Stagnant water

“ When the larger rivers are full the tributaries rise because their waters are dammed up or even flow backwards. The waters then become stagnant in every sense of the word, and decompose rapidly through the action of the heat and the vegetable and other detritus which they contain; at such times they produce paludian fevers; principally in April and May, when the waters begin to fall and the larger rivers receive the supplies of stagnant waters released from their tributaries. ”

“ It is often noted that with long streams the water becomes muddier farther down, and it may naturally be thought that it is because of the added erosion of the stream upon its bed in its longer course. ”

“ No break had occurred, not even a pause of ten minutes—rain, rain, rain, till people became as accustomed to the continuous fall upon their roofs of zinc or thatch as to the ticking of a clock—and the parched earth, now thoroughly soft and moistened, ran off the superfluous water in streams from every runnel and gully, which emptying themselves into the larger rivers, these in their turn came down in such force as to flood their banks, doing much and serious damage. ”

“ These transgressions are caused in part by the gradual sinking of the land and in part by the rising of the waters. It is not possible always to tell which agency is at work. Often both may be. One thing about the rising of the waters themselves might be looked at as particularly alarming. The rivers, which, of course, are parts of one great water system, whose centre and prime mover is the sea, are not only constantly - 219 - wearing the land down toward sea level but raising the sea level by the inpour of vast quantities of ground-up land. ”

“ Oh, we're going deeper down:
If we fail to get the water, then it's ruin to the squatter,
For the drought is on the station and the weather's growing hotter,
But we're bound to get the water deeper down. ”

“ When, too, in flood time, the hurrying current seems to respond more sensitively to the shape of the shallows and the banks beneath, there boils up from below a ceaseless succession of irregular circles as if the water there expanded from a centre, marking the verge of its outflow with bubbles and raised lines upon the surface. ”

“ After the height of the flood the stream clears itself by the flowing away of the turbid water much more rapidly than the water clears itself by sedimentation in the reservoir. That is to say, if at the time of maximum turbidity we take a certain quantity of water from the stream and put it aside to settle, at no time will the improvement by settling equal the improvement which has taken place in the stream from natural causes. ”

“ In the dry season the stream runs at the bottom of a narrow and deep groove, whose sides are polished and fluted by the boiling action of the water in flood, like the rims of ancient Eastern wells by the draw-ropes. The breadth of the groove is often not more than from forty to sixty yards, and it has some sharp turnings, double channels, and little cataracts in it. As we steamed up, the masts of the "Ma Robert," though some thirty feet high, did not reach the level of the flood-channel above, and the man in the chains sung out, "No bottom at ten fathoms." ”

“ 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. ”

“ Those extinct rivers, dead of drought, in connection with the great canon system, present perfectly overwhelming evidence that the general deposition of aërial water, the consequent floods and torrents, forming, as they all do, the distinct expression of a sharply-defined cycle of climate, as compared either with the water phenomena of the immediately preceding Pliocene age, or with our own succeeding condition, constitute an age of water-catastrophe whose destructive power we only now begin distantly to suspect. ”

“ The river inundations in hot countries usually take place but once in a year, and, though the banks remain submerged for days or even weeks, the water at that period, being derived principally from rains and snows, must be less highly charged with mineral matter than at lower stages, and besides, it is always in motion. ”

“ When the earth's crust is thrown up in mountain folds, and between them valleys are formed, the level of rivers is sometimes lowered and the rapidity of their flow is checked. A stream which has torn down its walls at a rapid rate becomes a sluggish water-course, its current clogged with sediment, which it has no power to carry farther. When such a river begins to build and obstruct its own waters it bars its progress and may form a lake as the outlet of its tributary streams. Many ancient rivers have been utterly changed and some obliterated by general movements of the earth's crust. ”

“ This heat comes in the middle of a drought, too, as we have not had rain for about four weeks—another phenomenon. Our rain-tank is empty, so we now depend on the supply of brackish water from the wells, and even that is reported to be limited, which is alarming, as one would commit almost any crime to get enough water for a bath. ”

“ Before going further with the discussion, however, it is well to remark that the comparative rarity or frequency of inundations in earlier or later centuries is not necessarily, in most cases not probably, entitled to any weight whatever, as a proof that more or less rain fell formerly than now; because the accumulation of water in the channel of a river depends far less upon the quantity of precipitation in its valley, than upon the rapidity with which it is conducted, on or under the surface of the ground, to the central artery that drains the basin. ”

“ A fall in the level of the ground-water may be due to a dry season, or to improved subsoil drainage. A rise in its level is due to an increase in the rainfall, or some obstruction in the outflow,223 as from a swollen river. The tide may influence the level of the ground-water at a great distance. A sudden alteration in the level of the ground-water is a common cause of floods in mines. ”

“ Land which requires draining, is that which, at some time during the year, (either from an accumulation of the rains which fall upon it, from the lateral flow, or soakage, from adjoining land, from springs which open within it, or from a combination of two or all of these sources,) becomes filled with water, that does not readily find a natural outlet, but remains until removed by evaporation. ”

