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

Abstract

A methodological approach to refining the identification and mapping of fluvial terraces has been applied, combining geomorphological field surveys with the computation and assessment of different morphometric parameters (local, statistical, and object-oriented), derived from a high-resolution digital terrain model (DTM) obtained from a LiDAR survey. The mid-sector floodplain of the Misa River basins was taken as a valid example of the main river valleys draining the northern Marche Apennines (Italy) and was considered an ideal site to test a combination of different geomorphological techniques for enhancing fluvial terraces’ detection and mapping. In this area, late Pleistocene–Holocene fluvial terraces are well exposed, and their geomorphological and geochronological characteristics have largely already been studied. However, a reliable distinction of the different Holocene terrace levels, including a detailed geomorphological mapping of different terrace features, is still lacking due to the very complex terrace geometry and the lack of good-quality deposit outcrops. Land-surface quantitative (LSQ) analysis has been coupled with the available outcomes of previous studies and ad-hoc geomorphological field surveys to enhance the identification and mapping of fluvial terraces. The results of this work provided information for the discernment of terrace remnants belonging to the full-glacial fill terrace generation (late Pleistocene) as well as reconstruction of the terrace top–surface, and can be used to distinguish the inner terrace limits coinciding with the margin of the floodplain. It has also been possible to identify and delimit the late Pleistocene terrace from a staircase of three younger strath terraces formed during the Holocene. The results of this study demonstrated that the investigation of fluvial landforms, at different scales, can strongly benefit from the integration of field surveys and quantitative geomorphic analysis based on high-resolution digital topographic datasets. In particular, the integration of LSQ analysis with ground-truth geomorphological data can be dramatically helpful for the identification and mapping of fluvial terraces.