Nearshore sticky waters

TL;DR

This paper investigates the phenomenon of tracers like pollutants and nutrients appearing to halt near the shoreline, explaining the mechanisms behind this 'nearshore sticky waters' effect using a simple model.

Contribution

It introduces a simple model that explains the parking of tracers near the shore and highlights the roles of bottom topography and non-uniform dispersion.

Findings

Tracers tend to accumulate just beyond the break zone.

Bottom topography significantly influences tracer parking.

Non-uniform dispersion can lead to eventual shoreline landing.

Abstract

Wind- and current-driven flotsam, oil spills, pollutants, and nutrients, approaching the nearshore will frequently appear to park just beyond the break zone, where waves break. Moreover, the portion of these tracers that beach will do so only after a long time. Explaining why these tracers park and at what rate they reach the shore has important implications on a variety of different nearshore environmental issues, including the determination of what subscale processes are essential in computer models for the simulation of pollutant transport in the nearshore. Using a simple model we provide an explanation for the underlying mechanism responsible for the parking of tracers, the role played by the bottom topography, and the non-uniform dispersion which leads, in some circumstances, to the eventual landing of all or a portion of the tracers. We refer to the parking phenomenon in this environment as nearshore sticky waters.