THE CANALIZATION OF STREAMS.

BY ROBERT MARSHALL BROWN,

State Normal School, Worcester, Mass.

The traffic of the Mississippi River has fluctuated during the last thirty years. With the fluctuations there has been at the same time. a constant decrease in the volume and tonnage of trade products transported along this water-way. The improvements of the low-water channel, while they have been efficient as far as the project of the maintenance of a channel is concerned, have not given the expected impetus to the use of the river as a commercial route. There is the handicap still of an uncertain passage during the low-water season even though the years of dredging are considered successful, and though the experience of the last ten years makes the engineers confident that the 250-foot width and 92-foot depth of channel of the dredging project is easily within the capacity and power of the corps and plant. Add to this, the possibility of the river falling to an extremely low stage, the restrictions and dangers during the flood stage of the river, the tortuous path, making the distance from Cairo to the Gulf three times the distance by air-line, the diversion of some trade to other paths and the competition of the valley lines, and we have the sum of the conditions affecting the river traffic. On the other hand, there is an increasing need of transporting lines out of the Great Valley. While the mileage of railroads is increasing, the demands for transportation are increasing with greater strides. Railroads are not giving the desired service. There seems to be ground for believing that the efficiency of the railroad lines has been sacrificed by straining the transporting power beyond a normal capacity. There is arising in the Mississippi Valley an increasing demand for better service. There are men in the valley who believe that the Mississippi River offers exceptional advantages as a trade. route, but not under the projects now in operation. There is heard the cry that the river must be canalized. "The cry has gone out from the Dakotas that wheat is rotting in the bins because there are not enough cars to carry it to market; from Nebraska and Iowa that corn is molding in the cribs because of exorbitant railroad tariffs;"* from Texas, Arkansas, Illinois, Mssouri, and all the other states of the valley that transpor

*Quotations are from Our Great River, W. J. McGee, World's Work, XIII. 8576, February, 1907.

tation service is not rendered to people and industries with the efficiency and dispatch which they consider their due. That the service cannot be rendered by the present lines is generally the belief. "Over all sounds the confession of the railroads that they cannot meet the demands for transportation without more cars, more locomotives, and more tracks." Consequently, the people of the Great Valley are turning to their great water-way as the only means of relieving their distress. They recognize that the present improvements of the river are not adequate to the needs of commerce; they foresee that under proper training a constant and efficient canalway may be substituted for the low-water stage. Realizing the helplessness of their industries under the present regime and the threatened stunting of their growth, and on the other hand. divining that the canalization of the Mississippi River is a remedy, the speakers for the people are pressing their claims in no uncertain tones. "They do not want to press matters, but— —. if they must, they have the votes, they have the means as well, to secure the traffic facilities on which their prosperity depends."

There are in extensive operation three processes for regulating the low-water stage of a river to the demands of navigation: training works, which confine the water under a low stage within narrow limits so that the increased depth of flow may be an instrument in scouring and maintaining a channel; dredging, where the deposits are removed from a shoaling channel as fast as the river falls in stage; and canalization, which turns the river during its low water season into a canal. Regulation by training embankments is in use on the Rhone. A rather swifter flow of water than is found in most navigable streams is instrumental in making these works effective. The suggestion of low-water levees on the Mississippi River was made a few years ago but the plan had but few commendatory features and was abandoned. Regulation by dredging is the process in operation on the Mississippi River. It is an unending process, the results of one season do not last through the spring floods to the next season. Oftentimes, a cut dredged early in the season may fill two or three times during the season under the deposition of sediment made at falling stages of secondary rises of the river. The results of the last ten years do not seem to satisfy the requirements for navigation. The dissatisfaction.

never assumed definite shape nor was it in any way trenchant until now, when we are told that, like it or not, the Mississippi River must be canalized. It is my purpose to instance two or three cases of successful canalization and to point out one or more concomitant problems. If extensive plans of this nature are being advocated and urged for our Great River, a few notes in anticipation of the larger discussion may, at least, be timely. Canalization is not a new way of gaining navigable depths of streams. It is in a cruder way the method often used by log-men to float their season's cuttings to the mill or market. The lock has its prototype in the stanch which was used for flushing so-called floatable streams. While the stanch affords intermittent navigation down stream only, the locks under canalization make navigation equally easy up and down stream. Canalization yields a definite depth of water and this depth can be maintained throughout the low-water season. Under extreme low-water stages, training levees and dredging projects must fail in maintaining a navigable channel. A canalized stream might lose so much water by the operation of the locks and leakage that in the dry season the channel would be affected. There is, however, a relief against this in storage reservoirs. if such relief should be necessary.

