Williams, J. J.¹ 
(1) Proudman Oceanographic Laboratory, Liverpool, United Kingdom

ABSTRACT: Acoustic Measurements of Bedform Dynamics

Acquisition of high spatial and temporal resolution measurements and images of bedforms in the turbid waters of large-scale laboratory flumes, rivers, estuaries and shelf seas is now possible with new acoustic instruments. Data from these instruments have contributed to improving understanding of contemporary bedform dynamics and hydrodynamics and have assisted attempts to interpret paleoenvironments preserved in the geological record. The present paper reports examples of recent studies using bedform profiling instruments and scanning sonars to study vortex ripples in a wave flume, gravel dunes in an estuary and megaripples in dynamic coastal environments. In the flume study attention is focussed on the sequence of bedforms that evolved in response to stepwise increases and decreases in wave height. The study of gravel dunes in the Severn Estuary UK examines hydrodynamics and associated bedform migration in a mixed grain size environment in rectilinear spring tidal flows. Studies of megaripples examine the formation and destruction of bedforms and the relationships between bedform geometry, detailed hydrodynamics and suspended sediments. Further applications of the new acoustic technologies are then considered and future requirements for further advancement of bedform knowledge in a range of geophysical flows are reviewed.

AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.