The water resources of a region include its running water or streams, its standing water or lakes, and its ground water, the source of wells and springs. Of these three, the second is absent in this region. There are no lakes or even ponds, except artificial ones made by building dams across water courses. The streams are highly important and the ground water most important of all.
The chief uses of streams are four: water supply, navigation, power, and irrigation. The last named, which is the chief use in the and west, need not be considered here; and water power is not important in this area as compared with the other two uses.
Ohio River.-Of all streams in America the Ohio has been the most used for navigation. In the latter part of the nineteenth century traffic by water decreased greatly, not only on rivers, but on canals as well.
In recent years, because of the vast amount of freight to be carried in the United States, and the relative cheapness of water transportation as compared with railroad transportation, there has been a great revival of interest in inland waterways. One river boat has been known to tow in barges 70,000 tons of freight at one trip. This is equal to the load of 2,333 modern freight cars, making a train more than fifteen miles long(See note 22). The cost of moving coal down the river is from one-fifteenth to- one-fourth the cost of carrying the same coal by rail. Because of such facts as these, the United States Government has for many years been building dams to canalize the Ohio and thus provide for a constant depth. Most of the work previous to 1904 was near Pittsburgh, and was designed to provide for a minimum depth of six feet. Operations since that time have contemplated a nine-foot stage.
The essential feature of canalization is the maintenance of a certain minimum depth, however small the discharge may be. In summer, when the discharge is small, the water instead of falling lower simply moves more slowly. This is effected by means o 'dams placed sufficiently near together so that the level of the stream between two consecutive dams is essentially flat. In this way any desired depth may be maintained by building the dams high enough; but it is to be remembered that, with increased depth, the water moves correspondingly slower between dams.
The total number of dams contemplated between Pittsburgh and Cairo is about fifty, and the entire cost will be somewhat more than sixty million dollars. The first dam built to retain nine feet of water was completed in 1911 at Fernbank, twelve miles below the suspension bridge at Cincinnati. The crest of this dam is sufficiently high to maintain a pool of water with an essentially horizontal surface and not less than nine feet deep, extending up stream several miles beyond California. The next dam to be constructed near Cincinnati will be at the upper end of this pool.
Miami River.-The Miami is not now navigated, but in the earlier years of settlement many flatboats plied as far north as Hamilton. It is still classed as a navigable stream, and as such is under the control of the federal government. The amount of water which it carries is many times what is necessary for a deep canal, but, in comparing the canalization of this river with that of the Ohio, it must be considered that the average fall per mile of the Miami is eight times that of the Ohio. Eight times as many dams of the same height would therefore be necessary in order to maintain the same depth of water.
Other Streams.-As to navigation, the Licking is similar to the Miami, but its lower course, lying within a great industrial community, is somewhat used as a harbor. In a similar way, Mill Creek, though a very small stream, offers opportunities for the making of a great harbor by the artificial enlargement of the channel in its lower course. As there is already a great concentration of railroads in this valley, it is not improbable that the opportunity of a great harbor by their side will some day be found one of the greatest commercial advantages of this locality.
Ohio River.-As a source of water supply the Ohio is quite as important as for navigation. The city of Cincinnati pumps from the river fifty-three million gallons daily for its city water systems. Fortunately for this purpose the water of the Ohio is relatively soft. Its headwaters are in the Allegheny plateau whose rocks are in large part sandstone and shale. Calcareous rocks are very subordinate. An average analysis of the river water at Cincinnati shows that it carries in solution only 120 parts of mineral matter in 1,000,000 parts of water.
The hardness, or content, of dissolved solids in the Ohio should be contrasted with that of the Mississippi at St. Louis, which has 269 parts per million, the Missouri at Kansas City, which has 426, and the Miami at Dayton, which has 289.