A good example of canalization is found in the Moldau and Elbe Rivers in Bohemia.* The Moldau River flows into the Elbe at Melnik. From Prague on the Moldau to the Elbe the river drops 82.5 feet; and on the Elbe from Melnik to Aussig, near the boundary line of Bohemia, 70.3 feet. This makes a drop of 152.8 feet in about 80 miles. The rivers to Prague were practically unnavigable during a part of the year. Canalization has so far improved these rivers as to provide a minimum depth of 7 feet from Aussig to Prague. Thus vessels of some 700-800 tons may reach the latter city at any season of the year.

Still better examples are found in the Seinet and the Main, a tributary of the Rhine. The Main was, for a season, regulated by training works which yielded a 3-foot channel from Frankfort to the Rhine. Canalization was tried and the depth of channel was thereby increased to 61⁄2 feet. The traffic under the former method was 12,000 tons, under canalization 300,000

1904.

*Canalization on the Elbe and the Moldau. Scientific American Supplement, 57, 23598, †Rivers and Canals. L. F. V. Harcourt, 1896.

tons. Later, during 1889, the navigable depth was increased to 84 feet by increasing the height of the canalization plant. The traffic in 1892 is reported to have been 709,000 tons. In this river the locks are 4 2-3 miles apart.

In the Seine there is a tidal water-way from the sea to Rouen. From Rouen to Paris locks 131⁄2 miles apart yield a depth of 10% feet and allow vessels of 1,000 tons to reach Paris. Above Paris, as in the Main, the locks are 4 2-3 miles apart and this distribution of locks yields a depth of 61⁄2 feet. Canalization is more costly in the upper parts of valleys than in the lower because of the increased number of dams required, although there is some compensation in the decreasing width of dam necessitated.

This method of improvement is in operation in the United States, notably on the Ohio, where a series of 18 locks and dams furnish a channel 8 feet deep and 100 feet wide.*

It is generally the custom to locate the locks in a chute made by an island and to block the flow of water in the main channel by dams or wiers. Where no islands appear in the river, as in the Main and the upper Seine, the locks are placed in artificial side cuts or close to one bank. The wier is the true barrier to the flow of the river and its height determines the depth of the river above it. The distance between wiers depends on the slope of the river and the minimum depth of channel required for navigation. In rivers of heavy floods, these wiers must be movable so as not to be destroyed by the force of the waters. The locks in a chute or in an artificial cut, inasmuch as they are only a small portion of the stream and not in the main line of scour, do not receive much of the flood attack. The movable wiers are constructed after various patterns. In some rivers, because of the suddenness of floods, an automatic opening of the wiers is necessary. On the Ohio, the wiers are of a wicket pattern; the wickets being lowered when the river approaches high-water stages. These wickets are supported by a prop, and are hinged a little above the center at the points where the props are fastened to them. The effect is that as long as the water is in a low stage the wickets are kept shut by the force of the water against them. High water, on the other hand, throws the weight on the upper parts of the wickets and tilts them, allowing the water to escape.

*Waterway Improvement on the Ohio. Scientific American, 89, 117, 1903.

The canalization of the Mississippi River will be an enormous task and will call for a large expenditure of public money. The sum already spent for the protection of the basin and the improvement of the low-water navigation aggregates over $52,000,000. The projectors of canalization are talking in terms of three and four times that sum for minimum demands. There are certain features of the river that will tax a canalization plant to the utmost; there are other features that mean nothing more than extensive works, much labor and time for the accomplishment, backed, of course, by lavish appropriations.

The river is a sediment-bearing stream. It transports to the Gulf annually 400,000,000 tons (about 247,000,000 cubic yards) of detritus. This is three times the amount carried by the La Plata in the same length of time, six times that of the Hooghly and the Danube, and eight times that of the Nile. This amount of material will be detrimental to canalization. It is difficult to see how such works can be successful unless the detritus is removed before it reaches the lower river. It is suggested that settling basins be utilized at the headwaters of navigation, that the sediment be eliminated from the tributary streams before such headwaters are reached and that the 400,000,000 tons of sediment be retained "in the townships where it belongs."

The river has a flood season during which an enormous amount of water sweeps down the valley. The difference between the high-water stage and the low-water stage is in some instances over fifty feet. The present works are scarcely able to cope with the floods and vigilance does not always prevent disaster. Not every year is a heavy flood experienced. There comes, however, a year in the course of time when a heavy flood fills the river, when the efforts to restrain the waters, to prevent caving in dangerous places, to give the inhabitants of the basin protection, seems of little avail. In this fluctuation of flood heights, it is always conceivable that the highest known flood may be excelled. Any training works in the river must engage this flood season force and better it. On the fall of a a flood in stage the present navigable quality of the river depends to a large degree. After a sudden fall in stage, a heavy deposit of detritus is dumped along the bed of the river and navigation can be kept open only by persistent dredging. Like sudden falls in river stages must still occur, and if I am allowed