The propagation at high Reynolds number of a heavy, two-dimensional gr
avity current of given initial volume at the base of a uniform flow is
considered. An experimental setup is described for which a known volu
me of fluid is rapidly introduced halfway down a 9m channel in which t
here is a uniform flow of water. The density excess of the released fl
uid is produced by either dissolving salt or suspending particles in w
ater. The upstream and downstream propagation of the current was measu
red for different initial salt concentrations, particle sizes and conc
entrations. A simple box model for the motion of and deposit from the
gravity current is constructed. The analytical results obtained compar
e well with our numerical solutions of one-layer and two-layer models
incorporating the appropriate shallow-water equations. Both sets of re
sults are in very good agreement with the experimental data.