirable. Furthermore, due to the accelerated velocity of the littoral currents as they move around the end of the impermeable jetty, the ne sands are carried with the current, and the majority of the iill adjacent the jetty will be of a coarser material. In addition, the action of the currents around the end of an impermeable' jetty wherein the velocity is greatly accelerated, will cause a marked scouring to take place at the outer end of the jetty, and thereby develop a deep water spot objectionable for bathing purposes. Y

With the present invention, it is to be noted that the majorportion of the length of the jetty is permeable, and as a result, while the littoral currents are obstructed in a manner to cause the deposit of sandand other material held in suspension, nevertheless, due to the permeable nature of theiwall, the water can flow through the spaces 10 and 11 so that there is not vthe tendency for the currents to move in a direction parallel to the jetty and travel around the outer end with accelerated velocity such as is the case with the jetty of the impermeable type. Thus scouring at the outer end is eliminated. Furthermore, due to the fact that the currents are slowed down in a uniform manner by the permeable jetty and can trickle through, an even deposit of iine material is encouraged on both sides of the jetty, and this deposit will gradually build up, not only directly 11G adjacent the sides, but for a substantial 'distance laterally therefrom to cause the formation of a long, gradually sloping beach composed of iine particles of sand. With the impermeable type of jetty, the littoral currents which rush around the 115 outer end and there cause scouring and which then move inwardly toward the shore on the other side of the jetty, will cause a scouring on the lee side.

with the permeable type of jetty wherein the 120 permeability gradually increases from the inner end tothe outer end, and wherein the outer end is. also partially submerged, the passing of the water through the jetty is increasingly encour aged toward the outer end to;eliminate 'causing movement of the currents around the end4 of the jetty with accelerated velocity and thereby eliminate. the objectionable scouring at the outer end and on the lee side.

By referring te Fig. 4, it will be seenrhat with 130 applicants type of jetty 13, that when the wind is traveling in an voblique direction toward the shore, asindicated by the arrow A, that the littoral currents indicated by the arrows B will ow somewhat in the manner indicated, that is, approximately parallelto the shore. Asesaid currents strike the permeable jetty, insteady of changing direction and traveling at right angles to the sides ofV the` jetty and around the outer end at accelerated velocity, they will pass through the 1m permeable jetty and there will only be a slight.v tendency to direct thecurrents outwardly.` The currents will then continue as indicated, passing approximately vparallel to the shore between each pairofl jetties and through the next successive M5 jetty. The result will be a gradual slowing down of the Alittoralcurrents to cause a gradual deposit. of sandfandthe formation of an everwiden'ing beach composed of une material, as indicated byV the numerall wherein the `'angle of the beach is relatively fiat, and wherein the tendency for the beach to concentrate directly adjacent the of the jetty,v is minimized.

It will further be seen thatwith the present invention, the area of newland formed will be much greater per foot of jetty than would occur with an ordinary type of construction, and rthat the sloped sides of the jetty shown in the cross sections tends to nullify wave action and to reduce the energy of thelittoral currents.

Although only one form ofthe invention has been shownand described, it is to be understood that various changes and modications may be made, and that all of such changes are contemplated as may come within the scope of the claims.

What I claim is:

1. A jetty comprising an elongated wall of yrock extending outwardly at an angle to the shore, said rock being laid in relatively loose formation to render the jetty permeable.

2. A jetty comprising an elongated wall of rock extending outwardly at an angle tothe shore, said rock being so laid as to render the jetty increasingly permeable outwardly.

3. A jetty comprising an elongated wall of rock extending outwardly at an angle to the shore, said rock being laid to provide sloping sides and in sides relatively loose yformation to render the jetty permeable.

4. A jetty for use on a lake shore bordered byy a hillside or the like, comprising an elongated wall extending from adjacent said hillside outwardly into the water'a substantial distance at an angle to said hillside, the portion of said wall extending into the water being formed of rock laid in relatively loose iormation to render the wall permeable.

5. A jetty for use on a lake shore borderedby a hillside or the like, comprising an elongated wall extending from adjacent said hillside outwardly into the water a substantial distance at anV

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