Watershed

“ The thirsty soil absorbs, and the unclouded sun of summer evaporates, the moisture in its progress; and this, I take it, is the solution of the apparent paradox, with respect to rivers—that they are sometimes greater at their source than at their mouth. Such is the state of the river in summer; but what must it be in winter, when every valley and ravine pours forth its tributary streams into one common channel, the sole outlet of the accumulated waters of an extensive district? ”

“ You see how the water, rebounding from its second plunge, shoots in a broken mass of foam into the brown pool below, and therein swirls and swashes for a while, and then escapes by an outlet that you might leap across, talking to thousands of stones as it spreads itself out in the shallow bed. Standing with your back to the fall, and looking down the stream, the view, shut in by the trees on one side, by a rough grassy acclivity on the other, is one that lures you to explore it, striding along the rugged margin, or from one lump of rock to another. ”

“ It is like some river that is composed of two affluents, one of which rises away up in the mountains, and is fed by the eternal snows; the other springs on the plain somewhere, and is but the drainage of the surface-water, and when hot weather comes, and drought is over all the land, the one affluent is dry, and only a chaos of ghastly white stones litters the bed where the flashing water used to be. ”

“ A strong, deep love, like the Nile in flood, leaves, like a sediment behind, which in so many cases renders marriages, from which the tumultuous stream has passed, happy and stable, an alluvial deposit, which makes the earth rich and fruitful in the sober green of friendship; but when the slender, light-hearted streamlet is dried up, the effect of its passage is only too often seen in the uncovering of ugly roots and stones, and a removal, not a deposit of sediment. ”

“ Miles to the right, miles to the left, miles away in any direction he might look, he could see, beyond whole sections of open water and flat acres of drift, the submerged woodlands of bottoms, the river banks two or three or four hundred feet high—so they looked—and great expanses of open water in which lone trees stood to mark places that on a hot summer day must offer grateful shade to cattle, or to grain reapers, or whoever came there when those bottoms were not covered with ten feet or so of water. ”

“ When spring freshets spread out sheets of débris over the flood plain of a river, as frequently happens when streams in high latitudes flow northward, the previously frozen soil and the ice of ponds and swamps may be buried and indefinitely preserved. ”

“ Works in River Valleys for diminishing Floods.—Rain falling on bare, impervious, hilly slopes rapidly flows into the nearest water-course, carrying with it any loose soil or disintegrated materials met with in its rush down the ravines, thereby intensifying the torrential character of the river, increasing the height of its floods and adding to the sediment obstructing its course to the sea. ”

“ Here is the fashion in which a mountain stream gets down from the perennial pastures of the snow to its proper level and identity as an irrigating ditch. It slips stilly by the glacier scoured rim of an ice bordered pool, drops over sheer, broken ledges to another pool, gathers itself, plunges headlong on a rocky ripple slope, finds a lake again, reinforced, roars downward to a pothole, foams and bridles, glides a tranquil reach in some still meadow, tumbles into a sharp groove between hill flanks, curdles under the stream tangles, and so arrives at the open country and steadier going. ”

“ 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. ”

“ But it seldom happens that pure water is employed for the purposes of irrigation. The water of rivers, more generally, is diverted from its course, more or less loaded with mud and other finer particles of matter, which are either gradually filtered from it as it passes over and through the soil, or in the case of floods subside naturally when the waters come to rest. ”

“ You all know from whence the soil comes which has filled up, in the course of ages, the great æstuaries below London, Stirling, Chester, or Cambridge.
It is river mud and sand. The river, helped by tributary brooks right and left, has brought down from the inland that enormous mass. You know that. You know that every flood and freshet brings a fresh load, either of fine mud or of fine sand, or possibly some of it peaty matter out of distant hills. Here is one indisputable fact from which to start. Let us look for another. ”

“ In later times, when an abundant and various soil covered the earth, when every river brought down to the ocean, not only its yearly tribute of mud or clay or lime, but the débris of animals and plants that lived and died in its waters or along its banks, when every lake and pond deposited at its bottom in successive layers the lighter or heavier materials floating in its waters and settling gradually beneath them, the process by which stratified materials are collected and gradually harden into rock is more easily understood. ”

“ But the irrigation engineers have lately discovered something wonderful about even these despised rivers. During the very driest seasons, when the stream is apparently quite dry, there is still a great body of water running in the sand. Like a vast sponge, the sand holds the water, yet it flows continually, just as if it were in plain sight, but more slowly of course. ”

“ With favorable conditions, as a stream carrying abundance of fine silt, the water moving sluggishly over the inundated surfaces will drop its earthy burden upon them in thin, loose layers, evenly at first, but, as shallows are formed, irregularly modified, or as sudden freshets produce stronger currents, eddies and ripple-bars gather or disturb the sediment. New lands in wet banks and knobs will begin to appear over the highest ridges. ”

