Investigation of the waves effects on sedimentary processes of inlets

Inlet is an area that fresh water is mixing with ocean salty water and it is a navigation path in coastal zones. So it is important to have enough information about currents patterns and sand transport. Sand transport at inlets is determined with waves, longshore currents and tidal currents. So because of importance of determining sand transport at inlets, in this research effect of waves on sand transport at inlets is investigated. Thus at first the inlet bathymetry designed with MIKE 21. Then the effect of wave direction and height on sand transport is evaluated. To determine the effect of wave height on the sand transport and currents at inlets, waves with different height but same period and direction radiated to the inlet. According to the results of tests, due to radiation of these Waves to the inlet, two vortexes appeared before inlet entrance and two vortexes appeared after inlet. These vortexes trap Sands at the inlet entrance and causes Decomposition of sands at inlets. Then these sands will be transport before and after the inlet entrance by currents at the inlet. So in this way ebb and flood shoals are created. If wave height increases, the current velocity and the bed level change will increase too. But wave height changes will not effect on the pattern of currents and sand transport. With wave direction changes, current velocity will change too. As the highest velocities obtained in normal direction. But the most important effect of wave direction on current velocity and sand transport is changing the total pattern. In other words normal direction and angular direction have different patterns. At last to figure it out why shoals create before and after the inlets, suppose a wave that propagates in shallow waters. So due to reducing the depth of the water, finally wave will be break. At inlets same conditions is happens too. When a wave that is propagating in deep waters get close to the inlet entrance, due to water swallowing it will break at inlet. Then two currents in opposite direction will be produced at bed floor and then these currents transport sands from inlet entrance to before and after the inlet. These conditions cause to creation of Flood and ebb shoals.