THE EARTH AS AN IMPOUNDER OF WATER.

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In designing storage reservoirs of limited extent, account must be taken of the minimum annual and minimum periodic rain-fall. It sometimes happens that the annual rain-fall continues to be less than the general mean through cycles of three or four years. Computations based on a number of selected stations of largest observation in the United States, extending throughout the whole country, give the average annual rain-fall of the least three-years cycle, at any one of these points, as 67 per cent. of the mean annual rain-fall at the same point, and the greatest three-years low cycle as 97 per cent. of the mean annual rain-fall at the same point. Taking 16 inches as the mean annual rain-fall at Fort Dodge, the mean annual rain-fall of the low cycle will be 67 per cent. of 16, equals 10 inches. Of this amount, favorably situated gathering-grounds of unbroken prairie will furnish at least 60 per cent. This will give a depth of 6 inches of water over the whole area drained for collection in a reservoir. Taking 16 inches depth of water over the area irrigated as the requirement in addition to the proportional part of 16 inches of rain-fall, and we have 16 divided by 6, equals 24; i. e., the water from 24 acres of drainage area will furnish sufficient water to irrigate one acre of land. Doubling this amount for contingencies (as evaporation and seepage), and 5 acres will suffice for one acre. On this basis the owner of a favorably-situated quarter-section of land can collect in a reservoir the required amount of water to irrigate 30 acres, which will allow 15 acres for agriculture, 15 for meadow, and 130 for grazing. The reservoir should be made deep, to prevent loss by evaporation. Should the gathering-ground be large, and owned by a number of persons, a reservoir of greater capacity might be constructed, and by purchase or exchange with each other, a unit of forty acres of irrigable land might be secured to each, with diminished cost per acre.

When, however, there is no suitable site for a reservoir, the rain-fall from the gathering-ground will run onto and be absorbed by the porous soil of the bottom lands. Pure sand, when saturated with water, will contain from 30 to 40 per cent. of its bulk, while gravel contains 25 per cent. The eminent scientist, Sterry Hunt, estimates that one square mile of sandstone 100 feet thick will contain, when saturated, water sufficient to sustain a flow of one cubic foot per minute for a period of thirteen years. Sandy soil at a certain depth is always saturated with water, which rises, after large accessions from rain, nearly to the surface of the ground, and falls again during periods of drought. In a region of sand and gravel a fall of 6 feet in the groundwater will give a discharge into the streams of from 40,000,000 to 50,000,000 cubic feet per square mile of ground. The water so held constitutes the reserve which goes to maintain the dry-weather flow of streams.

The water in the ground, like that in the streams, is in constant motion, although its rate is by comparison with that of streams very slow. The quantity of water flowing in an open channel 100 feet wide and 6 feet deep, with a fall of 1 foot per mile, is about 1,000,000,000 of gallons per day. The quantity flowing through a channel of the same dimensions and fall, filled with gravel, will not exceed 600 gallons at the same time. This extreme slowness with which the ground-water moves serves as a regulating sluice to the ground reservoir, securing it against rapid exhaustion. From the above it is evident that the water stored in the porous soil of the bottom lands is the source of the water supply of the Arkansas River valley, rather than the flowage of the river, which in fact for a portion of the year acts as a drain to the valley rather than as a supply to the under-current. The longitudinal fall of the ground-water in the valley in western Kansas is about 7 feet per mile. The writer found by measurement that the fall of the ground-water from the Arkansas River to Cow Creek, a distance of 2 miles, near Hutchinson, was 8 feet per mile. Observations made during the construction of water-works for cities show that in ordinary sand and gravelly soil a fall of 7 feet per mile will give a rate of motion of the groundwater of about 1 foot per hour.

ARTESIAN WELLS AND THEIR ECONOMIC VALUE.

An artesian well is one in which an artificial vertical shaft is filled to overflowing by water, which enters it at some distance below the surface of the ground. The water may spout up with force and rise higher than the surface or it may barely reach the point at which it flows over. The conditions under which this can occur are the same as those which govern the supply of water to the upper rooms of buildings in cities. The reservoir with which the water-mains are connected must be higher than the place supplied; for the same reason the stand-pipe which takes the place of a reservoir in towns located in a level country must be

higher than the tops of the highest buildings. This is made necessary by a well-known principle in hydrostatics, that a fluid will not rise in an irou tube higher than its source. There are some artesian wells whose flow is due to other than hydrostatic pressure here described, viz, to gas pressure and rock pressure, but these forces need no illustration. In nature the channel through which the water flows is more like a sponge than the orifice of a pipe. It is porous rock, sandstone, conglomerate, gravel, sand, or limestone more or less cracked or broken. The walls of a natural pipe must be impermeable and usually beds of clay or clayshale serve this purpose. To get the head of water the beds of sandstone, shale, etc., must have a dip, i. e., they must be higher at one part than another. The best conditions are when the rock strata take a basin formation, highest on the edge of, circular area, and a well sunk in the middle of the basin. It is to be understood that all the waters of the land are meteoric waters, having their origin in the rains and snows. If then the rain talls on porous rock on the upturned edge of a basin, which within the basin is overlaid and underlaid with impervious clays, a well sunk at or near the middle would be artesian.

