Land-Surface Quantitative Analysis to Investigate the Spatial Distribution of Gravitational Landforms along Rocky Coasts

Abstract

The increasing availability of high-quality digital elevation models (DEMs) has been associated with a growing interest in developing quantitative analyses aimed at taking advantage of these detailed, updated, and promising digital datasets. Land-surface quantitative (LSQ) analysis is valuable for describing the land-surface topography and performing measures of the signature of specific geomorphic processes, taking into account site-specific geological contexts and morphoclimatic settings, proving to be particularly effective in transitional environments, such as rocky coasts. This paper presents the results of research aimed at investigating the spatial distribution of gravitational landforms along rocky coasts, by means of LSQ analysis based on a DEM with a ground resolution of 2 m, derived from airborne LiDAR (light detection and ranging) surveys. The study area is at Mt. San Bartolo (Northern Marche, Italy) and characterized by a sea cliff diffusely affected by gravitational phenomena of different sizes and types. Geomorphological and geological field data, interpretations of remotely sensed datasets derived from ad hoc unmanned aerial vehicle (UAV) flights, and DEM-derived hillshades were also adapted to support LSQ analysis. In detail, four morphometric variables (slope, roughness, terrain ruggedness index, and elevation standard deviation) were computed and the outputs evaluated based on visual–spatial inspections of derived raster datasets, descriptive statistics, and joint comparison. Results reveal the best performing variables and how combined interpretations can support the identification and mapping of zones characterized by varying spatial distribution of gravitational landforms of different types. The findings achieved along the Mt. San Bartolo rocky coast confirm that an approach based on land-surface quantitative analysis can act as a proxy to efficiently investigate gravitational slope processes in coastal areas, especially those that are difficult to reach with traditional field surveys.

Enhancing the Identification and Mapping of Fluvial Terraces Combining Geomorphological Field Survey with Land-Surface Quantitative Analysis

“…In this work, a combination of field-based and remote sensing techniques consisting of geomorphological surveys and LSQ analysis [13,14] was performed along a sector, ca. 4 km long, of the Misa River floodplain.…”

“…Curvature was computed by exploiting the algorithm running in the Spatial Analyst tool of the ArcGIS software. R (Figure 4C) is a local-statistical parameter and was computed by considering the largest inter-cell absolute difference of a focal cell and its surroundings [14,37], defined as a 3 × 3 cell moving window. The R values were computed using the focal statistics approach in the Spatial Analyst tool of the ArcGIS software and the Raster calculator tool.…”

“…Nonetheless, the analysis of late Pleistocene-Holocene floodplains, characterized by a very complex spatial arrangement of terrace morphology and structure, can be difficult to perform, and the purely automatic detection of terrace features is challenging. Therefore, a great opportunity is offered by the combination of land-surface quantitative (LSQ) analysis based on high-resolution DTMs with ground-truth geomorphological investigations, which have proven to be effective for the analysis of Earth surface processes and landforms at different space-time scales [6,[13][14][15].…”

Quantitative Characterization of Coastal Cliff Retreat and Landslide Processes at Portonovo–Trave Cliffs (Conero, Ancona, Italy) Using Multi-Source Remote Sensing Data

“…The study of cliffed areas, with a particular focus on coastal retreats and slope failures, involves several factors such as geological, geomorphological, and structural settings [3,4], wave action [2,3,[5][6][7][8][9][10], sediment input [11,12], cliff topography [13,14], beach width [15], and energy contents of waves [16].…”

“…However, the spatial and temporal resolution of aerial photographs is often not suitable to gather significant results [28]. The adoption of more recent survey techniques (when available) for reconstructing coastal topography, such as Aiborne and Terrestrial Laser Scanning (ALS/TLS) and UAV, remarkably improve the evaluation of short-to medium-term cliff-erosion processes and rates [7,31,36,37]. TLS is very accurate, but it may be difficult to use in coastal areas because of the inaccessibility of many slopes.…”