“ 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. ”

“ 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. ”

“ Every shower of rain washes some dirt—by which we mean sand or gravel or loam or chalk—from the land into the nearest rivulet. The rivulet hurries with it down to the neighbouring river, and the river carries it down to the sea. If the river is going very fast it carries most of its dirt along with it, and we generally find the river muddy after rain. But when the river slackens its pace, as it usually does when it nears the sea and meets the sea's tides, then it lets the dirt fall; and thus at the river's mouth we find mud-banks or sand-banks. ”

“ Pouring its impetuous waters through wild tracks, covered with trees of little value except for firewood, it sweeps down whole forests in its course, which disappear in tumultuous confusion, whirled away by the stream now loaded with the masses of soil which nourished their roots, often blocking up and changing for a time the channel of the river, which, as if in anger at its being opposed, inundates and devastates the whole country round ”

“ At time of flood young tributaries with steeper courses than that of the trunk stream may bring down stones and finer waste, which the gentler current cannot move along, and throw them as a dam across its way. ”

“ The natural consequence is a stream of the most broken and impetuous character, a stream whose rushing, roaring, and foaming drowns all sounds contiguous to it; rapid after rapid of seemingly tempest-tossed and crested billows, of whirlpools and eddies, of backwaters and heavings into surface currents, and never a still pool to be found anywhere. ”

“ The curtailment of the trunk, by its immersion in the river, quite destroys the fair proportions of the tree, and thus makes us sensible of a regularity and propriety in the usual forms of nature. The flood of the present season-- though it never amounts to a freshet on our quiet stream--has encroached farther upon the land than any previous one for at least a score of years. ”

“ 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. ”

“ Take the finest River Sand you can get, after having sifted it several times through a fine sieve, throw it into a glass vessel full of clear Water, and rub it a good while between your fingers to render it still finer; then pour off the Water by inclination, and dry the Sand in the sun. The Sand being thus prepared, bury the Flowers gently in it with their Leaves and Stalk, disposing them in such a manner that their form may not be in the least injured. ”

“ Let us consider for a moment the differences which obtain between the conditions of life in water or in soft mud at the bottom of pool or river, and those which are undergone by a dweller in stiff soil or vegetable débris. In the first case the medium is fluid or at most very soft, while the soil is at least stiffer and harder to traverse. ”

“ 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. ”

“ The stream which, rightly directed, would have flowed in soft irrigation from field to field -- would have purified the air, given food to man and beast, and carried their burdens for them on its bosom -- now overwhelms the plain, and poisons the wind ”

“ Many women were carrying water in jars upon their shoulders from shallow wells scooped out of the sand in the bed of the stream, which is not a stream at all, save during the floods of the rainy season. ”

“ The few streams which creep in winter over this miserable waste shrink away and disappear before the scorching rays of the summer sun, which penetrate the soil to a great depth, and pump up every particle of moisture as far as they reach. ”

“ Water arising by land-floods brings along with it much of the most soluble parts of the manure from the higher lands to the lower ones. River-water in its clear state and those springs which are called soft are less beneficial for the purpose of watering lands, as they contain less earthy or saline matter; and water from dissolving snow from its slow solution brings but little earth along with it, as may be seen by the comparative clearness of the water of snow-floods. ”

“ The water in the soil, brought thither as snow or rain, or by stream and possibly by irrigating ditch, is vastly more necessary than the water in the pipe. The soil water, added to by rain and stream, conserved by cloud and fog, is still further preserved, for the plants which receive it into their roots, by the invisible moisture in the air. ”

“ Then they asked the Medicine Man again, and he said: “Let the people dance and sing and call upon the gods again. And afterwards let the women take jars and go and fill them at the river and bring them up and pour out the water upon the pond. Then the spirits of the water will return, and the pond will be filled.” So the people did all this; and the women carried up jars and jars full of water from the river and poured it into the pond. But the water sank away faster than they could pour it in, and there was nothing left but a puddle. ”

“ Even richer, if that be possible, than the fauna of the river, and at any rate more diverse, is that to be found at the proper season on the shores and surface of all the lakes and larger water-pools which lie within the forest and are filled either by the spring rains or by the full floods of the river. ”

“ A river flowing to the sea or emptying itself into an inland lake, carries its burden of gravel, sand, and mud, and sooner or later, as the rate of flow slackens, it deposits the materials in the river-bed or on the floor of the sea or lake. ”

“ Great rivers falling from the high country with prodigious violence, during the tropical rains, have in the plains washed away the soil down to the solid rock, and formed large basons of great capacity, where, though the water becomes stagnant in pools when the currents fail above, yet, from their great depth and quantity, they refill being consumed by evaporation, being also thick covered with large shady trees whose leaves never fall. ”