Summary
Irregular droughts are the main reason for serious yield reductions in tropical agriculture, with sometimes very serious consequences. These “agricultural droughts” are defined and delimited in relation to normal rainfall conditions, to which traditional agricultural production systems are fully adapted. Examples from East Africa and Malaysia, tropical areas which differ climatically and in the availability of climatic data, illustrate that it is necessary to use different statistical methods to estimate the probability of agricultural droughts.
Short droughts, often concealed by monthly rainfall figures, can have serious effects, particularly on annual crops with their short root systems. A simple water balance model, based on daily rainfall data, is used to estimate the probability of these dry periods. The same model can be used to predict periods of surplus rainfall, when soils are saturated. These periods can cause severe reduction in agricultural yields.
Zusammenfassung
Unregelmäßig auftretende Trockenperioden sind die Hauptursache von Produktionsverlusten in der tropischen Landwirtschaft, die katastrophale Folgen haben können. Diese „landwirtschaftlichen Trockenperioden“ werden in bezug auf die normalen Niederschlagsverhältnisse definiert und begrenzt, an die die traditionellen tropischen Landwirtschaftssysteme vollständig angepaßt sind. Beispiele aus Ostafrika und Malaysien zeigen, wie die statistischen Methoden zur Ermittlung der Wahrscheinlichkeit landwirtschaftlicher Trockenperioden an die Klimaverhältnisse sowie an die Verfügbarkeit von Klimadaten angepaßt werden müssen.
Monatliche Niederschlagsziffern verbergen oft kurze Trockenperioden, die erhebliche Schäden verursachen können, besonders an einjährigen Pflanzen mit ihren kurzen Wurzelsystemen. Ein einfaches Wasserbilanzmodell, basierend auf Tagesziffern der Niederschläge, zeigt die Wahrscheinlichkeit solcher kurzen Trockenperioden an. Dasselbe Modell kann auch Perioden mit saturierten Böden vorhersagen. Diese können schädliche Folgen für die Ernteerträge haben.
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Nieuwolt, S. Agricultural droughts in the tropics. Theor Appl Climatol 37, 29–38 (1986). https://doi.org/10.1007/BF00866102
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DOI: https://doi.org/10.1007/BF00866102