Short-term rainfall forecasts as a soft adaptation to climate change in irrigation management in North-East India

We explored the potential of using short-term weather forecasts to increase irrigation efficiency in rice cultivation, as a potential adaptation option to future climate change. We used 5-day hypothetically perfect rainfall forecasts and 4-day real rainfall forecasts for 2007–2008 issued by the India Meteorological Department (IMD). The rainfall forecasts were incorporated into the agro-hydrological model SWAP (Soil Water Plant Atmosphere), to produce alternative irrigation schedules. The SWAP model was calibrated with data from field experiments at Kharagpur, North-East India. Rice yield simulations were performed for observed weather (1989–2009) and for a future climate with more dry spells and more intense rainfall events. The model revealed that basing the decision to irrigate rice on short-term weather forecasts could reduce average water application by 27% when 5-day perfect rainfall forecasts were used. Even though the real 4-day rainfall forecasts were not very accurate, their use also resulted in a reduction in irrigation water application. Using 5-day hypothetically perfect forecasts under future climate conditions led to a saving of 32% of irrigation water compared to water use under the current climate.