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| Titel |
Determining spatial variability of dry spells: a Markov-based method, applied to the Makanya catchment, Tanzania |
| VerfasserIn |
B. M. C. Fischer, M. L. Mul, H. H. G. Savenije |
| 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 ; 17, no. 6 ; Nr. 17, no. 6 (2013-06-07), S.2161-2170 |
| Datensatznummer |
250018896
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| Publikation (Nr.) |
 copernicus.org/hess-17-2161-2013.pdf |
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| Zusammenfassung |
With a growing world population and a trend towards more resource-intensive
diets, pressure on land and water resources for food production will
continue to increase in the coming decades. Large parts of the world rely on
rainfed agriculture for their food security. In Africa, 90% of the food
production is from rainfed agriculture, generally with low yields and a high
risk of crop failure. One of the main reasons for crop failure is the
occurrence of dry spells during the growing season. Key indicators are the
critical dry spell duration and the probability of dry spell occurrence.
In this paper a new Markov-based framework is presented to spatially map the
length of dry spells for fixed probabilities of non-exceedance. The
framework makes use of spatially varying Markov coefficients that are
correlated to readily available spatial information such as elevation and
distance to the sea. The dry spell map thus obtained is compared to the
spatially variable critical dry spell duration, based on soil properties and
crop water requirements, to assess the probability of crop failure in
different locations.
The results show that in the Makanya catchment the length of dry spell
occurrence is highly variable in space, even over relatively short
distances. In certain areas the probability of crop failure reaches levels
that make rainfed agricultural unsustainable, even close to areas where
currently rainfed agriculture is successfully being practised.
This method can be used to identify regions that are vulnerable to dry
spells and, subsequently, to develop strategies for supplementary irrigation
or rainwater harvesting. |
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