Redefining Irrigation Potential-An Exercise in Clay Modelling

Redefining Irrigation Potential An Exercise in Clay Modelling S M Vidwans IN their paper, 'Redefining Gujarat's Irrigation Potential' (EPW, June 26, 1993), D H Parikh, A J Vora, and Y K Alagh (PVA for short hereafter) rush to do several things at one go. They claim to establish "a complete statistical model'' relating rainfall with the frequency with which the reservoir of a dam fills up to half its full capacity or less. With it, they further claim to ''prove... that major and medium irrigation potential... is determined by the variation of rainfall in the command (sic)" (emphasis added). They deduce from this that the estimates of irrigation potential in Gujarat should be 'seriously' down-rated and ask the reader to note that their paper is also a powerful argument for inter-basin transfer of water or regional grids. Finally, they pronounce that the case for SSP is strong. As a side-swipe, they call irrigation engineers "technical problem solvers" who are "not very concerned with irrigation statistics". One is indeed likely to be swept away by this effusion of confidence inspired by just a two-variable regression equation with a puny enough R2.