Water level

“ Lloyd-Davies, the difference being accounted for by the rain which is required to wet the surfaces before any flow off can take place, in addition to the rain-water collected in tanks for domestic use, rain required to fill up gullies the water level of which has been lowered by evaporation, and rain-water absorbed in the joints of the paving.
The intensity of the rainfall decreases as the period over which the rainfall is taken is increased. ”

“ In the great plateaus of the world, we often find immense tracts of land so nearly of the same level as scarcely to afford sufficient drainage for the surplus water; of course, we should expect to find, in such places, little variation of temperature arising from difference in elevation. ”

“ Ground air is in constant motion, its movements depending upon a great many factors, some among these being the winds and movements of the atmospheric air, the temperature of the soil, the surface temperature, the pressure from the ground water from below, and surface and rain water from above, etc.
Ground Moisture.—The interstices of the soil above the ground-water level are filled with air only, when the soil is absolutely dry; but as such a soil is very rare, all soils being more or less damp, soil usually contains a mixture of air and water, or what is called ground moisture. ”

“ In dry climates permanent ground water may be found only at depths of hundreds of feet. Ground water is held at its height by the fact that its circulation is constantly impeded by capillarity and friction. If it were as free to drain away as are surface streams, it would sink soon after a rain to the level of the deepest valleys of the region. ”

“ In considering the principles of well supplies it is important to bear the following facts in mind. The crust of the earth, so far as it is permeable and above the sea-level, receives from rainfall its supply of fresh water. That supply, so far as it is not evaporated or absorbed by vegetation, passes away by the streams or rivers, or sinks into the ground. If the strata were uniformly porous the water would lie in the rock at different depths below the surface according to the previous quantity and distribution of the rainfall. ”

“ The course of water flowing underground is not strictly analogous to that of rivers on the surface, there being, in the one case, a constant descent from a higher to a lower level from the source of the stream to the sea; whereas, in the other, the water may at one time sink far below the level of the ocean, and afterwards rise again high above it. ”

“ Now suppose the water basins which hold the lakes to be over a thousand fathoms (six thousand feet) deep. We know they are not more than four hundred and twenty feet deep; but suppose them to be six thousand feet deep. The process of evaporation, after the St. Lawrence has gone dry, might go on until one or two thousand feet or more were lost from the surface, and we should then have another instance of the level of an island water-basin being far below the sea-level, as in the case of the Dead Sea; or it would become a rainless district, when the lakes themselves would go dry. ”

“ Every considerable addition to its water wells up, and soaks its very surface; and that which is added after it is already brim full, must flow off over the surface, or lie in puddles upon it. Evaporation is a slow process, and it becomes more and more slow as the level of the water recedes from the surface, and is sheltered, by the overlying earth, from the action of sun and wind. ”

“ When the water table goes below the lowest reaches of the well, no more water can be pumped, and it is necessary to extend the well further into the earth until it again goes below the water table and reaches into the saturated area where water is abundant.
The water table is not constant around the world, even though water seeks its own level. The water table might be high in one section of the country, low in another. ”

“ Underground water, like surface water, tends to attain a level surface, but in so doing it may need to flow long distances through the pores of the soil, and to overcome the resistance incident to so doing some head will be required. ”

“ Such a salt-water saucer of fresh water is maintained full to overflowing by the rainfall, and owing to the frictional resistance of the sand and to capillary action and the fact that a given column of fresh water is balanced by a shorter column of sea water, the fresh water never sinks to the mean sea-level unless artificially abstracted. ”

“ It is obvious that if the levels of the sewers and other circumstances are such that the sewage can safely be discharged at low water, and the works are to be constructed accordingly, it is most important to have accurate information as to the level of the highest low water which may occur in any ordinary circumstances. ”

“ Hence if a well be sunk to the water-bearing level of any stratum, it forms a communication with a permanent subterranean sheet of water, affording plentiful supplies to the inhabitants of upland districts, which are above the level of natural springs. ”

“ THEIR SOURCE Springs, or the natural fountains of water, take their rise from reservoirs stored under ground. Water maintains a level, and hence the height to which a spring will rise depends on that of the level from which it is supplied. If the internal reservoir be on a hill, and the spring should gush out in a valley, the water may rise to a considerable height and form a natural fountain; but, on the other hand, if the reservoir be at some depth below the surface, the water may never reach the surface, and mechanical aid may be required to obtain it. ”

“ I cut the stump off level with the ground, floored it over, and placed a pump in it, and in the driest seasons it furnishes abundant water for my stock. I have about fifteen dug wells on my place, all within the space of two square miles; the depth of the water-surface in these varies from eight to fifteen feet. A large curbed well stands in my gin-house, within twenty feet of the bank of the river, and to-day the water stands in this well at least fifteen above the surface of the stream, and is in no manner affected by its rise or fall. ”

“ When the tide begins to flow up the river there may be a low-level salt water current moving landward and a high-level fresh water current moving seaward, but this is quite a temporary state of affairs. The surface slope is landward, and the water moving seaward is not moving in obedience to the surface slope. ”

“ It is a fixed rule that water, descending in the soil, will find the lowest outlet to which there exists a channel through which it can flow, and that if, after heavy rains, it rise too near the surface of the ground, the proper remedy is to tap it at a lower level, and thus remove the water table to the proper distance from the surface. This subject will be more fully treated in a future chapter, in considering the question of the depth, and the intervals, at which drains should be placed. ”

