Cost effective measuring technique to simultaneously quantify 2D velocity fields and depth-averaged solute concentrations in shallow water flows

This paper presents a cost-effective methodology to simultaneously measure mixing processes and surface velocity fields in shallow flows using multiple, synchronized low cost cameras and lighting. Velocity fields and depth averaged concentration of a soluble fluorescent tracer are obtained over a 4.8 × 1.22 m2 measurement area using the new techniques and the results verified against traditional point probe measurements in a laboratory flume. An example of simultaneous velocity/concentration measurement is presented for an instantaneous release of tracer into flow around an obstruction. The method will help to improve the understanding of mixing processes in shallow open channel flows. It is anticipated that the technique will be useful in physical modelling studies where the mixing and hydraulic length scales under investigation are in the order of 1–10 m, for example in compound channels and partially vegetated streams.