Note: Descriptions are shown in the official language in which they were submitted.
W O 92/06249 PCT/SE9l/00669
2~93323
A METHOD TO PREVENT EROSION OR INJURIOUS INFLUENCE OF EROSION AND AN
ARRANGEMENT FOR CARRYI~G OUT THE METHOD
This inv~ntion relates to a method to prevent erosion or injurious inf~
ence of erosion in areas between land and water, such as in shore areas,
and caused of for example a sea. The invention also relates in applicable
cases to produce an enlargement of land or shore.
s
As is well known erosion causes in many places devastation of land within
defined or more spread areas, why it exists a need of being able to prevent
erosion or injurious influence of erosion in such areas which are exposed
for erosion and where no natural means can be brought to prevent erosion
or its injurious influence on the surface of the ground. Thus, within cer-
tain areas erosion, its spreading or injurious influence on the surface of
the ground can be prevented by supplying a protective covering of vegetat-
ion or another plantation binding the surface of the ground, as in deflat-
ion. In other places it is more difficult or almost impossible to prevent
damage or ruin caused by erosion, as in so-called abrasion or in for examp-
'e unsheltered seashores or other shore areas. On at least such areas asbeaches having a surface layer of sand deflation will probably also often
have an injurious effect. Besides to be able to prevent and stop spreading
of erosion there is a need to be able to recreate eroded areas and if poss-
ible an enlargement of land. At this it would be an advantage if such stéps
could be taken without the need of making cuts in the surface of the ground
and also in other places, such as when filling materials must be picked out,
etc. It would be a considerable improvement if rebuilding of land and in
applicable cases an enlargement of land could be done with the same or at
least some of the means causing erosion in a cer~ain area, as at shore
~5 areas or on coast areas. Perhaps, it should also be mentioned the need of
preventing fluvial erosion and in that~ respect principally a washing of -
slopes and descents and m the ground contained water.
In attempts to prevent or at least mitigate the injurious effect of erosion
on shore and coast areas one has built moles or similar and often of stones
which have been placed on the bed seawards. In recen~ times there have been
made attempts with gabions or wire hampers of steel which have been filled
with stones and also cloth bags filled with sand which have been placed on
the bed. Ccmmonly for these methods are that there are loadings on the
bottom, whereby one yet gets erosion. Thus, the bottom is going to be
, -
WO 92/n6249 PCT/S~91/0066~9
`2093323 2
hollowed out by scouring where such shore protections are arranged, whereby
they are going to sink. Other methods to effect shore protections have con-
sist of mattresses filled with concrete, which have been placed on beach
slopes and also to place stones of diffe~ent dimensions along a beach and
sometimes also in the beach-line, which methods are intended for making a
barrier to waves and give resistance to waves. When using the latter method
an erosion will gradually occur behind the stone protection by the fact
that the waves force air through the slots in the stone protection, which
air in turn makes a pressing action on the ground surface and erosion
occurs, for example by the fact that sand are forced away. It has also been
proposed to join concrete tiles to larger units, which are placed in the
water. However, it has been shown that known methods does not have been
able to prevent erosion or till now have shown that erosion certainly can
be prevented.
The object with the method in accordance with the invention is to effect
a method preventing erosion or injurious influence of erosion in areas
where land and water are met, as in shore or coast areas. According to an
embodiment of the method in accordance with the invention, the object is
2Q not only to prevent or stop erosion but instead to produce an addition
of land or shore. mus, one should when using the method in accordance
with the invention be able to fulfil the requirements made, whereby the
disadvantages of the known methods are elimlnated. Furthermore, a method
in accordance with the inventic,n can be produced without visual interfer-
ence on nature. Used devices when enlarging land can, without any negativeeffects on the environment, be allowed to be buried in the newly created
ground and will thus become totally invisible and inaccessible. The method
in accordance with the invention is characterized in that in connection or
relatively close connection with la~d, as a distance from the shoreline or
shorestrip and in the water, guiding devices are arranged to extend frcm
; the bottom or its surface and in the direction of the surface of water and
in applicable cases holde~ elements æe arranged into or on the ground in
the water and/or on land.
