Sand deposition after flood to cause troubles around barrages, whose sill elevation is lower than that of former river bed, 2: Experimental study on probable technical countermeasures to prevent sand deposition
1991
Miwa, H. (Iwate Univ., Morioka (Japan). Faculty of Agriculture)
Sand and gravel were deposited by floods under gates of some new diversion dams. Deposition disturbed operation of these barrages. Some countermeasures to protect deposition are discussed and proposed. 1) In case of a sand-bed river, accumulated sand on sill of a barrage can be flushed by closing sluice gates during the falling stage of a flood. 2) In case of a gravel-bed river, gravel flushing is very difficult by closing sluice gates. 3) Probable technical countermeasure is to dredge river bed around a barrage. 4) But, usual dredging reach, which is only one-fourth of the length of a bar both in upstream and downstream of the barrage, is not enough. 5) Sufficient dredging reach to prevent deposition under gates is investigated in an experimental model canal in case of the Okajima Barrage. Practically proposed dredging reach is one and a half times as long as the length of the bar in upstream of the barrage and half in downstream
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