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| Titel |
Comparison of gliding box and box-counting methods in river network analysis |
| VerfasserIn |
A. Saa, G. Gascó, J. B. Grau, J. M. Antón, A. M. Tarquis |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1023-5809
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| Digitales Dokument |
URL |
| Erschienen |
In: Nonlinear Processes in Geophysics ; 14, no. 5 ; Nr. 14, no. 5 (2007-09-12), S.603-613 |
| Datensatznummer |
250012276
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| Publikation (Nr.) |
 copernicus.org/npg-14-603-2007.pdf |
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| Zusammenfassung |
We use multifractal analysis to estimate the Rényi dimensions of river
basins by two different partition methods. These methods differ in the way
that the Euclidian plane support of the measure is covered, partitioning it by
using mutually exclusive boxes or by gliding a box over the plane.
Images of two different drainage basins, for the Ebro and Tajo rivers,
located in Spain, were digitalized with a resolution of 0.5 km, giving image
sizes of 617×1059 pixels and 515×1059, respectively. Box sizes were chosen as
powers of 2, ranging from 2×4 pixels to 512×1024 pixels located within the
image, with the purpose of covering the entire network. The resulting
measures were plotted versus the logarithmic value of the box area instead of
the box size length.
Multifractal Analysis (MFA) using a box counting algorithm was carried out
according to the method of moments ranging from −5<q<5, and the
Rényi dimensions were calculated from the log/log slope of the
probability distribution for the respective moments over the box area. An
optimal interval of box sizes was determined by estimating the
characteristic length of the river networks and by taking the next higher power
of 2 as the smallest box size. The optimized box size for both river
networks ranges from 64×128 to 512×1024 pixels and illustrates the
multiscaling behaviour of the Ebro and Tajo. By restricting the multifractal
analysis to the box size range, good generalized dimension (Dq) spectra were
obtained but with very few points and with a low number of boxes for each
size due to image size restrictions. The gliding box method was applied to
the same box size range, providing more consistent and representative Dq values.
The numerical differences between the results, as well as the
standard error values, are discussed. |
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