This study was initiated to introduce non-submerged spur dikes as training structures to reduce erosion at the opposite bank to diversion channel at Naga Hammadi barrage through minimizing the velocity values near the banks. The length of the bank to be protected is 450m. The width of diversion channel is 172m; however the average channel width at the region under study is 450m. A two dimensional mathematical model were used to simulate many cases. To assure model validity, experimental results were used for verification. The model simulated longitudinal and transverse velocities as well as the spur working length. A financial economic evaluation as a function of groin length is introduced to help in selecting the optimum group with minimum cost. Eighteen runs (18) were executed where three (3) effective parameters were tested. These parameters were the contraction ratio, which is defined as the spur length to the channel width (L/B), the spur orientation angle; and the spur spacing. The contraction ratio was varied between 0.1 and 0.2 while the used orientation angle are 60º, 90º and 120º and the spacing was 2, 4, and 7 times as much as the spur length. The measurements covered 60 grid points along four longitudinal lines (A, B, C, and D) crossed by 15 lateral cross sections. The study recommended that 4 spur oriented at 60º with 10% contraction ratio length and spacing of 4 times spur length can be used to protect the attacked 450m at the bank facing the temporary diversion channel, while the repelling and straight types spur with 0.2 contraction ratio could be implemented to produce a deep channel. |
