Mathematical Modeling of water surface at Unsteady Flow in Al-Msharah River

This study is concerned with unsteady flow in open channels boundary conditions that may exist river or channel system. A software Hydrologic Engineering Center-River Analysis System (HEC-RAS) was used for a case study. The contains hydrodynamic model simulating the based on one-dimensional form of Saint-Venant equations, by formulating discrete using implicit finite difference scheme, then solving Newton-Raphson iteration procedure and modified Gaussian elimination technique. adopted help HEC-RAS application applied to reach Al Msharah River (channel) between AL Barrage (upstream)and Malah Bridge (Downstream), length (49 Km) divided (52) cross sections. Model runs comparison results actual field data indicate accuracy obtained for(?=1 ?t=5 minute) quite acceptable, where ? weighting parameter ?t time interval. paper covers normal depth observed water stage within period ( from January 2006 July 2006) . demonstrate area at Am'arah city distance 17.5 Km upstream(cross section 30)could be subjected flooding High Flow, therefore, it recommended adjust sections prevent this area. At last , Calibration achieved (water stage) along show good agreement.