Like all great rivers, the Ohio carries mud in suspension, though not so much as the Mississippi below St. Louis, and only a fraction of the amount carried by the Missouri, which furnishes the larger part of the Mississippi mud. The average amount of mud in the water of the Ohio is 230 parts per million.
stay That the softness of the Ohio water is due to the rocks which underlie its headwaters, is shown by the character of the Allegheny at Kittanning, Pa., which carries but eighty-seven parts of dissolved matter per million. The Monongahela, at Elizabeth, Pa., has eighty-one parts per million (See note 23). Much of the dissolved matter which appears in the river at Cincinnati is derived from tributaries in Ohio.
The municipal supply for Cincinnati is pumped from the river at California, nine miles above the suspension bridge. It is first allowed to stand in large open basins where a part of the mud settles. It is then filtered through sand, after adding a small amount of sulphate of iron and of lime, to cause the clay to flocculate, that is, to form small flakes or granules. After filtering, the water passes into other basins from which it enters the city mains. Although the filtering process is the mud rather than bacteria, experience calculated primarily to remove shows that most of the latter are removed at the same time.
Miami River.-No other stream in the area is used as a source of water supply. Cities not on the Ohio derive their water from wells. It is instructive, however, to compare the quality of the water 'm other streams with that of the Ohio. The Miami gathers its waters from western Ohio where the underlying rock is largely limestone. As shown on page 107 the overlying glacial drift is similarly calcareous. The water of this river at Dayton shows 289 parts of dissolved solids in one million parts of water. The water is therefore more than two and a half times as hard as that of the Ohio at Cincinnati. The water of the Miami at Hamilton (See note 24) is fifty -per cent harder than at Dayton, and the water of the Little Miami, near its mouth, is similar to that of the Miami at Hamilton.
The only use of water power in this area is at ]Kings Mills on the Little Miami. At this place one of the large powder factories of the United States is operated in part by water power, 700 horsepower being developed an d available for nine months in the year. At every dam, power is made available when the stream is at suitable stages. This is true of the large dams under construction in the Ohio. The use of power thus developed has not yet begun.
In the Ohio.-A physiographic question of great interest in this area is that of floods. The Miami Valley was perhaps the chief sufferer in the floods of March-April, 1913, when the direct property damage in Ohio alone was conservatively estimated at $143,000,000.
The Ohio at Cincinnati is said to be in flood when the water reaches a depth of fifty feet on the gauge. From 1862 to 1913, fifty-one years, this depth was surpassed forty-three times. The maximum height was 71.1 feet on February 14, 1884, but on April 1, 1913, the water fell short of that height by only 1.3 feet. Five years may pass without a flood, as from 1870 to 1875, and again there may be two destructive floods in one year, as in January and April, 1913. It should be understood that the selection of a height of fifty feet as the flood limit is purely arbitrary. Had a lower stage been selected as the limit, the number of floods would be greater. At that stage damage may be said to begin. At a stage of - 63 feet passenger trains fail to reach the Little Miami (Pennsylvania) station, and at 53.5 feet the Union Station is abandoned. Before that stage is reached the handling of freight is largely stopped.
In the Miami.-Previous to 1913 the Miami received no attention as a stream liable to dangerous floods. The highest stage recorded at Hamilton was in 1898, when the river reached 21.2 feet. On March 25, 1913, the stream suddenly passed that record and rose with great rapidity to a height of 34.6 feet, which 'was passed a-( three o'clock a. m. March 26. The experience at Dayton was similar. In both cases areas were deeply flooded which had always been classed as terrace lands and had never been considered liable to overflow.
Cause of Floods-The floods of this district are caused either by excessive rains or by melting snows. The greatest melting of snow is, of course, in the early spring or late winter. Excessive rains may come at any time of the year, though they are a little more frequent in spring and summer. Among the conditions favoring floods are frozen or very wet ground. Percolation is thereby hindered and prompt run-off is made necessary. All the conditions for floods are therefore most likely to be met in the late winter and spring. Of the forty-six floods on record at Cincinnati only three occurred outside the months of January, February, March, and April (See note 25), These three were in December, 1847, May, 1865, and August, 1875. Some of these floods have been aggravated by the breaking of ice gorges, and by the narrowing of the river channels by bridges and "made land." The breaking of levees or of reservoir dams has not affected this region.
