Erosion forms hills, coastlines and glaciated lakes, the edges of streams and rivers and transports rocks and soil particles between locations. Three processes underlie erosion: detachment, entrainment and transport.
Soil characteristics influence erosion, such as texture, size and shape of soil particles. Amount and quality of rainfall as well as slope characteristics also impact erosion rates.
Weathering
Weathering refers to the process of disintegrating or breaking down rocks at or near Earth’s surface by physical, chemical, or biological means.
Different rocks react differently when exposed to weathering and this factor has an influence on how quickly a rock erodes away.
Chemical weathering alters a rock’s original material into something soft and vulnerable to erosion, leaving behind sediment deposits over thousands to millions of years and changing soil quality and nutrient levels, even leading to its breakdown into hills and plains. The amount of weathering occurring has an enormous effect on sediment deposition patterns across space-time as well as on its impact on soil quality and nutrition levels. It may even cause mountains to recede into plains.
Entrainment
Entrainment is an integral component of gravity-driven mass flows like landslides, debris flows and snow avalanches; however, its influence can often be difficult to forecast in terms of runout distances and mobility gains.
To address this problem, we conducted simulations of erosion and entrainment in dense granular flows using the Material Point Method. Our results demonstrate that the entrainment velocity (ue) varies nonlinearly with energy input; low energy input favoring ploughing while higher levels promote basal abrasion.
We created an energy generator that accurately calculates erosional net momentum production and shows how erosion velocity determines whether or not a landslide generates higher mobility, providing us with the first mechanical quantification of erosional energy and an explicit description of mobility.
Detachment
Detachment occurs when soil particles become detached from their contact surfaces and exposed to lateral movement, depending on transport conditions. Depending on its extent, this lateral movement could expose carbon and nitrogen-containing organic matter (OM) such as microorganisms, leaching or dissolution losses as a result.
Flow transport requires the harmonious alignment of forces to achieve effective entrainment and erosion, with flow competence depending on factors like velocity, slope steepness, lithology, rainfall intensity and soil characteristics. Silt and clay particles, for instance, often form cohesive bonds which require higher flows velocities to break than larger sand particles – leading to reduced competence at points where underlying materials are soft or resistant to entrainment.
Aggravation
Erosion and deposition can be affected by various factors. Physical forces like wind can erode soil while liquid water or ice can wear away rocks, while plant growth can help mitigate or stop erosion by anchoring rocks to the earth and slowing or stopping further loss of sediments and rocks.
Earthen floodplains erode more rapidly than rocky river valleys; an area regularly subjected to heavy overbank floods can see its height surpass that of its channel bed.
Aggravation rates tend to be highest in areas experiencing intense human disturbance, such as those with high GDP and population densities, but their relationship is complex, depending on both erosion rate and intensity of disturbance; spatial conflicts/aggadations patterns typically exhibit an inverted “U”.
Degradation
Degradation refers to the physical or chemical deterioration of a substance due to external influences. Commonly caused by chemical exposure or environmental conditions, degradation can reduce the effectiveness of personal protective equipment (PPE), filters and other devices.
Degradation is an international problem that threatens soil quantity and quality – an invaluable natural resource essential to agriculture and sustaining life on Earth.
As topsoil erodes away, crop yields diminish and farmers lose valuable commodities. Furthermore, eroded material may move downstream and clog water reservoirs threatening wildlife habitat and decreasing yield.
Erosion can be avoided through restoration of damaged areas and prioritizing erosion-preventative measures in land management policies. For more information about how you can help, click here.