FLOOD FENCES.
Fig. 133.—Strong Flood-gate.
Fig. 134.—A Cheaper Flood-gate.
In a situation where a line of fence crosses a stream or a gully liable to be flooded, it is necessary to make special provision for it. A fence extending down near the surface and sufficiently rigid to withstand the current, would arrest the driftwood and other objects floated down on the flood, and soon become a dam. The right kind of a fence must therefore yield to the force of the flood, and renew its position, or be easily replaced after it has subsided. [Figure 133] is a very effectual flood-gate for a running stream. The posts, B, B, are firmly set on the bank, and a stick of timber, A, mortised on the top of them. The three uprights, C, C, C, are hinged to the cross-timber, and the boards, F, fastened in place by ten-penny steel fence nails. The gate easily swings with the current, D. [Figure 134] shows a form which operates in a similar manner like the other. It consists of two stout posts, five feet high, bearing a heavy cross-bar, rounded at each end, and fitted into sockets, in which the bar with gate attached can swing. The construction of the gate is easily seen from the engraving.
Fig. 135.—Fence For A Forest Stream.
The above forms are self-acting, and swing back to their places as the water subsides. For larger streams, it is necessary to construct fences that give way before the flood, and can be brought into position again when it is over. One of these, for a stream which is liable to bring down much driftwood, is shown in [figure 135]. The logs are the trunks of straight trees, about eighteen inches in diameter, which are hewed on two sides; posts are mortised in each of these logs, and on them planks are firmly nailed. The logs are then linked together with inch iron rods, and the first one connected by means of a long link to a tree or post firmly set in the ground upon the banks of the stream. The links must all work freely. When high water occurs, the fence is washed around and left on the bank; after the water has subsided sufficiently, the logs may be dragged back to their places, as shown in the engraving, by means of a horse, hitched to a staple in the end of the log. [Figure 136] shows a lighter fence made of poles or rails, held by interlinking staples to the posts on the side of the stream. As the floods come down, the rails are washed from the center, and float freely at either side of the stream. They can be laid up in place again when the water subsides.
Fig. 136.—Fence Of Movable Rails.
Fig. 137.—An Extemporised Flood-fence.
The fence shown in [figure 137], though rather rude and primitive, has the advantage of being cheaply constructed and permanent. Two strong posts are driven into the banks on the margin of the stream, to which a log, a foot or more in diameter, is fastened by pins, spikes or withes, about twenty inches above low water mark. Then fence rails are sharpened at one end, driven into the stream above the log, upon which the other ends rest, projecting about a foot. They are then securely spiked or pinned to the log, and the work is done. The pointed ends of the rails are up the stream, and in case of flood, the water pours over the obstruction, carrying with it brush, driftwood, etc.
Fig. 138.—Automatic Flood-gate.
The flood-gate, [figure 138], is designed to prevent small stock from passing from one field to another through a water-course under a fence where there is low water, while in time of high water the gate will rise sufficiently to allow the floating trash to pass through, but not higher, as it is self-fastening. The invention consists of a gate constructed of perpendicular slats hinged above, and moving. This hangs across a stream or ditch. On the down-stream side of the gate a swing paddle is fixed, which hangs in the water. This, marked a in the illustration, is attached to an angular bar, b, which is moved when the flow of water presses with force against the paddle. Two notched pieces, c c, attached to the gate, rest upon the angular bar, b, at low water; when both the paddle and the gate hang at rest, perpendicularly, these notched pieces, c c, hold the gate firmly shut; when, however, the water rises and the paddle is moved sufficiently to disengage the notches, the gate will be moved by the force of the water, and if sticks or rubbish of any kind float down against it they will be swept under it by the water. When the water subsides, the paddle swings back, the pieces, c c, catch and keep the gate closed at any height it may fall to. Let the cross-piece, d, that is halved into the posts, be about one foot above the banks of the ditch. The pieces, f f f f, represent the fence above the ditch, the small posts, g g, with the pieces nailed to them, are to prevent the stock from passing when the gate is partly closed, at the same time bracing the posts, e e; the holes at h are to raise and lower the paddle a; if small, a cleat on one of the arms upon which the piece B is hung, prevents the paddle from swinging towards the gate.
Fig. 139.—A Missouri Flood-fence.
[Figure 139] shows a kind of fence used in Missouri to put across sloughs. It is in effect two panels of portable fence. The posts are set three to four feet deep, with the tops about one foot above ground; the other posts, to which the planks are nailed, are bolted to the top of the inserted posts. The ends of the panel that connect with the post on the bank are slightly nailed with cross-strips near the top, so as to be easily broken loose when the flood comes. There are also temporary braces bearing upstream, put in to prevent the fence from falling, but are easily washed out, when the fence falls down stream, and logs and other obstructions pass by readily. As soon as the flood goes down, the fence is easily raised, a panel at a time, to a proper place.
Fig. 140.—Freshet Fence.
[Figure 140] shows a cheap and effective form of flood fence. The material used are square-hewn timbers, seven or eight inches for sills, stone pillars, split rails about ten feet long. The rails are driven in the ground about two feet deep; the upper ends project above the sill two or three feet, and are spiked down to the sill with large spikes; when the freshet comes, logs and driftwood are carried over, and the fence will be left in as good order as before the high water.
Fig. 141.—California Gulch Fence.
[Figure 141] represents a gulch fence or gate which is in common use in some parts of the Pacific Slope. It is particularly adapted to the gulches of the foot hills and the irrigating ditches of the plains. The whole gate swings freely by the upper pole, the ends of which rest in large holes in posts on either bank, or in the cross of stakes. The upright pieces may be of split pickets or sawed lumber, as may be the most convenient. If the stream is likely to carry floating brush, logs, etc., the slats should be of heavier material than is necessary when this is not the case. When constructed properly the gate will give, allowing rubbish and freshets to pass, and then resume its proper position. The principal advantage claimed for this gate is that it is not apt to gather the passing debris.
Fig. 142.—Fence For A Dry Gully.
A gully is sometimes difficult to fence properly, but by hanging a frame over it, as is seen in [figure 142], the object may be quickly accomplished. The frame can be spiked together in a short time, or framed together if a more elaborate one is desired. To make it serve its purpose completely, the rails must be closer together near the bottom than at the top of the frame, in order to prevent small animals from going through it.
A modification of this last named device, seen at [figure 143], gives greater space for the passage of brushwood or other large objects, which may be swept down on the flood. The width, strength and size of the bases supporting the side posts, and of the braces, will depend upon the width and depth of the channel. The base pieces can be firmly anchored by stakes driven slanting over the ends and outsides, or by stones piled on. For wide, shallow streams, three or even more braced uprights can be anchored eight or ten feet apart in the bed with heavy stones, with two or more swinging sections. If small trees or long timbers are likely to float down, the swinging gate may be twelve or fifteen feet wide. For smaller streams, with strong high banks, five or six feet will suffice.
Fig. 143.—A Freshet Fence.