The great flood of 1884 illustrates a combination of all conditions operative here -- heavy rains combined with melting snow on frozen ground. The flood of 1913 was due purely to excessive rains on ground already wet almost to saturation.
Flood Problems.-The complex question of the prevention and control of floods cannot be taken up here, except to mention and classify the different lines of effort. They fall into two 'distinct categories, flood prevention and flood control.
Increase of Percolation.-The water which falls as rain is disposed of in three ways, by immediate evaporation, by percolation, and by run-off. Anything which increases or decreases one of these processes affects the other in the opposite direction. Man cannot directly control evaporation very much, but he has considerable power over percolation and run-off.
The flow of streams at ordinary stages is supplied chiefly by springs and seepage. Water thus derived from the ground went in as rain some days, weeks, or even years earlier. Such water constitutes the permanent flow of streams. Over against this is storm water, which runs off without entering the ground. The body of a flood is of this character. It is important to remember that floods are made up essentially of water which has failed to percolate. How to increase percolation is therefore the most fundamental problem in flood studies. It is also a problem of the greatest magnitude in agriculture, which affects the human race far more vitally than floods. The United States Department of Agriculture is devoting much time and effort, already with some degree of success, to teach farmers on hilly lands to plow in such a manner as to assist percolation and retard run-off instead of the opposite. This is done by plowing around the hill in horizontal lines instead of up and down hill. The practice is known as "contour plowing."
All vegetation tends to retard run-off and increase percolation. Fortunately, slopes too steep for profitable agriculture support just as good forests as does flatter land. The conservation of forests on all steep slopes is now being strongly urged and, to a limited extent, applied. This is very wise for more reasons than one. It should not be forgotten however, that for one acre 'm forest there are many acres in crops or meadow, and the preservation of such vegetation so as to avoid washing of the soil and gullying is profitable not only from the standpoint of agriculture, but from that of floods.
Most hilly countries come sooner or later to the practice of terracing. As the population of the United States increases, and farming becomes more differentiated, and intensive agriculture displaces extensive attempts where they do not pay, terracing will be practiced more and more. This will be done primarily for agricultural reasons, but in decreasing immediate run-off it will also tend to decrease floods.
Reservoirs.-A reservoir is constructed by building a dam across a valley, usually at a place where the valley is narrow and above which it is wider. Within limits the deeper the valley the better. A project to prevent floods by reservoirs provides for many such dams in tributary valleys. When used simply to prevent floods they are supposed to be closed only when the main stream below is approaching flood height. The water is then to be held back until it can safely be released. The plan contemplates that in this way an excessive rain, instead of running off in three or four days of flood, may be disposed of in several weeks without flood. Such a plan for the upper Ohio (above Pittsburgh) is approved by many eminent engineers. (See note 26) There is no lack of reservoir sites in eastern Kentucky, West Virginia, western Pennsylvania, and eastern Ohio, that is, in the Allegheny plateau. In western that is, in the Till Plains, the case is different. There the valleys are not only fewer but shallow, and it is necessary to flood wide areas in order to retain enough water to affect great floods.
Despite these difficulties the State of Ohio has authorized the construction of an extensive system of reservoirs in the Miami drainage basin to protect Dayton and other cities from floods. The plan of preventing floods by wholly artificial reservoirs is not yet in operation on any American stream. It is complicated with questions of navigation, water power, and water supply, all of which must be taken account of in a comprehensive plan. Further difficulties arise from a conflict of local and general interests. Large rivers traverse more than one state, so that the only authority sufficient to control such an enterprise is the national government. There is a further question as to whether the purely public benefit would justify the expense. If the benefit which would accrue purely to individuals be added to that of the public, there can be no doubt that the resulting gain would greatly exceed the cost. No project has yet been seriously considered for the prevention of floods by this means at Cincinnati, or at any other place which receives the drainage from so vast a drainage basin as that which lies above Cincinnati. The prevention of floods by reservoirs is practiced to a considerable extent in Europe in drainage basins of a few thousand square miles.
