TY - JOUR
T1 - Density-driven secondary circulation in a tropical mangrove estuary
AU - Ridd, P. V.
AU - Stieglitz, T.
AU - Larcombe, P.
N1 - Funding Information:
Sonya Bryce spent days and nights on the Normanby River helping with data collection and she is gratefully acknowledged. The authors also want to thank Roger James, and Simon and Tanya Reed from Kalpowar Station for their invaluable assistance in providing access to the field sites. This work was funded by the Australian Research Council (ARC Major Grant to Larcombe and Ridd) and James Cook University. T. Stieglitz’s visit to James Cook University is funded by the Deutscher Akademischer Austauschdienst, Germany.
PY - 1998/11
Y1 - 1998/11
N2 - Observations of suspended sediment concentration (SSC), salinity and current were made in the Normanby River estuary, Cape York Peninsula, Northern Australia. The estuarine reaches are approximately 80 km in length, and are fringed by mangroves. A well-developed axial convergence was found to exist almost unbroken for a distance of at least 30 km on flood tides, clearly delineated by an accumulation of mangrove leaves and seed pods on the water surface. The convergence migrated to the inside of most bends. Suspended sediment concentration profiles were very well-mixed both vertically and laterally. Salinity profiles showed a cross-channel salinity gradient of 0.2/25 m, sufficient to form density-driven secondary cells. The cells produce an effective transverse mixing coefficient of 0.25 m2 s-1, of the same order of magnitude as the conventional transverse diffusion coefficients for natural meandering channels. Mangrove seeds were present in the channel centre during flood tides, and were moved to the channel banks during ebb tides. Due to the lateral shear in longitudinal currents, mangrove seeds are predicted to move landward up the estuary at a rate of 1 km per day when density-driven circulation cells are active, influencing mangrove seed dispersal.
AB - Observations of suspended sediment concentration (SSC), salinity and current were made in the Normanby River estuary, Cape York Peninsula, Northern Australia. The estuarine reaches are approximately 80 km in length, and are fringed by mangroves. A well-developed axial convergence was found to exist almost unbroken for a distance of at least 30 km on flood tides, clearly delineated by an accumulation of mangrove leaves and seed pods on the water surface. The convergence migrated to the inside of most bends. Suspended sediment concentration profiles were very well-mixed both vertically and laterally. Salinity profiles showed a cross-channel salinity gradient of 0.2/25 m, sufficient to form density-driven secondary cells. The cells produce an effective transverse mixing coefficient of 0.25 m2 s-1, of the same order of magnitude as the conventional transverse diffusion coefficients for natural meandering channels. Mangrove seeds were present in the channel centre during flood tides, and were moved to the channel banks during ebb tides. Due to the lateral shear in longitudinal currents, mangrove seeds are predicted to move landward up the estuary at a rate of 1 km per day when density-driven circulation cells are active, influencing mangrove seed dispersal.
KW - Convergence zones
KW - Estuarine circulation
KW - Mangroves
KW - Secondary current
UR - http://www.scopus.com/inward/record.url?scp=0032213114&partnerID=8YFLogxK
U2 - 10.1006/ecss.1998.0383
DO - 10.1006/ecss.1998.0383
M3 - Article
AN - SCOPUS:0032213114
SN - 0272-7714
VL - 47
SP - 621
EP - 632
JO - Estuarine, Coastal and Shelf Science
JF - Estuarine, Coastal and Shelf Science
IS - 5
ER -