Multimodel climate change projections of temperature for evapotranspiration scenarios and potential impact on the cropping system in Jamuna Command Area, Assam, Northeast India

Abstract North East India has a high potential for agricultural productivity, which is very vulnerable to climatic changes. Further limited surface water irrigation leads to rice-fallow mostly. Therefore, evapotranspiration (ET) assessment is essential for multiple cropping and annual irrigation management in the Jamuna command area (JCA). This work aims to describe the variability of potential evapotranspiration (PET) and irrigation needs at a basin level under changing climate. Multilinear Regression (MLR) model and predictors from 3 General Circulation Model (GCM) models of Coupled Model Intercomparison Project 5 (CMIP5) are used to examine the projected changes in mean monthly air temperature of JCA. Temperature-based best ET model after comparison was used for ET projections. Representative Concentration Pathway (RCP) scenarios 4.5 and 8.5 are used from 2025 to 2100. The results showed that the NSC and CC range was 0.88–0.94 and 0.94– 0.97 respectively. For the error indices − 0.02–0.35 and 0.24–0.35 for PBIAS and RSR, respectively. The results of the future trend analysis showed a significant climate change impact on temperature anomaly during future periods. Temperature change is projected to decrease in the forthcoming and then gradually increase upto 1.4°C in the distant future for RCP 8.5. The kharif crop evapotranspiration increased at the end of 21st centuary to 0.25% and 1.18% for RCP 4.5 and RCP 8.5 respectively. The rabi crop evapotranpiration increased by about 1% and 2.5% under RCP 4.5 and 8.5 scenarios, respectively. The zaid crop evapotranspiration increased approximately 1.3% and 2.4% under RCP 4.5, and 8.5, respectively.