Predicting the Water Requirement for Rice Production as Affected by Projected Climate Change in Bihar, India

Abstract

Climate change is a well-known phenomenon all over the globe. The influence of projected climate change on agricultural production, either positive or negative, can be assessed for various locations. The present study was conducted to investigate the impact of projected climate change on rice’s production, water demand and phenology for the state of Bihar, India. Furthermore, this study assessed the irrigation water requirement to increase the rice production by 60%, for the existing current climate scenario and all the four IPCC climate change scenarios (RCP 2.6, RCP 4.5, RCP 6.0 and RCP 8.5) by the 2050s (2050–2059). Various management practices were used as adaptation methods to analyze the requirement of irrigation water for a 60% increase in rice production. The climate data obtained from the four General Circulation Models (GCMs) (bcc_csm1.1, csiro_mk3_6_0, ipsl_cm5a_mr and miroc_miroc5) were used in the crop growth model, with the Decision Support System for Agrotechnology Transfer (DSSAT) used to simulate the rice yield, phenological days and water demand under all four climate change scenarios. The results obtained from the CERES-Rice model in the DSSAT, corresponding to all four GCMs, were ensembled together to obtain the overall change in yield, phenology and water demand for the 10 years from 2020 to 2059. We investigated several strategies: increasing the rice yield by 60% with current agronomic practice; increasing the yield by 60% with conservation agricultural practice; and increasing the rice yield by 30% with current agronomic practice as well as with conservation agricultural practices (assuming that the other 30% increase in yield would be achieved by reducing post-harvest losses by 30%). The average increase in precipitation between 2020 and 2059 was observed to be 5.23%, 13.96%, 9.30% and 9.29%, respectively, for RCP 2.6, RCP 4.5, RCP 6.0 and RCP 8.5. The decrease in yield during the 2050s, from the baseline period (1980–2004), was observed to be 2.94%, 3.87%, 4.02% and 5.84% for RCP 2.6, RCP 4.5, RCP 6.0 and RCP 8.5, respectively. The irrigation requirement was predicted to increase by a range of 39% to 45% for a 60% increase in yield using the current agronomic practice in the current climate scenario by the 2050s, for all four climate change scenarios from the baseline period (1980–2004). We found that if we combine both conservation agriculture and removal of 30% of the post-harvest losses, the irrigation requirement would be reduced by 26% (45 to 19%), 20% (44 to 24%), 21% (43 to 22%), 22% (39 to 17%) and 20% (41 to 21%) with the current climate scenarios, namely, the RCP 2.6, RCP 4.5, RCP 6.0 and RCP 8.5 conditions, respectively. This combination of conservation practices suggests that the irrigation water requirement can be reduced by a large percentage, even if we produce 60% more food under the projected climate change conditions.

Assessment of Climatic Parameters for Future Climate Change in a Major Agricultural State in India

“…The results obtained in this study suggest variability in climatic factors will affect the agricultural production and water requirements for those productions [12,18]. Variability in rainfall may cause flooding conditions, as currently, this situation also exists in major agricultural states in India, while change in temperature will lead to affect the crop production by altering the phenological days [33,34].…”

“…The flow chart of obtaining climate data is illustrated in Figure 2. This has been described in detail by Jha et al [12].…”

“…Further, the ensemble mean of all the four climate models were used to illustrate overall projected change. The projected climate change for each of the scenarios was estimated on a monthly basis for the 10 years of the interval using Equation (12). The average of monthly estimation for 10 years of the future segment was subtracted from the average of the baseline period , provided the expected future change in a particular climatic variable.…”

“…With an ever-increasing global population, the demand for increasing food production has increased substantially [11]. However, the patterns of change in climatic variables pose challenges in not only increasing crop production level, but even maintaining the current yield levels [12][13][14]. The problem intensifies for regions where majority of the people depend on agriculture, and climate change has already disrupted current agricultural production practices [15,16].…”

“…Our study focused on the State of Bihar in India, where the livelihoods of more than 80% of people rely on agriculture. The future climate will govern crop production, and thereby, livelihood of its people [12]. Recent frequent droughts, flooding, crop damage, and uncertainties in precipitation amount and timing have posed significant challenges in sustainability of the farming system in Bihar [18].…”