Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 57 7 2025 09 23 The Effect of Bedform on Increasing The Flow Depth The Effect of Bedform on Increasing The Flow Depth 1245 1264 5864 10.22060/ceej.2025.23639.8192 FA Mehdi Hasanzadeh Water Engineering Department, Agriculture Faculty, University of Tabriz, Tabriz-Iran Farzin Salmasi Department of Water Engineering, Faculty of Agriculture, University of Tabriz, Tabriz, Iran 0000-0002-1627-8598 Ali Hoseinzadeh Dalir Department of Water Engineering, Faculty of Agriculture, University of Tabriz, Tabriz-Iran Hadi Arvanagi Water Engineering Department, Agriculture Faculty, University of Tabriz, Tabriz-Iran Journal Article 2024 10 26 Through sediment transport in alluvial channels, regular and alternating triangular-shaped patterns known as bedforms develop on the riverbed. Depending on the flow characteristics and regime, the geometric dimensions of these bedforms evolve, significantly influencing bed roughness and, consequently, increasing flow depth—particularly under ripple and dune conditions. Predicting flow depth based on bed roughness is therefore a critical aspect of hydraulic modeling and the design of hydraulic structures. In movable-bed channels, estimating flow resistance and its corresponding depth poses a major challenge due to the inherent uncertainty associated with the formation and transformation of bedforms. As such, developing a reliable, straightforward, and practical relationship to estimate the maximum flow stage in the presence of bedforms is both important and necessary. This study presents a simple and practical linear relationship for predicting flow stage under lower flow regime conditions, based on 292 recorded experimental cases from four reputable research sources. From this relationship, a coefficient of 1.25—referred to as the Tabriz University coefficient—is introduced, which significantly simplifies calculations of flow depth in the presence of ripple and dune bedforms without requiring detailed geometric information of the bedforms. The accuracy of this coefficient in estimating flow depth was found to be acceptable. Furthermore, a corresponding relationship for estimating the Manning roughness coefficient based on the flat-bed Manning coefficient was derived using this special coefficient. The performance of the proposed relationship for Manning’s coefficient was validated under controlled laboratory conditions in rectangular flumes. however, its application to natural channels remains outside the scope of this study and is suggested for future research. Through sediment transport in alluvial channels, regular and alternating triangular-shaped patterns known as bedforms develop on the riverbed. Depending on the flow characteristics and regime, the geometric dimensions of these bedforms evolve, significantly influencing bed roughness and, consequently, increasing flow depth—particularly under ripple and dune conditions. Predicting flow depth based on bed roughness is therefore a critical aspect of hydraulic modeling and the design of hydraulic structures. In movable-bed channels, estimating flow resistance and its corresponding depth poses a major challenge due to the inherent uncertainty associated with the formation and transformation of bedforms. As such, developing a reliable, straightforward, and practical relationship to estimate the maximum flow stage in the presence of bedforms is both important and necessary. This study presents a simple and practical linear relationship for predicting flow stage under lower flow regime conditions, based on 292 recorded experimental cases from four reputable research sources. From this relationship, a coefficient of 1.25—referred to as the Tabriz University coefficient—is introduced, which significantly simplifies calculations of flow depth in the presence of ripple and dune bedforms without requiring detailed geometric information of the bedforms. The accuracy of this coefficient in estimating flow depth was found to be acceptable. Furthermore, a corresponding relationship for estimating the Manning roughness coefficient based on the flat-bed Manning coefficient was derived using this special coefficient. The performance of the proposed relationship for Manning’s coefficient was validated under controlled laboratory conditions in rectangular flumes. however, its application to natural channels remains outside the scope of this study and is suggested for future research. https://ceej.aut.ac.ir/article_5864_7cdace91c487558e27ce54df7cdb299c.pdf