Drivers and the socio-economic context

Drivers and the socio-economic context of soil erosion

Human Influence

Modern activities such as intensive farming, deforestation and urbanisation can accelerate erosion by reducing protective soil cover from vegetation and litter, compacting soil, and increasing field size, thereby decreasing obstacles to runoff.

Under intensive agriculture with frequent soil tillage and the use of heavy machinery, erosivity of surface runoff is enhanced by ploughing, leading to concentration of overland flow in furrows and decreasing resistance to flow. Compaction of the topsoil further enhances overland flow generation by reducing water infiltration capacity, which increases total overland flow. Ploughing also affects soil erodibility by destroying soil aggregates and decreasing soil organic matter content.

In forestry, logging and wood extraction reduce rain interception, expose more soil to splash erosion, and decrease resistance, resulting in greater and faster overland flow. Additionally, temporary or semi-permanent roads for timber extraction cause significant soil compaction and erosion.

Urbanisation increases the total area of impermeable surfaces. Water collected on these surfaces, if not properly managed, poses a risk of increased erosion on downstream (agricultural) land by increasing the overland flow rate.

Climate 

A major driver of water erosion is the weather. Rainfall intensity directly affects splash erosion (the detachment of soil particles).  It is also often a key factor in generating overland flow, especially in cases of so-called infiltration-excess overland flow. This happens when rainfall intensity exceeds the soil’s capacity to absorb all water.

Total rainfall is also a key factor in generating surface runoff, especially in cases of so-called saturation overland flow generation, where soil pores are already totally filled with water and no further absorption can occur. The overland flow will then detach and transport soil particles.

Temperature is an important factor in cold-climate regions, where the freezing-thawing cycles influence soil erodibility. Combined with precipitation, snowmelt events often lead to large volumes of overland flow, detaching and transporting significant amounts of soil particles.