Reliability of functional forms for calculation of longitudinal dispersion coefficient in rivers

Although dimensional analysis suggests sound functional forms (FFs) to calculate longitudinal dispersion coefficient (Kx), no attempt has been made quantify both reliability of the estimated Kx value and its sensitivity variation FFs' parameters. This paper introduces a new index named bandwidths similarity factor (bws–factor) FFs based on rigorous distinct calibration datasets tune FFs. We modified bootstrap approach ensure that each resampled dataset is representative available datapoints in rich, global database tracer studies. The dimensionless values were calculated by 200 tuned with generalized reduced gradient algorithm. Correlation coefficients for varied from 0.60 0.98. bws–factor ranged 0.11 1.00, indicating poor calculation, mainly due different sources error calculation process. exponent river's aspect ratio over wider range (i.e., ?0.76 1.50) compared computed friction term ?0.56 0.87). Since used combination one-dimensional numerical models water quality studies, estimation can result unrealistic concentrations being simulated downstream pollutant release into rivers.