Imágenes de páginas

On the east side of the pier there is a sea-wall and promenade, at the foot of which is a bank of small shingle, the average size being about an inch, which in calm weather reaches within 3 feet of the top of the wall. Seaward of this is firm dry sand.

Groynes are placed at right angles to the wall 60 to 70 yards a part. They consist of fir piles with 2-inch planking, and are 90 to 100 yards in length. There is about one plank above the beach where it is sand, but more where the shingle is.

The British Association Report of 1885 states, with regard to this part of the coast, that groynes had been erected since the middle of the present century of various heights and sizes, and placed at irregular distances apart, in some places three or four being crowded together, while other parts were devoid of any protection; and there the sea was encroaching, the greatest erosion being where there were no groynes or insufficient ones. Erosions of the shore of limited size were also observed to the eastward of large groynes, and also to the eastward of spots where three or four groynes were crowded together, such erosions being noticed as hollows in the shore, and large notches in the land, while shingle was largely piled up on the west side of the groynes. Erosions had always been noticed to be at a minimum, or altogether arrested where groynes of moderate height and length and in good repair stood, say, at 30 to 100 yards apart.

Worthing.–The shore at Worthing has been protected by groynes for upwards of fifty years. About twenty-seven years ago a number of low timber groynes were constructed, and others added more recently. These consist of 21-inch planking fastened to 9-inch fir piles, spaced 5 feet apart, and driven into the beach, having 7-inch walings bolted to them, and supported by 9-inch struts, which are bolted to short piles driven into the beach. The groynes are spaced at distances varying from 40 to 160 yards apart, the top being originally from 3 to 4 feet above the beach. They were placed in a south-easterly direction, at an angle of from 110 to 120 degrees from the shore-line. At the upper part of the beach, on the west side of the pier, for a width of about 60 feet, the shingle has accumulated nearly to the top of the sea-wall, and many of the old groynes are buried. The shingle tails down nearly to the end of the groynes, the lower end being 18 feet lower than at the sea-wall. The shingle varies from 2 to 5 feet higher on the west than on the east side of the groyne.

At the time these groynes were put down the beach had become quite bare of shingle, and the land was being destroyed by the action of the waves. Since their construction a fine beach has accumulated all along this part of the coast, which affords adequate protection to the sea-wall and road.

Although these groynes have answered the purpose for which they were intended—in raising the beach near the sea-wall—they were not carried far enough down towards low water. As the beach between half tide and low water is very low and flat, the inclination being at the rate of 1 in 300, the water is unable to drain off quickly; the sand is seldom hard and dry, and seaweed collects in the lows in great quantities.

The late Mr. Case, who made an inspection of the shore with the view of improving it by means of his system of groyning, reported that between mean high and low water it was the worst beach he had ever seen, and was of opinion that with proper groyning it might be made sound and good. He proposed the extension of the groynes for 130 yards to low water, making a total length of 200 yards. If this were done, he was of opinion that the inclination would be increased to 1 in 50, and the low part of the sands raised 5 feet. A limited number of these groynes were put in, but the system was never given a fair trial, objection being raised to their length; and a resolution was carried in the Town Council that the planking of the western groynes should be removed.

In 1901 it was determined to construct two new groynes east and west of the Brougham road, to replace old ones, at an estimated cost of £525.

Lancing.–The shingle here has drifted across an indent, forming a bank and enclosing an area about 600 acres, the surface of which is below low water of neap tides, this shingle forming its only protection from the sea. The top of this bank is about 6 feet above high water, and from 12 to 15 feet above the land, and is 150 yards wide. On the land side it slopes at an angle of 1} to 1. The shingle extends seaward for 14 yards beyond the line of H.W.S.T., below which the beach is covered with sand. The pebbles vary in size from ] inch to 2 and 3 inches, up to 6 inches in diameter, the average being about 1 to 11 inches. The pebbles are chalk flints, and are rounded, a few being angular and unworn.

In the British Association Report of 1895, Mr. R. F. Grantham, in his report, states that to the west of Lancing chalk rock and

flints are visible at low ebbs, and that in storms these flints are loosened, raised up, and washed ashore.

In south-west gales the shingle-bank is liable to be damaged by the waves, and it is stated that it was gradually being driven landward, the encroachment between 1875–91 varying from 70 to 320 feet. During a heavy gale in 1899 the sea made a breach through it and flooded the low land at the back, and also washed a large quantity of the shingle on to it.

Groynes have from time to time been constructed for its protection, and the shingle has been removed from the inner side and placed on the top, so as to raise it 3 to 4 feet, and above the height to which the waves reach.

In 1873 fifteen groynes were erected here by the late Mr. Grantham, each 66 yards in length, and spaced 166 yards apart, placed sloping away from the coast-line in a south-easterly direction at an angle of 100 to 117 degrees. They consist of fir piles and planking, supported by ties placed on the windward side, and are of similar construction to those described at Middleton. Some shorter intermediate groynes have been added.

