Mapping geomorphodynamics in high-magnitude events: contributions to the prevention of landslide-related disasters

Abstract

High-magnitude landslides are natural processes that shape steep slopes and valleys in southern and southeastern Brazil, while also being responsible for some of the most devastating natural disasters recorded in recent years. To improve disaster prevention strategies, this study aimed to analyze the geomorphodynamics of high-magnitude landslides in the Paraitinga Plateau (SP) associated with the extreme 2009/2010 event. The research adopted a detailed approach based on high-resolution geomorphological mapping, integrating multitemporal photointerpretation techniques, fieldwork, and analysis of erosional and depositional features. Results revealed that deeper landslides, linked to weathering mantle ruptures, were frequently associated with debris flows that reshaped valleys, forming depositional lobes in debris cones. Scouring from these flows was marked by plucking features in bedrock channels, contrasting with fluvial abrasion in downstream sections. Past deposits indicate historical recurrence of these processes, potentially intensified by anthropogenic changes like native vegetation removal. The study demonstrates that high-magnitude events, though rare, play a fundamental role in landscape as agents of slope and channel remodeling. Results highlight the importance of considering the integration of geomorphodynamic analyses into risk assessment, enhancing the understanding of mass movement dynamics and supporting forecasting in data-scarce regions, thereby contributing for more effective public policies for disaster prevention in humid tropical regions.