Fluorescent Particles for Non-intrusive Surface Flow Observations

The relevance of hydrological surface processes, such as drainage formation, landscape's evolution, pollutant diffusion, and sediment transport, has recently fostered the development of an array of novel sensing systems. In this context, the deployment and observation of enhanced fluorescent particles is studied in [Tauro et al., 2012] to non- intrusively estimate surface flow velocities and travel times. Such insoluble and buoyant fluorescent particles are not affected by adsorption issues, thus requiring minimal amounts of tracing material to be released in the environment, and are detected through commercially available inexpensive digital cameras. In this paper, we complement previously developed unsupervised particle detection tools with Large Scale Particle Image Velocimetry (LSPIV) analysis for surface flow estimations in natural settings. Specifically, we conduct several proof of concept experiments by deploying few grams of fluorescent particles in a natural brook and analyzing acquired videos with both unsupervised image analysis tools and LSPIV. Results from both methodologies suggest their complementary use for enhanced surface flow monitoring. In addition, the use of environmentally friendly highly visible fluorescent particles would sensibly improve the joint performance of such non-intrusive sensing systems.