Assessing Drought Scenario in the Vidarbha Region,India

Abstract

An attempt has been made in this study to assess drought scenario in the Vidarbha region utilizing long period (1901–1996) monsoon rainfall (June-September) data of the region. The analysis reveals that in Vidarbha drought may occur once in every six years. The probability of its occurrence for the two consecutive years is hardly 2% while that for the three consecutive years does not exist at all. During the drought years the region receives average seasonal rainfall of 64.8 cm, 30% less than the normal rainfall, while rainfall in the years prior to and succeeding the drought years is found to be 5–7% more than the normal rainfall. August is found to be the most dependable month during drought years associated with El nino as well as Enso, while September happens to be the worst month with −50% rainfall departure during the drought years associated with El nino. In good monsoon years, in spite of El nino, June happens to be the worst month with a rainfall departure of −27%. Despite reasonably high inter-annual variability, monsoon rainfall over the region has periodicities ranging from 6 to 24 years. Of great interest are the oscillations, which approximately are analogous to double sunspot cycle. Planners/farmers are interested to know the prospects of seasonal rainfall as the monsoon advances, particularly so during the initial period of the monsoon season. Study on this aspect reveals that when June rainfall is below normal there are 37% chances that the season too will receive below normal rainfall; this probability increases to 50% if cumulative rainfall till July end is below normal. Cumulative rainfall till August end generally foretells the possible seasonal rainfall pattern over the region.