Looking for permafrost signatures in Arctic streams: the case of meandering rivers

Meandering is one of the most common morphological pattern through which rivers manifest themselves. Here, the attention is devoted to meandering streams carving their path through permafrost floodplains, which typically characterize cold environments such as the Arctic. Despite meandering rivers have been widely studied in the last fifty years, little is known about the dynamics of streams where banks are composed of perennially frozen material. It is inquired whether there is a morphological signature in the planform of permafrost streams potentially deriving from specific thermo-mechanical processes occurring in Arctic landscapes, like the formation of thermo-erosional niches and sediment slumps caused by thaw-weakened soil. To this aim, a bend scale analysis of the planform geometry of several Arctic streams by means of Landsat satellite imagery is employed. Morphodynamic features such as lateral migration rates, channel curvatures, and width variations, are extracted from multispectral remotely sensed data by combining Google Earth Engine (GEE) with an established process-based software (PyRIS).  Following a methodology based on continuous wavelet transform, a set of metrics quantitatively defining the meander shape, which include fattening and skewing coefficients, are used to compare permafrost streams with a series of natural meandering rivers from tropical and temperate regions obtained from the literature. The present analysis opens the way to a systematic integration between remote sensing and physically-based morphodynamic models able to incorporate thermo-mechanical processes uniquely related to permafrost environments.