Assessment of impact of Hysteresis phenomenon on Magnitude-Frequency
Analysis for Godavari River basin, India
Abstract
The transport effectiveness of a stream flow event of a certain
magnitude in carrying a sediment load is defined as the product of the
effect of that event and the frequency with which it occurs. This
approach is famously known as Magnitude-Frequency Analysis (MFA). MFA
has been commonly used to calculate “effective discharge” which is
considered as the stream flow that is responsible for transportation of
the majority of the sediments from a river basin over a long period of
time. In MFA, the stream flow at a location is assumed to follow a
continuous probability distribution whereas the sediment transport is
described by a rating curve between stream flow and sediment load.
Despite the apparent good fit to the data, there are problems using a
rating curve to predict sediment load. The sediment load carried through
a stream network can be affected by the variability in stream flow
occurring during different months or seasons (i.e. time scales) and
consequent hysteresis phenomenon. Prediction of sediment load can be
improved by constructing separate rating curves for various time scales.
In this study, daily stream flow was assumed to follow the log normal
distribution, and rating curves (between stream flow and sediment load)
have been developed for total, monsoon, individual months data and
considering hysteresis phenomenon for total and monsoon data in
transport of sediments. Finally, MFA based effective discharges were
calculated at 16 stream gauges in the Godavari River basin, India. The
results of this study can find use in the effective planning and
functioning of dams/reservoirs.