Cluster dispersion of low cost GPS-tracked drifters in a shallow water

Managing the inlet of an Intermittently Closed and Open Lake or Lagoon (ICOLL) adjacent to urban areas is important because of risk of flooding and need to maintain the natural habitat. However, the opening and closing processes can result in an unstable system dynamics. This work investigates the dynamics of an ICOLL using clusters of low cost global positioning system drifters during a neap tide under an open inlet condition. Cluster analysis was applied to estimate the dispersion coefficients and the differential kinematic properties (DKP) of the channel. The lateral dispersion coefficient varied with the tidal phase with a flood tide mean value of 0.42 m2/s. Mean DKP values are in the order of 10-4 s-1. Results show that dispersion in the channel during an open inlet condition is dominated by the strain field resulting in convergence and divergence of surface layers. Regions of enhanced mixing likely associated with resonance were also identified. This study provides baseline information upon which to further examine the effect of conditions at the river mouth on the dynamics and particle transport in the main channel.