چكيده به لاتين
Information about bedload in rivers for different purposes such as designing stable channels, scouring and hydraulic structures is very important. In this thesis field estimation of bed load and relation between bed load and different characteristics of flows have been addressed. Field operation has been conducted in Mazandaran and Chaharmahal and Bakhtiari provinces and in three rivers of Haraz, Rostamabad and Beheshtabad. To measure velocity profiles and calculating flow characteristics like shear velocity and shear stress, ADV and current meter, and to sample bed load, helley-smith was used. To calculate shear velocity, boundary layer characteristics method is used. Also ADV had been used for collecting turbulence data and calculating Reynolds stress and as a result, measuring shear velocity in Beheshtabad. Based on results, using ADV for measuring velocity fluctuations and shear velocity by Reynolds stress method in bedload transport condition was satisfying. Comparing measured bedload with classic equations shows that schoklitsch, Duboys, Lajeunesse and Ashida & Michiue equations has estimated bedload well. Distribution of shields parameter and also river’s bed surface alteration in any section shows good synchronization with distribution of bedload in the same section. By increasing flow’s discharge per width, flow velocity and shields parameter, bedload’s discharge per width increases and exceptional occasions can be justified by river bed topography and sediment supply limitations. Shields parameter has a reverse relation with particles size and using bigger sizes presented by Meyer-Peter and Muller instead of D50 in classic equations can estimate the bedload better.
