Why is solifluction especially common in waterlogged Arctic soils?

Solifluction is particularly common in waterlogged Arctic soils because permafrost acts as an impermeable barrier to water.12

During the summer thaw, the "active layer" of soil—the upper portion that undergoes seasonal freezing and thawing—becomes saturated with water. Because this water cannot drain downward through the frozen ground beneath, the soil becomes oversaturated and loses its structural stability. Under the influence of gravity, this soggy, weakened soil mass flows slowly downslope. This process is further facilitated by the freeze-thaw cycle, which opens and weakens the soil structure, making it highly susceptible to this downslope movement.2341