--> A “Big Data” Approach for Studying Modern Alluvial and Delta Plain Channels and Channel Belts

AAPG ACE 2018

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A “Big Data” Approach for Studying Modern Alluvial and Delta Plain Channels and Channel Belts

Abstract

A large database of modern channel parameters has been compiled. The data includes alluvial plain, upper delta plain, and lower delta plain channel measurements from a large number of modern deltaic systems and estuaries. The systems cover a range of tectonic settings, climatic zones, drainage areas, rivers sizes, and channel slope gradients. The database contains measurements from close to 60,000 channel inflection points. Individual inflection points are named and placed in a hierarchical framework. They occur within named parent ‘channel stretches’, which in turn occur within named parent ‘channels’. Channels describe the regional drainage network of each system. Each inflection point contains several different hand-measured variables: channel width (W), along channel length (Lc) and direct channel length (Ld) distance to the next inflection point, and amplitude (A), which represents the offset between the Lc and the Ld lines. About 5,000 of the inflection points also contain a maximum thalweg depth parameter. Additional variables are then calculated using programming code: average, minimum and maximum W, Lc, Ld, A and Lc/Ld ratio for each occurrence of eight consecutive channel inflection points within the same channel stretch. In addition to the Lc/Ld ratio (inflection point pair sinuosity), we also calculate conventional sinuosity based on the same inflection point series (total along channel length / direct distance from the first to the last point). All data points in the database also contain calculations for the direct distance from the inflection point to the channel mouth of a related channel at the shoreline, as well as an extraction of the elevation above sea level using Google Maps API. Where geomorphologic mapping allows, a channel belt width measurement has also been included. A specially designed web-based software allows easy querying and cross plotting of all parameters, as well as viewing all selected channel points in a map-view window.

The dataset offers an unparalleled opportunity to examine the variability of channels and channel belts in nature. Examples will be shown that illustrate the importance of the size of the drainage basin, the amount of fluvial discharge, the channel gradient, the degree of channel confinement, the position on the delta plain, the distance from the shoreline, and the degree of tidal influence on channel and channel belt morphology, with subsurface implications also discussed.