Farm drainage / The Principles, Processes, and Effects of Draining Land with Stones, Wood, Plows, and Open Ditches, and Especially with Tiles :: CHAPTER XX EFFECT OF DRAINAGE ON STREAMS AND RIVERS.

CHAPTER XX EFFECT OF DRAINAGE ON STREAMS AND RIVERS.

Drainage Hastens the Supply to the Streams, and thus Creates Freshets.—Effect of Drainage on Meadows below; on Water Privileges.—Conflict of Manufacturing and Agricultural Interests.—English Opinions and Facts.—Uses of Drainage Water.—Irrigation.—Drainage Water for Stock.—How used by Mr. Mechi.

The effect of drainage upon streams and rivers, has, perhaps, little to interest merely practical men, in this country, at present; but the time will soon arrive, when mill-owners and land-owners will be compelled to investigate the subject. Men unaccustomed to minute investigation, are slow to appreciate the great effects produced by apparently small causes; and it may seem to many, that the operations of drainage for agriculture, are too insignificant in their details, perceptibly to affect the flow of mill-streams and rivers. A moment's thought will convince the most skeptical, that the thorough-drainage of the wet lands, even of a New England township, must produce sensible effects upon the streams which convey its surplus water toward the sea.

In making investigations to ascertain what quantity of water may be relied upon to supply a reservoir, whether natural or artificial, for the use of a town or city, a survey is first taken of the district of territory which naturally is drained into the reservoir, and thus the number of square miles of surface is ascertained. Then the rain-tables are consulted, and the fall of rain upon the surveyed district is computed. The ascertained proportion of rain-fall, which usually goes off by evaporation, is then deducted, which leaves with sufficient accuracy, the amount of water which flows both upon the surface, and through the soil, to the reservoir. With proper deductions for waste by freshets, when the water will overflow the reservoir, and for other known losses, a reliable estimate is readily made, in advance, of the quantity of water supplied to the reservoir.

Now, these reservoirs Nature has placed in all our valleys, in the form of lakes and ponds, and the drainage into them is by natural springs and streams; and the annual amount of the water thus naturally flowing into them may be readily computed, if the area within their head-waters be known. If the earth's surface were, like iron, impervious to water, the rain-water would come in torrents down the hill-sides, and along the gentle declivities, into the streams, creating freshets and inundations in a few hours. But instead of that, the soft showers fall, often on the open, thirsty soil, and so are gradually absorbed. A part of the rain-water is there held, until it returns by evaporation, to the clouds, while a part slowly percolates downward, finding its way into swamps and springy plains, and finally, after days or weeks of wandering, slowly, but surely, finds its outlet in the stream or pond.

If now, this surplus of water, this part which cannot be evaporated, and must therefore, sooner or later, enter the stream or pond, be, by artificial channels, carried directly to its destination, without the delay of filtration through swamps and clay-banks; the effect of rain to raise the streams and ponds, must be more sudden and immediate. Agricultural drains furnish those artificial channels. The flat and mossy swamp, which before retained the water until the Midsummer drought, and then slowly parted with it, by evaporation or gradual filtration, now, by thorough-drainage, in two or three days at most, sends all its surplus water onward to the natural stream. The stagnant clay-beds, which formerly, by slow degrees, allowed the water to filter through them to the wayside ditch, and then to the river, now, by drainage, contribute their proportion, in a few hours, to swell the stream. Thus, evaporation is lessened, and the amount of water which enters the natural channels largely increased; and, what is of more importance, the water which flows from the land is sent at once, after its fall from the heavens, into the streams. This produces upon the mill-streams a two-fold effect; first, to raise sudden freshets to overflow the dams, and sweep away the mills; and, secondly, to dry up their supply in dry seasons, and to diminish their water-power.

Upon the low meadows which border the streams, the effects of the drainage of lands above them are various, according to their position. In many cases, it must subject them to inundation by Summer freshets, and must require for their protection, catch-waters and embankments, and large facilities for drainage.

The effect of drainage upon "water privileges," must inevitably be, to lessen their value, by giving them a sudden surplus, followed by drought, instead of a regular supply of water. Water-power companies and mill-owners are never careless of their interests. Through the patriotic desire to foster home-manufactures, our State legislatures have granted many peculiar privileges to manufacturing corporations. Indeed, all the streams and rivers of New England are chained to labor at their wheels.

Agriculture has thus far taken care of herself, but is destined soon to come in collision with the chartered privileges of manufactures. Many questions, touching the right of land-owners to change the natural flow of the water, to the injury of mill-owners; many questions touching the right of mill-owners to obstruct the natural course of streams, to the injury of the farmer, will inevitably arise in our Courts. Slowly, and step by step, must the lesser interest of manufactures, recede before the advance of the great fundamental interest of agriculture, until, in process of time, steam, or some yet undiscovered giant power, shall put its hand to the great wheel of the factory and the mill, and the pent-up waters shall subside to their natural banks.

That these are not mere speculations of our own, may be seen from extracts which will be given from answers returned by distinguished observers of these matters in England and Scotland, to a question proposed to them as to the actual effects produced by extensive drainage. Some diversity of opinion is observable in the different replies, which were made, independently in writing, and so are more valuable.

Mr. Smith.—"During dry periods, more particularly in Summer, the water in the streams is greatly lessened by thorough-draining; for there is so great a mass of comparatively dry and absorbent soil to receive the rain, that Summer showers, unless very heavy and continuous, will be entirely absorbed."

Mr. Parkes.—"The intention and effect of a complete and systematic under-drainage is the liberation of the water of rain more quickly from the land than if it were not drained; and therefore the natural vents, or rivers, very generally require enlargement or deepening, in order to pass off the drainage water in sufficiently quick time, and so as to avoid flooding lower lands.

