Assessing landscape features and geomorphic processes influencing sediment dynamics in a geomorphologically highly active Mediterranean agroecosystem: The upper Val d'Arda case study (Northern Apennines, Italy)

The management of Mediterranean Agroecosystems is crucial to prevent or mitigate sediment-related threats like soil erosion, water quality issues, and reservoir sedimentation. Hence, the identification of type, extent, and location of sediment sources and sinks, in relation to geological and landscape features, is a key prerequisite for identifying erosion hot spot areas and assessing sediment dynamics at catchment scale. This study was carried out in the upper Val d'Arda catchment (Northern Apennines, Italy). We applied geomorphological field mapping together with multi-temporal photointerpretation, GIS-based hydrological modelling, terrain analysis and photogrammetry. Our approach was aimed at exploring the main landscape features, as well as identifying the variety of processes influencing sediment dynamics. In this poorly studied area, we identified a high heterogeneity in terms of type and extent of sediment sources and related processes. Landslides are the most common processes contributing to the sediment yield. Their morphogenesis, extent and location are controlled mainly by lithology and topography. Large ancient earthflows have been the most important geomorphic factor in shaping the landscape, strongly influencing the surficial drainage pattern and the morphological evolution of the main fluvial systems. Upland rill-interrill erosion is another main sediment source, particularly on arable lands. Piping and gullying locally contribute to the development of badlands, and have a high potential for soil loss and sediment production. Finally, fluvial processes significantly contribute to the sediment yield with several active fluvial erosion scarps and bank erosion source areas. Alluvial sediments are locally stored in transient landforms such as bars or more permanent sinks such as floodplains or river terraces. Our study shows that an integrated methodology based on fieldwork, geomorphological mapping, GIS applications and proximal sensing methods is an effective approach to characterize complex geomorphic systems in the Northern Apennines.