Modeling earthen treatments for climate change effects

Authors: HART, S. - Us National Park Service; RAYMOND, K. - Us National Park Service; Williams, Christopher - Jason; Rutherford, William - Austin; DEGAYNER, J. - Us National Park Service

Submitted to: Heritage
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/6/2023
Publication Date: 5/9/2023
Citation: Hart, S., Raymond, K., Williams, C.J., Rutherford, W.A., DeGayner, J. 2023. Modeling earthen treatments for climate change effects. Heritage. 6(5):4214-4226. https://doi.org/10.3390/heritage6050222.
DOI: https://doi.org/10.3390/heritage6050222

Interpretive Summary: Culturally important adobe structures throughout the American Southwest are at risk to degradation from climate change-induced increasing rainfall intensities. Cultural resource managers commonly apply preservation treatments to limit the erosive effects of high intensity rainfall on adobe structures. However, very little is known regarding the effectiveness of available treatments. This study used rainfall simulation techniques to assess the effectiveness of multiple treatments to minimize deterioration of adobe construction under high intensity rainfall (10.6 cm h-1, 30 min duration). Wall deterioration varied significantly across the four evaluated treatments. Basic adobe patching alone provided minimal protection against rainfall erosive energy whereas more extensive combinations of patching and wall reshaping provided the greatest protection against erosive high-intensity rainfall. The study results provide resource managers with improved knowledge for selecting and targeting adobe structure preservation methods and retention of culturally important adobe resources.

Technical Abstract: Adobe has been used globally for millennia. In the American Southwest, cultural heritage sites made of adobe materials have lasted hundreds of years in an arid environment. A common prediction across multiple climate change models, however, is that rainfall intensity will increase in the southwest US. This increased erosivity threatens the long-term protection and preservation of these sites, and thus resource managers are faced with selecting effective conservation practices. For this reason, modeling tools are needed to predict climate change impacts and plan for adaptation strategies. Many existing strategies, including patching damaged areas, building protective caps and shelter coating walls are already commonly utilized. In this study, we subjected constructed adobe test walls to a local 100-yr return interval rainfall intensity and tested earthen-coat patching strategies to minimize adobe wall deterioration. Findings from resultant linear regression models indicate that patching of earthen architecture alone will not prevent substantial damage, while un-amended encapsulation coats and caps provide greater protection than patching and statistically similar protection. Use of this model will enable local heritage resource managers to better target preservation methods for return on investment of material and labor costs, resulting in better preservation overall and retention of culturally valuable resources.