Land surface diversity: A geomorphodiversity index of Italy

Abstract

Geomorphodiversity refers to the variety of landforms and morphological processes characterizing the landscape. The definition of an index to quantify geomorphodiversity is a relevant step for multiple fields of Earth sciences, since it is widely accepted that the variability of the geosphere deeply influences the diversity of the biosphere. Such an index should describe the number and type of landforms and geomorphological processes. We propose a quantitative land surface diversity index valid for Italy, considering multiple input quantities to describe geological constraints and geomorphological processes. Critical issues were the selection of moving window size for focal statistics operations, to calculate local diversity of slope, lithology, drainage density and terrain forms in individual raster maps. We compared the index with traditional geomorphological maps, in selected locations, in which information was available. Results show that a minimal set of heterogeneous data is a satisfactory approach to investigate the landscape diversity. Relating processing parameters and terrain spatial characteristics to the dataset resolution is a good choice to assess a reproducible land surface diversity index. Inclusion of drainage density allows the improvement of results in flat areas, in which other factors show trivial results. We argue that the index is relevant for land use management, assessment of ecodiversity, and it may help describing the interaction between abiotic and biotic compartments.

Case studies associated with the 10 major geodiversity-related topics

“…The quantitative measurement or qualitative assessment of geodiversity is a very active field of research (e.g. [12][13][14][15][16]). Most of the studies that have been carried out have been based on published, small-scale maps of geology, topography, soils, drainage, etc.…”

Evaluating river morphology change with a geomorphic form variation approach

“…The variety statistic has been applied to large-scale (e.g., cell size 1000 m  1000 m) geodiversity analysis of abiotic surface elements (Nikolova & Zareva, 2022) and more recently proposed as a geomorphodiversity index for landform type classification (Burnelli et al, 2023). The novelty here is in its processing of component surface-form metrics applied to river morphology and GFV analysis at finer scales (e.g., particle and bed roughness, bar morphology and reach-scale topography).…”

“…GFV results and variety class values are sensitive to choice of neighbourhood window size and also pixel size relative to channel and feature scale. Although a standard 3 Â 3 square window was applied in this study, larger windows (e.g., 5 Â 5) and/or neighbourhood shapes (e.g., circle, annular and wedge) could be applied (see Burnelli et al, 2023, for circular window shape). More investigation is needed of neighbourhood window size and shape effects to guide selection of appropriate values for a given analysis and pixel size selection relates to this decision-making.…”

“…River channel morphology variation and geomorphic form more generally have not been explicitly thought of in this way, but variety computation has been applied to large-scale landform type diversity analysis (Burnelli et al, 2023). This may provide a fundamental approach to comparing channel forms of all types.…”

An assessment of the geomorphodiversity and land use/cover change (LUCC) effects associated with landslides in Meghalaya, India

“…When the emphasis is given to the variety and richness of geomorphological processes and landforms, it can be termed geomorphodiversity or geomorphological diversity (GmD), that is, 'geodiversity with respect to geomorphology' (Bollati et al, 2023;Melelli et al, 2017;Panizza, 2009). To assess GmD, various approaches can be broadly categorized into qualitative, quantitative and qualitative-quantitative methods (Burnelli et al, 2023;Zwoli nski et al, 2018). Qualitative methods encompass descriptive documentation, knowledge-based approaches and expert opinions (e.g., Panizza, 2009).…”