Jordflöde

Jordflöde, sometimes translated as earth flow, is a type of mass wasting event that occurs on gentle to moderate slopes. It is characterized by a slow, viscous movement of saturated soil and rock debris downslope. Unlike more rapid landslides, jordflöde can take days, weeks, or even years to fully develop. The movement is often described as a creeping or flowing motion, with the material deforming like a very thick fluid.

The primary cause of jordflöde is the presence of water. When soils become saturated, the pore water pressure increases, reducing the effective stress between soil particles. This loss of inter-particle friction allows the material to move downslope under the influence of gravity. Contributing factors can include heavy rainfall, snowmelt, changes in groundwater levels, and the presence of specific soil types, such as clay-rich soils that retain water effectively. Vegetation can play a role in stabilizing slopes, so deforestation can sometimes increase the risk of jordflöde.

Jordflöde can cause significant damage over time, even though its movement is slow. It can deform or destroy infrastructure like roads, buildings, and pipelines that lie in its path. The slow, continuous movement can also subtly alter drainage patterns and lead to the gradual degradation of agricultural land. Recognizing the signs of jordflöde, such as bulging or cracking of the ground, tilting trees, or the formation of scarps, is important for hazard assessment and mitigation in susceptible areas.