Factors controlling sediment transport

Sediment transport is defined as the process of carrying and moving different sediments from one place of their formation to another, by running water or wind, . Sediment is the solid material made up of rocks and minerals. In addition to the remains of plants and various animals that move from one place to another to be deposited, In general, the process of sediment transfer depends on many factors that control it, including:

water flow

Water flow is the most important and influential factor in sediment transfer; It controls the quantity and volumes of the transported sediments. Without the presence of flowing water, the sediment cannot move and move, and it may settle and be deposited if the water stops moving or moves at a slow speed. The effect of the water flow depends on many factors, including:

Water stability rate: The higher the watercourse water stability rate, the lower the sediment transfer rate (an inverse relationship).

To know the factors and conditions for the transfer of certain sediments, it is sufficient to study the shape of the changes that occurred in their grains, by observing them with a paired amplifier, especially the quartz grains, which are the most abundant in igneous rocks.

The study enables to identify three types of manifestations of quartz grains:

Non-segmented beads ( Non use (NU) : transparent, angled, and often not grooved, indicating a river or glacial transport

Emousse Luisant (EL) : transparent with shiny faces indicating long-range transport in a water medium (a seashore or lower course of a river). Figure Edge Shear Strength: It expresses the amount of force required so that the flowing water can begin to move the sediment.

Sediment Size: Large sediment volume requires a high velocity of the flowing water; In order to be able to carry and transport these sediments, and conversely, sediments of smaller sizes can be transported by a lower velocity of the flowing water than that required to transport larger volumes of sediments.

The shape of the channel and its topography: The shape of the channel in terms of length, width, and depth controls the amount of water flowing, which in turn controls the amount of sediment that can be transported. ; Because of the many obstacles that sediment can be exposed to during the transportation process.

weather and water level

Depending on what was previously mentioned, flowing water is the main medium for sediment transfer. The flowing water, its speed, and quantity are affected by many factors, including the water level, which depends directly on the amount of rain, weather, and melting ice; The higher the precipitation rate, or the ice melting rate, the higher the water level, which in turn increases the sediment transfer in terms of quantity, size, and distance traveled.

Sediments in this area are affected by the river water inferior load and the strength of currents and sea waves. Elements similar to river sediments are deposited in the water channels of the high delta, while in the delta plain we find microelements rich in organic matter in a humid climate and evaporators in a dry climate, while we find various deposits on The edge of the delta, according to the river load, is characterized by sediments rich in organic matter with traces of the activity of living organisms.

human influence

The human impact on the transportation process is the process of creating dams, cutting down trees to use land for construction, or for other urban activities, where the construction of dams leads to water retention, and restriction of its movement, which leads to the stability of sediments, and the lack of movement as a result of the almost non-existent movement of water, and on the other hand, Removing these dams, or their collapse leads to the flow of large quantities of water, and at a high speed; Lead to loosening, carrying large amounts of sediment of different sizes, and transporting them over long distances, and urban activities that include removing vegetation for the use of land for construction leads to exposure of the upper layer of soil and rocks to a greater rate of weathering and erosion; Because there are no obstacles to falling or flowing water, which leads to an increase in the amounts of sediment transported.