UC Berkeley

Permafrost in Arctic floodplains impacts carbon stores, ecosystems, and infrastructure, yet the processes controlling its distribution remain poorly constrained. Here we present a numerical model for the coupled evolution of river meandering and floodplain permafrost that captures the competition between bank erosion and permafrost growth. We show that permafrost extent reaches a dynamic equilibrium in which removal by channel migration is balanced by epigenetic permafrost generation on newly deposited land. This behavior collapses onto a regime space defined by two dimensionless ratios—the rate of bank thaw relative to sediment entrainment and the timescale of permafrost growth relative to meander-bend cutoff—which organizes three emergent regimes: permafrost-bounded, confined, and alluvial meanders. Rivers in the confined regime are most sensitive to warming, in which modest increases in bank thaw rates or the permafrost-growth timescale produce large increases in migration rates and substantial permafrost loss.