عنوان مقاله [English]
نویسندگان [English]چکیده [English]
The paper describes the evolution of local scour hole downstream of an adverse stilling basin. The research was conducted using a wide range of the Froude number, sediment size, tailwater depth, length and slope of stilling basin. The results showed that 87.5% of maximum depth of scour and 86.3% of its distance from the stilling basin were occurred in the first 24 hours when the experiment was continued for 54 hours. A power equation was adopted to describe the characteristic dimensions of the scour-hole, time scale as well as the geometry of stilling basin and sluice gate. The effects of different parameters on the dimension of the scour-hole were investigated and some equations were presented for estimating the variation of scour-hole dimensions with time under relative equilibrium condition. The results also showed a certain similarity among the scour profiles developed at different times. However, the shape of the holes was influenced by the change in length and slope of stilling basin. As the slope of stilling basin increased by 15%, the volume of sediment removed from the unit width of the hole, was increased by 30%.