Introduction

Abstract

“Hydraulics” is a nebulous term that evokes images of pumps, dams, brake fluid and lifting machines. In geophysics the term has been applied to wind or current systems that exhibit behavior found in spillways, aqueducts, dams and other open channel engineering applications. Many oceanic and atmospheric flows are topographically constrained in the same way that rivers and reservoirs are, and so it is not surprising that similar physical features arise. For instance, the spillage of dense air over a mountain range and the resultant strong down-slope winds are visually and dynamically similar to the flow of water over a dam or weir. Overflows of dense water flowing along the ocean bottom or in sea straits exhibit similar behavior.