Estuarine Fronts

Secondary flows, driven by lateral density gradients, can have an important role in estuarine dynamics. I have been looking at the hydrodynamics of such fronts in the Tay Estuary, Scotland, and the sediment dynamics of fronts in the Conwy Estuary, North Wales. I have developed a non-hydrostatic model of an estuarine cross-section (TEXSM - Tay Estuary cross-sectional model) to study estuarine frontal dynamics and validated the model with in situ ADCP and density observations. The work in the Tay Estuary was the subject of my NERC CASE PhD studies and a subsequent 1 year postdoctoral project funded by EPSRC (GR/M88020/01). I am still actively engaged in researching estuarine fronts, particularly their role in larval dispersal.

My latest results (Neill, 2009) demonstrate the role of estuarine fronts in sediment dynamics. Analogous to the lateral sediment grain size sorting which occurs in river meanders (see Figure A, below), my model studies have demonstrated that estuarine fronts can similarly affect lateral grain size sorting in the absence of channel curvature (Figure B). The magnitude of the sorting is small compared to the effect of lateral shear in the longitudinal velocity, but in such a biologically productive region as an estuarine front, the influence on estuarine benthic biogeochemical and biological processes may be significant.

Relevant publications

Robins P.E., Neill S.P., Giménez L. (2012) A numerical study of marine larval dispersal in the presence of an axial convergent front. Estuarine, Coastal and Shelf Science 100, 172-185.
Neill, S.P. (2009) A numerical study of lateral grain size sorting by an estuarine front. Estuarine, Coastal and Shelf Science 81, 345-352.
Ferrier, G., Macklin, J.T., Neill, S.P., Folkard, A.M., Copeland, G.J.M. and Anderson, J.M. (2005) Observing estuarine currents and fronts in the Tay Estuary, Scotland, using an airborne SAR with along-track interferometry (ATI). International Journal of Remote Sensing 26, 4399-4404.
Neill, S.P., Copeland, G.J.M., Ferrier, G. and Folkard, A.M. (2004) Observations and numerical modelling of a non-buoyant front in the Tay Estuary, Scotland. Estuarine, Coastal and Shelf Science 59, 173-184.