The basin form is, however, comparatively rare in nature, but continuous dip of rocks in one direction is by no meaus uncommon, so that the form of a trough is more often found. If the relative position of porous and impervious rocks is the same, artesian wells may be found on the slope or at the lowest point. The general dip of the geological strata on the plains is from west to east, by south, as is also the slope of the surface of the country. The conditions for finding artesian wells are thus widely distributed.

Prof. P. H. Van Diest, of Denver, Colo., who has had an almost worldwide experience as an engineer in connection with artesian waters and wells, gives some interesting data, as a basis for the consideration of the economic uses of such supplies. He says:

I have had something to do in India with artesian borings and gathered some statistics about the amount of water which percolates the lower strata. In the Paris and London basins, by careful observation it was ascertained that a third of the water-fall on a certain extent of land gives a certain flow; that another one-third evaporates and is taken off by the plants, and that the last third percolates to the lower strata. How far that is the case here is difficult to know because there are no observations taken. That is the experience, however, in London, England, and Paris, France, where considerable artesian water has been got. Similar observations have been made in India. Batavia is now supplied with artesian waters after surveys made by me. No observations are made here, and it is difficult to say what the case is. From the very sandy condition of a great deal of the outcropping rocks in the arable regions of Colorado, a good deal must percolate to great depths. That is proven to be the case in Denver, the Denver basin having observations made in it to some extent.

The conclusion is that there must be considerable water running down to the lower strata. By borings that have been made (about two hundred flowing wells having been bored) we have observed that there are three different flows. Speaking of those flows, I would say that the upper flows, to which many wells have been bored, are very limited. The lower flows take water from a greater extent of country. Much trouble has occurred in the artesian diggings by the bad construction of the tubing. There are a great many of such basins here all along the foot-hills, and it has been proven that there is much loss, as, for instance, in the San Luis Valley, where they have had flows of water to a great amount. There would be a chance to apply water for irrigation. The same is the case in the San Bernardino Valley, in California, where over two thousand artesian wells are aiding in irrigation. They are under regulations, so that during the night they must be closed off with stop-cocks. Thus there is no unnecessary water flowing off. There are many streams that run east from here, such as the Bijo, the Badger, and other creeks, which at their best are all running streams and have considerable water. Over distances of 20 to 30 miles they are entirely sunk and lost. The Platte Valley is increased farther down in its flow. Without seeing it directly here, the volume of water in the Platte is increasing. It

THE EXTENT OF UNDERFLOW SUPPLIES.

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must be that the water from some of the mountains flows invisibly away, probably not at a very great depth. Perhaps at 15 or 20 feet deep there may be an impermeable layer and that it flows under the surface away. I think that that water could be made useful by pipes from a distance out, carrying the pipes to a place where the water is needed. Certainly a great deal of land could be redeemed by the percolation of water which is now lost.

SPRINGS, UNDERFLOW, AND LOST STREAMS.

In eastern New Mexico there is an extensive region of large springs, showing the existence of water under ground that comes by artesian force or otherwise to the surface. When we come to northern Texas, and to what are known as the Staked Plains and the Panhandle region of that State, there are in existence to-day a great body of wells some of which are artesian in character, but there are many that flow so near to the surface and with such force that it is evident that if these wells were sunk deeper they would have the artesian quality; they would strike that stream. It is a general belief that the water under the Staked Plains, the water from which these wells are supplied, has the character of a flowing stream. Some experiments have been made in the neighborhood of Marienfelt, Odessa, and Midland, on the Texas Pacific Railroad, which seem to indicate the correctness of that theory. The altitude lowers abruptly, and the land is of a totally different character. Beyond the westerly limit of the Staked Plains the land is all of a distinctively arid character, as arid as Nevada or Arizona. It has no precipitation exceeding 8 to 11 inches of fall per annum. But throughout northwestern Texas there is unquestionably a large underground water supply. The springs which come to the surface, the evidence of the wells upon Staked Plains and in the Panhandle region, indicate this. Indeed, the testimony all goes to show that there is sup ply sufficient if it could be brought to the surface to answer the purposes, by small storage, of almost that entire region.

In southern Arizona there are areas of underground supply that can be developed. The Santa Cruz River, for example, flows under ground to Maricopa, in the Gila Valley. It runs into the Gila River near that point. The Santa Cruz River rises a few miles below the southern line of the United States, in Mexico. It runs almost directly north to Tucson. Nine miles beyond Tucson it is lost under ground, and then for some 87 miles it flows under ground, until it enters the Gila and helps to swell that river. The valley of the Santa Cruz contains about 1,140,000 acres, a very large proportion of which, if there were water for it, could actually be brought under the most efficient horticultural It is a region admirably adapted for fruit. At the Mission of Tumacacori, and at Tubac, Calabasas, and other places, there are the remains of fruit gardens that the missionaries planted and used. In years past all the semi-tropical fruits have been growing on some farms that were maintained there against the Apaches The Santa Cruz River should be taken out, as near its source as possible, and distributed by means of high-line canals.

use.