"The sluggish rivers of the midland and southern counties of England especially, oppose great obstacles to land-drainage, being usually full to the banks, or nearly so, and converted into a series of ponds, by mill-dams erected at a few miles distance below each other; so that, frequently, no effectual drainage of the richest alluvial soil composing the meadows, can be made, without forming embankments, or by pumping, or by resort to other artificial and expensive means.

"The greater number of the corn and other water-mills throughout England ought to be demolished, for the advantage of agriculture, and steam-power should to be provided for the millers. I believe that such an arrangement would, in most cases, prove to be economical both to the landholder and the miller.

"Every old authority, and all modern writers on land drainage in England, have condemned water-mills and mill-dams: and if all the rivers of England were surveyed from the sea to their source, the mills upon them valued, the extent of land injured or benefitted by such mill-dams ascertained, and the whole question of advantage or injury done to the land-owner appreciated and appraised, I have little doubt but that the injury done, would be found so greatly to exceed the rental of the mills, deduction being made of the cost of maintaining them, that it would be a measure of national economy, to buy up the mills, and give the millers steam-power."

Mr. Spooner.—"The effect which extensive drainage produces on the main water-courses of districts, is that of increasing the height of their rise at flood times, and rendering the flow and subsidence more rapid than before. I have repeatedly heard the River Tweed adduced as a striking instance of this fact, and that the change has taken place within the observation of the present generation."

Mr. Maccaw.—"It has been observed that, after extensive surface-drainage on the sheepwalks in the higher parts of the country, and when the lower lands were enclosed by ditches, and partially drained for the purposes of cultivation, all rivers flowing therefrom, rise more rapidly after heavy rains or falls of snow, and discharge their surplus waters more quickly, than under former circumstances."

Mr. Beattie.—"It renders them more speedily flooded, and to a greater height, and they fall sooner. Rivers are lower in Summer and higher in Winter."

Mr. Nielson.—"The immediate effect of the drainage of higher lands has often been to inundate the lower levels."

In a prize essay of John Algernon Clarke, speaking of the effect of drainage along the course of the River Nene, in England, he says:

"The upland farms are delivering their drain-water in much larger quantities, and more immediately after the downfall, than formerly, and swelling to the depth of three to six feet over the 20,000 acres of open ground, which form one vast reservoir for it above and below Peterborough. The Nene used to overflow its banks, to the extreme height, about the third day after rain: the floods now reach the same height in about half that time. Twelve hours' rain will generally cause an overflow of the land, which all lies unembanked from the stream; and where it is already saturated, this takes place in six or even in two hours. Such a quick rise will cause one body of flood-water to extend for forty or fifty miles in succession, with a width varying from a quarter of a mile to a mile; but it stays sometimes for six weeks, or even two months, upon the ground. And those floods come down with an alarming power and velocity—bridges which have stood for a century are washed away, and districts where floods were previously unknown have became liable to their sudden periodical inundations. The land being wholly in meadow, suffers very heavily from the destruction of its hay. So sudden are the inundations, that it frequently happens that hay made in the day has, in the night been found swimming and gone. A public-house sign at Wansford commemorates the locally-famed circumstance of a man who, having fallen asleep on a hay-cock, was carried down the stream by a sudden flood: awakening just under the bridge of that town, and being informed where he was, he demanded, in astonishment, if this were 'Wansford in England.'"

The fact that the floods in that neighborhood now reach their height in half their former time, in consequence of the drainage of the "upland farms," is very significant.

Mr. Denton thus speaks upon the same point, though his immediate subject was that of compulsory outfalls.

"Although the quantity of land drained was small, in comparison to that which remained to be drained, the water which was discharged by the drainage already effected found its way so rapidly to the outfalls, that the consequences were becoming more and more injurious every day. The millers were now suffering from two causes. At times of excess, after a considerable fall of rain, and when the miller was injuriously overloaded, the excess was increased by the rapidity with which the under-drains discharged themselves; and as the quantity of water thus discharged, must necessarily lessen the subsequent supply, the period of drought was advanced in a corresponding degree. As the millers already saw this, and were anticipating increasing losses, they would join in finding a substitute for water-power upon fair terms."

It is not supposed, that any considerable practical effects of drainage, upon the streams of this country, have been observed. A treatise, however, upon the general subject of Drainage, which should omit a point like this, which must, before many years, attract serious attention, would be quite incomplete. Whether the effect of a system of thorough-drainage make for or against the interest of mill and meadow owners on the lower parts of streams, should have no influence over those who design only to present the truth, in all its varied aspects.

As some compensation for the evils which may fall upon lands at a lower level, by drainage of uplands, it may be interesting to notice briefly in this place, some of the uses to which drainage-water has been applied, for the advantage of lower lands. In many cases, in Great Britain, the water of drainage has been preserved in reservoirs, or artificial ponds, and applied for the irrigation of water meadows; and as is suggested by Lieut. Maury, in a letter quoted in our introductory chapter, the same may, in many localities, be done in this country, and thus our crops of grass be often tripled, on our low meadows. In many cases, water from deep drains, will furnish the most convenient supply for barn yards and pastures. It is usually sufficiently pure and cool in Summer, and is preferred by cattle to the water of running streams.

On Mr. Mechi's farm at Tiptree Hall, in England, we observed a large cistern, in which all the manure necessary for the highest culture of 170 acres of land, is liquified, and from which it is pumped out by a steam engine, over the farm. All the water, which supplies the cistern, is collected from tile drains on the farm, where there had before been no running water.

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