Regional Patterns of Coastal Erosion and Sedimentation Derived from Spatial Autocorrelation Analysis: Pacific and Colombian Caribbean

Abstract

Coastal erosion is a common phenomenon along the world’s coasts. Studying it is complex because such studies must cover large portions of land, and it is necessary to understand the multiple processes that interact in each area, so it is important to recognize regional patterns that allow for defining representativeness in relation to the surrounding dynamics. Spatial statistics can be used in coastal geomorphology to identify and quantify trends in coastal morphodynamics. This study analyzes and interprets the spatio-temporal patterns present in the changes in a shoreline, that is, the processes of erosion and coastal sedimentation in the Pacific and the Colombian Caribbean. The results are derived from the detection of significant changes in the coastline via satellite images. For this study, the shoreline of Colombia was digitized for the years 1986 and 2016, thus obtaining changes in the shoreline at a medium temporal scale. The Global Moran’s Index, Local Moran’s Index and Getis–Ord Index were used to explain the spatial statistics. The Global I Moran values for the Pacific were I = 0.190, z = 31.063 and p = 0.01, and for the Caribbean I = 0.624, z = 74.545 and p = 0.01, which suggests good grouping in the Caribbean and very low grouping for the Pacific. The local indices (Moran’s and Getis–Ord) allowed us to visualize and spatialize the significant points of coastal erosion and sedimentation. According to the results, three conceptual models are herein proposed that relate the indices with the geomorphological characteristics: (a) the greater the geomorphological heterogeneity, the greater the grouping; (b) the greater the geomorphological homogeneity, the lower the degree of clustering; (c) the greater the geomorphological complexity, the lower the degree of clustering. Finally, it is confirmed that coastal erosion and sedimentation processes predominate along low coasts.