Submission Type
Poster
Abstract
This study describes geomorphology, triggers, and monitoring of a slow, rotational slope failure at Shongo Valley Creek in Caneadea, NY. One- and two-dimensional (dry/wet) factor of safety (FS) models were produced using a 1-meter digital elevation model (DEM) in ArcGIS Pro. Fieldwork and drone imaging were also completed for active slide monitoring and informing FS analysis. The Factor of safety (FS) is a non-dimensional ratio relating resisting and driving forces for failure. FS values above 1.2 indicate slopes that are unconditionally stable, 1 stable, 0.8 unstable, and below 0.8 unconditionally unstable. The analysis revealed most of the region surrounding Shongo exhibited stability (FS 1 to 10), some small zones of instability were identified along the canyon walls of Shongo Creek (FS 0.2 to 1). One of the locations of low FS values corresponds to a steep-walled, east-facing cut-bank comprised of thick (10m), Pleistocene-age, lacustrine clay deposits (varves) overlain by a 1-meter-thick permeable gravel layer. These deposits were identified in areal and field data. We posit that the gravel layer serves as a conduit for surface water flow, applying pore pressure at the interface of the clay-rich deposits. However, the FS models indicate that this relationship alone may not be sufficient to trigger failure. Hillslope failure is ultimately triggered here by undermining Shongo Creek. Field reconnaissance further indicates that FS models runs had limitations by only considering single compositions, precipitation values, and deposit thickness, whereas the area comprises various surface geology type, thicknesses, contributing drainage areas, and specific external triggers.
Recommended Citation
Herberger, Jeffrey, "086 - Shongo Valley Creek Thin Skinned Slump Monitoring and Modeling" (2025). GREAT Day Posters. 25.
https://knightscholar.geneseo.edu/great-day-symposium/great-day-2025/posters-2025/25
086 - Shongo Valley Creek Thin Skinned Slump Monitoring and Modeling
This study describes geomorphology, triggers, and monitoring of a slow, rotational slope failure at Shongo Valley Creek in Caneadea, NY. One- and two-dimensional (dry/wet) factor of safety (FS) models were produced using a 1-meter digital elevation model (DEM) in ArcGIS Pro. Fieldwork and drone imaging were also completed for active slide monitoring and informing FS analysis. The Factor of safety (FS) is a non-dimensional ratio relating resisting and driving forces for failure. FS values above 1.2 indicate slopes that are unconditionally stable, 1 stable, 0.8 unstable, and below 0.8 unconditionally unstable. The analysis revealed most of the region surrounding Shongo exhibited stability (FS 1 to 10), some small zones of instability were identified along the canyon walls of Shongo Creek (FS 0.2 to 1). One of the locations of low FS values corresponds to a steep-walled, east-facing cut-bank comprised of thick (10m), Pleistocene-age, lacustrine clay deposits (varves) overlain by a 1-meter-thick permeable gravel layer. These deposits were identified in areal and field data. We posit that the gravel layer serves as a conduit for surface water flow, applying pore pressure at the interface of the clay-rich deposits. However, the FS models indicate that this relationship alone may not be sufficient to trigger failure. Hillslope failure is ultimately triggered here by undermining Shongo Creek. Field reconnaissance further indicates that FS models runs had limitations by only considering single compositions, precipitation values, and deposit thickness, whereas the area comprises various surface geology type, thicknesses, contributing drainage areas, and specific external triggers.
Comments
Sponsored by Nicholas Warner