Control of Channels.-The control of floods by alterations of stream channels has been much more practiced in the past than any kind of flood prevention. Levees have long been built and channels straightened to provide greater fall and more speedy discharge. Channels may be deepened where the amount of fall permits. The control of channels has become a specialized branch of engineering science, because in altering the channel at one place the effects farther down' stream must be considered.
Of recent years an increased amount of attention has been given to the obstruction of streams by bridge piers, and the narrowing of the channel by artificial filling and by buildings. In doing the latter, not enough consideration has been given to the fact that intermittent floods are normal occurrences on a stream which does not flow through lakes. It is not necessary to appeal to human records to ascertain this. The existence of flood plains covered by silt is the final proof., In view of this fact it would seem reasonable that the human race should find out how much room is necessary for the movement of recurring excess waters, and then adapt itself to the circumstances. Perhaps the largest factor under the direct and immediate control of the public is the artificial narrowing of stream channels.
How Contained.-Ground water, as the name implies, is water in the ground. It is contained in pores and larger cavities and passages in both bed rock and mantle rock. The pores may be very small like those in our shale or our limestone, or they may be such as exist between sand grains and pebbles in gravel, or between the crumbs of soil. Ground water also exists in cracks and between beds of rock which fit as closely as the leaves of a book tightly pressed. Again, these cracks, either between beds or across them, may be enlarged by .solution, making passages. (See < A HREF="Fig-30-m.jpg">Fig. 30Outline of the Problem of Floods
The Water Table. All such pores and passages may be either full of water or empty, or merely wet on the sides. Near the surface they generally contain air, the moisture simply coating the grains or lining the cavities. Beyond certain depth the pores are full. If a hole be dug or drilled beyond that depth it will fill with water. If the rock. into which it is drilled has only very small pores, the hole will fill with exceeding slowness: Nevertheless, it will fill in time if the moisture is not evaporated as fast as it comes in. This level beneath which the pores are full, is called the level of ground water or the "water table." In valleys the water table is near the surface, and beneath hills it is generally far below the surface, but not at so low a level as beneath the adjacent valleys. The relation between the surface of the ground and the water table is shown in figure 54.
Ground water is constantly acted on by gravity which tends to flatten out the water table. Where an impervious rock below the water table crops out on a hillside, the ground water rests on it, following its upper surface and issuing as a hillside spring. Near Cincinnati, the Eden shales afford less passage for water than the alternating limestone and shale of the overlying Fairview; hence it is quite common to find springs and seepage at the contact of these two formations about half way up on the bluffs.
In a similar way, the flattening out of the ground water within the hill or upland causes it to enter the stream channel in the valley. This is the only source of supply for a stream between rains. It is a general principle that streams do not become permanent until their channels are cut below the water table.
Between impervious beds, the effect of gravity on ground water is to cause it to move laterally as it would in a pipe, from the end where the level is higher toward some outlet at a lower level. This is a fundamental principle in artesian wells, and is well illustrated in the artesian conditions at Cincinnati described below.
Ground water is constantly being exhausted by another process, namely, evaporation. This evaporation is not mainly at the water table but at the surface of the ground above. It is lifted from one to the other by capillary attraction.
As ground water is being constantly depleted in these ways, so it is intermittently replenished by rains. There is evidence to show that the level of ground water in this part of the United States has subsided a number of feet since occupied by civilized man.(See note 28) In some cases this is desirable, as where swamps are drained but in general it is a serious loss of a great natural resource. The drying up of some wells, and the necessary deepening of others, is the least of the losses. The real loss consists in the decreased moisture supply for crops. As the water table gets farther below their roots, the rise of moisture by capillarity becomes slower, and the ability to resist drought becomes less and less. It would not be unreasonable to estimate that a lowering of the water table five feet over the state of Ohio would be equivalent to the total loss of a year's crops with all the live stock dependent on it.
For this reason, as well as to prevent floods, it is highly important that farmers should favor percolation by plowing always on horizontal lines, and by keeping suitable vegetation on all slopes steep enough to wash.
