MORPHOMETRY OF KARST DEPRESSIONS AT DETAILED SCALE: EL CEDRAL, COZUMEL – MEXICO

Abstract

Background. The morphological study of the relief allows an adequate classification of the shape and structure of the karst relief developed over time. Nowadays, there is a classification of the karstic relief that differentiates the units according to the dimension of its X, Y axis, in 3 main categories: poljes, uvala and doline (compactness index). Objective. Analyze and classify the karst depressions of the area known as El Cedral, located on the island of Cozumel, Mexico, as an alternative in understanding the evolution of the insular relief of the Caribbean. Methodology. The karstic relief was analyzed from the construction of a Digital Elevation Model (DEM) obtained from the construction of a light detection and ranging (LiDAR) data mosaic, derived from the nearest neighbor interpolation method applied to a cloud of points generated from the LAS. This model has a data resolution of 5 m for the X, Y axes, and 0.50 cm for the z axis; 45 cenotes were georeferenced from the field database and another 190 depressions were identified through remote sensing, taking as a criterion a minimum depth of 1m; in addition, the longitudinal profiles were generated by interpolating altitude data through the X axis of the depression, and the longitudinal profile was visualized and interpreted, which was drawn manually in 232 depressions. Results. Thus, a typological of the depressions is presented, based on the morphology of the profile in plan (in "V", "U" and " LI " forms), the depth and the gradient of the slopes. The main results are: The major axis oscillates from 31 to 434 m, with an average of 106 m; the maximum depth is 10.75 m and the minimum is 1.45 m, being the average 7.60 m; In the configuration, it is recognized that 56% corresponds to depressions of type V, 27% of type U and 17% to box type profiles; these last one’s present bottom in contact with the phreatic mantle and 70% with processes of permanent flooding. Implications. Geomorphological analyses of this type applied to places of low altitude contrast are scarce, many applied on a larger scale, adapting to the inputs available. The closest classification to this type of study, based on the profiles, is done in valleys, where the scale is larger and the altitude contrast is much greater. Conclusions. The distribution of these depressions is of a radial nature, which highlights the dissolution process associated with the original geological structure.