Erosion is a natural process that has profoundly changed our landscape, moving away soil and rock and altering sloped areas by carrying away soil and rock; creating features such as alluvial fans, deltas and sandbars along its route.
Erosion risk in soil depends on its texture and particle size distribution; those soils with more medium to larger-sized particles tend to be more vulnerable than clay- and sandy-textured soils to erosion.
Detachment
Erosion involves the detachment, movement and deposition of soil. Detachment typically results from raindrop impact and splash that shatters surface aggregates and moves soil particles up to three feet away; they then float away into water bodies where they may clog and seal soil pores thereby decreasing infiltration rates resulting in reduced cropland productivity as well as water erosion issues in streams, lakes, reservoirs or deltas.
Erosion limited transport requires most runoff energy to detach and transport 0.02 mm clay particles and fine silt, while coarse sand typically originates through splash detachment [8]. Tc and hydraulic parameters often differ for different sediment size classes as well as for slope gradients with gentle or steep gradients [9, 10].
Sheet erosion is an ongoing and often unnoticed issue in agricultural settings, particularly due to tillage and drainage practices which reduce soil organic matter levels, leading to poor soil structure and altered horizon thickness changes that lead to heavy clay build-up on knolls and shoulders. Its severity can be compounded by ineffective management practices like ploughing, sowing or ploughing.
Entrainment
Transportation of particles within a medium depends upon a delicate balance between forces that affect detachment and those that control entrainment, including gravity, particle slope angle relative to flow direction of an eroding medium, particle mass, surface roughness and particle mass density. Complicating matters further are cohesive bonds weakened due to weathering or force of erosion (e.g. abrasion, plucking raindrop impact or cavitation), which may resist being taken up.
Influences of snow properties at the release zone and in an erodible bed on entrainment and erosion are examined in detail, with various erosion patterns identified and correlations established between erosion rate, runout distance, entrainment rate and runout distance; distinguishable differences between entrainment and erosion also identified.
The main factor affecting the entrainment and erosion of snow is the eroding velocity. When flow can break apart and remove weaker particles faster than stronger ones, more snow becomes trapped and erosion results in greater entrainment and erosion.
Transport
Erosion requires particles being lifted by an element capable of transporting them; wind, water or ice are commonly used mediums for this process. These mediums also play an integral role in erosion as they transport sediment from its source site to where it needs to go.
Entrainment and detachment can be difficult to distinguish, as many particles pass through these processes multiple times during their journey. Furthermore, certain types of particles such as silt or clay require higher flow velocities in order to erode. This occurs because these materials form cohesive bonds that require higher speeds for breaking.
Sediment transport can bring physical changes to the landscape, such as erosion of river banks and beds and formation of sand dunes, as well as decreased availability of nutrients for aquatic plants. Understanding sediment movement is vitally important when managing natural resources. Sediment transport models can be developed to predict how much sediment will settle at one site over time.
Deposition
Deposition occurs when pieces of Earth that have been worn away through erosion are transported away and deposited elsewhere; this can happen near where they were weathered, or farther afield – such as when sand is washed into the sea.
Erosion often moves rocks and soil by water erosion; however, wind or glaciers may also carry materials to other locations.
Streams, from small rivulets to massive rivers, perform both erosion and deposition as they flow towards oceans. They carry away weathered materials on their journey while simultaneously shaping unique landscapes and landforms along their journey.