Sediment Transport in Distributary Channels and Its Export to the Pro-Deltaic Environment in a Tidally Dominated Delta: Fly River, Papua New Guinea
ARTICLE IN PRESS Continental Shelf Research 24 (2004) 2431–2454 www.elsevier.com/locate/csr Sediment transport in distributary channels and its export to the pro-deltaic environment in a tidally dominated delta: Fly River, Papua New Guinea Peter T. Harrisa,Ã, Michael G. Hughesb, Elaine K. Bakerb, Robert W. Dalrymplec, Jock B. Keeneb aMarine and Coastal Environment Group Geoscience Australia, GPO Box 378, Canberra, ACT 2601, Australia bSchool of Geosciences, University of Sydney, Sydney, NSW 2006, Australia cDepartment of Geological Sciences and Geological Engineering, Queens University, Kingston, Ontario, Canada K7L 3N6 Available online 11 November 2004 Abstract Current metre deployments, suspended sediment measurements and surface sediment samples were collected from three locations within distributary channels of the tidally dominated Fly River delta in southern Papua New Guinea. Net bedload transport vectors and the occurrence of elongate tidal bars indicate that mutually evasive ebb-and flood- dominant transport zones occur in each of the distributary channels. Suspended sediment experiments at two locations show a phase relationship between tidal velocity and sediment concentration such that the net suspended sediment flux is directed seaward. Processes that control the export of fluid muds with concentrations up to 10 g lÀ1 from the distributary channels across the delta front and onto the pro-delta are assessed in relation to the available data. Peak spring tidal current speeds (measured at 100 cm above the bed) drop off from around 100 cm sÀ1 within the distributary channels to o50 cm sÀ1 on the delta front. Gravity-driven, 2-m thick, fluid mud layers generated in the distributary channels are estimated to require at least 35 h to traverse the 20-km-wide, low-gradient (2 Â 10À3 degrees) delta front.
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