Study of long shore sediment transport in the vicinity of hydrotechnical constructions

This paper considers results of experimental investigations incorporating fluorescent tracers to analyze sediments transport in the vicinity of hydrotechnical constructions in Lake Kinneret (Israel). The fluorescent tracer method uses sediments tagged with ecologically-harmless fluorescent stains of several colors. The tracers, having the same hydrodynamic properties as the original (un-coated) particles, are placed at their original sites and then traced 'downstream' of the nearshore currents. Due to high sensitivity of the method, very small concentrations of the stained sediment particles can be detected providing precise quantitative data on bed-load transport processes. We have developed three methods for quantitative measurements based on: 1) visual scanning and counting, 2) excitation emission scanning spectroscopy, and 3) optical absorption of extracts in organic solutions. An example of application of two differently colored tracers is presented, showing the patterns of bed load transport in the vicinity of hydrotechnical constructions. These investigations show that hydrotechnical constructions, like jetties, disrupt the long-shore transport (partially or completely, depending on the bottom slope at the littoral zone) and activate sediment separation process within the space between these constructions.