How does permafrost affect drainage in Arctic tundra soils?

In the Arctic tundra, permafrost acts as an impermeable barrier that significantly retards the downward movement of water through the soil. Because this frozen layer prevents water from draining into the ground, the lowlands of the Arctic tundra frequently become saturated and boggy during the summer thaw.1

This impeded drainage is a defining characteristic of the ecosystem's hydrology. Furthermore, because the soil remains waterlogged near the surface, it can easily slide down slopes in a process known as solifluction, which contributes to the formation of various landscape features like terraces and lobes.1