‘Mixing and Dispersion in Adelaides Coastal Waters’

The investigation of mixing and dispersion rates is an important area of coastal research with significant implications for the management of nearshore contaminant discharges. Surf zone drifters developed by Johnson et al. (2003) were used to obtain Lagrangian measurements of dispersion rates in Adelaides ’ coastal waters. The drifters were deployed on Henley Beach, near the Torrens River outflow, under contrasting seasonal conditions between the 1st and the 3rd of September 2004 and the from the 20th to the 23rd of March 2005. Data obtained from these deployments was used to estimate the dispersion coefficient K as well as the cross-shore and longshore dispersion coefficients, Kx and Ky respectively. During the September deployments the total dispersion coefficient was estimated as K = 0.11ms-1 within a 95% confidence interval of ±0.08ms-1, whilst during March K = 0.12±0.07ms-1. A significant volume of water is known to enter the nearshore zone along the metropolitan coastline through a variety of river, stormwater and wastewater discharges. During the post war period considerable marine environmental degradation, symptomised by a decrease in seagrass abundance close to shore, has been observed within the off Adelaides coast. This ha