Assessing multi-hazard susceptibility to cryospheric hazards: lesson learnt from an Alaskan example

Abstract

Classifying a given landscape on the basis of its susceptibility to surface processes is a standard procedure in low to mid-latitudes. Conversely, these procedures have hardly been explored in periglacial regions, primarily because of the limited presence of human settlements and, therefore, the little need for risk assessment. However, global warming is radically changing this situation and will change it even more in the future. For this reason, understanding the spatial and spatiotemporal dynamics of geomorphological processes in peri-arctic environments can be crucial to make informed decisions in such unstable environments and shed light on what changes may follow at lower latitudes. For this reason, here we explored the use of data-driven models capable of recognizing locations prone to develop retrogressive thaw slumps (RTSs) and/or active layer detachments (ALDs). These are cryospheric hazards induced by permafrost degradation, and their development can negatively affect human settlements or infrastructure, change the sediment budget dynamics and release greenhouse gases. Specifically, we test a binomial Generalized Additive Modeling structure to estimate the probability of RST and ALD occurrences in the North sector of the Alaskan territory. The results we obtain show that our binary classifiers can accurately recognize locations prone to RTS and ALD, in a number of goodness-of-fit (AUC_RTS = 0.83; AUC_ALD = 0.86), random cross-validation (mean AUC_RTS = 0.82; mean AUC_ALD = 0.86), and spatial cross-validation (mean AUC_RTS = 0.74; mean AUC_ALD = 0.80) routines.Overall, our analytical protocol has been implemented to build an open-source tool scripted in Python as part of an interactive Jupyter notebook where all the operational steps are automatized for anyone to replicate the same experiment. Our protocol allows one to access cloud-stored information, pre-process it, and download it locally to be integrated for spatial predictive purposes. Data and codes can be accessed at this GitHub repository: https://github.com/zincoblenda/CryoS