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| Titel |
Hydrological change in the Mekong river - flood trends and variability |
| VerfasserIn |
J. Delgado, B. Merz, H. Apel |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250028423
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| Zusammenfassung |
| Daily average discharge is analyzed in the Mekong river in South
East Asia, focusing on tendencies and variability of floods in the 20th
century, in an effort to separate unfounded perceptions and empirical
evidence. After using trend detection methods usually suggested in
literature, other less common approaches to trend analysis were used,
namely non-stationary general extreme value (GEV) function and the
wavelet power spectrum.
Data from four gaging stations downstream of Vientiane, Laos, were
used, covering two distinct hydrological regions within the basin. These
time series span for over 80 years and are the longest daily discharge
time series available in the region.
Results from commonly used techniques like Mann-Kendal test and
a resampling of linear regression were contradictory and did not show
a clear signal. The introduction of the non-stationary GEV allowed to
isolate variability from the average trend and to have a more complete
view of the changes. Variability could also be translated into significant
amplitude changes in a wavelet power spectrum, which confirmed the
results of the non-stationary GEV. Overall, results showed increasing
likelihood of extreme floods and variability with time, although the
mean flood tends to decrease in magnitude.
We conclude that the initial absence of clear signals in the hydro-
logical time series was a methodological misconception due to over-
simplistic models. More adaptive methods, as well as increasingly
non-linear hypothesis yield more coherent results. |
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