In this paper the effect of releasing (emergency and maximum) flow discharges on bed shear stress at 3.5 km length meandering river reach at Kafr El-Zayat City from km 145.00 to km 148.50 D.S of El-Roda Gauge at Kafr El-Zayat City. 2-D numerical model “SMS” in addition to hydrographic measurements were combined for this purpose. The available data related to hydrographic and hydraulics of the reach under study were collected.Water levels and discharges at several years were studied to determine the different flows passing in the Rosetta branch.The bed levels data at several years were compared to study the development of the morphology on the bend. The studied reach was simulated four times by the 2-D numerical model using theavailable survey reach at years 1982, 1998, 2003 and 2006. The flow discharges were used as upstream boundary condition and the water level was used as downstream boundary condition. The model was calibrated and verified using the field measured velocities. Two proposed alternatives were suggested as possible solutions of the problems of scour and deposition for the tested reach.The first alternative, the outer bends were filled with layers of filter and riprap up to level -5.00 m MSL. In additional to the first alternative, the inner sides of the bends were dredged to level -3.00 m MSL as second alternative.The two alternatives were numerically tested for the maximum and emergency flows and bed shear stress was estimate. The results showed that in the case of alternative 2 the bed shear stress was reduced in the vicinity of the banks compared to the basic case and the first alternative. Consequently, alternative 2 was presented as a proper solution for the meandering problems in this reach in addition to its high protection against the bank failure. |
