Investigation on time variation of scour around T shape spur dike in a 90 degree bend

Spur dike is an important element for protection of river banks. Spur dike causes variations in flow field, sediment transport and bed topography. The mechanism of flow and sediment transport in a channel bend is very complex, especially when a spur dike is constructed in a bend. In this paper the time variations of dimension of the scour hole and the bed’s topography were considered around a T shaped spur dike located in a 90 degree bend. For this purpose, the experiments were carried out in a 90 degree channel bed with uniform sediments having average diameter of 1.28 mm under clear water condition. The time variations of parameters such as length of the spur dike and its wing, the location of the spur dike in the outer part of the bend and Froude number on dimensions of scour hole around a T shaped spur dike and the bed’s topography were studied. The results showed that by increasing the length of the spur dike, decreasing the wing length of the spur dike, increasing the Froude number and changing the location of spur dike towards the down stream of bend, the dimension of scour hole increased.