The Effect of submerged wall constructed by six leg elements on the Bed Topography of the 90-degree mild bend

The main causes of scouring and erosion of the river’s bed and banks are the interaction of secondary flows and the sediment bed particles. Bank erosion causes disturbance of private and public lands, damages aquatic and riparian ecosystems, and degrades water quality. In addition, the eroded sediments will deposit downstream in front of intakes, flood control and navigation channels and valuable wetland areas (Biedenharn et al, 1997; Julien, 2002).Numerous studies have been conducted on the pattern of flow, erosion and deposition in bend and in the presence of banks protection structures. One of the structures that has been used in recent years is the use of six-leg concrete elements called A-Jack. In recent years, some studies have been conducted on the use of these components to control the pier and abutment scour bridge. In late 1998 and early 1999, a series of 54 tests of 6-inch model scale A-Jacks was conducted at Colorado State University (CSU) to examine their effectiveness in pier scour applications. This program is described in detail in CSU’s test report entitled, "Laboratory Testing of A-Jacks Units for Inland Applications: Pier Scour Protection Testing" (Thornton et al. 1999a and b). So far, no comprehensive research has been done on the effectiveness of these elements as controllers of banks toe erosion. Therefore, the purpose of this study is to investigate the effect of the geometry of the submerged wall constructed by six-leg elements on bed topography of a flume bend.