“ When the stream is in flood and comes roaring down the rocky gorge bearing along with it a vast amount of mud, gravel, and - 169 - stones, one can easily see how the friction of the transported material must wear down the hard bed and sides of the channel, and how this process repeated month after month and year after year, must aid the decomposing forces in scooping out a deep ravine. From the cascade the ascent of the stream becomes steeper and the run of water is consequently more rapid. ”

“ They have now become broad, shallow stream beds, in which muddy water trickles in slender currents during the dry seasons, while when it rains there are freshets, and roaring muddy torrents come tearing down, bringing disaster and destruction everywhere. ”

“ This drains off from the surface, forming rills, which collect as they descend, by their own weight, into the lowest channels of the ground, and form into streams and rivers, and back into the sea comes the water which the air had taken away, with this difference, that it is free from salt and fit for the many uses to which fresh water alone can be applied; when the vapour rises from the sea, none of the saline matters rise with it, for, although the water is volatile, yet they are not, and this is the whole source of fresh water. ”

“ Unequal evaporation and precipitation likewise disturb the level of the sea and occasion movement. In the open sea the movements generated by differences of level, like those generated by differences of density, are chiefly slow, creeping movements, but movements which never cease. In bays and gulfs, on the other hand, the surface of the water may be so raised, either as the result of wind, river discharge, or heavy precipitation, as to give rise to strong outward currents. ”

“ The main causes of lake destruction are the lowering of outlets by stream cutting which results in ultimate drainage of lakes, and by sedimentation from streams entering lakes which results in the depressions being filled up. Lake basins are being filled constantly with sediment from inflowing water, and also by wave action along the shores and particularly by organic matter deposited by shell-bearing animals, plants and other growths. ”

“ As long as the mud remains soft enough to allow the fish to rise slowly through it, they come to the surface every now and then to take in a good hearty gulp of air, exactly as gold-fish do in England when confined with thoughtless or ignorant cruelty in a glass globe too small to provide sufficient oxygen for their respiration. But when the mud hardens entirely they hibernate, or rather æstivate, in a dormant condition until the bursting of the monsoon fills the ponds once more with the welcome water. ”

“ Muddy waters result principally from the action of rains upon the surface of ground capable of being washed, and the turbidities of the stream at any point below will occur at the times when the muddy waters reach it in the natural course of flow, and will disappear again when the muddy waters present in the stream system at the end of the rain have run out, and have been replaced with clear water from underground sources, or from clearer surface sources. ”

“ In a very loose, gravelly, or sandy soil, which has a perfect outlet for water below, all but the heaviest falls of rain will sink at once, while on a heavy clay, no matter [pg 032] how well it is drained, the process of filtration will be much more slow, and if the land be steeply inclined, some of the water of ordinarily heavy rains must flow off over the surface, unless, by horizontal plowing, or catch drains on the surface, its flow be retarded until it has time to enter the soil. ”

“ To produce a flood the rainfall must be heavy and widely distributed, and to produce a flood of exceptional height the duration of the rainfall must be so great that the flood waters of the most distant affluents reach the point considered, simultaneously with those from nearer points. The larger the catchment basin the less probable is it that all the conditions tending to produce a maximum discharge should simultaneously occur. Further, lakes and the river bed itself act as storage reservoirs during the rise of water level and diminish the rate of discharge, or serve as flood moderators. ”

“ These floods are succeeded by periods of drought. The flow of water in the streams shrinks away, often leaving their beds almost dry. As a consequence, crops and herds suffer, the mill-wheels are stopped or turn but slowly and feebly, the transportation of merchandise is impeded, and the various industries of life suffer. The forests prevent such a deplorable condition of things. The spongy soil formed by their fallen leaves, accumulated for years, retains the rain which falls upon it as in a great reservoir, and obliges it to flow off gradually instead of with a sudden flood. ”

“ The deeper the water in which it falls the greater the possibility of its drifting farther still, since in sinking, it would fall, not vertically, but rather as the drops of rain in a shower when being driven before a gale of wind. ”

“ 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. ”

“ In arid regions the ground-water surface lies so low that for the most part stream ways do not intersect it. Streams therefore are not fed by springs, but instead lose volume as their waters soak into the thirsty rocks over which they flow. They contribute to the ground water of the region instead of being increased by it. Being supplied chiefly by the run-off, they wither at times of drought to a mere trickle of water, to a chain of pools, or go wholly dry, while at long intervals rains fill their dusty beds with sudden raging torrents. ”

“ But unless the water-supply is very great—and it is only so occasionally—the stream is swallowed by the thirsty sands and absorbed by the atmosphere, which is so dry that nothing ever decays, and causes more rapid evaporation than is known elsewhere. ”

“ In the heaviest storms, some water will flow over the surface of even the dryest beach-sand; but, in a well drained soil the water of ordinary rains will be at once absorbed, will slowly descend toward the water-table, and will be removed by the drains, so rapidly, even in heavy clays, as to leave the ground fit for cultivation, and in a condition for steady growth, within a short time after the rain ceases. ”

“ It is no less clearly shown by the way in which almost every drop of running water—whether in gutter, brooklet, stream or large river—becomes discoloured after each heavy rainfall, since the matter which causes this discolouration must be derived from the surface {214}of the country, must always pass from a higher to a lower level, and must ultimately reach the sea, unless it is first deposited in some lake, or by the overflowing of a river goes to form an alluvial plain. ”