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The Hjulström curve, named after Filip Hjulström (1902–1982), is a graph used by hydrologists and geologists to determine whether a river will erode, transport, or deposit sediment. It was originally published in his doctoral thesis "Studies of the morphological activity of rivers as illustrated by the river Fyris. [1]" in 1935. The graph ...
Splash erosion is generally seen as the first and least severe stage in the soil erosion process, which is followed by sheet erosion, then rill erosion and finally gully erosion (the most severe of the four). [10]: 60–61 [13] In splash erosion, the impact of a falling raindrop creates a small crater in the soil, [14] ejecting soil particles. [4]
The model in its original form is intended to explain relief development in temperate landscapes in which erosion by running water is assumed to be of prime importance. [5] [7] Nevertheless, the cycle of erosion has been extended, with modifications, into arid, semi-arid, savanah, selva, glacial, coastal, karst and periglacial areas.
The amount of matter carried by a large river is enormous. It has been estimated that the Mississippi River annually carries 406 million tons of sediment to the sea, [5] the Yellow River 796 million tons, and the Po River in Italy 67 million tons. [6] The names of many rivers derive from the color that the transported matter gives the water.
In geomorphology a river is said to be rejuvenated when it is eroding the landscape in response to a lowering of its base level. The process is often a result of a sudden fall in sea level or the rise of land. The disturbance enables a rise in the river's gravitational potential energy change per unit distance, increasing its riverbed erosion rate.
Long-lived river systems can produce a series of terrace surfaces over the course of their geologic lifetime. When rivers flood, sediment deposits in sheets across the floodplain and build up over time. Later, during a time of river erosion, this sediment is cut into, or incised, by the river and flushed downstream. The previous floodplain is ...
There are two primary mechanisms of stream bank erosion: fluvial erosion and mass failure. Fluvial erosion is the direct removal of soil particles by flowing water. The rate of fluvial erosion is determined both by the force of the flowing water (e.g. faster flow equals more force) and the resistance of the bank material to erosion (e.g. clay is generally more resistant to erosion than sand).
Hydraulic action, most generally, is the ability of moving water (flowing or waves) to dislodge and transport rock particles.This includes a number of specific erosional processes, including abrasion, at facilitated erosion, such as static erosion where water leaches salts and floats off organic material from unconsolidated sediments, and from chemical erosion more often called chemical ...