According to an embodiment of the method in accordance with the invention
the guiding devices are arranged in such a way that their weight or load
does not load or principally load the bottom or its surface.
..
WO ~2/06249 P~r/SE91/~0669
3 2~3323
In another embodiment of the method in accordance with the invention one
end of the guiding devices is arranged at a distance from the shoreline,
whereby holder elements are arranged between the guiding devices and the
shv 21in2 or to the area for the shoreline. The task Or the hoider ei~llents
are to catch particles or sand in the water and keep the particles or the
sand and in applicable cases to drain or facilitate drainage of ground.
According to still another embodiment of the method in accordance with the
invention two guiding devices are arranged at a distance from each other
along a shore area influenced by erosion, whereby the guiding devices are
arranged for co-operation with each other and in applicable cases, when the
affected shore area is of some length, one or more units of guiding devices
are arranged at a distance from the first mentioned unit of guiding devices,
whereby the guiding devices' relative angle, i.e. directions towards land,
in respective unit of guiding devices can vary or be different dependiny on
local conditions.
In an additional embodiment of the method in accordance with the invention
measurings are carried out of certain parameters, registration of the mea-
surement results and evaluation before that the guiding devices and inapplicable cases also the holder elements are arranged or put in position,
whereby the direction or extension of the guiding devices is settled with
regard to the measurings made, etc.
Further characteristics of and advantages with the method and the arrange-
ment in accordance with the invention will in the following description of
the invention be apparent by an embcdiment example, whereby reference will
partially be made to the accompanying schematic drawings, of which Fig. 1
shows from above schematically an example of an arrangement to effect a
method according to the invention, Fig. 2 shows in cross-section an example
of a device in forrn of a guiding device, Fig. 3 shows frorn above part of a
guiding device, Fig. 4 shows frcm above an additional e~ample of a method
and an arrangernent according to the invention, Fig. 5 shows Prorn above a
method according to the invention and adopted in an arrangement or a part
of an arranger~ent according to the invention, Fig. 6 shows in section a
part of an arrangement, Fig. 7 shows in a perspective view a holder element
in the course of joining to another holder elen~nt and which holder ele-
m~nts can be included in a method and be part of an arrangement according
to the invention, Fig. 8 shows fr~n above a number of individual holder
WO 92/0624g P(:~l/S~ 0661,~
~'~)9~323 ~
elements according to Fig. 7 and arranged into a unit of holder elements
and Fig. 9 shows frcm above an arrangement according to the invention and
used in a test.
In previous arranging of shore protection one has often placed some kind of
obstacle in the water, as a mole of stone, whereby its direction has been
decided upon visual impressions or supposed conditions. In more elaborated
studies one has made geotechnical measurements in the water 50 metres from
the shoreline and on land also 50 metres from the shoreline but never in
the strip bordering the body of water, i.e. in the real area where erosion
is in progress or perhaps has the strongest influence. Further, one has
totally avoided studying the phenomena taking place under the surface of
water and down to the bed.
In the method in accordance with the invention one uses guides in the water
2 in form of guiding devices 4 and in applicable cases holder elements 5,
which also can be used on land l and in the shoreline 3, see for example
Fig. 1.
~ method in accordance with the invention can start with measurements of
certain parameters, as currents in the water and in that respect not only
surface currents but also bottom currents and sand movements on or near the
bottom. Further, measurements of wave motions and that consideration can
be taken to latitude with other centrifugal forces, ebb and flood, tempera-
ture, atmospheric pressure and specific weights, the slope of the bottom,depth of water, etc. The most im~ortant groups of calculation are the
direction and force of sand and water and the earth-layer along the shore.
The said measurements are carried out at depression and high pressure.
After that registration of the measurement tests and evaluation of these
æe done, which give a basis for the arrangement of guides 4 and holder
elements 5, if any and in that respect patience, strength or resistance of
the devices used, size and directions for preventing or stop erosion. Place
of reference can at this be the direction of shore and the direction from
l~nd and towards the water. If an enlargement of the shore is desired it ~ -
can also be attained by calculations based upcn the measurement results.
