Stress on the bottom of an estuary

MANY estuaries are sufficiently deep relative to their maximum fetch that even in severe storms the bottom remains undisturbed by wind-generated waves. Yet observations of sediment transport and of changes in benthic animal populations indicate that agitation of the bottom of deep estuaries is not infrequent (refs 1-3, and D. C. Rhoads, unpublished). We report here an analysis of current meter records which shows that such bottom disturbances can arise because wind stress at the surface causes increased turbulence deep in the water column and, consequently, a more frequent occurrence of unusually high velocities near the bottom.