Longitudinal dispersion in natural channels: 1. Experimental results from the River Severn, UK

A tracer experiment using Rhodamine WT dye was carried out to measure longi tudinal dispersion in a 14-km reach of the River Severn in Wales, U.K. The river's discharge was measured at six points and the depth, width and cross -sectional area were measured at 86 points along the test reach. The channe l geometry was close to being statistically uniform. Discharge and velocity were both nearly constant. Dye concentrations were recorded at stations be tween 210 and 13775 m downstream of injection. Dye was injected over a shor t interval as a near-uniform line source across the channel. These conditio ns make the data useful for testing mathematical theories of dispersion. Th ey are presented in full.