Evaluation of gully erosion for archaeological preservation in Wupatki National Monument
Wieting C, Rathburn S, Kemper J. 2024. Evaluation of gully erosion for archaeological preservation in Wupatki National Monument. Natural Resource Report. NPS/WUPA/NRR—2024/2630. National Park Service. Fort Collins, Colorado. https://doi.org/10.36967/2302447
Wupatki National Monument contains an abundance of prehistoric and historic archaeological sites that are vulnerable to gully erosion from heavy sporadic rainstorms. Increased erosional risks are predicted as more extreme weather causes frequent or intense rainfall, flooding, and gullying. At Wupatki National Monument, gullies generally form on hillslopes within volcanic-derived cinders that are ubiquitous across the landscape and are unconsolidated, non-cohesive, highly mobile, and permeable. Lithological differences between volcanic cinders and underlying sedimentary rocks, and surface runoff influence the progression of gully erosion near archaeological sites. We assessed gullies based on changes in gully morphology and categorized archaeological sites based on vulnerability from erosion and runoff processes. We found that 35 measured gullies are actively eroding, with statistically significant changes in gully depth from 2016 to 2021. Up to 0.5 m of incision was documented over a five-year period. A structure from motion analysis at the hillslope scale confirmed gully morphological changes and supports the applicability of conducting similar analyses on a larger scale. More erosion occurred in gullies with catchments predominantly covered with cinders because of cinder mobility. We noted a weak relationship between gully catchment area and gully head slope, likely related to runoff processes from outcrops of resistant sedimentary rocks forming cliffs and characteristics of cinders that maximize infiltration and transport. Based on our assessment of gully morphologic change and substrate characteristics, 22 archaeological sites along Wupatki Wash were identified as having a high vulnerability to erosion, helping monument managers to prioritize their monitoring initiatives.
- Type
- Published Report
- Authors
- Wieting, Celeste; Rathburn, Sara; Kemper, John
- Date of Issue
- 2024-02
- Publisher
- National Park Service
- DOI
- 10.36967/2302447
- Units
- NRSS , WUPA
- Keywords
- archaeological preservation, archaeological site management, climate change, gully erosion, vulnerability assessments