Climate Change Impact On Blue Water Footprint Of Kharif Rice Production At Farm-Level: A Case Study in India

Despite the substantial production, rice productivity is affected by ongoing climate change and reduction of available water resources. Thus, assessing the responses of rice consumption and productivity to more pronounced climate change is of great significance to water resources management in terms of relieving the resources shortage and meeting the food demand. In this case study, based on farm level survey of a rice field in Odisha, India, the temporal change of the blue water footprint of two locally grown varieties of kharif rice has been discussed for the near future period upto 2050 under RCP scenarios 4.5 and 8.5. The yield and water resources utilization has been evaluated using calibrated and validated DSSAT crop simulation model. Results revealed that the total WF will increase upto 71.8% and 80.7% respectively, for the two cultivars. Moreover, compared to the green water footprint, the blue water footprint is projected to significantly increase (around 250450%) in future; rising minimum temperature (about 1.7 °C) and maximum temperature (about 1.5 °C) and declining precipitation during the rice growing period being the main causes. Although the amount of rainfall during rainfed rice season is expected to be higher under both scenarios, the average future monthly rainfall is expected to increase in July and August, but decrease in September and October under both scenarios. Decreasing future rainfall during the reproductive phase of rice growth (September to October) can have a significant influence on the rice yield. Furthermore, the rice yield is projected to continually decline in the future (2050) with respect to baseline (1980-2015) as much as 18.8% and 20% under RCP 4.5 and 8.5 scenarios, respectively. The green-blue WF of crops appeared contradictory to climatic conditions, indicating that high annual rainfall does not necessarily make a region better in terms of blue water saving. This study also found that farm-survey based environmental assessments for crop production can better capture the existing management practices among farmers, and provide accurate inputs for effective policy formulation.