Wells.-Wells are classified as surface wells and deep wells. This distinction has no reference to absolute depth. A surface well is one fed by ground water which is in direct communication with the surface, that is, it -may have percolated straight down (even though slowly). The level of water in such a well marks the local level of the water table. It is higher in wet seasons than in dry. Such wells are generally shallow, but they may be several hundred feet deep if no impervious bed is struck at a higher level. Deep wells derive their water from beneath an impervious cover; it may be very near the surface, but in all such "deep wells" the water must have entered the ground at a distance -- it may be a few miles or a few hundred miles. Very frequently such water is found to be under pressure or "head" and rises in the well. This is because it stands higher at the place of entrance than the level at which it is struck. It may even overflow at the mouth of the well. This was the original conception of an artesian well. As the word is now used, it is not necessary that the water should overflow or even rise to the surface, but only that it should rise by hydrostatic pressure, showing that it has been held down by an impervious cover. Generally speaking, such waters in humid lands contain more mineral matter in solution but less organic matter. Danger to health lies mainly in the latter.
Alluvium.-Well waters, sometimes under more or less pressure, may be obtained from almost any of the formations within this area, but they differ greatly in the quantity of water yielded. More wells of large capacity are finished in alluvium (including that of glacial age) than in any other formation. All municipal supplies, except those taken from Ohio River, are from wells in the glacial outwash of the great valleys. Where this is of Illinoian age, as at Norwood, the wells may penetrate sheets of glacial till as well as sand, gravel, and clay, but the water is derived from the sand and gravel beds. Such wells may strike water-bearing beds very near the surface, and many wells for domestic purposes go no deeper. In going deeper other waterbearing beds are pierced, and many wells derive water from three or four different beds. Frequently they go down to the underlying rock, and may even enter it a few feet, but the amount of additional water thus obtained from the rock is insignificant. Many manufacturing plants and other private interests have wells of the same kind as those which furnish municipal supplies.(See note 29)
All such water is decidedly hard as compared with that of the Ohio. The total amount of mineral matter in solution in the latter is 120 parts per million while water from the alluvium contains in general from three to six times as much.(See note 30) This is to be expected in view of the calcareous nature of all the glacial drift including the outwashed gravel. It also emphasizes the fact that local ground waters are not derived from the streams, but, on the contrary, are moving toward them. Thus the Ohio becomes more and more hard as it proceeds.
Surface Silt and Till.-The surface silt rarely affords well waters because it is generally so thin that its base is above the water table. On the other hand, the base of the till is frequently below the level of ground water, and therefore saturated. Being essentially a clay formation its pores are small and the water moves through them slowly. Wells which stop in this formation have therefore but small capacity, but usually sufficient for small domestic supplies. Among farms on the uplands, more wells stop in this formation than in any other. The disadvantage of small yield is to some extent offset by the advantage of less contamination. The dense texture of the clay protects these wells better from surface impurities than a more porous material would. This advantage cannot be emphasized very strongly when the careless way is observed in which many farmers allow contaminated water to drain into the well from the top.
The supply of well water from the till is somewhat enhanced by the joints described in Chapter VI. Water percolating through till also makes for itself small passages or tubes. In digging wells, or even post holes, water may sometimes be seen to gush from one of these tubes. Locally also there are pockets of sand and gravel from which the Yield is good In some such cases the water is found to be under a slight artesian pressure. The newer drift is on the whole better for wells than the older. It is generally less dense and more porous and is locally sandy. Well waters from the till are hard like those from the alluvium, containing on an average at least five times as much mineral matter as the Ohio River water.(See note 30)
Maysville and Richmond Groups.-Water supplies from the solid rock formations in this area are uncertain in both quantity and quality. From the standpoint of water supply, the solid rock formations of this area may be treated in four divisions, as follows: formations above the Eden shales, the Eden shales, the Trenton and underlying limestones, and the St. Peter sandstone. In the upper division, consisting of the Maysville and Richmond groups, both the limestones and shales are so dense that the water contained in their pores is almost unavailable. That which follows joints and bedding planes has freer flow. Joints in the limestone are thus frequently enlarged (See Fig. 30 and Plate. IV-B). These are often nearly circular in cross section and may be four or five inches in diameter. The finding of abundant water in the fresh rock depends on striking some such passages below the water table. In a group of nearby wells, one well may strike such a passage at small depth, another at great depth, and another not at all. One well may yield abundant water and another little. One may show considerable pressure -and another none. The outcome is always uncertain. Near the surface the bed rock is weathered and more porous, and the likelihood of striking water is correspondingly greater.
