[11] Justice, pp. 110, 111.
[THE TORRENTS OF SWITZERLAND.]
By EDGAR E. DAWSON, M. E.
Mark Twain once said that he was in constant expectation in Switzerland of seeing a farmer fall out of his farm. The farmer has in many cases appreciated his hazardous position when harvesting his crops, and has put on crampoons to prevent a precipitous trip into the valley below. The crampoons prevent the farmer leaving his farm in such an undignified manner, but they do not prevent that same farm leaving its position on the mountain side. To show how, in many cases, the mountain sides are kept intact is the object of this paper. The old simile, "I am as sure of it as of the ground on which I stand," would be as much out of place in some parts of Switzerland as in those parts of the world where earthquakes are endemic. In fact, in these latter places, though the surface may receive a good shaking, it generally returns to somewhat the same neighborhood after its nervous peregrinations are over. Not so with the Swiss mountain side. When part of the mountain takes leave of the rest, it is forever.
Switzerland is often spoken of somewhat derisively as a garden, so perfectly have its pleasure grounds been laid out, and so completely comfortable does one find one's self in the midst of Nature's grandeurs. If its water courses had not been controlled and cared for as are those of a well-conducted park it would be chaos! The constant and vigilant struggle the Swiss have been forced to maintain against the liquid element is much to their credit, for they have generally been victorious. They have spent enormous sums of money in keeping their torrents and rivers within reasonable limits, and are even now, at times, forced to suppress new insurrections on the part of these irresponsible agents. The corrections of the water courses have been necessary for several reasons. In the first place, the erosions on the mountain sides result in deposits which present different inconveniences, of which I shall speak later. In the second place, the erosions are frequently the cause of landslides. The work of regulating the action of the water courses is now done according to accepted rules based on experience and on theories which have been confirmed by facts. Years ago, before the confederation took charge of this matter, it was done often in a haphazard, empirical fashion by the local authorities, with or without the aid of an engineer. But some great disasters in the canton of Grisons awakened the people to what might occur to many of them who had hitherto been more fortunate. At the end of September, 1868, both slopes of the Alps, and particularly the cantons of Valais and Grisons, were visited by floods of enormous magnitude. Such was the devastation caused that an appeal was made to the generosity of the nation at large in behalf of the sufferers. This was responded to with such liberality that a large portion of the sum subscribed was put aside for the purpose of improving the water courses permanently. The fact that collective action was necessary in the attempts to control the turbulent streams became very apparent. This being the case, the state was called upon to take charge of this colossal enterprise. In July, 1871, by federal decree, the confederation declared that the correction and extinction of torrents was a matter of public utility, and worthy of the subsidies of the national Government. At the same time the relative burdens of the cantons and the confederation were settled. The importance of the improvement of the water courses and of the wooding of the regions where they rise was recognized in the Constitution of 1874. There the matter was definitely put under federal control and classed with the allied question of the conservation of the forests. The problem of keeping the waters under control in Switzerland ranges from the marshy lowlands to the summits of the passes. In spite of the varying conditions that this range entails, there are certain general principles that bear on all cases where the water is in movement. As the Swiss supplies his want of coal by harnessing his streams, so he makes the water do a large share of the work of correcting its erring ways and preparing itself to be harnessed. This he does by utilizing its power of carrying or depositing stones and soil, according as it is held within narrow banks or allowed to roam at will. As this power depends also on the steepness of the slope down which it runs, he uses this latter factor as well.
When he has got the water courses into what he considers good working condition and one that should be permanent, he tries to clinch matters. This is done by so combining the various conditions of cross-section, slope, and quality of soil that the action of the water is automatic—that is, it brings down no more earth and stones than it is capable of carrying below to safer places where the dangers of floods are small. Whenever the force with which the water moves along is stronger than the cohesion of the soil, erosion occurs. This erosion will continue, the channel of the stream becoming ever deeper, until a soil is encountered whose resistance is equal to the erosive action of the water. As the alluvion is carried on, the slope of the stream will become steeper and steeper the higher one goes. This circumstance would be of much greater importance if the gorges and gullies in which most of the streams run were not so well provided with rock. The power of the water to cause erosion is lessened in proportion to the amount of material it is carrying with it, which material is generally the product of previous erosions. Whenever the current needs all its strength to carry the material it has in suspension, together with the solid matter it is pushing along, it will have lost all its power to cause erosion. If the slope is decreased, or if the matter in suspension is increased in any manner, deposits will occur. These deposits render the slope less steep at that point but steeper below, so that the action of the water beyond will make itself felt, and by digging gradually up stream tend to restore the original slope.
In some cases there is very little erosion where the current is much stronger than the cohesive power of the soil, for the reason that the beds of the streams have been almost paved with stones that have been carried along by the propulsive action of the water.
This has in many cases produced an equilibrium between the resistance and the destroying power; in others the equilibrium has been brought about in a different way by the same natural agents. The current of a stream will very often go on causing erosion until arrested by some rocky obstacle that determines a waterfall. These falls cause breaks in the action of the water not only in stopping the erosive action in its upward march, but also in checking the velocity of the water. Then, as basins are often formed just above the falls and where the current is much less swift, matter in suspension is deposited, so that when the stream is swollen it has material to work upon, before starting to make the original slope steeper.