Understanding sediment dynamics in mountain catchments is crucial for flood hazard assessment, risk management, and land planning. Monitoring hillslope processes provides insights into sediment production and basin evolution. Meteorological variables, like precipitation, play key roles in sediment movement and hazard prediction, especially under climate change scenarios. Unmanaged debris flow-prone channels, such as those in the Italian Dolomites' Fassa Valley, are dynamic environments shaped by precipitation dynamics. This study investigates erosion and deposition patterns within one channel (Rio Gardeccia), focusing on their relationship with precipitation events. This research used high-resolution topographic surveys and DEM of Differences (DoDs), to analyze its morphological evolution between July 2018, September 2020, July and October 2023. Significant erosion and deposition have been quantified and linked to intense rainfall events. Several rainfall events have exceeded historical thresholds for debris flow generation (2015 and 2017), including large erosion and deposition, and high triggering potential. By studying precipitation patterns and their impact on channel morphology, this research enhances our knowledge of the debris flow effects on the evolutive stages of a debris-flow channel. The findings also highlight the importance of ongoing monitoring using high-resolution topographic methods. The correct assessment of the erosive/depositional sediment yield rates can improve our ability to manage the debris flow hazard in mountain catchments.