The water from this group is harder than that from the alluvium. In fact, since the edges of these beds abut against the alluvium in the great valleys, it is quite probable that much of the water in the latter is derived from these formations. Chemical analysis may show some common salt in these rock waters. In a few wells it is sufficiently abundant to spoil the water for drinking.(See note 32)
Eden Shales.-The Eden shales illustrate the general principle, a highly important one in other lines of geology, that soft rocks do not fracture to the same extent as hard ones. Their fractures are mainly near the surface. Moreover, fractures in shale do not enlarge by solution like fractures in limestone. Between the density of the Eden shales on the one hand and the lack of enlarged joints on the other, they afford almost no water to wells. Only where the formation immediately underlies the soil and is in a weathered condition is there much chance of obtaining water, and then only in dug wells. Where the passage of ground water is slow, it is evident that much more water will issue from the large rock surface exposed in a dug well than from the small surface exposed in a drilled well.
Trenton and Underlying Limestones.-For 800 to 1,000 feet below the Eden shales the beds of the Trenton, Black River, and Stones River groups are composed largely of limestone. The water conditions in these are essentially the same as in those above the Eden. Solution grooves and passages are perhaps still more prominent. They afford the only water available for wells. Unfortunately, the water from these formations is liable to be both salty and sulphuretted. It is frequently unfit for domestic use. In exceptional cases these rocks yield strong brines. The Eikenbrecker salt well at Ludlow Grove is 271 feet deep, and therefore stopped in the Trenton. Its water contains dissolved mineral matter, mainly common salt, to the extent of 98,222 parts per million, or nearly one-tenth of its weight.(See note 33)
St. Peter Sandstone.-Below these limestones is the St. Peter formation consisting largely of sandstone, one of the most widespread formations of the Upper Mississippi Valley. It yields a brine which is about one-third as strong as sea water, about one per cent of its weight consisting of mineral matter in solution. Common salt and sulphates are the chief ingredients. A number of deep wells in and near Cincinnati derive their water from this formation, but it is used only for mechanical purposes, such as cooling in the process of brewing and distilling.
An old analysis of the water from such a well at the Cincinnati Gas Works showed nearly one per cent of common salt, beside a considerable amount of lime and other salts(See note 34). A brine four times as salt as the sea was obtained from the same formation in a well at the works of the Champion Coated Paper Company at Hamilton.
The St. Peter sandstone is the chief bearer of water under artesian pressure. While the chief water-bearing stratum is here 1,100 to 1,200 feet below the level of Ohio River, the formation comes to the surface in Missouri, northern Illinois, and Wisconsin. Probably most of the water in this formation under Cincinnati entered at those outcrops, since the formation is overlain by many impervious beds. If this be true, the distance which it travels is about 350 miles. The surface of outcrop is about 850 feet above the sea. At Cincinnati the water rises to about 600 feet above the sea, or fifty to sixty feet above the street level in the business section of the city. This failure to rise to the full height at which it stands elsewhere is called by engineers 'loss of head." This is due to friction in the pores. A loss of only 250 feet of head in 350 miles is relatively small, and indicates an open texture in the sandstone through which the water travels. Where it comes to the surface in the states named, it is composed of large round quartz grains, with much pore space. Chippings brought up in drilling wells at Cincinnati and Hamilton indicate that a part of the water-bearing stratum in this region is of similar character, though the formation embraces also other beds which are not of this character.
Since the water from the St. Peter sandstone has here an effective head of 600 feet, it would actually flow from the mouth of the well in the lower parts of Cincinnati where the altitude is about 540 feet.
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