Possibilities and limitations of rainfall analysis for predicting crop-available water (uncertainties in the length of the rainy season)
1988
Robertson, G.W.
Monthly climatological data were used to determine general rainfall characteristics and to perform a simple water budget calculation. Weaknesses in the analysis were considered and a simple falling-rate soil water budget, using daily rainfall data, was used to improve the calculation of daily soil water from long-term records. These daily data were then used to calculate the probability of days with wet and dry soil, and runs of consecutive days with wet soil from which the beginning, duration, and ending of the rainy season could be calculated at various probability levels. This simple budget involves a number of assumptions and estimated parameters. Variations in these were used to evaluate uncertainities in the final agroclimatic product, such as length of the rainy season. It is proposed that complex models depending upon many assumptions and estimated parameters may be subject to too many uncertainities to be widely applicable in estimating agroclimatic factors. Further sensitivity research and testing of such models is required.
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