Adapting to Monsoon Variability in India: the Case for Irrigation

How will future changes in precipitation affect irrigation demand and supply in India? This paper provides econometric evidence for the demand side of the analysis by examining the relationship between monsoon changes and irrigation variability for one of the world’s most water stressed countries, India. Using detailed crop-wise agriculture and weather data spanning 35 years, the econometric model isolates the historical impact of the distribution and total supply of monsoon precipitation on irrigation demand via the use of irrigated area for crops grown in the dry(Rabi) and wet(Kharif) seasons. We find differential impacts of the monsoon by crop, by season and by source of irrigation. In general, for crops grown in the wet season, irrigation is sensitive to both distribution and total monsoon rainfall but not to ground or surface water availability. For crops grown in the dry season, total monsoon rainfall matters most, and its effect is sensitive to groundwater availability. Over the historic period of analysis, the effect of the monsoon on irrigation has remained relatively stable. The econometric analysis, when combined with a process based hydrology model that accounts for the supply side response of water availability, can help quantify the (un)sustainable water use trajectory that different regions within India will face.