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The effects of extremes and temporal scale on multifractal properties of river flow time series
Author(s) -
Hekmatzadeh Ali Akbar,
Torabi Haghighi Ali,
Hosseini Guyomi Kianoosh,
Amiri Seyed Mehrab,
Kløve Bjørn
Publication year - 2020
Publication title -
river research and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.679
H-Index - 94
eISSN - 1535-1467
pISSN - 1535-1459
DOI - 10.1002/rra.3550
Subject(s) - multifractal system , series (stratigraphy) , streamflow , environmental science , scale (ratio) , scaling , time series , discharge , temporal scales , climatology , meteorology , mathematics , statistics , geology , drainage basin , geography , fractal , ecology , cartography , mathematical analysis , paleontology , geometry , biology
For accurate forecasting of extreme events in rivers, streamflow time series with sub‐daily temporal resolution (1–6 hour) are preferable, but discharge time series for long rivers are usually available at daily or monthly resolution. In this study, the scaling properties of hourly and daily streamflow time series were measured. As an innovation, the effects of extreme values on the multifractal behavior of these series were evaluated. Interestingly, both hourly and daily discharge records led to nearly identical scaling trends and identical crossover times. Daily and hourly discharge time series appeared to be non‐stationary when the timescale ranged from 75 to 366 days. Otherwise, the signals may be considered stationary time series. In addition, the results indicated that the extreme values strongly contribute to the multifractality of the series. The width of singularity spectra decreased considerably when the extreme events were removed from both hourly and daily discharge records.