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| Titel |
Impacts of high inter-annual variability of rainfall on a century of extreme hydrologic regime of northwest Australia |
| VerfasserIn |
A. Rouillard, G. Skrzypek, S. Dogramaci, C. Turney, P. F. Grierson |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 19, no. 4 ; Nr. 19, no. 4 (2015-04-29), S.2057-2078 |
| Datensatznummer |
250120698
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| Publikation (Nr.) |
 copernicus.org/hess-19-2057-2015.pdf |
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| Zusammenfassung |
| Long-term hydrologic records provide crucial reference baselines of
natural variability that can be used to evaluate potential changes in
hydrologic regimes and their impacts. However, there is a dearth of
studies of the hydrologic regimes for tropical drylands where
intraseasonal and interannual variability in magnitude and frequency of
precipitation are extreme. Here, we sought to identify the main
hydroclimatic determinants of the strongly episodic flood regime of a large
catchment in the semi-arid, subtropical northwest of Australia and to
establish the background of hydrologic variability for the region over the
last century. We used a monthly sequence of satellite images to quantify
surface water expression on the Fortescue Marsh, the largest water feature
of inland northwest Australia, from 1988 to 2012. We used this sequence
together with instrumental rainfall data to build a statistical model with
multiple linear regression and reconstruct monthly history of floods and
droughts since 1912. We found that severe and intense regional rainfall
events, as well as the sequence of recharge events both within and between
years, determine surface water expression on the floodplain (i.e. total
rainfall, number of rain days and carried-over inundated area;
R2adj = 0.79; p value < 0.001, ERMSP = 56 km2).
The most severe reconstructed inundation over the last century was in March
2000 (1000 km2), which is less than the 1300 km2 area required to
overflow to the adjacent catchment. The Fortescue Marsh was completely dry
for 32% of all years, for periods of up to four consecutive years.
Extremely wet years (seven of the 100 years) caused the Marsh to remain
inundated for up to 12 months; only 25% of years (9% of all months)
had floods of greater than 300 km2. The prolonged, severe and
consecutive yearly inundations between 1999 and 2006 were unprecedented
compared to the last century. While there is high inter-annual variability
in the system, if the frequency and intensity of extreme rainfall events for
the region were to increase (or be similar to 1999–2006), surface water on
the Marsh will become more persistent, in turn impacting its structure and
functioning as a wetland. |
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