S2S - Scientific-technical report 1st year

S2S aims to characterize landslide sediment supply to stream channels and evaluate hillslope-channel feedback mechanisms in small- (e.g., 5-10 km^2) to medium- (e.g., 100-200 km^2) sized drainage basins. This objective is pursued through integration of hillslope and channel geomorphic components within the framework of sediment connectivity in the context of sediment management plans. Building on ongoing research efforts and existing data, this project focuses on selected mountain catchments of the Northern Apennines (Italy) and the North Island (New Zealand). These two settings, which share actively uplifting tectonic forcing, comparably weak lithologies, and a history of intense deforestation, differ in terms of climate. The latter being wetter (MAP = 1000-2500 mm) than the former (MAP = 600-850 mm), due to tropical cyclones occurring between March and May. In the Northern Apennines, S2S analysis are performed on the earthflow-dominated basin of Sillaro River. In particular, S2S builds on previous knowledge and existing data, including: (i) a multi-temporal landslide inventory (1954-2018), which is currently being compiled; (ii) historical documentation of planform channel changes (1954-2021); (iii) an airborne LiDAR survey conducted along the entire channel main stem in February 2021; and (iv) geomorphic change detection and bedload monitoring performed in one channel reach through UAV photogrammetric surveys and RFID particle tracking. Within the North Island of New Zealand, S2S analyses are performed on the Waiapu River basin, one of the most prolific conveyors of sediment in the world, annually delivering roughly 35 Mega tonnes of fine material to the ocean from eroding gullies, hillslopes, and reworked sediment on valley floors. Considering these relevant characteristics, and the ongoing monitoring efforts and historical reconstructions, the Waiapu River catchment is one of the most relevant places to study hillslope-channels interactions and represents a useful benchmark against which to compare sediment dynamics and management policies in the Northern Apennines. The project is organized in three work packages (WP) with specific activities (Tasks). The project partners include the University of Bologna (UNIBO), the Istituto di Ricerca per la Protezione Idrogeologica, Consiglio Nazionale delle Ricerche (IRPI), the University of Auckland (UNIAU), and the University of Milano Bicocca (UNIMIB).