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| Titel |
Exploring the link between drought indicators and impacts |
| VerfasserIn |
S. Bachmair, I. Kohn, K. Stahl |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1561-8633
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| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Sciences ; 15, no. 6 ; Nr. 15, no. 6 (2015-06-30), S.1381-1397 |
| Datensatznummer |
250119544
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| Publikation (Nr.) |
 copernicus.org/nhess-15-1381-2015.pdf |
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| Zusammenfassung |
| Current drought monitoring and early warning systems use different
indicators for monitoring drought conditions and apply different indicator
thresholds and rules for assigning drought intensity classes or issue
warnings or alerts. Nevertheless, there is little knowledge on the meaning
of different hydro-meteorologic indicators for impact occurrence on the
ground. To date, there have been very few attempts to systematically
characterize the indicator–impact relationship owing to sparse and patchy
data on drought impacts. The newly established European Drought Impact
report Inventory (EDII) offers the possibility to investigate this linkage.
The aim of this study was to explore the link between hydro-meteorologic
indicators and drought impacts for the case study area Germany and thus to
test the potential of qualitative impact data for evaluating the performance
of drought indicators. As drought indicators two climatological drought
indices – the Standardized Precipitation Index (SPI) and the Standardized
Precipitation Evapotranspiration Index (SPEI) – as well as streamflow and
groundwater level percentiles were selected. Linkage was assessed though
data visualization, extraction of indicator values concurrent with impact
onset, and correlation analysis between monthly time series of indicator and
impact data at the federal state level, and between spatial patterns for
selected drought events. The analysis clearly revealed a significant
moderate to strong correlation for some states and drought events allowing
for an intercomparison of the performance of different drought indicators.
Important findings were strongest correlation for intermediate accumulation
periods of SPI and SPEI, a slightly better performance of SPEI versus SPI, and a similar
performance of streamflow percentiles to SPI in many cases. Apart from these
commonalities, the analysis also exposed differences among federal states
and drought events, suggesting that the linkage is time variant and region
specific to some degree. Concerning "thresholds" for drought impact onset,
i.e. indicator values concurrent with past impact onsets, we found that no
single "best" threshold value can be identified but impacts occur within a
range of indicator values. Nevertheless, the median of the threshold
distributions showed differences between northern/northeastern versus
southern/southwestern federal states, and among drought events. While the
findings strongly depend on data and may change with a growing number of
EDII entries in the future, this study clearly demonstrates the feasibility
of evaluating hydro-meteorologic variables with text-based impact reports
and highlights the value of impact reporting as a tool for monitoring
drought conditions. |
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