Accumulated Basin Storage (ABS) is a parameter that reflects average soil moisture conditions in a drainage basin. It can be determined by sequentially adding precipitation to and subtracting runoff and evaporation from the total storage in the basin. The method of calculating the ABS is presented for the Assiniboine River upstream of the City of Brandon. The ABS is shown to be a useful indicator of agricultural drought in the region investigated. Compared with other hydrologic parameters it showed the highest correlation with crop yield data for the period 1914#x2013;1974. The parameter can be used in assessing the probability of drought at the beginning of a new growing season. The parameter can also be used in a statistical analysis of the frequency of occurrence of droughts since it allows a rational definition of the severity of droughts in terms of intensity, duration, or time-averaged magnitude.
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