Toward an Objective Method to Distinguishing Deltaic Depositional Environments

Abstract:

The most commonly used method of delta classification is to interpret formation processes from observation of the resulting geomorphic features, and to place the delta on a ternary diagram based on the relative dominance of the associated wave, tidal, or fluvial influences. This system has worked well and has been in use for more than 40 years - but it suffers from the subjectivity inherent to visual interpretation techniques. We aim to establish an alternative classification method that is both objective and reliable for the classification of deltaic systems. At the corner stone of our current approach, we use the statistic of lacunarity to quantitatively describe the variability of deltaic footprints across a wide range of spatial scales. Lacunarity has been used for more than 20 years to identify and characterize stratigraphic patterns, and is currently in use in such diverse fields as urban planning and medicine to characterize spatial distribution of properties. Here, we apply lacunarity to satellite images of modern deltas in order to quantitatively describe the distribution of land and water at scales ranging from the data resolution to that of the entire system. The results of our lacunarity analyses provide the basis for a new, objective, system of delta classification.