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TitleClimatic and morphologic relationships of rivers: implications of sea-level fluctuations on river loads
AuthorMulder, T; Syvitski, J P M
SourceJournal of Geology vol. 104, no. 5, 1996 p. 509-523,
Alt SeriesGeological Survey of Canada, Contribution Series 20295
PublisherUniversity of Chicago Press
Mediapaper; on-line; digital
File formatpdf
Subjectssurficial geology/geomorphology; rivers; discharge rates; hydrologic environment; hydrologic properties; hydrosphere; sea level changes; sea level fluctuations; deltas; deltaic sediments; turbidity currents
AbstractThe characteristics of 279 rivers that discharge into the world oceans are analyzed in terms of their basin hydrology (river discharge), morphometry (basin slope and area, river length, extension of the continental shelf seaward of the river mouth), and climate (precipitation). Statistically reliable relationships are found between discharge and basin area, and between sediment load and a combined function of basin area and slope. These functions are used to demonstrate how river hydrologic features would be strongly influenced by sea-level fluctuations, particularly under the influence of continental shelf emergence. A fall in sea level toward a glacioeustatic lowstand would induce the merging of rivers on the subaerial continental shelf, thereby allowing giant rivers to form. For example, rivers of western Europe would reorganize themselves into two or three very large rivers. Sediment concentration carried by these mega-rivers would decrease, and thus the number of hyperpycnal plumes generated at river mouths would be reduced. There would, however, be a strong increase in global sediment delivery and thus in the frequency of undrained delta-front failures because of both the progressive concentration of depocenters at the mouths of giant rivers and delta migration toward the shelf breaks. The global increase of sedimentation rate should then be empha-sized at giant river mouths. Associated with a global increase of hypsometry would be a significant increase in the frequency and volume of turbidity currents, since high slopes facilitate flow acceleration and slope erosion.