Once a Week (magazine)/Series 1/Volume 7/Sea-waifs and sea-strays
SEA-WAIFS AND SEA-STRAYS.
This sea is ever at work as well as the fresh water, and, between them both, they contrive to work strange changes in the land, adding here and taking away there. Low, flat, sea-coast land, pierced by rivers, presents a very similar appearance the world over, where river current and sea-tide are not hemmed in by lofty barriers. Over the low land the sea washes, and in channels down to the sea from the higher levels the river “rives” its way. Gradually, as it approaches the sea, the bed becomes more horizontal, and the earth suspended in the water is as gradually deposited in the bed of the channel. Slowly it rises, and slowly the bed attains a higher and higher level, forming banks on either hand. If the channel becomes too shallow, or the current becomes too rapid, the natural banks get overflowed, a breach ensues, and some portion of the material is washed away, forming a “rapid” to a lower level, and thus forms a Delta like the Nile, or the Mississippi, or other many-mouthed rivers, up which, if there be a sea-tide, and the shore be low, the water flows and re-flows, inundating large tracts and rendering them useless to man, other than in his hunting or fishing capacity.
But when man settles, and thickens in numbers, he begins to covet the permanent possession of the long ranges of marsh meadow spread before him and occasionally exposed to view, and so he watches the processes of Nature in heaping up material, and seeks by art to prevent the reaction of washing away. On the flat shores of the North Sea short stakes are driven into the sand near together, and ropes of straw are wattled into them, forming small ledges, which intercept the sand in its reflux, and so gradually raise the surface. On the banks of rivers, raised by Nature at the outset, the bordering people watch carefully to prevent lateral breaches, and the levels are raised artificially at the banks, in order to correspond to the natural raising of the bed of the stream. Over large marshy and water-covered districts, artificial raised rivers or channels are made with wholly artificial banks, the water being pumped from the low flats into the channels so made. And so, in process of time, large tracts of land are covered with high banks or dikes following the lines of the water-courses and the sea-shore, the sea being shut out by flood-gates, which open at the low sea-tides to let out the land waters, and people live and move and have dwellings below the level of the high tides. Valuable is the land thus gained, but costly is the process of maintaining it. Thus has Holland been won from the sea by an amphibious race of men as described by Andrew Marvel:
A land that lies at anchor and is moored,
Whereon men do not live, but go on board.
And as a ground rent on which land, a Dutchman once exclaimed to me, they “paid ten per cent. to Nature previous to working it,” and they watch carefully for all signs of sea-worms or burrowing animals lest they should spring a leak and drown a province. At New Orleans the bed of the Mississippi and the embankments, or levée, are raised so high that ships float above the level of the house-tops.
In the neighbourhood of the Great Lincoln Wash, which devoured the army of the Third Richard, lie the great marsh lands of England, won from the water by man’s energy during successive generations. If our engineers could have their way, they would cause this England of ours to rise out of the sea like a twelfth cake, surmounted on all sides by perpendicular cliffs with convenient landing places. They would wall England round, not as Friar Bacon proposed, with brass, but with iron armour plates of unlimited thickness, and deeply galvanised to set rust at defiance. They laugh at difficulties, and only ask for cash, and the thought of reclaiming from the sea the flat fat lands deep in vegetable detritus, sets astir the covetous faculties of land owners and farmers to any extent. What matters it that houses unequally weighted sink in all manner of ways out of the perpendicular, and that women grow to look like witches, if to the marsh manner born, and men purvey them wives with money from the uplands, which, after three widowings, sets them up in capital,—what matters all this if sheep thrive, and hay is made, and corn grows?
The Middle Level Drain, an artificial river some 200 feet in width and twenty in depth, carried off the inland waters from the Bedford Level, and delivered them into the Ouse river where it divides into two channels, one running eastward and entering the Wash near King’s Lynn, the other running westward under the name of the Nene, and, entering the Wash below Wisbeach, enclosing between them the district called Marshland.