Thus, the direction and dimension of the guides 4 are accurately settled
by such preparations and examinations for just that place in question.
Geotechnical measurements give a basis for subsoil and surface water on
land and by that it can be calculated necessary protection to prevent
W O 92tOfi249 PCT/SE91/0066g
2~93323
erosion from land 1. Measurements in water 2 give basis for control of
sand movements and reduction of the influence of water force motions on
the shore or shoreline 3. In other words measuring and evaluation of sur-
face currents, bottom currents and sand movements and in applicable cases
wave motions are necessary to bring about effects instead of only study
motions of the water from above the surface of the water plus any geotech-
nical measurements far from the shore 3 or shoreline. Thus, it is estab-
lished any drainage and stabilization of ground towards land 1, directions
of guiding devices 4 in the form of protective guide elements and their
dimensions and beach locks in the form of the said holder elements 5 and
their dimensions and possible directions.
Through other or further parameters, as movements of air masses, densities,
i.e. the salinity of the water, etc., a fine adjustment can be realized of
said directions and classification of the power, whereby an improved effect
is attained to keep the beach or sand and collection of sand for addition
of the beach.
The rotation of the earth has a certain influence but above all the cori-
olis power has such an influence that one must take that fact into consid-
~` eration when using the method and the arrangement in accordance with the
invention. Thus, on the northern hemisphere the sand in the waves, for
example, are transported to the right or anti-clockwise. It is on the
contrary on the southern hemisphere. Sand removal or sand movements in the
water or along the bed are one and the same on a certain place and are done
without any influence of water currents and waves and happen also in calm
weather. Sand transfer is also done by the influence of low pressure and
high pressure and pressure differences into and at wave motions. Certain
sand transfer is also done at low pressure because of intensity. Further,
the movements or the bottom currents are fluctuating dependent on low
pressure and high pressure and different or contrary at low pressure and
high pressure respectively. Wind affects the height of waves but not or
only to some extent the direction of waves, i.e. surface currents. Certain
effect or erosion is obtained owing to the force of impact. However, it is
particles and means in the water giving the real erosion. High salt content
gives increased erosion.
The reference designation 1 in Figs. 1, 4, S and 9 shows land and the refe-
rence designation 2 in Figs. 2 and 6, as well, water, whereby the shore or
W ~ 92t0624~ PCT/S~gl/~669
2~93323 6
the shoreline between land 1 and water 2 is shown by the reference design-
ation 3. In order to stop or prevent erosion or injurious influence of
erosion in an area, as on beaches, and in applicable cases to produce an
enlarg~ment o~ iand l or shore 3, guiding devices 4 are arranged in the
water 2 in that area and in the form of guides in connection or relativelv
close connection with land 1, as a distance from the shoreline 3 or strip
of shore and in that respect principally two by two and in areas of some
length more guiding devices 4 or at a distance from one another units of
guiding devices 4 in pairs. In applicable cases there are also arranged
holder elements 5 into or on the bed or bottcm 12 and in the water 2 and/
or on land 1, as between the ends 6 of the guiding devices 4 directed to-
wards the shore or shoreline 3 and the shore or shoreline 3, between the
guiding devices 4 in the shoreline 3 and in applicable cases on land 1,
for example, in banks, in the water 2 on shallow water and perhaps between
or in connection with sandbanks, etc.
The holder elements S can be in form of individual elements 20, which are
arranged to be able to be joined together or the like to form an unit of
holder elements 5, see Figs. 1, 7 and 8 and the arrow 21 in Fig. 7. As is
evident from said figures, the holder elements 5 show rectangular shape and
can be made as a plastic construction consisting of a central rectangle
surrounded by several or e.g. ten equal squares. Further, the individual
elements 20 show drain channels 22 within the walls 23 allowing drainage
; in four directions. When elements 20 are linked together the drain channels
are automatically aligned allowing unimpended flow. The units are easily
laid and linked without the aid of tools and can be anchored by means of
anchoring devices 7 or cables. Flrther, the material can be made of a chem-
ically inert and harmless material when in contact with foc~, vegetables,
etc. and allowing trees and vegetation to follow their normal growing
cycle. It is not essential to have level foundation as the element 20 can
be flexible and allows it to settle according to the ground contour. Thus,
the elements 5 involve also to construct steeper slopes thus saving on land
utilization and avoiding the need to level out. The elements 20 can either
be linked side by side or corner to corner.
