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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 .
By 1956 Åke Sundborg had greatly improved the Hjulström curve diagram adding lines and a higher level of detail. [3] Subsequently, he was employed by the Uppsala University where he directed the construction of the geomorphological laboratory. Over time this laboratory attracted numerous visiting scholars and Ph.D. students. [1]
The logarithmic Hjulström curve. In 1935, Filip Hjulström created the Hjulström curve, a graph which shows the relationship between the size of sediment and the velocity required to erode (lift it), transport it, or deposit it. [23] The graph is logarithmic.
Eventually the velocity will fall low enough for the grains to be deposited. This is shown by the Hjulström curve. A river is continually picking up and dropping solid particles of rock and soil from its bed throughout its length. Where the river flow is fast, more particles are picked up than dropped.
Filip Hjulström's doctoral thesis, "The River Fyris", contained one of the first quantitative studies of geomorphological processes ever published. It was a study of sediment transport and soil erosion in the drainage area of the river Fyrisån, based on a daily water sample that he took as he passed on the way to the department, and analyzed ...
Another important property comes into play when discussing stream competency, and that is the intrinsic quality of the material. In 1935 Filip Hjulström published his curve, which takes into account the cohesiveness of clay and some silt. This diagram illustrates stream competency as a function of velocity. [12]
Hjulström diagram. Suspended load is often visualised using two diagrams. The Hjulström curve uses velocity and sediment size to compare the rate of erosion, transportation, and deposition. While the diagram shows the rate, one flaw about the Hjulström Diagram is that it doesn't show the depth of the creek giving an estimated rate.
A wide variety of river and stream channel types exist in limnology, the study of inland waters.All these can be divided into two groups by using the water-flow gradient as either low gradient channels for streams or rivers with less than two percent (2%) flow gradient, or high gradient channels for those with greater than a 2% gradient.