Extreme erosion processes are widespread in degraded and mountainous terrain due to high and/or intense rainfall, tectonic and seismic activity, soil conditions, geological history, and expanding anthropogenic pressures. While these processes span the gambit from sheet erosion to gully erosion to mass wasting processes, herein we focus on extreme occurrences of individual or combinations of erosion types and their connectivity to fluvial systems. These events, which manifest during individual storms, as the result of precipitation forcing, or in combination with other factors (e.g., earthquakes, volcanic activity, climate change), contribute greatly to sedimentation in streams and rivers. Understanding the linkages between these extreme terrestrial processes and fluvial systems is a major challenge in hydrogeomorphology. Furthermore, a catchment connectivity characterization could improve the behavioural understanding of such extreme events by means of assessing a degree of coupling or effectiveness in sediment transfer. Presentations may include results from field investigations, experimental research, remote sensing studies, or modelling, including combinations of these approaches. We particularly encourage presentations that address connectivity impacts and feedbacks (lateral, longitudinal and vertical) of extreme erosion events.

This session hopes to engage perspectives on soil science, hydrology, geosciences, engineering, and ecology. Specific themes we wish to promote include:
- Extreme surface erosion processes, including gully erosion and their connectivity to streams
- Landslide erosion and linkages to headwater catchments
- Hillslope processes and their characterization in terms of erosion and sedimentation in rivers, channels, floodplains and reservoirs
- Different modelling approaches to estimate runoff and soil erosion processes
- Small-scale experimental studies on erosion and runoff processes
- Recent methodological and technological advances in the characterization of hillslope processes, including remote sensing, GIS tools, photogrammetry, LiDAR, UAVs and geomorphic change detection.
- Understanding the hydrological and sediment connectivity throughout catchments, including methods, process-based concepts, quantification techniques such as indices and models application and scale approach investigations.

This session will be a venue to communicate findings from different perspectives and promote debate amongst geomorphologists, soil scientists, and hydrologists. We wish to promote an integrated, conceptual framework for sharing expertise developed at local and regional scales to better understand the hydrological processes and sediment dynamics involved in extreme erosion processes, to foster better management of soil and water resources in the world.