GB2352751A

GB2352751A - Means to prevent cliff erosion

Info

Publication number: GB2352751A
Application number: GB9918110A
Authority: GB
Inventors: Graham Howard Chaplin
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-08-03
Filing date: 1999-08-03
Publication date: 2001-02-07
Anticipated expiration: 2019-08-03
Also published as: GB2352751B; GB9918110D0

Abstract

A means for preventing or arresting soil erosion on a sloping surface comprising a nylon net (a) having attached, by short ropes (c), a plurality of flexible narrow gauge mesh tiles which are allowed to overlap at a bottom edge and where the net is secured to the ground by means of retaining rods (d). Where the slope is bounded by the sea an additional means of erosion prevention may be utilised comprising stacking tyres onto a pole and arranging at least one stack on top of the net at the base of the slope, when the stacks are in place they may be filled with earth or other suitable material.

Description

2352751 THE SYSTEM FOR THE ARRESTMENT, STABILISA TION, AND NA TURAL

REINSTA TEMENT OF SOFT CLIFF EROSION

1. DETAILED DESCRIPTION - Page 112

2. The System for the arrestinerit, stabilisation, and natural reinstatement, of soft cliff erosion has been developed to combat the increasingly rapid destruction of areas of soft coast line, and associated habitats, by the elements - wind, rain, waves etc.

3. The essentially unique feature of the system is its' inbuilt and natural reinstatement of cliff formations and habitats. This is achieved via the use of the flexible net tile, which sets it aside entirely from other systems or methods of coastal defence, which only protect, defend or maintain the existing state, with reinstatement necessarily being an additional exercise, requiring a distinctly separate methodology. In short the system addresses these two problems at once.

4. A detailed description of the working of the system now follows, preceded by a very simple overview of the causes and effects of the erosion which it seeks to address.

5. Erosion and soft cliff destruction is largely brought about by certain natural forces working in unison. 6. These are wind, rain, frost, and the action of the sea.

7. Wind simply blows, whilst rain washes, loose earth or other surface material into the sea. Frost freezes rain, or other water, trapped in vertical fissures, causing expansion and yet more serious cracking. The action of the sea undercuts the base of cliffs and, in combination with the vertical cracking, causing whole 'slices' of cliff face to collapse onto the shore and to be washed away by the sea.

8. The system about to be described will be seen to tackle all of the foregoing and ftirther to provide a process of natural reinstatement of effected environments.

9. The foundation of the system is the base net, Fig I a, formulated from l2nim diameter nylon rope, in 200nu-n squares, which acts as the main support for the flexible nylon tiles, Fig 2b, which are fixed to the horizontal ropes of the net. These tiles are made of 6mm nylon mesh, 200mm. wide, 275mm long, with each overlapping the next beneath by 75mm. The effect is thus similar to that of a roofing tile, shedding the heaviest, most damaging, rain but allowing a steady trickle to feed through the mesh. The most damaging effects of the wind are likewise deflected and the results are twofold. Most obviously erosion, from these sources, is drastically mitigated, if not prevented. Simultaneously a damp, warm, wind free environment is created beneat the net and tiles, which greatly encourages and protects the growth of new vegetation. CONTINUED..........

......... CONTINUED DETAILED DESCRIPTION - Page 212

The base net is secured to the top level surface of the cliff, and at intervals down the cliff face, by steel rods of suitable length of 16m diameter. This has the effect of retaining the soil etc., and the existing angle of repose, in the absolute short term.

Vegetation growth will be established beneath and through the base net. This will push upwards against the flexible tiles, protruding through the sides and lower edges, and forming a natural 'cup' in each tile. This cup, in turn, will trap air born dust and moisture slowly reinstating the soft cliff surface on top of both the base net and the flexible tiles.

Short hessian based ropes, Fig.2C, 75nim long, will be used to secure the tiles and prevent flapping until the vegetation has taken hold. In due course, however, these will rot allowing further growth of plant life. Additionally, grasses etc. will penetrate through the tile itself, as growth becomes more established, causing a matrix to form, and creating a natural barrier against erosion, Fig. 4e.

To secure the base of the cliff against the backwash action of the sea, stacks of old tyres, Fig. 5f, 1500mm high, are to be arranged in ranks. These stacks are to be secured by 50mm diameter galvanized steel poles, Figs. 56g and 6g, driven through the base net, laid out along the foot of the cliff. The poles, viewed in plan, form a square, over which the tyres are placed and secured with a top locking bar, Fig. 5h.

The tyres are to be filled with suitable fibrous earth and rocks, mixed with the seeds of suitable grasses etc.. The main net and tiles are then pulled back covering the ranks of tyres. As backwash from the sea removes the sub base from beneath the tyre stacks, the tyres will slide down the galvanized poles, protecting the cliff base against further erosion. Once the gasses etc. become established tiles, net and tyres will all be completely hidden from view by the same interaction of vegetation and surface reinstatement, as was previously explained, being both protective and aesthetically pleasing.

3

Claims

SCHEDULE OF CLAIMS a) The essentially unique feature of the system is its'

inbuilt and natural reinstatement of cliff formations and habitats. This is achieved via the use of the flexible net tile, which sets it aside entirely from other systems or methods of coastal defence, which only protect, defend or maintain the existing state, with reinstatement necessarily being an additional exercise, requiring a distinctly separate methodology. In short the system addresses these two problems at once.

b) As will be very much self evident, from the details given of the materials and methods employed, the system is of extremely low cost by comparison to more conventional alternatives. There is, thus, the obvious advantage of cost saving. It is, however, the designers belief and that prohibitive cost alone has probably been the sole reason why so much coastal erosion has been allowed to continue unchecked for so long. The reasoning follows that a drastic reduction in cost should lead to the problem actually being addressed on the widest of scales.

c) The system is environmentally sound employing bio degradable and non degradable materials judiciously and offering the opportunity to dispose usefully of non degradable waste (old tyres).

d) The system will aver-t the loss, or cause to be saved or reinstated wildlife, both flora and fauna, together with their, and other, natural habitats contributing to bio diversity.

e) Heritage sites or those of other interest, likewise threatened, can be saved.