In what way does water contribute to mass wasting?

Water contributes to mass wasting primarily by adding weight to the slope. When water saturates the soil and underlying materials, it increases the overall load on the slope. This added weight can make the slope more unstable, particularly in cases where the material is already susceptible to movement. Saturation can lead to decreased friction between particles, weakening the cohesive forces that hold the material together. As a result, the increased weight can trigger landslides or other forms of mass wasting, particularly on steeper gradients where gravity plays a significant role in the movement of materials.

The presence of water also affects the pore pressure within the soil, further compromising the stability of the slope. While it might seem that adding water could have benefits, such as promoting plant growth and increasing soil fertility, in the context of mass wasting, the key factor is the weight and the associated increase in instability that water brings to the slope structure.