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| Titel |
Identification and simulation of space–time variability of past hydrological drought events in the Limpopo River basin, southern Africa |
| VerfasserIn |
P. Trambauer, S. Maskey, M. Werner, F. Pappenberger, L. P. H. Van Beek, S. Uhlenbrook |
| 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 ; 18, no. 8 ; Nr. 18, no. 8 (2014-08-07), S.2925-2942 |
| Datensatznummer |
250120429
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| Publikation (Nr.) |
 copernicus.org/hess-18-2925-2014.pdf |
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| Zusammenfassung |
| Droughts are widespread natural hazards and in many regions their frequency
seems to be increasing. A finer-resolution version (0.05° × 0.05°) of the continental-scale hydrological model
PCRaster Global Water Balance (PCR-GLOBWB)
was set up for the Limpopo River basin, one of the most water-stressed
basins on the African continent. An irrigation module was included to
account for large irrigated areas of the basin. The finer resolution model
was used to analyse hydrological droughts in the Limpopo River basin in the
period 1979–2010 with a view to identifying severe droughts that have
occurred in the basin. Evaporation, soil moisture, groundwater storage and
runoff estimates from the model were derived at a spatial resolution of
0.05° (approximately 5 km) on a daily timescale for the entire
basin. PCR-GLOBWB was forced with daily precipitation and temperature
obtained from the ERA-Interim global atmospheric reanalysis product from the
European Centre for Medium-Range Weather Forecasts. Two agricultural drought
indicators were computed: the Evapotranspiration Deficit Index (ETDI) and
the Root Stress Anomaly Index (RSAI). Hydrological drought was characterised
using the Standardized Runoff Index (SRI) and the Groundwater Resource Index
(GRI), which make use of the streamflow and groundwater storage resulting
from the model. Other more widely used meteorological drought indicators,
such as the Standardized Precipitation Index (SPI) and the Standardized
Precipitation Evaporation Index (SPEI), were also computed for different
aggregation periods. Results show that a carefully set-up, process-based
model that makes use of the best available input data can identify
hydrological droughts even if the model is largely uncalibrated. The
indicators considered are able to represent the most severe droughts in the
basin and to some extent identify the spatial variability of droughts.
Moreover, results show the importance of computing indicators that can be related
to hydrological droughts, and how these add value to the identification of
hydrological droughts and floods and the temporal evolution of events that would
otherwise not have been apparent when considering only meteorological
indicators. In some cases, meteorological indicators alone
fail to capture the severity of the hydrological drought. Therefore, a
combination of some of these indicators (e.g. SPEI-3, SRI-6 and SPI-12 computed
together) is found to be a useful measure for identifying agricultural
to long-term hydrological droughts in the Limpopo River basin. Additionally,
it was possible to undertake a characterisation of the drought severity in the
basin, indicated by its time of occurrence, duration and intensity. |
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