Rivers each year carry million tons of solid and sedimentary materials from headwater to stuary

Whereas the happened damages by sedimentation by rivers to nature , agriculture , hydraulic structutre , is too large and harmful , therefore exact identification of this phenomenon and decreasing methods of these damages are the goals of hydraulic engineers . Also for selection of maning grittiness of river by using the given equation for estimating maning grittiness with the amount of materials , maning grittiness is estimated equal to 0.032 . This model is evaluated for 12 executive years and its results once for 4 years with bridge and without bridge . The result of study of floor profile shows that , in the primer 500.m of both in condition of with or without bridge the intensive erosion will be happened , and after this path , floor profile has 0. To 1.m. erosion , and it has been effected by bridge about 3000.m. from upstream of river . In without bridge Condition , after about 3 k.m., river had more erosion and it has sedimentation between Tehran – Karaj high –way bridge and Metro bridge .Using England – Henson sediment transport equation shows that , in general this method has more intensive erosion comparing to Ikerz and Wite equation . In general during study gorge , aggregated weight of erosion is more than sedimentation and in fact most of the path is entreched Amount of erosion and sedimentation was in tensive in several areas and their intensity will be decreased by passing the time of modeling , Weight amount of sediment erosion in upstream of Tehran – Karaj bridge in condition of without bridge in model is intensive and in downstream , sedimentation happens . In case of bridge modeling in this model , this manner is reversed around the bridges and we have sedimentation in upstream of bridge and erosion in downstream . In general , amount of erosion in England – Henson is more than Ikerz and Wite method

Keywords:

Sediment , River , Bridge , Erosion , MIKE 11