Density-driven exchange flow between open water and an aquatic canopy

Abstract

Differences in water density can drive an exchange flow between the vegetated and open regions of surface water systems. A laboratory experiment has been conducted to investigate this exchange flow, using a random array of rigid, emergent cylinders to represent the canopy region. The flow pattern was captured using a CCD camera. The velocity of the current entering the canopy and the volume discharge both decrease with increasing vegetative drag and also decrease gradually over time. Theoretical predictions for velocity and discharge rate are developed and verified with experimental observations. Extensions to field conditions are also discussed.