“ The existence of lakes in hollows of the land depends upon the balance between precipitation and evaporation. A stream flowing into a hollow will tend to fill it up, and the water will begin to escape as soon as its level rises highLakes and internal drainage. ”

“ The resistance of the sea water to the ascent of the fresh water is cut off by this ingenious contrivance, and the fresh water rises above the level of the sea through the pipe, by natural causes, the head or source of the spring being in the upper ground of the mainland. ”

“ This is a very good arrangement where the land is not entirely level, as it will cause the low places to dry up as quickly as possible. But a better way is to have the ground so level that the water will sink evenly and leave no sinks nor any high and prematurely dry places. ”

“ But the magnitude of a stream is more especially regulated by the extent of country which forms the declivities of its basin, though there is no invariable proportion here, for a small basin in a humid region will yield a greater quantity of water than one much more considerable in a different situation. High mountains, a humid climate, and a wide superficial drainage, are the three physical circumstances which lead to the accumulation of vast bodies of water, the magnitude of which will be proportionate to the degree in which these causes are in combined operation. ”

“ What in water did Bloom, waterlover, drawer of water, watercarrier, returning to the range, admire?
Its universality: its democratic equality and constancy to its nature in seeking its own level: its vastness in the ocean of Mercator’s projection: its unplumbed profundity in the Sundam trench of the Pacific exceeding 8000 fathoms: the restlessness of its waves and surface particles visiting in turn all points of its seaboard: the independence of its units: the variability of states of sea: its hydrostatic quiescence in calm: its hydrokinetic turgidity in neap and spring tides: ”

“ The nearer and steeper the elevation, the greater the force with which the water flows through the valley pipes, and hence the stronger the discharge from the faucets.
Relatively few cities and towns are so favorably situated as regards water; more often the mountains are too distant, or the elevation is too slight, to be of practical value. Cities situated in plains and remote from mountains are obliged to utilize the water of such streams as flow through the land, forcing it to the necessary height by means of pumps. ”

“ A permanently high ground water, that is, within 5 feet of the surface, is bad, while a permanently low ground water, that is, more than 15 feet from the surface, is good; and (2) violent fluctuations are bad, even with an average low ground water; a comparatively high ground water with moderate and slow fluctuations may be healthful. ”

“ In the sheets of water which we find distributed over that and every other inhabitable inland basin, we see reservoirs or evaporating surfaces just sufficient for the supply of that degree of moisture which is best adapted to the well-being of the plants and animals that people such basins. ”

“ The measurements made indicate that tens of thousands of acre feet of water are annually contributed by mountain streams and by rainfall to the underground reservoir, and that about the same quantity of ground- water is annually discharged into the atmosphere through the soil and the plants in the shallow water areas. ”

“ If a lake were about to be formed it would be in this way—the rain descending on the surrounding high lands would run in rills to the lowest part, and there collect, forming a pool which would gradually increase in size as the water flowed into it, this increase continuing until the surface became so large that the evaporation from it exactly equalled the supply, it would then extend no further, but remain a permanent lake or inland sea, giving off vapour to refresh the surrounding country, and again receiving it back by streams and rivers, as does the ocean. ”

“ The consequence of the ancient evaporation, by which the great Pleistocene lake was reduced to its present modest dimensions, and of the ceaseless modern daily evaporation, is the impregnation of the waters of the lake with salts and other mineral substances to a remarkable degree. Ocean water contains on an average 4-6% of salts: Dead Sea water contains 25%. ”

“ We have seen, that evaporation proceeds much more rapidly from a surface of water, as a pond or river, than from a land surface, unless it be fully saturated, and that evaporation from the water exceeds the whole amount of rain, about as much as evaporation from the land falls short of the amount of rain. ”

“ The former part of the volume is occupied with discussion of the laws that govern stream-flow, rainfall, evaporation, ground storage, surface storage, and surface or flood flows. Gauging flows and the method of computing them are next considered. The local water systems are then described. The latter part of the book is devoted to generalizations as to water supply, chemical analyses, public water supplies, water power, evaporation, ground storage, effects of vegetation, and stream-flow; and a list of the developed water powers and the drainage systems is given in the appendix. ”

“ The whole surface of the earth is divided into drainage areas that lead either directly through rivulets and rivers to the ocean, or into some land-locked basin, where it either finds an outlet under ground or is kept within bounds through the process of evaporation, the same as is the case with our great oceans. ”

“ Upon every water-shed which is drained into the sea, the precipitation, for the whole extent of the shed so drained, may be considered as greater than the evaporation, by the amount of water which runs off through the rivers into the sea. In this view% all rivers may be regarded as immense rain-gauges, and the volume of water annually discharged by any one, may be taken as an expression of the quantity which is annually evaporated from the sea, carried back by the winds, and precipitated throughout the whole extent of the valley that is drained by it. ”

“ If the spring is located higher than the grounds and buildings to be supplied, a simple gravity supply line may be carried from it, with pipes of good size, thus avoiding undue friction in the line, and stoppages. If lower than the house, the water from the spring must be raised by some pumping method.
All water found underground owes its origin to the rainfall. If concealed water is returned to the surface by natural processes it is called spring water, but if recovered by artificial means it is called well water. ”

“ The tide flows up the river many miles past the waterworks, carrying up with it the filth from the sewers. The supply of water was, to be sure, obtained when the tide was down, but as the banks of the river are clothed with sedges in many parts, and its bottom deep with mud, the water can never be free from sewage. ”