Abstract

AKSOY, Aysegul Ozgenc  and  DOGAN, Mustafa. Experimental investigation of time-dependent local scour downstream of a stepped channel. Water SA [online]. 2019, vol.45, n.3, pp.411-419. ISSN 1816-7950.  http://dx.doi.org/10.17159/wsa/2019.v45.i3.6738.

In this study, temporal variation of local scour occurring at the downstream part of the stepped channel were investigated experimentally. The experimental tests were carried out in a stepped flume with a height of 2.4 m. The width of the rectangular flume was 0.10 m and the length of the stilling basin was 2.12 m. Bed material was placed in a sediment box with a height of 24 cm and length of 2.48 m, without any compaction. Experiments were carried out by using bed material of 4 different grain size distributions, 2 different sill heights and 6 different flow rates. Two empirical equations which include Shields parameter (θ) and densimetric Froude particle number (F_d) were proposed by using the experimental findings to predict the temporal variation of the scour depth. The R² (coefficient of determination) values were computed for both proposed equations as 0.866 and 0.865. The scatter index (SI) values were also determined and computed as 8.73% and 8.25%. The fit of the equations was also determined by means of Fisher's test.

Keywords : stepped channel; local scour; temporal variation.

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