TY - JOUR ID - 20441 TI - Field study of flow resistance in step-pool streams (case study of Dizin River) JO - Scientia Iranica JA - SCI LA - en SN - 1026-3098 AU - Tahershamsi, Ahmad AU - Majdzadeh Tabatabai, Mohammad Reza AU - Torabizadeh, Abbas AD - Faculty of Civil and Environment Engineering, Amirkabir University of Technology, Tehran, Iran AD - Faculty of Water and Environmental Engineering, Shahid-Beheshti University, Tehran, Iran AD - Faculty of Civil and Environmental Engineering, Amirkabir University of Technology, Tehran, Iran Y1 - 2018 PY - 2018 VL - 25 IS - 5 SP - 2537 EP - 2549 KW - Step-pool KW - Flow Resistance KW - Mountain Streams KW - Chezy Coefficient KW - Dizin River DO - 10.24200/sci.2018.20441 N2 - A series of steps and pools are ubiquitous bed forms in mountain stream channels, occurring where gradients exceed 2% and materials are in the gravel to boulder size range. Flow resistance, reflected by roughness elements, appears to be an important control on bed load transport rates and mean flow velocity. To estimate flow resistance some morphological features and velocity were measured in the step-pool channel of Dizin River, located in Karaj River watershed in Iran. Topographic surveys and bed sediment sampling were made in low flow condition while three-dimensional velocity measurements were made in low, medium and high flow conditions. Gradient variations are in the range of 7% to 14%. As flow resistance is a function of geometric, bed material size, longitudinal slope and hydraulic radius, dimensional analysis was conducted to develop a non-dimensional relationship for flow resistance in step-pool reaches. Thereafter, it was calibrated for the measured data set of Dizin river and validated for Rio Cordon data set. Comparable results of validation with a river located in a different environment may suggest that flow resistance features in semi arid and humid streams may have similar effects on non-dimensional resistance coefficient UR - https://scientiairanica.sharif.edu/article_20441.html L1 - https://scientiairanica.sharif.edu/article_20441_d38efb18bc3769279fb3ed72a132dc95.pdf ER -