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| Titel |
Retrospective drought analysis over Germany during the last 60 yrs |
| VerfasserIn |
Luis Samaniego, Rohini Kumar, Matthias Zink, Sabine Attinger |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250048910
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| Zusammenfassung |
| Droughts are among the most costly natural disasters because they impact heavily on the
economy of a region as well as on its social and cultural activities. Ultimately they may also
lead to unprecedented environmental disasters that contribute to a further decline of
the already precarious conditions. In the past, droughts have been associated with
the turning points and the decline of human societies. Droughts do not only occur
in arid or semiarid regions but also in humid ones. The year 2007, for example,
was the sunniest, hottest and driest in Germany in the last two centuries. In this
case, it was too dry too early. As a result, the harvest was cut by half leading to
enormous losses in the primary sector. Consumer prices of some agricultural products
went up 26 percent. The hydro-meteorologic mechanisms originating droughts
are relatively well understood. It is difficult, however to predict their occurrence.
Consequently, the development of improved prediction methods is key for implementing
adaptation strategies. Droughts have been classified as meteorological, agricultural,
and hydrological, depending on whether they deal with shortages of water in the
atmosphere, in the soil, or in the streams, respectively. To characterize these kinds of
droughts, a number of indices have been proposed, for instance, the standardized
precipitation (SPI), soil moisture (SSMI), and runoff (SRI) indices, which can be estimated
for 1, 3, 6, and 12 month accumulation periods. The purpose of this study is to
identify the major drought events in Germany since 1950 based on their severity,
duration and areal extend. To achieve this goal, a 60-yr retrospective hydrological
simulation of the land surface water budget over Germany was carried out with
the process based distributed hydrological model mHM (Samaniego et al. 2010,
WRR) forced with grided daily precipitation and temperature data at 4Ã4Â km. Point
measurement data from more than 5600 rain gauges and about 1120 meteorological stations
(German Meteorological Service) were interpolated with external drift Kriging to
produce highly consistent fields of meteorological variables. Land cover change
was also considered during this period. Principal component analysis using these
three drought indices was used to identify homogeneous climatic regions whereas
canonical correlation analysis has been employed to identify extreme events and their
relationship with macro-circulation patterns and other potential predictors. The high
spatial and temporal resolution of the mHM simulations ensured that the drought
indices take into account the short-term changes in the meteorological variables as
well as the long-term effects of the climatic variations. Processes such as snow
accumulation and melting as well as infiltration in partially frozen ground were also
considered. These considerations alone make this study more reliable than standard
approaches. |
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