With further reference to Fig. 2 it is shown a guiding device 4 comprising
guiding elements 16 in form of a wall, ~nbankmPnt or another guiding ele-
mrnt. The guiding device 4 is meant for being arranged on the bottcm 12 and
follow the bed without loading or essentially loading the bottcm 12 or the
WO 92/0624~ P~/SE93 ~0~669
7 ~332~
surface 14 of the bottom with its load and extend from the bottc~ 12 or its
surface 14 and in the direction towards the surface 15 of the water.
.
The guiding devices 4 or the guiding element 16 can be formed of for examp-
le a Nylon mattress, which is filled with a fine concrete mixture and is
then formable until the concrete stiffen. Such a shaping of the guiding
devices 4 lead to tight and durable guiding devices, which can resist
pressure. The guiding devices 4 can be adapted in dimensions according to
the local circumstances. Further, the guiding devices 4 are meant for being
anchored into the ground or bottom 12. As is evident from Fig. 3 the guid-
ing devices 4 or the mattress are shaped or being shaped with an edge port-
ion 17, which is folded in order to connect with the bed or bottom 12. That
edging 17 can be utilized for the anchoring of the guiding device 4 or the
guiding element 16 or wall or the guiding elements or walls comprised by
the guiding device. At this one uses the anchoring devices 7, which show a
proportionately small cross-section in at least that part breaking through
the surface 14 or the surface layer of the bottom 12 and preferably with
engagement devices 19 loading the load of the guiding devices 4 a distance
below the surface 14 or surface layer of the bottcm 12. The anchoring
devices 7 are thus arranged besides to anchor the guiding devices 4 and the
guiding elements 16 to transfer the load of the guiding devices and the
; guiding elements a distance below the surface of the bottom and can by this
show engagement devices, which are arranged to be able to engage the bottom
a distance below the surface of the bottom.
` 25
According to the embo iment exanples shown the guiding devices 4 show a
crGss-section mainly of a V or U turned upside down, whereby one or both
legs form such a said wall 16 or similar. The arr~ngement comprises sup-
ports 8 for the support and bearing of the guiding device 4, whereby the
guiding device 4 rests against the upper part of the support by the fact
that the guiding device lie against the support 8 in the angle between the
legs of the gulding device or the area for the connection of the legs with
each other and the support is anchored preferably by means of such a said
anchoring device 7, which transfer the load of the guiding device 4, the
support 8, etc. to a distance below the surface 14 or surface layer of the
bottc~ 12.
.:
The support 8 comprises besides an anchoring device 7 a carrier 3, for
example in form of a tube and a spacer 10, which according to the embodi-
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W ~ ~2/~624'J PCT/S~93/~0~
ment example extends between the carrier 9 and the anchoring device or to
the surface 14 of the bottcm 12. The support 8 can be shaped in such a way
that the anchoring device 7 forms an extension of the support 8 or the
spacer 10.
The guidm g devices 4 will be totally concealed in the water 2, i.e. will
not or does not need to be visible, as they only will extend fifty centi-
metres fm m the surface 14 of bed. According to one embodiment the guid-
ing devices 4 reach to just under the surface 15 of the water and by that
stop all movements in the water 2, which in turn i.a. give less or elimin-
ate the force of impact of waves against the shore and spread the force
exposed to the coast of especially the pressure of the sand. Foremost shall
the guiding devices 4 or the guiding elements 16 guide bottom currents 11
and break wa~-es 18, see Fig. 6. Thus, one can with the guiding devices 4 or
the guiding elements 16 guide sand movements and the sand transfer and get
the sand directed towards the shore 3 for addition 25 of land and shore,
i.e. one captures and dixects the sand towards the shore and addition is
done. The use of beach locks or holder elements 5 create a more rapid addi-
tion, as they capture, keep and stabilize the ground so that the sand have
time to settle and in applicable cases drain the surface water and subsoil
water, which is lead off to the water 2. The holder elements 5 or the indi-
vidual elements 20 are shaped in such a way that they does not stem the
water but the water shall be able to pass, why holder elements 5 or indi-
vidual elements 20 are arranged between the guiding devices 4 or the end 6
2S of them and shore 3 or shoreline, see the arrows 24 in Fig. 5.
