Dynamic Manning's roughness coefficients for hydrological modelling in basins

• Published in: Hydrology Research Vol. 49; no. 5; pp. 1379 - 1395
• Main Authors: Ye, Aizhong, Zhou, Zheng, You, Jinjun, Ma, Feng, Duan, Qingyun
• Format: Journal Article
• Language: English
• Published: London IWA Publishing 01.10.2018
• Subjects: Basins; Coefficients; Computer applications; Computer simulation; Floods; Friction; Hydraulics; Hydrologic models; Hydrology; Kinematics; Modelling; River basins; Rivers; Roughness; Roughness coefficient; Simulation; Slope; Spatial distribution; Statistical analysis; Statistical methods; Stream discharge; Stream flow; Studies; Surface water; Temporal distribution; Vegetation; Water depth; China; Yellow River
• ISSN: 0029-1277; 1998-9563; 2224-7955; 2224-7955
• DOI: 10.2166/nh.2018.175

Manning's roughness coefficient (n) has a significant impact on routing in hydrological models. However, computational methods for dynamic roughness coefficients are of little concern in current research. Few studies have produced spatial-temporal distributions of the roughness coefficients in basins. In this study, a formula to calculate the n value was established based on a statistical analysis of estimated n values by Manning's formula. The routing model of a distributed hydrological model was then improved using the new formula to calculate n. The roughness coefficient is not a constant; instead, it changes dynamically with changes in water depth and vegetation in the improved hydrological model. The improved model was applied to the Yellow River basin. The results show that using dynamic n can improve the streamflow simulation of hydrological models, especially on slopes. The dynamic spatial-temporal distribution of n can now be used in other models.