Assessment of longitudinal dispersion coefficients using Acoustic Doppler Current Profilers in large river

摘要

The present paper provides algorithms to be used in calculating longitudinal dispersion coefficients using ADCP data driven by either vertical or transverse velocity gradients in large river, and describes software components capitalizing on these ADCP measurement capabilities to provide the longitudinal dispersion coefficients based on in-situ measurements. The paper couples in an innovative way the wealth of data provided by ADCPs with robust and theoretical algorithms to compute longitudinal dispersion coefficient relying only on actual velocity data, rather assuming horizontal or vertical velocity models due to traditional lack of field data. The paper clearly provides the promise of ADCP data and the associated analytical algorithms for estimating longitudinal dispersion coefficients. We also compared longitudinal dispersion coefficients obtained with the theoretical formula using ADCP with those from the other available alternative empirical formulas, and found that empirical formula overestimated the longitudinal dispersion coefficient in large river. Therefore, further use of the software and the embedded procedures can uniquely support in-situ measurement campaigns designed to document important aspects of the dispersion processes and formulation of reliable knowledge that circumvent the empirical approaches of the past.