The relationship between sand transfer and bottom currents in water and
surface currents in water relate to movements in water at high and low
pressure at the place in question. With refexence to Fig. 9 the movements
at high and low pressure are shcwn by the arrow~ 26 and 27 respectively.
Sand is added when currents in the water 2 are influenced by high pressure,
as it i5 forced towards land 1. Sand is torn off the shore 3 by the cur-
rents at low pressure. In change of currents can, for example, refilling
25 of sand decrease or deteriorate. Thus, according to the method in accor-
dance with the invention one takes up the sand currents 11 and the bottomcurrents by guiding devices 4 and direct the currents towards land 1 for
addition 25 of shore. At reverse pressure (low pressure) the sand is caught
so it does not is swept into the water 2.
WO g2/06249 PC~/SE91/OU66g
2~9332~
The erGsion system can thus be based on the factors:
a) No load on bottom/bed.
b) The protective guidings are underneath the surface of water in order to
~irect sand and bottom currents.
c) The protective guidings are in a direction from the shore so that the
waves are broken in the middle of a trough of a wave or so when normal
; water level and normal waves exist, approximately 0,5 to 1 metre in
height.
d) The beach locks are attached in the direction from the protective guid-
ings and towards the shore and between the guidings perpendicularly to
the shore~
e) The beach lock is applied to the shoreline with excavation and is filled
up.
In tests one installation was arranged, as shown in Fig. 9, whereby the
result was amazing with an immediate stop for continued erosion and with
rapid addition of shore. At this guiding devices 4 were arranged in the
shown manner as shown in the installation and at shown angles and distances
according to the local conditions which was ruled.
~ 20
`~ Alon~ a shore line it is arranged at least two guiding devices 4 at a dis-
tance from one another, whereby two adjacent guiding devices are arranged
i for an united action with each other, of which one guiding device isarranged at an angle preferably below 90 to land or shoreline and the
other guiding device is arranged at an angle preferably exceeding 90 to
land or shoreline, i.e~ at an angle below 90 but seen from land in a
divergent direction to the first mentioned guiding device. Along one of
erosion influenc0d shore area two guiding devices 4 are arranged at a
distance from each other for co-operation with each other and in applic-
able cases, when the affected shore area is of some length, one or moreunits of guiding devices 4 are arranged at a distance from the first
mentioned unit of guiding devices, whereby the relative angle of the guid-
m g devices, i.e. directions towards land, m respective unit of guiding
devices can vary or be different depending on local conditions.
Without exceeding the scope of the concept of the invention, modifications
of the methcd and the arrangement in accordance with the invention should
be possible. Thus, the guiding devices can be of another construction and
shape, the directions a~d the number of guiding devices can vary, as well
,
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W O g2/06249 P~T/S~1/0~66~
2~93323 lo
as the location and the number of holder elements. Materials and shape of
guiding devices and holder elements can be another. The anchoring devices
can also be of another type or shaping but should fulfil the dem~nds of a
small cr~ss-section in the area of the ground, bed or in the bredk~y
through of the surface or surface layer of the ground or bed and transfer-
ring of the load from the arrangement and/or the protective guidings to a
distance below the surface of the gr~und or bed. The method and the arran-
gement are also applicable for the intended purpose or purposes in other
areas between land and water than the exemplified, as in lakes, streams,
rivers. Further, the method and the arrangement are applicable in the
cases where foremost erosion or injurious influence of erosion shall be
prevented or be stopped, whereby perhaps foremost guiding devices are
utilized, while the holder elements in applicable cases are formost utili-
zed for anchoring the shoreline or banks. The method and the arrangement
in accordance with the invention are thus not restricted to what has been
shown and described in the embodiment examples, but soley by the following
claims.
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