Discharge and location dependency of calibrated main channel roughness: Case study on the River WaalBoyan C.A. Domhof, Koen D. Berends, Aukje Spruyt, Jord J. Warmink and Suzanne J.M.H. HulscherE3S Web Conf., 40 (2018) 06038DOI: https://doi.org/10.1051/e3sconf/20184006038