The land is very fertile. The river has a great drainage area at its head. It is fed by several very important small streams on both sides, and if it were taken out and placed in a new channel, and distributed over the valley, the entire region at and below Calabasas, for some 10 or 12 miles wide and 150 miles long, could be made a perfect garden. We used to fancy in years gone by, in traveling over the Cienega, north of Tucson, that we could hear the waters running under ground.

We do not know whether that was a correct inference or not. East ward, and lying beyond the Dragoon Mountains, will be found the San Simon Valley, or plain, known in the olden days as the principal route southward of the Apaches. Water can be got in the San Simon and Sulphur Valleys anywhere at from 8 to 40 feet below the surface. All through, in this low table-land, will be found wet places-the Mexicans call them cienagas. There are a number of ranches in that valley now supplied by such waters, either from wells or tanks and ponds. The San Pedro River also, between the San Simon and the Santa Cruz, rises in Mexico, as the Santa Cruz does, and can be, by storage near its head, made of much greater service than is now the case. Upon the plateau on which Tombstone is situated they have some artesian water. There are two flowing wells at that place.

Crossing into New Mexico, over the Chiracahua Mountains and beyond the eastern foot-hills of that range, Deming is reached and the table-land around it. Water has been found there within 25 or 30 or 40 feet of the surface. It is an important railroad junction. It is so near that slight pumping brings it to the surface, and makes it valuable for the small irrigation, for fruit and gardens, that is going on in that region. From what can be learned in relation to it it would be possible to develop the whole well and under-flow water there, and create a storage system which would bring a large proportion of that mesa or bench-land under cultivation for grass and root crops as well as for fruit. Through this region and up to the lower foot-hills water can almost always be found a short distance from the surface. Most of these little valleys of that region could be reclaimed by the use of small storage.

THE DAKOTA WELLS.

In no section of the United States can there be found so many artesian wells, of as great pressure and supplying as immense a volume of water, as those flowing in North and South Dakota. They are chiefly in the valley of the James River, and are in successful operation from Yankton on the extreme southern boundary of the territory to Grafton on the north, covering a distance of nearly 500 miles. In Yankton over a dozen wells, from a depth of 550 to 600 feet, pour forth a bountiful supply of water, the increase in the number of wells not having the least effect on the flow or pressure from the underground source.

There is nothing strange in the flow of artesian wells. The principle is precisely that of a reservoir system of water works, or of the artificial fountain. By storing a supply of water in a basin at some high point and carrying it in pipes to a lower level convenient water power is obtained. Nature has constructed a vast system of underground waterworks on the same plan, the pervious strata of sand rock underlying the earth's surface at various depths serving as pipes to convey the water from a distant reservoir or source of supply.

There are now more than one hundred wells in the two Dakota States, of remarkable pressure and supply. This does not include numerous flowing wells. At Yankton various factories now utilize the force furnished by the pressure of the underground current. Wells cost from $4,000 to $6,000. The pressure varies in different localities from 30 to 180 pounds to the square inch, and the flow from 50 gallons to 4,000 gallons a minute. The Woonsocket well (South Dakota) is much larger. The water is more or less mineralized, but the constituents are such as

THE DAKOTA ARTESIAN WATERS AND WELLS.

93 have imparted to the water undoubted hygienic and remedial properties, analyses showing the presence of carbonates and sulphates of iron, lime, magnesia, soda, sodium, potash, etc. Artesian water is almost invariably soft, and of excellent quality for general household purposes. The temperature of the water partakes of the internal heat of the earth.

The records kept by well-borers, showing the penetration of various strata, establish the fact that the Dakota geological formation contains all the essential features which scientists state are pre-requisites to flowing wells. The water is found in coarse-grained sand rock, which has above it a confining stratum of shale, clay, or lime rock.

According to Professor Chamberlin, president of the Wisconsin (Madison) State University, and other geologists, the artesian wells in the Dakotas are situated east of the one hundred and first meridian, and, with the exception of the one at Pierre, they are east of the one hundredth meridian. They occur in great numbers in the Red River Valley, making a belt through the Dakotas, with adjacent portions of Minnesota and Manitoba, and making a second nearly parallel belt running from Yankton northward to Devil's Lake.

The successful wells of the Dakotas, thus far bored, can be arranged in four groups, with reference to the geological horizons from which they derive their water supply. These are, (1) wells of little depth which do not pass through the drift; numerous in the Red River Valley; (2) those which penetrate to the Cambrian rocks, as at Grafton, N. Dak.; (3) those deriving their water supply from the middle or upper portion of the Cretaceous, illustrated by a single well in the western part of Cass County, and by several wells in the Red River Valley which pass through the drift; (4) those penetrating to the Dakota sandstone, the basal member of the Cretaceous. This group is important, and is illustrated by numerous wells ranging from Vermillion and Yankton northward to Devil's Lake. The available data concerning these are given in the following