Popular Science Monthly/Volume 24/February 1884/A Prehistoric Water-System
|A PREHISTORIC WATER-SYSTEM.|
By M. A. LÜDERS.
THE canton of Valais, though not so much frequented by travelers as some of the others, is really one of the most attractive cantons of Switzerland, and possesses, in its Alpine heights and its temperate valleys, many beauties peculiarly its own. There are also many features worthy of notice in the customs and the economical devices of its population. One of the most interesting features of the latter class is its system of conduits for watering the pasturage and tillage lands. This canton, in fact, possesses the model system of water-supply in the Alps. The people have maintained it from primitive times, and have by it, during the whole period of their history, drawn the water from the glaciers and mountain-springs, to be applied directly to every part of their farms and garden-plots. Without such watering as it makes practicable, the production of the district would fall off one half. This was exemplified in the experience of some of the towns during the building of the Simplon road in 1802, when their canals were interrupted and their water-supply was cut off. The grass-crop was so greatly diminished that the number of cattle fell off to one fourth of what it had been, and the former productiveness of the fields was not restored till new canals were made in 1810. In the little town of Zenegger, also, the springs were dried up, in consequence of an earthquake in 1855, and the number of cattle that could be maintained was reduced from two hundred to fifty. New conduits had to be made for this place also, with much labor and at great expense.
The maintenance of the water-system of the Canton Valais is intimately associated with the communal and family life of the people. The water is brought down in wooden flumes, that have to cross precipitous clefts at hundreds of metres above the bottom. A watchman has to go over them daily, and sometimes at night. His pay is very small, and his office is rather one of honor, full of dangers, to which some fall victims in nearly every year. By an ancient prescription, no one can hold a public office till he has served for some time as a guard of the aqueducts. It is not unusual, when repairs are to be made in particularly dangerous places, to send a priest along with the workmen, so that, if any of them meet with an accident, they may be provided with the consolations of religion.
The water is drawn from glaciers, lakes, or reservoirs, springs, and melted snow. Glacier-water is best esteemed, and is preferred if it is turbid, for then it holds valuable mineral constituents; lake or reservoir water contains less of such matters, for they have settled. Spring-water is least in favor, because it is most deficient in mineral substances, and because the time it occupies in running down the conduits is so short that it does not become warm enough to be used with advantage. The same objection is alleged against snow-water. The glacier-water, however, which is exposed to the sun for hours while running down the flumes, reaches the fields at an agreeable temperature, and ready for immediate application. This water is here free from oxide of iron, and is entirely fertilizing; but additional richness is sometimes given to it by carrying it around through the barn-yards, and making it the means for transporting manure directly to the fields.
The chief canals which bring the water down from the mountains vary in length from one thousand to fifty-five thousand metres; or, measured by the time it takes the water to run through them, from a quarter of an hour to six hours. The total length of the canals in the canton is one million five hundred thousand metres, or two hundred and fifty hours. The skill with which they have been located and constructed excites an admiration that is increased when it is remembered that they date from a remote antiquity and are the work of a simple country-people. Beginning often in the immediate neighborhood of the glaciers, crossing treacherous hills and lofty precipices, and spanning deep abysses, passing through tunnels and cuts, led along artificial terraces, that sometimes require additional embankments or walls to support them, these canals are really formidable works. They furnish the life-blood of civilization to the canton, and stand for a capital of incalculable value. They have been built and are kept up by the villages; and a badly kept one is an exception.
In most of the valley-slopes they lie in groups of three or four, the uppermost one being the longest, and reaching far up toward the glacier-source, and have an average descent of about 0.5 per cent. The subordinate ditches are of a simpler character, till finally a mere mark on the ground is all that directs the water to the particular spot where it is wanted.
The application of the water begins at about the first of April in the valleys, and later as the height of the locality increases, till, on the highest cultivated grounds, it is delayed till the middle of June, and is continued for from two and a half to three months. The right to draw off the water is apportioned out by village officers into turns, of which there are from four to twelve in the season, of from eight to twenty-one days or more each, according to the number of land-owners claiming to share in it.Among the most remarkable of the main aqueducts are those of the Gradetsch Valley, where the water is led down by eleven canals, the highest of which starts from an altitude of 2,300 metres, or nearly 7,500 feet above the sea. Some of the canals require wooden conduits three or four thousand metres long, that have at times to be supported by poles for six hundred metres at a stretch. To reach them for repairs the workmen have in some places to be let down the perpendicular rock-walls with ropes.
The oldest of the canals date unquestionably from pre-Roman times. The "Roth" Canal supplies three villages with water, and is 19,200 metres (more than eleven miles), or four hours and twenty-three minutes long. It starts from "La Plaine Morte" glacier, on the Weisshorn, 2,673 metres above the sea, crosses several clefts, is conducted through a tunnel more than three hundred metres long, is covered for 9,600 metres, exhibits other features of high engineering skill, has an average section of a metre and three tenths, and delivers nearly a cubic metre of water a second. An artificial lake, or reservoir, has been built in the same district, to hold the water that is not wanted for immediate use. Its water, however, has not the same value as that taken directly from the glaciers, because it has lost most of its mineral constituents by settling; but, as it has become thoroughly warmed, it is admirably adapted to those applications in which water is wanted simply to refresh vegetation, and make the soil more friable.
The villages of Ried and Bietsch have three aqueducts (Kehrwasser, Bietscherrinne, and Riederrinne), severally 8,400, 2,400, and 12,000 metres long, to bring down the muddy water from the great Aletsch glacier, which are led for long distances along vertical cliffs and over giddy chasms. At one point on the "Kehrwasser" three men have been killed, within twenty-five years, by falling into the gorge. The water of the Bietscherrinne issues foaming from a fearful-looking chasm. The canal, having a border formed of stones laid with sods, and masked by bushes from the Massa ravine that yawns beneath it, is safe to walk along at first. The bushes soon disappear, and the aqueduct becomes simply a wooden conduit, made of planks that have to be drawn to the place, and adjusted there with great danger, while the narrow, slippery gang-plank, which is the only walk, offers but the most precarious footing to one who has to look down through the high trestles or into the steep ravine of the wild Massa, on one side, while he must watch on the other side lest he hit his head against the overhanging rocks and lose his balance. The highest of the three canals, the Riederrinne, is distinguished from the others by its loftier rock-walls and deeper chasms. It reaches to the foot of the Aletsch glacier, and draws the water from its source. Near it may be seen older, abandoned canals.
Near where these three canals start is the Marjälen Lake, having its surface covered, even in summer, with floating ice. Its natural outlet is by the valley of Viesch into the Rhône, but occasionally, in seasons of extraordinarily high water, it overflows in the opposite direction, and pours its floods into the Massa, causing breaks in the canals and stopping the conveyance of water. The existence of the villages of Bietsch and Ried depends upon their obviating the mischievous effects of these overflows, and it is customary to give a pair of shoes to the mountaineer who first notifies the dwellers in the valley of the occurrence of a break. A canal has been built to reduce the level of the lake, but it is not sufficient for the purpose.
The irrigation-canals of Lombardy and Lucca are more scientifically constructed, and display more technical skill, but they are not laid out on a more extensive scale than those of the Canton Valais. It is a fact deserving admiration that all of these colossal works have been and are still being built without the aid of technical knowledge, without any expensive instruments, by the people of the country; and that these people not only make great sacrifices of money and labor, but put their lives at stake, to assure themselves of a supply of water. Certainly a real struggle for existence is going on here; for, without a system of water-supply, there would be in many of the villages no grass, no vegetable crops, no corn, and no wine.—Translated for the Popular Science Monthly from Das Ausland.