Magnitude-Frequency Relationship in Geoscience
The magnitude and frequency relationships are important to geosciences because they are used in studying catastrophic events. They evaluate the relative amounts of work done on the landscapes over the long-term by events of all magnitudes. Geologists also conclude that large parts of sediment transportation are performed by events of moderate magnitude that recur relatively frequently rather than rare events of unusual magnitude. In this regard, gravity is the bus that drives sediments of the sea, sediment transports in streams.
The nature of the movement of sediments by water or air is dependent upon magnitude and frequency. On implications of geomorphic effectiveness on the formation of rivers and channels, erosion process is driven by gravitational force acting on water drives water downslope in a confined channel, where the water surface represents the balance between the energy gradient and friction resistance from channel beds and banks. Magnitude and gravity bring about shear and flow products of water depth. Here, when water levels exceed the bankfull stage, water flows out on the floodplain and increases water flow.
The effectiveness of processes on the formation of river channels depends on their distribution in time and their magnitude. For example, the major portion of work performed by events of moderate magnitude recur relatively frequently than by rare events of unusual magnitude. Magnitude/frequency analysis effectiveness has been demonstrated throughout geomorphology.
Effectiveness in terms of supply and transport of materials by the geomorphic process, sediment transportation by rivers operate relatively frequently and are low threshold process. Channel modification by erosion and disposition is also a result of the magnitude frequency relationship since their relationship transport materials in/out of the catchment. In terms of channel distribution, higher peak discharge and flow durations above a given threshold level may cause channel alterations.