The owners of the Middle Level Drain were not satisfied with the outfall where it entered the Ouse, and so they applied to Parliament for permission to extend their drain across a portion of the Marshland to enter the Ouse some miles nearer the sea. And Parliament gave them permission against the will of the Marshland owners, who had no interest in the drain beyond considerable fear of being overflowed.
In the Ouse the tide rises and falls, so it is necessary to stop the mouths of the great drains going into it, which is done by a structure of timber or brick-work like the gates of a dock, which close at high tides to keep out the sea-water, and open at low tides to let out the land water. Either from insufficient workmanship or bad locality, or unusual pressure, or from burrowing animals, the land water, or sea water, or both, made a flank movement, and burst up the whole sluice, so that the tide, instead of being confined to the river, obtained free way up the drain also. The drain apparently had not been constructed sufficiently strong for this contingency, and a breach was made in a weak part of the bank, and six thousand acres of Marshland was overflowed, the tide running through the breach at eight miles an hour. The lower part of the bank was of clay, the upper part of silt. When the water rose high enough, the silt washed away, and then the stream rapidly cut a channel through the clay.
How to stop this breach, was the problem not to be solved by a miscellaneous throwing in of clay-bags, or other material, nor by hampers of stones, with a rush of water at eight miles speed per hour; and the engineer, Mr. Hawkshaw, took the right method. He drove sheet or close piles along the banks, on either side the level in a double row, and in the water-way of the breach he drove the piles with openings between them. These openings were fitted with sliding-doors, or sluice-gates of timber, weighted. Some of the openings being closed, the rush of water through the others became more violent, tearing up the bed. A scaffold was then erected, and at the turn of the tide, the whole of the sluices were closed together, in both rows of piles, and clay-bags were rapidly thrown into the space between, and the water found its master.
But how is the drowned land to be laid dry without any sluice gate to open? Very simply! A number of cast-iron pipes, three feet six inches in diameter, are laid with their ends in the water at a low level, and sloped up the bank at an inclination of one in two, then pass horizontally over the bank, and with another slope of one in two, down the outer bank. These pipes are syphons, into which the water is first raised by an engine, and will continue to flow through by the action of gravity, so long as the head is higher at one end of the pipes than it is at the other. The outflow is received on an apron, or bed of stonework, and thus a solid bank is retained without any sluice. The result of this will probably be to dispense with a good many scoop wheels and pumps, and if so, good will grow out of evil.
And, now, about the amount of evil. The engineering cost will probably be some 30,000l. The loss of crops, at ten pounds per acre, will be 60,000l., say altogether some 100,000l. But what will be the result in the year to come? The water is brackish, not salt, and it may result in a general manuring of the land, like an inundation of the Nile, which will be some compensation for the homesteads damaged.
Apart from this, there will be much money changing, between landowners, and farmers, and lawyers. The Marshland folk did not want the drain, which did not drain their land, but that of their neighbours, and they will naturally ask for compensation, and a very pretty quarrel it will be.
Years past there was a breach in the bank of the Thames, at Dagenham, which swamped a thousand acres of land, leaving a small lake behind it to this day. It was a troublesome affair to close that bank, ruining many sets of contractors and speculators, and occupying the term of eight years ere it was closed.
The Marshland breach, swamping six thousand acres, has been stopped in two months, and now a company are about to convert Dagenham Lake into a dock. We do things now that were formerly impracticable, because in addition to ample capital, we have got tools, and machines, and plans of a more effective kind. We circumvent the wild operations of Nature, by following the laws of Nature in the processes of art, and the engineer hails every overthrow of his works as a basis whereon to accomplish still greater things. And we are yet very far from having exhausted the resources of mechanical art, whilst we are only just entering on the domain of chemistry, in the pursuit of sea-changes round our island home. Our sea-waifs shall become more and greater, and our sea-strays shall be tethered, even as the coral-insects raise up islands in the deep.
W. Bridges Adams.