Occasional Papers ..., Temas41-55 |
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Página 22
... length . EXTENT OF CAVING Numerous attempts have been made to determine the average amount of bank caving going on , and , as might be expected , the different estimates vary much , depending on the way the estimates are made . Some ...
... length . EXTENT OF CAVING Numerous attempts have been made to determine the average amount of bank caving going on , and , as might be expected , the different estimates vary much , depending on the way the estimates are made . Some ...
Página 23
U.S. Army Engineer School. ( 228 R ) a half - mile length of bank in one season cut back 750 feet . As an example of continued rapid caving the following may be mentioned : Hopefield Bend near the point receded 2,800 feet in five years ...
U.S. Army Engineer School. ( 228 R ) a half - mile length of bank in one season cut back 750 feet . As an example of continued rapid caving the following may be mentioned : Hopefield Bend near the point receded 2,800 feet in five years ...
Página 26
... length . In the bends the current from its centrifugal force impinges quite strongly against the concave bank , and the velocity of the water close to the surface of this bank is quite great . and consequently its erosive force is great ...
... length . In the bends the current from its centrifugal force impinges quite strongly against the concave bank , and the velocity of the water close to the surface of this bank is quite great . and consequently its erosive force is great ...
Página 46
... length of the river from Cairo to ï Volg * WA more than sufficient for the making of 15 miles per a La " A fa ti m a t t krym w theme facts together it became apparent several years ago - not W MAR , ha gradually , as facts accumulated ...
... length of the river from Cairo to ï Volg * WA more than sufficient for the making of 15 miles per a La " A fa ti m a t t krym w theme facts together it became apparent several years ago - not W MAR , ha gradually , as facts accumulated ...
Página 52
... length . Later in the season a new form dike was tried . ( Type C , Plate VII . This consisted of two p of piles , each pile standing vertical . The front piles had an el tion of 25 feet above low water , while the rear ones were ...
... length . Later in the season a new form dike was tried . ( Type C , Plate VII . This consisted of two p of piles , each pile standing vertical . The front piles had an el tion of 25 feet above low water , while the rear ones were ...
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Términos y frases comunes
50 feet angle Ashport azimuth ballast bank protection Beal street begun bottom break built cables Caruthersville cause caving bank channel chute close completed connecting mats construction cost course crib Cross Dike damage dike constructed distance downstream drift eddy edge Elmot Engineers erosion extended fascine mat fastened feet long feet of bank feet wide Fletchers Bend flood foot mat front Gold Dust graded grillage head high water hour angle hydraulic head inches increased length levee linear feet located longitudinal low water low-water line lower end mat barges mat-head Memphis mooring barges Mound City Osceola Bar paving piles placed Plate Plum Point Reach pocket poles portion prevent repairs riprap river mats Royal Engineers sand bar scour season sill mat silt sinking slope spur dikes stage stone barge subaqueous mats sunk thick tion upstream usually velocity vertical width wire strands Wolf River woven
Pasajes populares
Página 41 - The plan of improvement recommended was discussed at some length in general terms, beginning with the general statement that "the bad navigation of the river is produced by the caving and erosion of its banks, and the excessive widths and the bars and shoals resulting directly therefrom.
Página 39 - It shall be the duty of said Commission to take into consideration and mature such plan or plans and estimates as will correct, permanently locate, and deepen the channel and protect the banks of the Mississippi River; improve and give safety and ease to the navigation thereof; prevent destructive floods; promote and facilitate commerce, trade, and the post*] •erria; 2.
Página 39 - Sec. 3. It shall be the duty of said commission to direct and complete such surveys of said river, between the Head of the Passes near its mouth to its headwaters as may now be in progress, and to make such additional surveys, examinations and investigations, topographical, hydrographical and hydrometrical, of said river and its tributaries, as may be deemed necessary by said commission to carry out the objects of this act.
Página 41 - In other words, bad navigation invariably accompanies a wide low-river water-way, and good navigation a narrow one. The work to be done, therefore, is to scour out and maintain a channel through the shoals and bars existing in those portions of the river where the width is excessive, and to build up new banks and develop new shore-lines, so as to establish as far as practicable the requisite conditions of uniform velocity for all stages of the river.
Página 273 - If, then, the final effect of a flood which rises from 30 to 50 feet above low- water is to raise the low- water bed of the river at shoal places, may it not be possible that if the height of this flood be somewhat increased by levees the bed may rise still further instead of being depressed, thus injuring instead of improving navigation.
Página 272 - It is known that during the last twenty years the levee system ha¿ been continuously interrupted by a great number of crevasses between Cairo and Red River. Before the levees were built, a large portion of the flood-waters spread out over the banks of the river in a thin sheet, of which the average depth at the margin of the stream, where it escaped, did not probably excwl a lew inches, or, at most, a foot.
Página 28 - ... and reflected images of a smooth portion of the distant horizon coincide. Now rotate the instrument until it makes an angle with the vertical. If the two images do not separate the glasses are parallel, and if the index glass has been first adjusted the horizon glass will also be in adjustment. 3. To make the Line of Sight of the Telescope Parallel to the Plane of the Arc.
Página 273 - River, and greatly lessen the necessity of their permanent maintenance for that purpose below Red River, even at a reduced height. While it is not claimed that levees in themselves are necessary as a means of securing ultimately a deep channel for navigation, it is believed that the repair and maintenance of the extensive lines already existing will hasten the work of channel improvement through the increased scour and depth of river bed which they would produce daring the highriver stages.
Página 273 - Orleans, where the flood rise is small. In that case the annual discharge might be diminished without, increasing the slope beyond its present value. 2. We do not concur with the majority of the Commission in their estimate of the value of the closure of gaps in existing levees as a factor in the improvement of low-water navigation ; this estimate being derived in part from the theoretical views already referred to. Existing evidence seems to show that during low-water stages the bars below Cairo...
Página 46 - I reaches, by reason of excessive widths, shallow depths, and shifting bars offered unusual difficulties to low-water navigation. It was felt that by attempting their correction the feasibility of the work of the improvement could be thoroughly tested and its value to the country estimated. The plan of improvement contemplated the closure of chutes and the contraction of main-river width where necessary by means of lightly built permeable-training walls connected at intervals to the bank by...