High-resolution remapping of the coastal dune fields of south east Queensland, Australia: a morphometric approach

Abstract

The sand islands and shore-attached dune fields of south east Queensland form the world's oldest and largest coastal sand dune system. Here we present updated morphological maps for the dune fields based on topographic expression and geomorphic relationships. Individual dunes were delineated using high-resolution elevation data and were grouped into morphosequences based on the elevation, drainage characteristics and slope characteristics of the individual dunes. The slope characteristics focussed on high resolution derived slope-curvature and slope-elevation parameters. Morphosequences were recognised from cross-cutting relationships and relative position in the dune field. Our method was developed for the Cooloola Sand Mass and then applied to Fraser Island, Moreton Island and North Stradbroke Island, the other major sand islands in south east Queensland. In total, five Holocene and four Pleistocene units have been identified. The new mapping underpins current work on the geomorphic evolution of the dune fields.

Measuring landscape evolution from inception to senescence

“…Dune selection and OSL dating overview. We focus on the Holocene sections of the Cooloola Sand Mass (CSM) as dated by Walker et al and Ellerton et al 24 and mapped by Ward 48 and Patton et al 49 . Small aliquot 24 and single grain 23 Optically Stimulated Luminescence (OSL) ages for dunes were acquired from previously published sources.…”

“…Any dunes with multiple ages, were averaged and the resultant ages were utilized to produce the σC-age relationship. Additionally, three Pleistocene aged dunes, as defined by previous published work 23,24,48,49 , were delineated to provide a topographic end member for our analyses (not incorporated within the σC-age relationship). Dune delineation.…”

“…Dated dunes are individually defined as polygons in ArcMAP and delineated at the base of crests and trailing arms. A more detailed explanation of our mapping procedures can be found in Patton et al 49 . Each dune was allocated into a geomorphic stage according to definitions given in Extended Table 2.…”

“…In this study we have evaluated the application of common morphometric variables such as elevation, slope, curvature for all delineated dunes. We elected to resample the original DEM using bilinear interpolation to a 5 m resolution to dampen topographic noise, removing DEM artefacts, and decrease roughness associated with dense vegetation 49,50 . Each layer was produced in ArcGIS (version 10.6) spatial analysis tools and calculated to the same extent.…”

“…We utilize topography from the CSM and run a one-dimensional landscape evolution model for a model time of 10 ka. A 1.13 km transect from a young dune (~0.3 ka) 49 with elevation extracted every 5 m is used, see Extended Fig. 2.…”