During the last five or six years twenty-five new groynes have been constructed by Mr. R. F. Grantham. They are 100 yards long, spaced from 70 to 100 yards apart, the height of the planking at the shore end being 8 feet above H.W.S.T., and at the lower end 10 feet below that level, or when first fixed from 3 to 4 feet above the level of the shore. These, like those previously erected, incline away from the shore in a south-easterly direction.

Shoreham.—The drift of the shingle along this part of the coast has caused the river Adur to be driven out of its course eastward. About 70 years ago the outfall was at Aldrington, nearly 4 miles from its original position. A new outfall was subsequently opened out about 1} miles east of Shoreham, and piers have been constructed to keep the channel in its place and prevent it being choked with the shingle. The west pier, constructed in 1874, has acted as a groyne, stopping the travel of the shingle and increasing the size of the bank, which is now a quarter of a mile wide. The depth of water at the end of the pier at low tide is only about 3 feet, and as the shingle has for some time past reached the end of the pier, it now works round into the harbour, whence large quantities are removed by dredging; but as the accumulation in the barbour grows faster than its removal, it is now proposed to extend the west jetty into deeper water.

On the beach west of Shoreham groynes have been constructed within the last twenty years. They consist of fir piles and planks with timber ties, similar to those described at Middleton and Lancing. They are about 90 yards long, and from 100 to 150 yards apart, and point in a south-easterly direction, or away from the coast-line at an angle of 105 degrees. The shingle in calm weather reaches to the top of the planking at the end next the shore, but at a short distance down the material is from 4 to 7 feet higher on the west than on the east side of the groynes. Between the pier and these groynes, a distance of about 14 miles, the beach is level and without obstruction, the upper part to about a quarter ebb being shingle, below which, for a quarter of

upper part tó

a mile to low wobb being shingle, below the

The shingle on the Shoreham beach consists almost entirely of rounded flint pebbles, with a few quartzite scattered among them, and varies in size from } inch to 3 and 4 inches in diameter, the average being } inch to 13 inches.

Shingle is removed in large quantities from the harbour by dredging, and sold for concrete-making and other purposes, the sum annually realized by the sale during the last few years amounting to over £2000.

Southwick and Portslade-by-Sea.—The coast between Shoreham and Hove is low, and the beach covered with shingle to about half-tide level, and below this sand. The shingle varies from rough pebbles to stones the size of peas, and the bank may be taken approximately at 15 feet wide. The Brighton and Hove gas works were erected on the foreshore in 1871, between the harbour and the sea, and the premises are protected by a timber sea-defence. Groynes of piles and planks similar to those at Shoreham have been erected on the beach at right angles to the shore, and are about 80 yards long and 60 yards apart. The top of these groynes is from 2 to 5 feet above the surface of the beach.

Brighton and Hove.—The waste of the cliffs in front of Brighton has been the cause of considerable trouble and expense for upwards of three centuries. About two hundred years ago, in consequence of serious damage and injury to the houses, attempts were made to protect the cliffs by the construction of groynes, and at the present time the beach is provided with the most elaborate and expensive system of groyning to be found on the South Coast.

In describing these groynes, it has been said that “there are more groynes than beach ;” and in another account, that, “as the result of an average annual expenditure on groynes of £2500 for several years, the only result has been the collection of several triangular spits of shingle, while the natural beauty of the beach has been entirely destroyed.”

The lengthening of the west pier at Shoreham in 1874 stopped the supply of shingle, and the beach in front of Hove and Brighton became much denuded. Previous to 1874 there was an ample supply of shingle below the Brunswick Lawns, but five years afterwards the sea had begun to erode the slope, and in 1880 the lawns themselves were being washed away. Mr. Ellice Clark has stated that in September, 1878, the beach in front of Hove was 15 feet 6 inches above mean tide-level ; in the following summer it had decreased 9 feet 6 inches, and in the winter of 1879 to 4 feet 6 inches, showing a decrease of 11 feet during fourteen months. Subsequent to this groynes were constructed in front of Hove and the Brunswick Lawns, and in June, 1881, the beach had risen again to 16 feet 6 inches above mean tide. Mr. Ellice Clark calculated that during a gale as much as 10,000 tons had passed Brunswick terrace in two tides, and that on another occasion a survey showed that 27,000 tons of shingle had been removed during a storm from 770 yards of foreshore.

In 1886 the beach east of Hove was practically bare of shingle. Beyond the Chain Pier the loss of shingle became so great that the waves attacked the road of the Undercliffe. In 1894 it was reported that there only remained a few yards of sand where formerly the shingle extended seaward for a great distance.

To make up for the loss of shingle on the Hove shore, about 25,000 tons, obtained from the dredging in Shoreham Harbour, were deposited on the beach 400 feet below high water, which gradually drifted up and was deposited in front of the sea-wall to a depth of 8 feet, and in places within 5 feet of the top of the wall.

For the protection of the road and promenade in front of Hove and Brighton, a nearly continuous line of sea-wall has been constructed from Aldrington on the west to Black Rock on the east, a distance of nearly 4 miles, forming one of the finest promenades in the country.

« AnteriorContinuar »