online_scour_jainandfisher:  Calculation of local scour using Jain and Fisher's equation   

F = v /(gy)1/2

Vc = Ku y1/6D501/3

Fc = Vc /(gy)1/2

For clear-water scour (F - Fc ≤ 0.2):

ys = 1.84 a Fc0.25 (y /a)0.3

For live-bed scour (F - Fc > 0.2):

ys = 2 a (F - Fc)0.25 (y /a)0.5

[ SI Units (metric):  ys, y, a, and D50 in m; Ku = 6.19 ]
[ U.S. Customary Units:  ys, y, a, and D50 in ft; Ku = 11.17 ]
[ F = Froude number; g = gravitational acceleration ]


DESCRIPTION      [Sample Input]     [Main page]

To determine the bridge scour depth ys, the calculator requires the following input data:

  • Flow depth directly upstream of the pier y1, in m (or ft).

  • Mean flow velocity directly upstream of the pier v1, in m/s (or fps).

  • Pier width in a horizontal direction normal to the flow a (Fig. 1), in m (or ft).

  • Median diameter of the bed material D50, in mm.

Fig. 1  Definition sketch.

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