COMPARING FLUVIAL AND DEEP-MARINE CHANNEL MORPHOMETRICS IN A STATISTICAL META-ANALYSIS; IMPLICATIONS FOR THE STUDY OF FLOW DYNAMICS AND DEPOSITION IN TURBIDITY CURRENT CHANNELS

Morphometric relations between channel characteristics such as width and meander wavelength are well known in geomorphology. During the past 30 years a number of researchers have suggested that submarine and fluvial channels have different scaling relations, however, none of these studies quantified this dissimilarity in a statistical significant manner. Here, we present a meta-analysis of the combined data of those studies, supplemented with our own experimental sandy turbidity current data, as well as some extra remote sensing data of fluvial channels. A rigorous statistical treatment of such a meta-analysis is typically capable of supplying significant answers that could not be attained by analyzing the sub-samples presented in individual studies.

The results firmly establish the long held impression that submarine and fluvial sinuous channels obey different morphometric relations. The fluvial results are consistent with long established empiric relations, and a new relation for submarine sinuous channels is presented. We focus our further analysis on submarine systems. While system average morphometrics (that is, the characteristics of all bends within a channel) are predicted by the regression models to a very high accuracy, the intra-channel variability is always large. The structure of this variability is such that local morphometrics can change wildly, in a statistical sense, over a series of bends or even from bend to bend, suggesting that channel morphology and flow dynamics are in a constant state of severe adjustment and dis-equilibrium.

This realization has implications for the approach taken in studies of flow dynamics and deposit characteristics in submarine sinuous channels, which tend to analyze a physical or numerical experiment for coherent, steady behavior, often using a series of identical bends to allow the flows to adjust to the channel morphology. However, the natural system doesn’t observe this cleanliness and shows us a large degree of messiness. It is precisely this messiness, i.e. the deviation from predicted system behavior that will govern to a large extent the depositional patterns of sandstones in submarine sinuous channels.