Evaluation of tidal bores effects of Persian Gulf on the stage-discharge curve of the Karun River

The rivers that pour to seas and oceans are known as tidal rivers. A governing factor on tidal rivers is tidal bores which are produced by the gravity of moon and sun. Reflection of waves from beaches and the shape of beaches and effects of shallow water، effect on tidal bores in the mouth of tidal rivers. These factors convert tidal bores from time periodic condition to no periodic condition. Tidal bores move to upstream of river while fluvial flows go toward downstream of river. Because of combination of Tidal bores and fluvial flows، hydraulic and hydrologic conditions are very complex in the tidal rivers. Measurement of velocity and discharge of current is impossible in the tidal limit of tidal rivers. For determination of stage-discharge curves، an especial method is needed. In this research، water surface elevation is estimated by using discharge of fluvial flow in Ahvaz and tidal height in Khoramshar in tidal limit of the Karun River (from Khoramshar to Darkhovein). Water surface elevation is shown by structural curves and regression relations. These curves and relations are suitable tools for determination of water surface elevation in the tidal limit of the Karun River by using discharge of fluvial flow in Ahvaz and tidal height of Khoramshar.