Investigation of Average Shear Stress in Natural Stream

Average shear stress is an important parameter for prediction of sediment transport,bank protection and other river engineering problems in natural streams. For this purposevelocity measurements were taken on Kızılırmak River sub branch, named Sarimsakli streamand Barsama station in center of Turkey. Acoustic Doppler Velocimeter (ADV) was used forthis purpose at six different periods and flow conditions. Nikuradse's equivalent sandroughnesses (ks) for each vertical along the wetted perimeter were determined using measuredvelocity distributions. Shear velocity (u*) and shear stress (meas) were determined thenaverage values were calculated for each flow condition. The commonly used one-dimensionalmean boundary shear stress equation at cross-section was re-arranged according to entropyparameter M and it reflects the real flow condition in natural stream