Is the rain in India on the wane? Biometeorological consideration

Abstract

The trends in the total and seasonal rainfall and rainy days of 13 stations analysed by means of the 20-year running mean reveal no out and out decreasing tendency. Slight importance is to be attached to the decline in the statistically dry season of little value to agriculture. The waning tendency reported earlier for Ranchi plateau since 1920 following deforestation is not substantiated. As for the accentuation of aridity in NW India since 1960 that has been suggested earlier, the conclusion was based on the combined precipitation data of several arid Afrasian stations having mediterranean and tropical regimes. 20-year moving mean of combined rainfall of 5 stations in and around Indian tropical desert as well vegetational data do not support this view. Opinion is expressed in recent years that the rainfall in India and Africa is declining steadily in the last decades (Warren, 1974; Winstanley, 1973). The present paper aims to examine critically how far this notion is true for India from the view point of a bioclimatologist.